Dna Protein Synthesis Recombinant Dna Test Page 4
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4DNA, Protein Synthesis and Recombinant DNA
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13.
The diagram above shows a part of the
process of protein synthesis.
a) Identify the following labelled
structures. (4 marks)
W:ribosome
X: mRNA
Y: tRNA
Z: amino acid
b) Where in the cell is X synthesized?
(1 mark) nucleus
14.
List two factors that could cause changes in the type of protein formed. Explain why each factor causes
a change in the protein formed. (2 marks)
•
•
Radiation (x-rays, gamma rays, alpha
Benzene
•
particles)
Cigarette smoke
•
•
UV light from the sun
Asbestos
REASON: these substances (mutagens) alter the sequence of the nucleotides in the DNA
sequence during replication
15.
a) List the events which occur during the replication (copying) of DNA. (4 marks)
•
Unwinding – enzyme (helicase) causes double helix to untwist
•
Unzipping – H bonds between base pairs are broken
•
Complementary base pairing – nucleotides free in the nucleoplasm bond
C always
with G and A always with T
•
Bonding of adjacent nucleotides - covalent bonds form between sugar (deoxyribose)
and phosphate molecules
b) Why does DNA replication occur before cell division? (1 mark)
Both new cells require a copy of DNA to carry out normal cellular metabolism
16.
Give the location of the following processes in the cell:
i)
transcription (1 mark)
nucleus
ii)
translation (1 mark)
on rough ER or cytoplasm
17.
Due to a mutation, one base pair is lost from a DNA molecule. Describe the effect this mutation has on
the protein being synthesized. (1 mark)
See # 6 g iii
18.
Describe the role of each of the following in protein synthesis: (5 marks)
a) DNA – provides the template that produces mRNA thus codes for the amino acid sequence
b) mRNA – carries the genetic code (from the DNA) out of the nucleus to the ribosome
c) tRNA - brings a specific amino acid from the cytoplasm to the ribosome
d) ribosome - brings mRNA and tRNA together thus allowing for the production of a protein
e) peptide bond – elongates the protein
19.
a) Name the process
shown in the diagram.
(1 mark) Replication
b) Give the letter of the
strand that is identical to
strand A. (1 mark) D
c) Name the molecule
indicated by X. (1 mark)
DNA
d) Where in a human cell
does the process shown
above occur? (1 mark)
B
B
C
D
Nucleus
A
A
A
B
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