SBIOAC BIOLOGY
Molecular
Genetics
Name: . 2003 06 02
Read each question carefully.
Answer all questions, as no marks will be deducted for incorrect responses.
Value of question appears in
parentheses after the question.
Total = 50
1. The two polynucleotide strands in a DNA
molecule are like the east-west
lanes of the 401 highway because they show
A. cloverleaf
structures
B. they are
constantly under repair
C. a helical
structure
D. anti-parallel
orientation
2. A nucleotide is added to a growing chain by
means of a (A) bond
and it is
always attached to the (B) end of the existing chain. Choose
one answer only.
(A) (B)
A. phosphodiester
3’
B. phosphodiester 5’
C. hydrogen 3’
D. peptide 3’
3.
Which of the following is NOT an absolute requirement for DNA replication to
take place?
A. single-stranded
DNA
B. RNA primer
C. DNA
polymerase
D. ribosomes
4. DNA
contains different genes that are transcribed into all of the following EXCEPT:
A. proteins
B. mRNA C.
rRNA D.
tRNA
5. mRNA is synthesized
by
A. replication B. duplication C. transcription D.
translation
6. carries
coded instructions for amino acid sequence to the ribosomes.
A. mRNA B.
rRNA C.
ribosomes D.
tRNA
7. tRNA:
A. delivers amino acids to ribosomes
B.
picks up genetic messages from rRNA
C.
synthesizes mRNA
D.
all of the above
8. How many amino acids are coded for in this
mRNA sequence?
CGUUUACACCGUCAC
A. six B. five C.
seven
D. fifteen E. four
9. An anticodon
pairs with the nitrogen-containing bases of :
A. mRNA codon B. DNA codons C. tRNA
anticodon
D. amino
acids
10. Each codon
specifies a(n) :
A. protein B. polypeptide C. amino acid
D. carbohydrate
11. The loading of mRNA onto a ribosome occurs
during the stage of translation.
A.
initiation B. elongation C. termination D. transcription
12. Match the terms related to protein building
(6)
F disrupts genetic instructions A.
initiation, elongation, termination
C genetic code word B. polypeptides are
synthesized
D transcription C.
base triplet for an amino acid
B translation D.
one DNA strand is template for the process
A translation stages E.
amino acid is attached to acceptor end
E tRNA activation F.
gene mutation
13. In eukaryotes, the non-translated portion
of a gene is called:
A. transcript C. replicon
B. intron D.
exon
14. Which does not occur inside the nucleus?
A. transcription C. translation
B. rRNA
synthesis D.
splicing
15. For the
amino acid cysteine, give (3)
The mRNA codon UGC or UGU .
The DNA triplet ACG or ACA .
The tRNA anticodon ACG
or ACA .
16. Which of the following statements regarding DNA replication is incorrect?
A. DNA polymerase can start only at the 3’ end of the old DNA strand.
B. DNA polymerase requires an RNA primer.
C. DNA replication is always in the 5’ ® 3’ direction
D. DNA
replication is always in the 3’® 5’ direction.
17. From this diagram, identify the leading and lagging
strands. Use the initial
primer (P) as reference
(2).
leading: I
& IV . lagging II & III .
18. Using the genetic code, translate the following portion of a gene. Show the orientation of each product (3)
DNA 3’ TTAGCGTGGAGACTTACTGTA 5’
mRNA 5’
AAU CGC ACC UCU GAA UGA CAU 3’ UGA
means STOP CHAIN!
Protein N-asparagine – arginine – threonine – serine – glutamate
- C
19. DNA and RNA have similar structures in that both molecules
__________.
A. are double helices
B. have either purines and pyrimidines in their structures
C. have five kinds of nitrogenous bases in their structures
D. have a sugar-phosphate backbone with
bases attached to the sugars
20. DNA is different from RNA in that DNA, but not RNA, __________
A. is single-stranded
B. binds a purine only to ribose and
a pyrimidine only to deoxyribose.
C. has two kinds of sugars rather than one.
D. has deoxyribose
21. Which does not occur in prokaryotes?
A. transcription B. tRNA activation C.
translation D. mRNA
processing
22. The
process of protein synthesis occurs in
A. bacteria only
B. eukaryotes only
C. plants only
D. animals only
E. all living things
23. Frame
shift mutations are caused by
A. base additions
B. base deletions
C. substitutions
D. a and b only are correct
24. During
polypeptide elongation, each amino acid to be incorporated is first
carried
to the
A. interior of the small ribosomal subunit
B. P site of the large ribosome subunit
C. A site of the large
ribosome subunit
D. 5’ end of the bound mRNA
25. The
structures called snRNPs are . . .
A. a
type of specialized carbohydrate.
B. involved in the removal of exons from DNA.
C. a
critical component of the initiation complex.
D. part of a spliceosome.
26. What
happens to the RNA primers that are essential for initiation of DNA
replication?
A. the RNA
nucleotides are replaced by DNA nucleotides
B. The pieces of primer
become a permanent part of the DNA molecule
C. RNA primase
removes each primer, which is then replaced by a DNA primer
D. When the RNA primers are
removed, they become known as
27. In this diagram of the process of DNA replication at a replication
fork, the strand labeled B is the:
A. leading strand
B.
lagging strand
C.
Okazaki fragment
D.
template strand
28. In the diagram above of the process of DNA replication at a replication
fork, the black boxes labeled D and E are:
A. RNA primers
29. Which
mRNA codes for the following polypeptide? met
arg ser leu glu
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A. |
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B. |
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C. |
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D. |
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/6
30. For the DNA strand 5'-TACGATCATAT-3' the correct complementary DNA
strand is:
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A. |
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B. |
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C.
|
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D.
|
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E.
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31. With what mRNA codon would the tRNA in the diagram be able to form a codon-anticodon
base pairing interaction?
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A. |
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B. |
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C. |
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D. |
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32. During translation in eukaryotes, anticodons
on the tRNAs
A. never bind
to the mRNA codons
B. ensure that
each amino acid is delivered to its proper "address" on the mRNA
C. assist
in the assembly of fats
D. consist of a
three-nucleotide sequence at the 3’ end of the transfer RNA molecule
33. As amino acids are added to the protein
chain, they are held together by
A. peptide bonds
B.
hydrogen bonds
C.
ionic bonds
D.
water molecules
34. Initially, every polypeptide chain formed in translation begins with the
amino acid
A. tryptophan
B. glutamine
C. methionine
D. phenylalanine
35. Introns which are spliced out of pre-mRNAs are not translated
into polypeptides because
A. they are not
capped or polyadenylated or transported from the
nucleus
B. they never contain a codon for methionine
C. they do not contain
nucleotides
D. they turn into other types
of RNA
36. Match
the following with their role in translation (5)
a. start codon
b. initiation complex
c. tRNA
d. anticodon
e. P-site of ribosome
f. A-site of ribosome
g. nonsense (stop) codon
h. release factors
___d__ A
series of three tRNA bases complementary to a mRNA codon
___f__ The ribosomal site where a tRNA carrying an
amino acid first attaches during translation
__e___
The ribosomal site where the growing amino acid chain
is temporarily being held by a tRNA as the next codon in the mRNA is being read
__g___
A series of three mRNA bases coding for no amino acid
c Transports
amino acids to the ribosome during translation
BONUS (2)