Chapter 12 DNA and RNA - Biology2Nash -...

Biology IIChapter 12 DNA and RNA

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Tabla de contenidoSummary...............................................................................................................................................2

Vocabulary Review...............................................................................................................................3

Genetic Material....................................................................................................................................4

Base Pairing...........................................................................................................................................4

12-1 DNA..............................................................................................................................................5

Workbook Section 12–1 DNA (pages 287–294)...................................................................................5

Section Review 12- 1.............................................................................................................................8

Enrichment -- Radioisotopes.................................................................................................................9

Section Assessment 12-2.....................................................................................................................10

Workbook Section 12–2 Chromosomes and DNA Replication (pages 295–299)................................10

Exploration Modeling DNA Replication.............................................................................................11

Section Review 12-1............................................................................................................................13

Transcription.......................................................................................................................................14

Decoding mRNA.................................................................................................................................15

Translation...........................................................................................................................................16


Workbook Section 12–3 RNA and Protein Synthesis (pages 300–306)...............................................18

Section Review 12-3............................................................................................................................20

Chromosomal Mutations.....................................................................................................................21


Workbook Section 12–4 Mutations (pages 307–308)..........................................................................22

Section Review 12-4 Reviewing Key Concepts.................................................................................23

Chapter Vocabulary Review.................................................................................................................25

Graphic Organizer Flowchart..............................................................................................................26

Vocabulary Review.............................................................................................................................27

Chapter 12 Assessment........................................................................................................................27


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Summary12–1 DNATo understand genetics, biologists had to learn the chemical structure of the gene. Frederick Griffith first learned that some factor from dead, disease-causing bacteria turned harmless bacteria into diseasecausing ones. Griffith called this transformation. Griffith thought that the transforming factor might be a gene. Oswald Avery and his research group later found that DNA was the transforming factor. Alfred Hershey and Martha Chase also showed that genes are made of DNA with their experiments with bacteriophages, viruses that infect bacteria.

Scientists began studying the structure of DNA to learn how it can carry information, determine an organism’s traits, and replicate itself. DNA is a long molecule made up of units called nucleotides. Each nucleotide is made up of a 5-carbon sugar, a phosphate group, and a nitrogen-containing base. There are four kinds of bases: adenine, guanine, cytosine, and thymine. James Watson and Francis Crick discovered that DNA is shaped like a double helix, or a twisted ladder, in which two strands are wound around each other. The two strands are held together by hydrogen bonds between adenine and thymine and between guanine and cytosine. The sugar phosphate backbone makes up the sides of the ladder. 12–2 Chromosomes and DNA ReplicationSingle-celled organisms without a nucleus have DNA in the cytoplasm. Most have one circular DNA molecule. In organisms with a nucleus, DNA is in the nucleus. The DNA is organized into different numbers of chromosomes, depending on the organism.

DNA molecules are very long. To fit inside cells, they must be tightly folded. The DNA in a chromosome is wound around proteins, called histones. The DNA and histones wind together to form nucleosomes. Nucleosomes pack together to form a thick fiber, which is further shortened in loops and coils.

Before a cell divides, it copies its DNA in a process called replication. The DNA molecule separates into two strands. Then two new strands form, following the rules of base pairing. Each strand of the DNA molecule serves as a template, or model, for the new strand

. Many enzymes carry out DNA replication. One enzyme, called DNA polymerase, joins individual nucleotides to produce the DNAmolecule. It also checks that the correct nucleotide is added.12–3 RNA and Protein SynthesisIn order for a gene to work, the genetic instructions in the DNA molecule must be decoded. The first step is to copy the DNA sequence into RNA. RNA makes it possible for a single gene in a DNA molecule to make hundreds of copies.

RNA has a structure like DNA, except for three differences. The sugar in RNA is ribose instead of deoxyribose. RNA is singlestranded. RNA has uracil in place of thymine.

Three kinds of RNA molecules work together to make proteins. Messenger RNA has the instructions to put together amino acids to make a protein. Proteins are put together on ribosomes. Ribosomes are made up of proteins and ribosomal RNA. Transfer RNA carries each amino acid to the ribosome according to the coded message in messenger RNA.

RNA is copied from DNA in a process called transcription. The enzyme RNA polymerase binds to DNA and separates the two strands. Then RNA polymerase builds a strand of RNA using one strand of DNA as the template. The sequence of DNA that signals RNA polymerase where to bind and start making RNA is called the promoter.

The instructions for making proteins are found in the order of the four nitrogenous bases. This code is read three letters, or nucleotides, at a time. Each codon, or group of three nucleotides, specifies a certain amino acid that makes up a protein. In the genetic code, some


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amino acids are specified by more than one codon. One codon is a start signal for translation. Three codons signal the end of a protein.

Translation is the process in which the genetic code in RNA is used to make proteins. Translation takes place on ribosomes. Before translation can begin, messenger RNA is transcribed from DNA. Then the messenger RNA moves into the cytoplasm and attaches to a ribosome. As each codon of the messenger RNA moves through the ribosome, the proper amino acid is brought into the ribosome by transfer RNA. The ribosome joins together each amino acid. In this way, the protein chain grows. When the ribosome reaches a stop codon, it falls away from the protein chain and the messenger RNA molecule. Transcription has ended. 12–4 MutationsMutations are changes in the sequence of DNA. Gene mutations are changes in a single gene. Chromosomal mutations cause changes in whole chromosomes. Gene mutations that occur at a single point in the DNA sequence are called point mutations. When a point mutation causes one base to replace another, only one amino acid is affected. If a nucleotide is added or taken away, it causes a frameshift mutation. All the groupings of three nucleotides, or codons, are changed. This can cause the gene to produce a completely different protein.

In a chromosomal mutation, there is a change in the number or the structure of chromosomes. There are four kinds of chromosomal mutations: deletions, duplications, inversions, and translocations.

Vocabulary ReviewMatching In the space provided, write the letter of the definition that best matches each term._____ 1. base pairing_____ 2. nucleotide_____ 3. histone_____ 4. transcription_____ 5. intron_____ 6. translation_____ 7. transfer RNA_____ 8. promoter_____ 9. mutation_____ 10. polyploidy_____ 11. operon_____ 12. Differentiationa. making a protein using messenger RNAb. having extra sets of chromosomes

c. hydrogen bonding between adenine and thymined. sequence in messenger RNA that is cut oute. cells specializing in structure and functionf. carries amino acids to the ribosome during protein synthesisg. unit of DNAh. copying part of DNA into RNAi. change in the genetic materialj. group of genes that work togetherk. DNAsequence that binds RNA polymerasel. protein that binds DNA into tight coils

Labeling Diagrams The diagrams below show the steps of DNA replication. Place the numbers 1 to 3 on the lines above the diagrams to show the order in which the steps occur.

13. ____________________ 14. ____________________ 15. ____________________


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Genetic MaterialThe Hershey-Chase experiment was designed to find out whether DNA or protein carried a virus’s genetic information. The scientists used radioactive substances to label the DNA in some viruses and the protein coat in other viruses. Then they let the viruses inject their genetic material into bacteria. Label the DNA with radioactive label, and the DNA without radioactive label.

What did Hershey and Chase conclude was the genetic material of the virus?DNA protein

Base PairingFour nucleotides make up DNA: adenine, cytosine, guanine, and thymine. These nucleotides always occur in pairs called base pairs. Write the missing letter to complete each base pair. The first two have been done for you.


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Use the diagram to answer the questions.1. What nucleotide is always paired with thymine? ______________________________

2. What nucleotide is always paired with guanine?____________________________

12-1 DNA1- List the conclusions Griffith, Avery, Hershey, and Chase drew from their experiments.____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________2- Describe Watson and Crick’s model of the DNA molecule.____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________3- What are the four kinds of bases found in DNA?___________________________________________________________________________4- Did Watson and Crick’s model account for the equal amount of thymine and adenine in DNA? Explain. _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________5- Why did Hershey and Chase grow viruses in cultures that contained both radioactive phosphorus and radioactive sulfur? What might have happened if they had used onle one radioactive substance? ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________


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Workbook Section 12–1 DNA (pages 287–294)This section tells about the experiments that helped scientists discover the relationship between genes and DNA. It also describes the chemical structure of the DNA molecule.Griffith and Transformation (pages 287–289)1. What did Frederick Griffith want to learn about bacteria? __________________________________________________________________________________________________2. The strain of bacteria that caused pneumonia grew into ________________ colonies on culture plates; harmless bacteria produced colonies with ________________ edges.3. Circle the letter of each sentence that is true about Griffith’s experiment.a. Mice injected with bacteria from smooth colonies died.b. Mice injected with bacteria from rough colonies died.c. Mice injected with heat-killed bacteria from smooth colonies died.d. Mice injected with a mixture of bacteria from heat-killed smooth colonies and live rough colonies died.4. What result from Griffith’s experiment suggested that the cause of pneumonia was not a chemical poison released by the disease-causing bacteria? __________________________________________________________________________________________________________________________________________________________________________________5. What is transformation? ________________________________________________________________________________________________________________________________6. What hypothesis did Griffith form from the results of his experiments? ______________________________________________________________________________________________________________________________________________________________________Avery and DNA (page 289)7. Is the following sentence true or false? Avery and his colleagues thought that the molecule required in transformation might also be the molecule of the gene. _________8. Briefly describe how Avery and his group determined which molecule was most important for transformation? _________________________________________________________________________________________________________________________________________________________________________________________________________________9. Transformation did not occur when _________________________ was destroyed.10. What was the conclusion from Avery’s experiments? ________________________________________________________________________________________________________The Hershey-Chase Experiment (pages 289–290)11. What is a bacteriophage? ______________________________________________________________________________________________________________________________12. Circle the letter of each part that makes up a bacteriophage.

a. lipid coat c. carbohydrate coreb. protein coat d. DNA core

13. What happens when a bacteriophage infects a bacterial cell? _____________________________________________________________________________________________________________________________________________________________________________


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14. How would Hershey and Chase learn whether genes were made of protein or DNA?_________________________________________________________________________________________________________________________________________________________________________________________________________________________________15. Circle the letter of the molecule for which phosphorus-32 (32P) is used as a radioactive marker.

a. protein b. lipid c. DNA d. carbohydrate16. Is the following sentence true or false? If 35S was found in the bacteria, it would mean that the viruses’ DNA had been injected into the bacteria. ____________________________17. What results did Hershey and Chase observe?______________________________________________________________________________________________________________18. Hershey and Chase concluded that the genetic material of the bacteriophage was _______________________.The Components and Structure of DNA (pages 291–294)19. List the three critical things that genes were known to do.a- ____________________________________b- ____________________________________c- ____________________________________

20. Adenine, guanine, cytosine, and thymine are four kinds of ___________ bases in DNA.21. Identify the components of a nucleotide in the diagram below. Label the bases as purines or pyrimidines.

22. Is the following sentence true or false? Adenine and guanine are larger molecules than cytosine and thymine because they have two rings in their structure. ___________23. What forms the backbone of a DNA chain? ______________________________________________________________________________________________________________24. Is the following sentence true or false? The nucleotides must be joined together in a specific order. ________________________25. According to Chargaff’s rules, the percentages of _______________ are equal to thymine and the percentages of _______________ are equal to guanine in the DNA molecule.26. Rosalind Franklin’s work with X-ray diffraction showed that the DNA molecule isshaped like a(an) __________________ and contains __________________ strands.


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27. How did Francis Crick and James Watson try to understand the structure of DNA?_________________________________________________________________________________________________________________________________________________________________________________________________________________________________28. How did Watson and Crick describe the structure of DNA?______________________________________________________________________________________________________________________________________________________________________________29. Is the following sentence true or false? According to the principle of base pairing,hydrogen bonds could form only between adenine and cytosine. ___________________

Section Review 12- 1Reviewing Key ConceptsMatching On the lines provided, match the letter of the scientist(s) with the description of his or their conclusions.

a. Griffith b. Avery c. Hershey and Chase___________ 1. concluded that the genetic material of a bacteriophage is DNA___________ 2. concluded that DNA was the factor that caused one bacterium to transform into another___________ 3. concluded that bacteria could be transformed from harmless to disease-causing by an unknown factorCompletion On the lines provided, complete the following sentences.4. The structure of a DNA molecule can be described as a(an) _____________________.5. The structure of DNA was discovered by __________________ and ________________.Interpreting Graphics On the lines corresponding to the numbers on the diagram, identify the following parts of the DNA molecule: hydrogen bonds, nucleotide, sugarphosphate backbone.

Reviewing Key Skills9. Using Analogies A double helix looks like a twisted ladder. Which parts of a twisted ladder are analogous to the hydrogen bonds and sugar-phosphate backbones of a double helix of DNA?


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____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

10. Calculating Use Chargaff’s rules to determine the approximate percentage of thymine in a DNA molecule, if 28% of the nucleotides in the molecule contain adenine.____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Enrichment -- RadioisotopesThe widespread use of radioactive isotopes in biology began just after World War II. Wartime research in nuclear physics had generated a stockpile of radioactive materials, and these materials were soon made available to scientists. Biologists quickly began using radioisotopes to construct tracers. Tracers are molecules that can be tracked while they are being used by living cells. Molecules containing radioisotopes make very effective tracers because they constantly send out bursts of radiation.

Biologists can track these bursts and follow the paths of the tracers as they move within the cell. The paths taken by the tracers can give biologists valuable information about the nature of the chemical reactions taking place in the cell.

Tracers are prepared by combining a radioisotope (such as phosphorus-32, carbon-14, or sulfur-35) with other nonradioactive atoms to form molecules that will be taken into cells. Because cells are unable to distinguish between radioactive and nonradioactive isotopes, they treat tracer molecules the same as nonradioactive molecules.

Once the tracers have entered the cell, scientists must have a way to monitor their movements. Biologists generally use two methods to do this. The first method is autoradiography. In autoradiography, tracers take pictures of themselves! Cells are exposed to tracer molecules and given time to incorporate the tracers into their chemical processes. Then, the labeled cells are covered by a type of photographic paper that is sensitive to radiation. The radioisotopes emit radiation that forms an image on the photographic paper. Biologists can then study these photographic images to determine the location of the radioisotopes.

The second common method of detecting radioactive tracers is called quantitative assay. An assay is an analysis of a substance to determine the nature of its components. In a quantitative assay, scientists allow cells to take in and use tracer molecules. Scientists then separate the cells into their component parts and test each group of components to determine where the tracer molecules are concentrated. This was the method Hershey and Chase used to determine whether the material transferred from bacteriophages to bacteria was DNA or protein.


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Evaluation Answer the following questions on a separate sheet of paper.1. What problems might result from using a tracer that contained a radioisotope that was either too strongly or too weakly radioactive?2. A scientist has been inserting a tracer molecule containing phosphorus-32 into a population of bacteria to see where they store phosphorus. Which method might the scientist use to monitor the movement of the tracers within the bacteria? Explain your answer.

Section Assessment 12-21- Explain how DNA is replicated._________________________________________________________________________________________________________________________________________________________________________________________________________________________________2- Where and in what form is eukaryotic DNA found?___________________________________________________________________________3- How are the long DNA molecules found in eukaryotes packed into short chromosomes?________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________4- How are histones related to nucleosomes?______________________________________________________________________________________________________________________________________________________5- What is the role of DNA polymerase in DNA replication?______________________________________________________________________________________________________________________________________________________6- How is the structure of chromosomes in eukaryotes different from the structure of chromosomes in prokaryotes? ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Workbook Section 12–2 Chromosomes and DNA Replication (pages 295–299)This section describes how DNA is packaged to form chromosomes. It also tells how the cell duplicates its DNA before cell division.DNA and Chromosomes (pages 295–296)1. Circle the letter of the location of DNA in prokaryotic cells.

a. nucleus b. mitochondria c. cytoplasm d. vacuole2. Is the following sentence true or false? Most prokaryotes contain a single, circular DNA molecule. _________________


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3. Eurkaryotic DNA is generally located in the cell _____________ in the form of a number of chromosomes.4. Is the following sentence true or false? All organisms have the same number of chromosomes. ___________________5. Is the following sentence true or false? The E. coli chromosome is longer than thediameter of an individual E. coli bacterium. ____________________6. Circle the letter of each sentence that is true about chromosome structure.

a. The DNA in eukaryotic cells is very loosely packed.b. Prokaryotic cells contain more DNA than eukaryotic cells.c. A human cell contains more than 1 meter of DNA.d. The DNA of the smallest human chromosome is nearly 10 times as long as many bacterial chromosomes.

7. Eukaryotic chromosomes contain both DNA and protein, packed together to form _______________.8. What are histones? ___________________________________________________________________________________________________________________________________9. Why are individual chromosomes visible only during mitosis? _________________________________________________________________________________________________10. Is the following sentence true or false? Changes in chromatin structure and histone-DNA binding are associated with changes in gene activity. _________________11. What do nucleosomes do? ________________________________________________________________________________________________________________________________________________________________________________________________________

Exploration Modeling DNA ReplicationLiving cells synthesize exact copies of DNA molecules that are passed on to each daughter cell during cell division. In this investigation, you will model DNA replication.ProblemHow is DNA replicated?Materials• construction paper (tan, gray, green, yellow, red, and purple) • scissors• transparent tape• metric rulerSkills Using ModelsProcedure1. Cut out rectangles of construction paper in the sizes and colors indicated below:Sugars: 36 tan pieces, each 2 cm _ 2 cmPhosphates: 36 gray pieces, each 1 cm _ 2 cmAdenines (A): 12 green pieces , each 1 cm _ 2 cmThymines (T): 12 yellow pieces , each 1 cm _ 2 cmGuanines (G): 6 red pieces , each 1 cm _ 2 cm


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Cytosines (C): 6 purple pieces , each 1 cm _ 2 cm2. To model a nucleotide, tape together a phosphate group, a sugar, and a guanine molecule (G) (see Figure 12-5 on page 291).

3. Assemble eight additional nucleotide models with the following nitrogenous bases: 3 thymines (T); 3 adenines (A); 2 cytosines (C).4. To model a single strand of DNA, tape the sugar of each nucleotide to the phosphate group of the next nucleotide in the following order: G T T A C AA T C.5. Construct a strand of DNA that is complementary to the first strand. Tape the nucleotides of the second strand together as you did in step 4.Record the positions of the bases in both strands of your model in the data table below.

6. Place the two strands side by side so that their complementary nucleotides face each other. Do not tape the two strands together. Write “original” on each strand.7. Separate the two strands. Simulate the action of DNA polymerase by constructing a new complementary strand for each original strand. 8. Tape the bases of each new strand to the complementary bases of its matching strand.

Analyze and Conclude1. Comparing and Contrasting Compare the new double-stranded DNA models with your original DNA model. Are their nucleotide sequences identical?


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____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

2. Using Models After a cell’s DNA is replicated, the cell may divide in two. Each new cell receives one copy of the original cell’s DNA. According to your model, how are the new strands and the original strands divided between the two new cells?____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________3. Drawing Conclusions What problems would you expect to occur if DNAwas not copied accurately as it is replicated?____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Section Review 12-2Reviewing Key ConceptsCompletion On the lines provided, choose the words that correctly complete the following sentences.1. During DNA replication, the DNA molecule (separates/combines) into two strands.2. At the end of DNA replication, (four/two) new strands of DNA have been produced, giving a total of (four/six) strands of DNA.3. New DNA is replicated in strands complementary to old DNA because production of new DNA follows the rules of (base pairing/the double helix).Identifying Structures On the lines corresponding to the numbers on the diagram, write whether the strand pointed to is an original strand or a new strand.


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Reviewing Key Skills8. Hypothesizing The length of a bacterium’s DNA may be 1000 times the length of the cell within which it is contained. Suggest an explanation for how this can occur.______________________________________________________________________________________________________________________________________________________

9. Comparing and Contrasting How does the structure of a eukaryotic chromosome during mitosis differ from its structure during the rest of the cell cycle?____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Transcription In transcription, RNA polymerase splits the two halves of a strand of DNA. RNA then uses one half as a template to make a copy of the other half. RNA contains the nucleotide uracil instead of the nucleotide thymine.Label the DNA and RNA. Then, label the missing nucleotides marked on the diagram.

In RNA, which nucleotide is always paired with uracil?adenine guanine


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Comparing DNA Replication and TranscriptionDNAreplication is the process by which a cell copies its DNA. During replication, both strands of the double helix are used as templates to make complementary, or matching, strands of DNA. DNAtranscription is the process by which a single strand of DNA is used as a template to generate a strand of mRNA.Fill in the missing information. One row has been completed for you.

Give another example of a template DNA code that is at least four base pairs long. Then give its matching complementary DNA and mRNA codes.


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______________________________________________________________________________________________________________________________________________________

Decoding mRNAThe diagram shows the mRNA codes that correspond to amino acids and stop codons. Read the diagram from the center outwards. For example, the mRNA code UAC corresponds to the amino acid tyrosine.Write the name of the amino acid that corresponds to each mRNA code. The first one has been done for you.

1. Which two mRNA codes correspond to histidine?____________________________________________________

2. How many different mRNA codes correspond to arginine?________________________________________________

TranslationDuring translation, transfer RNA (tRNA) anticodons match to messenger RNA (mRNA) codons. Each tRNA molecule can carry one particular amino acid. The amino acids are joined to form a polypeptide.Number the four tRNA anticodons in the order in which they should appear to match the codons in the mRNA strand.


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List the amino acids in the order they would appear in the polypeptide coded for by the mRNA. ___________________________________________________________________

Section Assessment 12-3

1- List the three main types of RNA___________________________________________________________________________2- What happens during transcription?_________________________________________________________________________________________________________________________________________________________________________________________________________________________________3- What happens during translation?_____________________________________________________________________________________________________________________________________________________4- Describe the three main differences between RNA and DNA._________________________________________________________________________________________________________________________________________________________________________________________________________________________________5- Using the genetic code, identify the amino acids that have the following messenger RNA strand codes: UGGCAGUGC___________________________________________________________________________

Workbook Section 12–3 RNA and Protein Synthesis (pages 300–306)This section describes RNA and its role in transcription and translation.The Structure of RNA (page 300)1. List the three main differences between RNA and DNA.a- ___________________________________________________________________b- ___________________________________________________________________c- ___________________________________________________________________2. Is the following sentence true or false? RNA is like a disposable copy of a DNA segment. __________________3. What is the importance of the cell’s ability to copy a single DNA sequence into RNA?


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______________________________________________________________________________________________________________________________________________________Types of RNA (pages 300–301)4. What is the one job in which most RNA molecules are involved?____________________.__________________________________________________________________________5. Complete the compare-and-contrast table about the types of RNA

Transcription (page 301)6. Circle the letter of each sentence that is true about transcription.

a. During transcription, DNA polymerase binds to RNA and separates the DNA strands.b. RNA polymerase uses one strand of DNA as a template to assemble nucleotides into a strand of RNA.c. RNA polymerase binds only to DNA promoters, which have specific base sequences.d. Promoters are signals in RNA that indicate to RNA polymerase when to begin transcription.

7. Many RNA molecules from eukaryotic genes have sections, called _______________, edited out of them before they become functional. The remaining pieces, called __________________, are spliced together.8. Is the following sentence true or false? RNA editing occurs in the cytoplasm of the cell. ______________________9. What are two explanations for why some RNA molecules are cut and spliced?a- ____________________________________________________________________________________________________________________________________________________b- ____________________________________________________________________________________________________________________________________________________

The Genetic Code (pages 302–303)10. Proteins are made by joining into long chains called _______________polypeptides.11. How can only four bases in RNA carry instructions for 20 different amino acids?


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_________________________________________________________________________________________________________________________________________________________________________________________________________________________________

12. What is a codon? ____________________________________________________________________________________________________________________________________13. Circle the letter of the number of possible three-base codons.

a. 4 b. 12 c. 64 d. 12814. Is the following sentence true or false? All amino acids are specified by only one codon. ____________15. Circle the letter of the codon that serves as the “start” codon for protein synthesis.

a. UGA b. UAA c. UAG d. AUGTranslation (pages 303–305)16. What occurs during the process of translation? ________________________________________________________________________________________________________________________________________________________________________________________17. Where does translation take place?_________________________________________________________________________________________________________________________________________________________________________________________________________________________________

18. Circle the letter of each sentence that is true about translation.a. Before translation occurs, messenger RNA is transcribed from DNA in the nucleus.b. Translation occurs in the nucleus.c. It is the job of transfer RNA to bring the proper amino acid into the ribosome to be attached to the growing peptide chain.d. When the ribosome reaches a stop codon, it releases the newly formed polypeptide and the mRNA molecule.

19. What is an anticodon? ________________________________________________________________________________________________________________________________

The Roles of RNA and DNA (page 306)Match the roles with the molecules. Molecules may be used more than once.Roles____ 20. Master plan____ 21. Goes to the ribosomes in the cytoplasm____ 22. Blueprint____ 23. Remains in the nucleus

Moleculesa. DNAb.RNA

Genes and Proteins (page 306)24. Many proteins are ________________, which catalyze and regulate chemical reactions.


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25. Is the following sentence true or false? Genes are the keys to almost everything that living cells do. _____________________

Section Review 12-3Reviewing Key ConceptsCompletion On the lines provided, complete the following sentences.1. The three main types of RNA are _______________, ____________________, and _____________________.2. Copying part of a nucleotide sequence of DNA into a complementary sequence in RNA is called ________________________.3. An enzyme that binds to DNA during transcription is RNA ______________________.4. During the process of ____________________, the information carried by mRNA is used to produce proteins.5. Each tRNA molecule contains three unpaired bases, called the _________________, which ensure that amino acids are added in the correct sequence.Reviewing Key Skills6. Comparing and Contrasting How are DNA and RNA similar? How are they different?___________________________________________________________________________________________________________________________________________________________________________________________________________________________

7. Comparing and Contrasting How are the three types of RNA different?___________________________________________________________________________________________________________________________________________________________________________________________________________________________

8. Hypothesizing How would it benefit a cell to possess a sequence of DNA that could be transcribed and then edited into several different mRNA molecules?___________________________________________________________________________________________________________________________________________________________________________________________________________________________

9. Applying Concepts What amino acid sequence would be produced from the mRNA sequence CGCUAUAGC?___________________________________________________________________________________________________________________________________________________________________________________________________________________________

10. Applying Concepts Suppose the DNA sequence GCTATATCG was changed to GCGATATCG. How would the products of transcription and translation be affected?


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_________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Chromosomal MutationsEach diagram represents a possible mutation of the chromosome shown below. Use the diagrams and descriptions below to help you complete the table. One row has been completed for you.

1. Which types of mutation can add genes to a chromosome?___________________________________________________________________________

Section Assessment 12-4

1- What is a mutation?_________________________________________________________________________________________________________________________________________________________________________________________________________________________________2- What is the significance of mutations to living things?_________________________________________________________________________________________________________________________________________________________________________________________________________________________________3- What are two kinds of frameshift mutation?


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_________________________________________________________________________________________________________________________________________________________________________________________________________________________________4- What are four types of chromosomal mutations?_________________________________________________________________________________________________________________________________________________________________________________________________________________________________5- The effects of a mutation are not always visible. How might a biologist determine whether a mutation has occurred, and if so, what type of mutation it is?____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Workbook Section 12–4 Mutations (pages 307–308)This section describes and compares gene mutations and chromosomal mutations.Introduction (page 307)1. What are mutations? ____________________________________________________________________________________________________________________________________________________________________________________________________________2. Is the following sentence true or false? Chromosomal mutations result from changes in a single gene. ________________________

Kinds of Mutations (pages 307–308)3. Mutations that occur at a single point in the DNA sequence are ______________ mutations.4. A mutation involving the insertion or deletion of a nucleotide is a(an) ______________mutation.5. Complete the compare-and-contrast table of types of chromosomal mutations.


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6. Circle the letter of each sentence that is true about gene mutations.a. Point mutations affect just one nucleotide.b. The substitution of one nucleotide for another in the gene never affects the function of the protein.c. Point mutations that involve the insertion or deletion of a nucleotide change the reading frame of the genetic message.d. Frameshift mutations affect every amino acid that follows the point of the mutation.

Significance of Mutations (page 308)7. Mutations that cause dramatic changes in protein structure are often _________________.8. Mutations are a source of ________________________ in a species.9. What is polyploidy?__________________________________________________________________________________________________________________________________________________________________________________________________________

Section Review 12-4 Reviewing Key ConceptsCompletion On the lines provided, complete the following sentences.1. Genetic information is altered when changes in the DNA sequence,called _____________________, occur.2. Changes in the DNA sequence of a single gene are called _________________.3. The DNA sequence of an entire chromosome is affected by a(an) ____________.


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Identifying Structures On the lines provided, identify each diagram as one of the following mutations: translocation, inversion, duplication, deletion. Then, describe what happens during each mutation.

Reviewing Key Skills8. Comparing and Contrasting How are frameshift and substitution mutations similar? How are they different?____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

9. Applying Concepts How can polyploidy in plants benefit humans?___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

10. Applying Concepts Compare the original sequence GCA CCG AGA to the mutant sequence GCA CAC GAG and determine what type of mutation has occurred.____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________


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Chapter Vocabulary Review

Matching On the lines provided, write the letter of the answer that best matches each description._____ 4. transformation_____ 5. bacteriophage_____ 6. histone_____ 7. replication_____ 8. DNApolymerase_____ 9. promoter_____ 10. introns_____ 11. codon_____ 12. mutation_____ 13. polyploidy_____ 14. operon_____ 15. differentiation

a. process in which one strain of bacteria changes into another oneb. process in which DNA makes a copy of itself

c. protein that DNA wraps around in eukaryotic chromosomesd. virus that infects bacteriae. signal in DNA that indicates to an enzyme where to bind to make RNAf. a change in the genetic materialg. sections of RNA molecules that are removed before a eukaryotic gene becomes functionalh. a group of genes that operate togetheri. three nucleotides that specify a single amino acid to be added to a polypeptidej. process in which cells become specialized in structure and functionk. the principal enzyme involved in DNA replicationl. condition of having extra sets of chromosomes

Completion On the lines provided, complete the following sentences:16. A(an) ________________ is made up of three parts: a deoxyribose sugar, a phosphate group, and a nitrogenous base.17. The principle of ________________ states that hydrogen bonds can form only between certain bases in DNA.18. Eukaryotic chromosomes contain both DNA and protein tightly packed together to form a substance called ________________.19. During the process of ________________, RNA molecules are produced by copying part of the nucleotide sequence of DNA into a complementary sequence in RNA.20. The enzyme that uses one strand of DNA as a template to assemblenucleotides into a strand of RNA is called .21. After introns have been cut out of RNA molecules, the remaining pieces called ________________ are spliced together.


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22. The decoding of an mRNA message into a protein is known as ________________.23. The three bases on the tRNA molecule that are complementary to one of the mRNA codons are called a(an) ________________.24. When the lac repressor protein binds to the ________________ , the lac operon is turned off.25. A series of genes, called the ________________, controls the development of organs and tissues in various parts of an embryo.

Graphic Organizer FlowchartUsing information from the chapter, complete the flowchart for DNA replication by arranging the events listed below in the order they occur.DNA polymerase joins individual nucleotides to produce a new strand; DNA molecule “unzips” and the two strands unwind; DNA polymerase proofreads the new strands; Unwound strands of DNA serve as templates for new DNA.


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Vocabulary ReviewMatching In the space provided, write the letter of the definition thatbest matches each term.

1. transcription2. chromatin3. codon4. replication5. translation6. nucleotide7. transformation8. anticodon9. messenger10. ribosomal11. intron12. mutation13. operon

a. three bases on a tRNA molecule that complement an mRNAcodonb. process in which an mRNA molecule is made by copying DNAc. process in which cells use information from mRNA to make proteins

d. sequence of mRNA that is cut out while still in the nucleus e. basic unit of DNA that is made up of a phosphate, a sugar, and a nitrogenous basef. process in which a cell duplicates its DNAg. process in which one strain of bacteria is changed by a gene or genes from another strainh. DNAtightly coiled around proteinsi. type of RNA that carries the instructions for assembling amino acids from the nucleus to a ribosomej. group of genes that work togetherk. type of RNA that makes up part of a ribosomel. three consecutive nucleotides on an mRNA molecule that specify an amino acidm. a change in genetic material

Chapter 12 Assessment

1- The process by which one strain of bacteria is apparently changed into another strain is called

a- Transcriptionb- Translation

c- Transformationd- replication

2- Bacteriophage area- Tiny bacteriab- Enzymes

c- Coils of RNAd- viruses

3- A nucleotide dos NOT containa- A 5-carbon sugarb- Polymerase

c- A nitrogen based- A phosphate group

4- In prokaryotes, DNA molecules are located in thea- Nucleus b- Ribosome


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c- Cytoplasm d- histone5- The diagram below shows the process of DNA

a- Replicationb- Transcription

c- Translationd- transformation

6- The main Enzyme involved in linking individual nucleotides into DNA molecules isa- Transfer RNAb- Ribose

c- RNA polymerased- DNA polymerase

7- The process by which the genetic code of DNA is copied into a strand of RNA is called

a- Translationb- Transcription

c- Transformationd- replication

8- In messenger RNA, each codon specifies aa- Nucleotideb- Purine

c- Amino acidd- pyrimidine

9- Changes in the DNA sequence that affect genetic information are known asa- Replicationb- Mutation

c- Transformationd- prokaryotes

10- As scientists tried to discover the natrure of genes, what three critical gene functions had they identify? _________________________________________________________________________________________________________________________________________________________________________________________________________________11- Describe the components and structures of a DNA nucleotide.____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________12- Explain how Chargaff’s rules helped Watson and Crick model DNA._________________________________________________________________________________________________________________________________________________________________________________________________________________________________13- What is meant by the term base pairing? How is base pairing involved in DNA replication? ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________14- Describe the appearance of DNA in a typical prokaryotic cell._________________________________________________________________________________________________________________________________________________________________________________________________________________________________


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15- Explain the process of replication. When a DNA molecule is replicated, how do the new molecules relate to the original molecule?____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________16- Describe the relationship between DNA, chromatin, histones, and nucleosomes._________________________________________________________________________________________________________________________________________________________________________________________________________________________________17- What is the difference between exons and introns?___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________18- What is a codon? ____________________________________________________________________________________________________________________________________________________________________________________________________________19- What is an anticodon? How does it function? ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________20- If a code on a DNA molecule for a specific amino acid is CTA, what would be the messenger RNA codon? The transder RNA anticodon?___________________________________________________________________________21- Explain why controlling the proteins in an organism controls the organism’s characteristics. _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________22- Name two major types of mutations. What do they have in common? How are they different? Give an example of each._______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________23- Describe how a TATA box helps position RNA polymerase in a eukaryotic cell.______________________________________________________________________________________________________________________________________________________

Chapter 12 DNA and RNA - Biology2Nash -...

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