Download amino acid

a
a
From gene to protein
nucleus
cytoplasm
transcription
DNA
a
a
translation
mRNA
a
a
a
a
a
a
a
a
a
a
a
protein
a
a
a
a
a
a
a
ribosome
trait
Translation
• from
nucleic acid language
to
amino acid language
How does mRNA code for
proteins?
DNA
TACGCACATTTACGTACGCGG
4 ATCG
mRNA
4 AUCG
protein
AUGCGUGUAAAUGCAUGCGCC
?
Met Arg Val Asn Ala Cys Ala
20
How can you code for 20 amino acids with only
4 nucleotide bases (A,U,G,C)?
mRNA codes for proteins in triplets
DNA
TACGCACATTTACGTACGCGG
codon
mRNA
AUGCGUGUAAAUGCAUGCGCC
AUGCGUGUAAAUGCAUGCGCC
?
protein
Met Arg Val
Asn
Ala
The code
• Code for ALL life!
– strongest support for a
common origin for all life
• Code is redundant
– several codons for each
amino acid
– 3rd base “wobble”
Why is the
wobble good?

Start codon



AUG
methionine
Stop codons

UGA, UAA, UAG
How are the codons matched to
amino acids?
DNA
mRNA
3
5
5
3
TACGCACATTTACGTACGCGG
AUGCGUGUAAAUGCAUGCGCC
3
UAC
tRNA
amino
acid
codon
5
Met
GCA
Arg
CAU
Val
anti-codon
a
a
From gene to protein
nucleus
cytoplasm
transcription
DNA
a
a
translation
mRNA
a
a
a
a
a
a
a
a
a
a
a
protein
a
a
a
a
a
a
a
ribosome
trait
Building a polypeptide
• Initiation
– brings together mRNA, ribosome
subunits, initiator tRNA
• Elongation
– adding amino acids based on codon
sequence
• Termination
3 2 1
– end codon
Leu
Val
Met
Met
Met
Met Leu
Ala
Leu
Leu
release
factor
Ser
Trp
tRNA
5'
mRNA
UAC
AA U
A UGC UG
3'
E
P
A
5'
UA C G A C
A UG C U GA AU
5'
3'
U A C GA C
A U G C U G AA U
3'
5'
U A C G A CG A A U
AUG C U
3'
ACC
U GG UA A
3'
RNA polymerase
DNA
Can you tell the
story?
amino
acids
exon
intron
tRNA
pre-mRNA
5' GTP cap
mature mRNA
poly-A tail
large ribosomal subunit
aminoacyl tRNA
synthetase
3'
polypeptide
5'
small ribosomal subunit
tRNA
E P A
ribosome