1. Please answer the following multi-step problem: a) An in vitro translation ex
ID: 63640 • Letter: 1
Question
1. Please answer the following multi-step problem:
a) An in vitro translation experiment like the ones carried out by Khorana in the 1960's was performed with a dinucleotide repeat of A and C (ie 5'-ACACACACACAC-3') and then translated in vitro. Which amino acids would you expect to be present in the peptides produced? Choose all that apply
options:
Ala
Arg
Asn
Asp
Cys
Gln
Glu
Gly
His
Ile
Leu
Lys
Met
Phe
Pro
Ser
Thr
Trp
Tyr
Val
b) An in vitro translation experiment like the ones carried out by Khorana in the 1960's was performed with a dinucleotide repeat of A and C (ie 5'-AACAACAACAACAAC-3') and then translated in vitro. Which amino acids would you expect to be present in the peptides produced? Choose all that apply
options:
Ala
Arg
Asn
Asp
Cys
Gln
Glu
Gly
His
Ile
Leu
Lys
Met
Phe
Pro
Ser
Thr
Trp
Tyr
Val
c) Below is a prokaryotic mRNA ready to be translated. How many amino acids would be present in the small peptide encoded by this sequence? (Note: you must use the rules of prokaryotic translation to answer this correctly…follow the steps)
5’-AAUCGCAUGCUGCCAGGAGCUGAUGUUUAGGAUCGGCUCUAUGAAGAUAUGACGUGGA-3’
options:
a
5 aa long
b
6 aa long
c
7 aa long
d
8 aa long
e
9 aa long
f
10 aa long
d) The first six N-terminal amino acids of a peptide are: Met-Cys-Ala-Ser-Met-Arg
How many different mRNAs could code for this sequence?
options:
a
1
b
20
c
128
d
192
e
288
e) A gene has 6 exons and can code for proteins containing any 4 or more of these exons (ie 4, 5 or all 6). How many different proteins can be encoded by this single gene?
options:
a
1
b
3
c
15
d
22
e
70
f
256
Ala
Arg
Asn
Asp
Cys
Gln
Glu
Gly
His
Ile
Leu
Lys
Met
Phe
Pro
Ser
Thr
Trp
Tyr
Val
Explanation / Answer
1.a) In all the reading frames, ACA (Thr) and CAC (His) are produced
b) 5'-AACAACAACAACAAC-3'
AAC-Asn ACA-Thr CAA-Gln
c) Prokaryotic mRNA should contain Shine-Delgarno Sequence 7base pairs upstream of AUG.
Shine Delgarno sequence is 5'-AGG AGG3'; which is not present in this sequence. Either your question is wrong or I would suggest, the question maker has not considered this point of having Shine Delgarno sequence at all.If considering only start and stop codon, the number of amino acids should be:-
5’-AAUCGC AUG CUG CCA GGA GCU GAU GUU UAG GAU CGG CUC UAU GAA GAU AUG ACG UGG A-3’
The highlighted portion gives a sequence of 7 amino acids (UAG is stop codon and AUG is start)
5’-AAUCGCAUGCUGCC AGGAGC UGAUGUUUAGGAUCGGCUCU AUG AAGAUAUGACGUGGA-3’
Look if I consider the bold portion as the Shine Delgarno sequence, then also it is not 7 base pairs upstream of AUG.
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