fig. 17-5
DESCRIPTION
Fig. 17-5. Second mRNA base. First mRNA base (5 end of codon). Third mRNA base (3 end of codon). the mechanism of translation. Amino acids. Polypeptide. tRNA with amino acid attached. Ribosome. Trp. Phe. Gly. tRNA. Anticodon. Codons. 5 . 3 . mRNA. 3 . Amino acid - PowerPoint PPT PresentationTRANSCRIPT
Fig. 17-5Second mRNA base
Firs
t mRN
A ba
se (5
end
of c
odon
)
Third
mRN
A ba
se (3
end
of c
odon
)
Polypeptide
Ribosome
Aminoacids
tRNA withamino acidattached
tRNA
Anticodon
Trp
Phe Gly
Codons 35
mRNA
the mechanism of translation
Fig. 17-14
Amino acidattachment site
3
5
Hydrogenbonds
Anticodon
(a) Two-dimensional structure
Amino acidattachment site
5
3
Hydrogenbonds
3 5AnticodonAnticodon
(c) Symbol used in this book(b) Three-dimensional structure
Amino acid Aminoacyl-tRNAsynthetase (enzyme)
ATP
AdenosineP P P
AdenosineP
PP i
PPi
i
tRNA
tRNA
Aminoacyl-tRNAsynthetase
Computer modelAMPAdenosineP
Aminoacyl-tRNA(“charged tRNA”)
Attaching amino acids to tRNAs:Amino-acyl tRNA synthases
-20 different synthases-Require ATP-Each must be specific to the right amino acid and tRNA(s)
tRNAGLN
Aminoacyl-tRNA synthase(ATSGLN)
Adenylated Glutamine
Fig. 17-16b
P site (Peptidyl-tRNAbinding site) A site (Aminoacyl-
tRNA binding site)E site(Exit site)
mRNAbinding site
Largesubunit
Smallsubunit
(b) Schematic model showing binding sites
Next amino acidto be added topolypeptide chain
Amino end Growing polypeptide
mRNAtRNA
E P A
E
Codons
(c) Schematic model with mRNA and tRNA
5
3
The Ribosome
LSU
SSU
Fig. 17-18-1
Amino endof polypeptide
mRNA
5
3E
Psite
Asite
Fig. 17-18-2
Amino endof polypeptide
mRNA
5
3E
Psite
Asite
GTP
GDP
E
P A
Fig. 17-18-3
Amino endof polypeptide
mRNA
5
3E
Psite
Asite
GTP
GDP
E
P A
E
P A
Peptide bond formation- Transfer of growing chain from tRNA in P site to tRNA in A site
Fig. 17-18-3
Amino endof polypeptide
mRNA
5
3E
Psite
Asite
GTP
GDP
E
P A
E
P A
Fig. 17-18-4
Amino endof polypeptide
mRNA
5
3E
Psite
Asite
GTP
GDP
E
P A
E
P A
GDPGTP
Ribosome ready fornext aminoacyl tRNA
E
P A
Fig. 17-17
3355U
UA
ACGMet
GTP GDPInitiator
tRNA
mRNA5 3
Start codon
mRNA binding siteSmallribosomalsubunit
5
P site
Translation initiation complex
3
E A
Met
Largeribosomalsubunit
Initiating translation
Fig. 17-19-1
Releasefactor
3
5Stop codon(UAG, UAA, or UGA)
Terminating translation
Fig. 17-19-2
Releasefactor
3
5Stop codon(UAG, UAA, or UGA)
5
32
Freepolypeptide
2 GDP
GTP
Terminating translation
Fig. 17-19-3
Releasefactor
3
5Stop codon(UAG, UAA, or UGA)
5
32
Freepolypeptide
2 GDP
GTP
5
3
Terminating translation
Fig. 17-20
Growingpolypeptides
Completedpolypeptide
Incomingribosomalsubunits
Start ofmRNA(5 end)
PolyribosomeEnd ofmRNA(3 end)
(a)
Ribosomes
mRNA
(b) 0.1 µm
Second mRNA base
Firs
t mRN
A ba
se (5
end
of c
odon
)
Third
mRN
A ba
se (3
end
of c
odon
)
The genetic code:-read in triplet codons
-once a start codon is specified, codons are read in order (5’ to 3) until a “stop” codon is read
-redundant
-unambiguous
-universal*
DNA sequence
RNA sequence
Amino acid sequence
Protein structure and function
tRNAGLN
Aminoacyl-tRNA synthase(ATSGLN)
Adenylated Glutamine
tRNAGLN
Aminoacyl-tRNA synthase(ATSGLN)
Adenylated Glutamine
Altered DNA sequence
Altered RNA sequence
Altered (?) Amino acid sequence
Altered (?) Protein structure and function
Fig. 5-17Nonpolar
Glycine(Gly or G)
Alanine(Ala or A)
Valine(Val or V)
Leucine(Leu or L)
Isoleucine(Ile or I)
Methionine(Met or M)
Phenylalanine(Phe or F)
Trypotphan(Trp or W)
Proline(Pro or P)
Polar
Serine(Ser or S)
Threonine(Thr or T)
Cysteine(Cys or C)
Tyrosine(Tyr or Y)
Asparagine(Asn or N)
Glutamine(Gln or Q)
Electricallycharged
Acidic Basic
Aspartic acid(Asp or D)
Glutamic acid(Glu or E)
Lysine(Lys or K)
Arginine(Arg or R)
Histidine(His or H)
The 20 amino acids
Fig. 17-23a
Wild type
3DNA templatestrand
3
355
5mRNA
Protein
Amino endStop
Carboxyl end
A instead of G
33
3
U instead of C
55
5
Stop
Silent (no effect on amino acid sequence)
Fig. 17-23a
Wild type
3DNA templatestrand
3
355
5mRNA
Protein
Amino endStop
Carboxyl end
A instead of G
33
3
U instead of C
55
5
Stop
Silent (no effect on amino acid sequence)
Fig. 17-23b
Wild type
DNA templatestrand
35
mRNA
Protein
5
Amino endStop
Carboxyl end
53
3
T instead of C
A instead of G
33
3
5
5
5
Stop
Missense
Fig. 17-22
Wild-type hemoglobin DNA
mRNA
Mutant hemoglobin DNA
mRNA
33
3
3
3
3
55
5
55
5
C CT T TTG GA A AA
A A AGG U
Normal hemoglobin Sickle-cell hemoglobin
Glu Val
Fig. 17-23cWild type
DNA templatestrand
35
mRNA
Protein
5
Amino endStop
Carboxyl end
53
3
A instead of T
U instead of A
33
3
5
5
5
Stop
Nonsense
Fig. 17-23e
Wild type
DNA templatestrand
35
mRNA
Protein
5
Amino end
Stop
Carboxyl end
53
3
missing
missing
33
3
5
5
5
Frameshift causing extensive missense (1 base-pair deletion)