Transcript Transcription and Translation

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Transcription and Translation
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Central Dogma
DNA
RNA
transcription
Protein
translation
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Central Dogma
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DNA vs. RNA
DNA
RNA
Base pairs: ATGC
(Adenine, Thymine, Guanine,
Cytosine)
Base Pairs: AUGC
(Adenine, Uracil, Guanine,
Cytosine)
Deoxyribose sugar
Ribose sugar
OH
Phosphate group
Phosphate group
Double stranded, in helix
Single stranded
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Transcription
 Transcription
is the process of turning the information in
DNA into mRNA
 Why
does the cell want to do transcription?
So it can eventually make a protein!
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Transcription: Step by Step
1.
DNA “unzips”: enzymes
breaks bonds between A – T
and G – C
2.
Two strands of DNA are
formed (coding and noncoding)
3.
Enzyme reads DNA base
pairs and adds new
nucleotides to match the
base pair (Uracil in place of
Thymine = A – U and G – C)
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Transcription: Step by Step
3’
5’
5’
3’
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Transcription: Step by Step
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Transcription
How does the enzyme (RNA Polymerase) know where to
start in the long string of DNA and where to end?
 Promoters: a
sequence of bases that indicate a start point
 Terminators: a
sequence of bases that indicate an end point
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Translation
 The
process of turning the information in mRNA into a
protein.
 To
do so, the mRNA must be exported out of the
nucleus into the cytoplasm
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Translation: Step by Step
1.
First codon (3 base pair
combination) of mRNA strand
attaches to a ribosome
2.
tRNA carrying a specific amino
acid, approaches ribosome
3.
Enzyme helps tRNA anti-codon
to pair with codon on mRNA
4.
tRNA remains with amino acid
attached to it
5.
Next codon on mRNA slides
along ribosome. Steps 2-5 repeat
continually until end.
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Translation: Step by Step
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Translation
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You Try:
Type
Sequence
DNA
T T A G C A C G A A T T
mRNA
tRNA
Protein
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You Try:
Type
Sequence
DNA
T T A G C A C G A A T T
mRNA
A A U C G U G C U U
tRNA
Protein
A
A
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You Try:
Type
Sequence
DNA
T T A G C A C G A A T T
mRNA
A A U C G U G C U U
tRNA
U U A G C A C G A A U U
Protein
A
A
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You Try:
Type
Sequence
DNA
T T A G C A C G A A T T
mRNA
A A U C G U G C U U
tRNA
U U A G C A C G A A U U
Protein
Asparagine – Arginine – Alanine
A
A