Download Translation and the Genetic Code

MOLECULAR GENETICS
1
Translation and the Genetic Code
1. Stop codons block further translation because the tRNA that binds to them functions as a
termination factor. (T/F)
2. Which of the following RNA species are required for protein synthesis?
a. mRNA
b. tRNA
c. rRNA
d. a and b
e. a, b and c
Questions 3 - 5 refer to the following short mRNA sequence: 5’AUGCCCUACUAC3’
3. The sequence of the template (sense) strand of the gene that codes for the message will be
a. AUGCCCAACUAC
b. TACGGGATGATG
c. UACGGGUUGAUG
d. UACGGGUUGAUG
e. ATGCCCTACTAC
4. The anticodon in the tRNA that attaches to the first codon of this strand will be __.
a. UAC
b. TAC
c. AUG
d. GUA
e. ATG
5. The peptide coded for by this message will have __ amino acids.
a. 1
b. 3
c. 4d. 6
e. 12
6. The energy to drive the formation of peptide bonds during translation comes directly from
a. the hydrolysis of ATP to ADP. b. the hydrolysis of ATP to AMP.
c. the breakdown of rRNA in the ribosome.
d. breaking the bond between the tRNA and its amino acid.
7. The intact ribosome has sufficient space for the placement of __ codon(s).
a. 1
b. 2
c. 4
d. 12
e. all of the
8. New tRNAs move into the ribosome’s __ site and thus position the next amino acid in the
right spot for peptide bond formation.
a. A
b. B
c. P d. D
e. Q
9. When not bound to mRNA, ribosomes are found as three separate pieces, called the small,
intermediate and large subunits. (T/F)
10. During translation, the first amino acid put into the polypeptide chain is always methionine.
(T/F)
11. During translation, stop codons code for the amino acid tyrosine which is always the last
amino acid in a polypeptide chain. (T/F)
12. The genetic code is redundant, meaning that most amino acids are specified by more than
one codon. (T/F)
MOLECULAR GENETICS
2
Matching. Indicate whether the structural or functional features below are true for:
A. mRNA only
B. rRNA only
C. tRNA only
D. all RNA
E. no RNA
1.____ has an anticodon at one end and a binding site for an amino acid at the other.
2.____ forms part of the ribosome.
3.____ serves as a template for protein synthesis.
4.____ is synthesized from a DNA template in the nucleus.
5.____ carries the code for a particular protein to the ribosome
Definitions. Write clear, concise definitions of the words or phrases below of no more than one
sentence
Codon
Anticodon
Stop codon
Short Answer
1. The sketch below illustrates the initiation of protein synthesis with the tRNA carrying
methionine located in the P site. Either by adding to the sketch or with words describe how the
next amino acid would be added to start the elongation of the polypeptide chain. Why will
translation stop when the ribosome reaches a stop codon?
Molecular Genetics