DNA Structure notes

DNA Structure notes

DeoxyribonucleicAcidMeaning?Monomers of macro monomersCarbohydrates- Proteins- Lipids- Nucleic Acids- Carbohydrates- monosaccharidesProteins- Lipids- Nucleic Acids-Carbohydrates- monosaccharidesProteins- Amino AcidsLipids- Nucleic Acids-Carbohydrates- monosaccharidesProteins- Amino AcidsLipids- glycerol and fatty acidNucleic Acids-Carbohydrates- monosaccharidesProteins- Amino AcidsLipids- glycerol and fatty acidNucleic Acids- a nucleotide2 types of nucleic acids DNA and RNA- Monomer is called a nucleotideThere are three parts of a nucleotideThree Parts to a nucleotidePhosphate group, sugar (dexyribose or ribose)Nitrogenous base- 4 different types put into 2 groups

a. Purines (5 carbons and 4 Nitrogens in a ring)examples-Adenine (A) and Guanine (G)

b. Pyrimidine (4 Carbons and 2 Nitrogens in a ring)examples-Thymine (T) and Cytosine (C)

The nitrogenous bases make up the rungs of the DNA spiral stair caseOne rung is made of 2 bases bonded together by a weak hydrogen bondAdenine always bonds with thymineGuanine always bonds with cytosine

The phosphate group and the sugar are bonded together with a strong phosphate bond to make the sides of the DNA ladder

DNA Replication

When does this occur in the cell cycle?Histone- A protein that DNA can coil around, allows DNA to pack tightly into small space Nucleosome- a histone with coiled DNAPage 297-figure 12-10

DNA uses enzymes to unzip at the weak hydrogen bonds to replicate. DNA will unzip at hundreds of places at once. Where the DNA unzips is called a replicating fork.

An enzyme called DNA Polymerase is used to attach nucleotides to the open DNA strands.Great picture on page 298 in book

As DNA unzips, free floating nucleotides will come in and pair up with the correct nitrogen baseThe end result should be two identical strands of DNA

http://www.youtube.com/watch?v=yqESR7E4b_8http://www.youtube.com/watch?v=zdDkiRw1PdU

RNA structureThree main differences between RNA and DNA1. RNA is a single strand2. RNA has the sugar- ribose3. RNA has the nitrogenous base Uracil instead of thymine

Found in nucleusstarts in nucleus, moves to cytoplasm

Types of RNA (3) page 300 figure 12-12

Messenger RNA- mRNAServes as a messenger from DNA, found in nucleus and cytoplasm

Transfer RNA- tRNACarries very specific Amino acids to rRNA. Found in the cytoplasm

Ribosomal RNA- rRNAServes as a meeting place btw mRNA and tRNA. Its where proteins are assembled. Found in the cytoplasm

Protein Synthesisassembling amino acids into proteinThe making of protein is broken into two parts:Transcription and TranslationTranscription- using RNA to make a complimentary copy of the information from DNAAn area of DNA called Promoter will identify the part of the DNA that will be used to make the mRNARNA polymerase separates the DNARNA nucleotides will come in and temporarily bonds with DNA creating a mRNA

Once mRNA is made it separates from DNA (which zips back up) mRNA will check itself. Parts of mRNA that will represent a protein will be kept (exon). Parts of the mRNA that does not represent a protein is cut out (intron).

After this mRNA will travel out of the Nucleus and into the cytoplasm.

Every three bases on a mRNA is called a codon. Each codon will represent an amino acid There are 20 different types of amino acids, which are joined together to make proteins. The order of the codons on mRNA determines the order the a.a. are joined and this determines what protein is made.

We can use the Codon Wheel to show which codon represents which a.a.Example: RNA: UCGCACGGU Codons: UCG CAC GGUa.a:serine, histidine glycine

c. The codon AUG is a start codon there are three stop codons, UAA UAG UGA, which signal the end of the protein

Translation: interpreting mRNA to make proteins- page 304 fig. 12-18-once mRNA is made it leaves the nucleus and goes into the cytoplasm where it attaches to a ribosome (rRNA)-rRNA is in 2 sections, this allows the mRNA to go through it.

-tRNA looks like a swiggle it has 3 nitrogen bases at one end has amino acids at the other.

-the nitrogen bases are called the anticodon and they each carry a specific a.a.

-rRNA reads the mRNA one codon at a time. The tRNA that compliments the mRNA will come to the rRNA, match up with the mRNA and drop off the a.a it carries.-this continues until a stop codon is reached.

Mutations

-Change in the genetic materialA. Point mutations- change in one nucleotide that occur at a single point in the DNA sequence, usually only affects one amino acid in a protein. May not cause any changes

An example is substitution-the wrong bases bond togetherDNA: ATG GCC TAT AAA CGG mRNA: UAC CGG AUA UUU GCCAmino acids:DNA: ATG GTC TAT TTT CGG mRNA: UAC CAG AUA UUU GCCAmino acids:

B. Frame Shift mutations- a nucleotide is inserted or deleted. All amino acids are changed from that point on, can affect the entire protein, this is the most danderous kind of mutationDNA: ATG GCC TAT AAA CGG mRNA: ATT GGC CTA TAA ACG GAmino Acids: