The Central Dogma Replication-> Transcription-> Translation Modified from Kim Foglia.
DNA replication, transcription, and translation
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Transcript of DNA replication, transcription, and translation
ACTIVITYGetting to Know the
DNA and RNA Structure
GUIDE QUESTIONSQ1. What are the components of the DNA and RNA molecule?
Fill in the comparison table below.Basis of Comparison DNA RNA
1. Number of Strands 2 1
2. Location in the cell nucleus cytoplasm
3. Type of sugar deoxyribose ribose
4. Nitrogenous base pair A,T,C,G A,U,C,G
ANSWER: SugarPhosphate GroupNitrogenous Base
GUIDE QUESTIONSQ2. What is the structural difference between DNA and RNA?
ANSWER: DNA and RNA are different in the following: a. DNA is double stranded while RNA is single-
stranded. b. The sugar in DNA is deoxyribose while that in RNA is ribose.
c. The nitrogen bases in DNA are adenine (A), guanine (G), thymine (T) and cytosine (C). In RNA are adenine, guanine, cytosine and uracil.
GUIDE QUESTIONSQ3. What nitrogenous base is found in RNA but not in DNA?
ANSWER:
Uracil
DNA(DEOXYRIBONUCLEIC ACID)
- is the main component of chromosomes (packaged form of the DNA)
DNA(DEOXYRIBONUCLEIC ACID)
- is the material that transfers genetic characteristics in all life forms
Where is DNA
found?
DNA STRUCTURE- has three main components:
1. deoxyribose (a pentose sugar)2. base (there are four different ones)3. phosphate
DNA STRUCTURE
nucleotide- formed by the condensation of a pentose sugar, phosphate and one of the 4 bases
DNA STRUCTURENucleotides are linked together by covalent bonds called phosphodiester linkage
DNA STRUCTURE -are divided into two groups:Pyrimidines (are single ring bases.)
Nitrogenous Bases:
C
C
C
C
N
N
O
N
DNA STRUCTURE -are divided into two groups:Pyrimidines (made of one 6 member ring)
ThymineCytosine
Nitrogenous Bases:
C
C
C
C
N
N
O
N
cytosine
C
C
C
C
N
N
O
O
thymine
C
DNA STRUCTURE -are divided into two groups:Purines (made of a 6 member ring, fused
to a 5 member ring; double ring bases)
Nitrogenous Bases:
CC
CC
N
N
N
N
N
C
DNA STRUCTURE -are divided into two groups:Purines (made of a 6 member ring, fused
to a 5 member ring; double ring bases) AdenineGuanine
Nitrogenous Bases:
C
C
C
C
N
N
N
Adenine N
N
C
C
C
C
C
N
NO
N
Guanine N
N
C
• Adenine and Thymine always join together because they form two H bonds with each other
A T• Cytosine and Guanine always join together because they form three H bonds with each other
C G
CHARGRAFF’S RULE
Antiparallel StrandsThe strands run opposite of each other.
The 5’ end always has the phosphate attached.
5’
3’
3’
5’
DNA-is a very long polymer that is double helix with about 10 nucleotide pairs per helical turn
James D. Watson and Francis Crick, co-originators of the double-helix model.
One Strand of DNA
• The backbone of the molecule is alternating phosphates and deoxyribose sugar
• The teeth are nitrogenous bases.
phosphate
deoxyribose
bases
One Strand of DNA
• One strand of DNA is a polymer of nucleotides.
• One strand of DNA has many millions of nucleotides.
nucleotide
Two Strand of DNA
22
• Remember, DNA has two strands that fit together something like a zipper.
• The teeth are the nitrogenous bases but why do they stick together?
HYDROGEN BONDS
C
C
C
C
N
N
O
N
C
C C
C
N NO
N
N
N C
• The bases attract each other because of hydrogen bonds.
• Hydrogen bonds are weak but there are millions and millions of them in a single molecule of DNA.
• The bonds between cytosine and guanine are shown here with dotted lines
DNA by the Numbers
• Each cell has about 2 m of DNA.
• The average human has 75 trillion cells.
• The average human has enough DNA to go from the earth to the sun more than 400 times.
• DNA has a diameter of only 0.000000002 m.
The earth is 150 billion mor 93 million miles from the sun.
What does DNA do?
DNA stores an organism's genetic information and controls the production of proteins and is thus responsible for the biochemistry of an organism.
26
THE CENTRAL DOGMA OF MOLECULAR BIOLOGY
REPLICATIONWhere does
REPLICATION happen?Inside the Nucleus
REPLICATIONWhen does
REPLICATION occur?
occurs during S phase of the
cell cycle.
DNA REPLICATION--- is the process of producing two identical replicas from one original DNA molecule that occurs in all living organisms. --- is the basis for biological inheritance.
DNA REPLICATION--- is a semi conservative
means that each daughter DNA consists of half parental DNA and half of new DNA
2 old strands
2 new strands
SEMICONSERVATIVEand
SEMIDISCONTINOUS
5’
REPLICATION• DNA double helix unwinds
Helicase is the enzyme that splits the two strands. The structure that is created is known as "Replication Fork".
REPLICATION• DNA now single-stranded
Single-Strand DNA Binding Proteins (SSB) for work to bind individuals strands in a DNA double stranded helix and aid the helicases in opening it up into single strands. They are particularly useful in stabilizing the unwound single-stranded formation.
REPLICATION• New DNA strand forms using complementary base
pairing (A-T, C-G)
Example of DNA Replication
5’ TAC CGG AAT GCA ATG CAT ATG 3’ OLD3’ ATG GCC TTA CGT TAC GTA TAC 5’ OLD
5’ TAC CGG AAT GCA ATG CAT ATG 3’ OLD3’ ATG GCC TTA CGT TAC GTA TAC 5’ NEW
5’ TAC CGG AAT GCA ATG CAT ATG 3’ NEW3’ ATG GCC TTA CGT TAC GTA TAC 5’ OLD
REPLICATION• Used to prepare DNA for cell division• Whole genome copied/replicated
REPLICATIONThe following is the base sequence
on one strand of a DNA molecule. If replicated, write the complimentary strands.
1. A A T G C C A G T G G T2. C C T G A C T A A T C G
3. G G A C T G A T T C G G
4. T G G C C T A T A T C C5. G T C A C T G C C G G A
RNA(RIBONUCLEIC ACID)
- Usually one strand
RNA(RIBONUCLEIC ACID)
- The sugar is ribose
RNA(RIBONUCLEIC ACID)
- Contains uracil (U) instead of thymine (T)
RNA(RIBONUCLEIC ACID)
- can both store information and catalyze chemical reactions.
- is used in protein synthesis
TYPES OF RNA(RIBONUCLEIC ACID)
1. messenger RNA (mRNA)-brings information from the DNA in the nucleus to the cytoplasm(cytosol).
2. ribosomal RNA (rRNA)-holds tightly to the mRNA and use its information to assemble amino acids.
TYPES OF RNA(RIBONUCLEIC ACID)
3. transfer RNA (tRNA)-attaches the correct amino acid to the protein chain that is being synthesized in the ribosome
TRANSCRIPTION-is the process by which genetic information from DNA is transferred into RNA. DNA sequence is enzymatically copied by messenger RNA (mRNA) to produce a complementary nucleotide transfer RNA (tRNA) strand.-synthesis of mRNA from a DNA template
TRANSCRIPTION-only one strand of DNA, the antisense strand or template strand, is used to make mRNA
sense strand – is the non transcribed strand
-mRNA is complementary to the antisense strand
Protein Synthesis Transcription
Transcription process•RNA polymerase attaches to DNA at a special sequence that serves as a
“start signal”.•The DNA strands are separated and one strand serves as a template.•The RNA bases attach to the complementary DNA template, thus synthesizing mRNA.
Protein Synthesis: Transcription
•The RNA polymerase recognizes a termination site on the DNA molecule and releases the new mRNA molecule.(mRNA leaves the nucleus and travels to the ribosome in the cytoplasm.)
Protein Synthesis: Transcription
DNA
Cytoplasm
Nucleus
Eukaryotic Transcription
ExportG AAAAAA
RNA
Transcription
Nuclear pores
G AAAAAA
RNAProcessing
mRNA
TRANSCRIPTIONWhere does
TRANSCRIPTION happen?
Inside the Nucleus
http://novella.mhhe.com/sites/0070070017/student_view0/biology_1/chapter_17/mrna_synthesis__transcription___quiz_2_.html
TRANSLATION-process of converting information in mRNA into a sequence of amino acids (polypeptide chain) in a protein-mRNA is in ribosome-Each combination of 3 nucleotides on mRNA is called a codon or three-letter code word. -Each codon specifies a particular amino acid that is to be placed in the polypeptide chain (protein).
TRANSLATION
SUG
AR
-PHO
SPHATE B
AC
KB
ON
E
B A
S E S
H
P OO
HO
O
O
CH2NH2N
NH
N
N
HOH
P
O
O
HO
O
O
CH2
NH2
N
N
N
N
H
P
O
OH
HO
O
O
CH2
NH2
N
N
N
N
O
A Codon
Guanine
Adenine
Adenine
Arginine
TRANSLATION-tRNA brings amino acids to mRNA in the ribosome
TRANSLATION AUG (methionine) serves as the “initiator”
codon, which starts the synthesis of a protein
UAA, UAG, and UGA are stop codons, which signify the end of a polypeptide chain (protein).
THE GENETIC CODE
Ribosomes• 2 subunits, separate in cytoplasm until
they join to begin translation• Large• Small
• Contain 3 binding sites• E• P• A
EP A
Large subunit
Peptidyl-tRNA binding site
Aminoacyl-tRNA binding site
mRNA
5’
Exit site
Small subunit
3’
TRANSLATION
AERibosome P
PheLeu
Met
SerGly
Polypeptide
Arg
Aminoacyl tRNA
UCUCCAGAG...CU-AUG--UUC--CUU--AGU--GGU--AGA--GCU--GUA--UGA-AT GCA...TAAAAAA5’mRNA
3’
TRANSLATION
AERibosome P
CCA
Arg
UCU
PheLeu
Met
SerGly
Polypeptide
GAG...CU-AUG--UUC--CUU--AGU--GGU--AGA--GCU--GUA--UGA-AT GCA...TAAAAAA5’mRNA
3’
TRANSLATION
AERibosome P
Aminoacyl tRNA
CGA
Ala
CCA
Arg
UCU
PheLeu
Met
SerGly
Polypeptide
GAG...CU-AUG--UUC--CUU--AGU--GGU--AGA--GCU--GUA--UGA-AT GCA...TAAAAAA5’mRNA
3’
TRANSLATION
AERibosome PCCA
Arg
UCU
PheLeu
Met
SerGly
Polypeptide
CGA
Ala
GAG...CU-AUG--UUC--CUU--AGU--GGU--AGA--GCU--GUA--UGA-AT GCA...TAAAAAA5’mRNA
3’
TRANSLATION
EXERCISESDetermine the protein formed by the following old DNA strand:
CCCATGGAGCGAGAGTTACCGGGTTAGAGGCAC
new strand:
mRNA:
tRNA:Protein (Amino Acids):
EXERCISESDetermine the protein formed by the following old DNA strand:
AGCATGTGCTACTAGCCGGTGAGC
new strand:
mRNA:
tRNA:
PROTEIN (Amino Acids):
EXERCISESDetermine the protein formed by the following NEW DNA strand:
TGCCGCCAGTCGCTCGGG
a. normal
b. If in the process of transcription, all of the purine, GUANINE is changed to cytosinec. If during transcription, all thymine bases are deleted or not read by the mRNA. d. If all cytosine will be substituted by adenine.