transcription

1
Protein Synthesis
transcription
translation
protein
DNA
RNA
2
URACIL (U) base with a single-ring structure
phosphate group
sugar (ribose)
3
DNA
G C A T
base-pairing during DNA replication
DNA
C G T A
G C A U
RNA
base-pairing during transcription
DNA
G C T A
4
sugar-phosphate backbone of one strand of
nucleotides in a DNA double helix
sugar-phosphate backbone of the other strand of
nucleotides
part of the sequence of base-pairs (blue)
5
RNA polymerase, the enzyme that catalyzes
transcription
DNA
6
Transcription
transcribed DNA winds up again
DNA to be transcribed unwinds
newly forming RNA transcript
DNA template at the assembly site
7
Transcription
growing RNA transcript
3
5
3
5
direction of transcription
5
3
8
unit of transcription in a DNA strand
exon
intron
exon
exon
intron
5
3
9
From DNA to RNA
G
A
T
A
C
C
A
A
T
A
A
C
C
A
C
base sequence of gene region
C
U
A
U
G
G
U
U
A
U
U
G
G
U
G
mRNA
10
From Codons to Amino Acids
C
G
G
G
G
G
U
U
U
U
U
U
U
A
A
arginine
glycine
tyrosine
tryptophan
tyrosine
11
(No Transcript)
12
Codon-tRNA-Amino Acid
codon in mRNA
anticodon
amino-acid attachment site
amino acid
OH
13
Ribosomes
tunnel
intact ribosome
small ribosome subunit
large ribosome subunit

14
Initiation
intact ribosome
small ribosomal subunit
initiator tRNA
mRNA transcript
15
binding site for mRNA
(first binding site for tRNA)
(second binding site for tRNA)
platform on small ribosomal subunit
16
Translation
Elongation
17
Translation
Elongation
18
Termination
mRNA
mRNA
new polypeptide chain
19
original base triplet in a DNA strand
a base substitution within the triplet (red)
During replication, proofreading enzymes make a
substitution
possible outcomes
or
original, unmutated sequence
a gene mutation
20
Mutations
mRNA
parental DNA
amino acids
arginine
glycine
tyrosine
tryptophan
asparagine
altered mRNA
DNA with base insertion
altered amino- acid sequence
arginine
glycine
leucine
glutamate
leucine
21
Transcription
mRNA
rRNA
tRNA
protein subunits
mRNA transcripts
ribosomal subunits
tRNA
Translation
amino acids, tRNAs, ribosomal subunits
Protein