CMB521S - CELL AND MOLECULAR BIOLGY - 2ND OPP - JANUARY 2025


CMB521S - CELL AND MOLECULAR BIOLGY - 2ND OPP - JANUARY 2025



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nAmlBIA un,vERSITY
OF SCIEnCE Ano TECHnOLOGY
Faculty of Health, Natural
Resourcesand Applied
Sciences
School of Health Sciences
Department of Clinical
Health Sciences
13 Jackson Kaujeua Street
Private Bag 13388
Windhoek
NAMIBIA
T: +264 61 207 2970
F: +264 67 207 9970
E: dchs@nust.na
W: www.nust.na
QUALIFICATION : BACHELORof MEDICAL LABORATORYSCIENCES
QUALIFICATION CODE: 0SBMLS
LEVEL:5
COURSE:CELLAND MOLECULARBIOLOGY
COURSECODE: CMBS21-S
DATE: JANUARY 2025
SESSION: 1
DURATION: 3 HOURS
MARKS: 100
SECONDOPPORTUNITY: QUESTION PAPER
EXAMINER:
MODERATOR:
Ms Belinda Roselin Tsauses
Ms Vanessa Tjijenda
INSTRUCTIONS:
1. Answer all questions in the answer book.
2. Please write neatly and legibly.
3. Do not use the left side margin of the exam paper. This must be allowed for the
examiner.
4. No books, notes and other additional aids are allowed.
5. Mark all answers clearly with their respective question numbers.
PERMISSIBLEMATERIALS:
1. None.
ATTACHEMENTS
1. None.
This question paper consists of 7 pages including this front page.

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SECllON A: MULTIPLE CHOICE AND TRUE/ FALSE
QUESTION 1: MULTIPLE CHOICE QUESTIONS
[10 MARKS]
Evaluate the statements in each numbered section and select the most appropriate
answer or phrase from the given possibilities. Fill in the appropriate letter next to the
number of the correct statement/phrase in your ANSWERBOOK.
(10]
1.1 The site for transcription is the:
(1)
a) Nucleus.
b) Cytoplasm.
c) Ribosomes.
d) Mitochondria.
1.2 The site for translation is the:
(1)
a) Nucleus.
b) Cytoplasm.
c) Ribosomes.
d) Mitochondria.
1.3 The site for the assembly of the growing polypeptide chain in protein synthesis is:
(1)
a) rRNA.
b) tRNA.
c) mRNA.
d) None of the above.
Cell and Molecular Biology (CMB521S)
2nd Opportunity January 2025
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1.4 During the processing steps of mRNA, ________
intrans from newly synthesized mRNA strands.
a) Polyadenilation.
b) Termination.
c) Slicing.
d) Capping.
involves removal of
(1)
1.5 The enzyme responsible for unwinding and separating double stranded DNA as it moves
along the DNA is called:
(1)
a) DNA ligase.
b) DNA gyrase.
c) DNA polymerase.
d) DNA helicase.
1.6 _____
are arranged in two long strands that form a spiral called a double helix. (1)
a) Genes.
b) Ribosomes.
c) Histones.
d) Nucleotides.
1.7 In DNA, together, a base, sugar, and phosphate are called -----
(1)
a) Nucleosides.
b) Base pairs.
c) Nucleotide.
d) Histones.
1.8 Besides the nucleus, a small amount of DNA can also be found in the -----
(1)
a) Mitochondria.
b) Ribosomes.
c) Golgi complex.
d) Lysosomes.
Cell and Molecular Biology (CMB521S)
2nd Opportunity January 2025
3

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1.9 ______
"proofreads" the newly formed DNA to check, remove and replace
any errors.
(1)
a) Exonuclease.
b) DNA gyrase.
c) DNA primase.
d) None of the above.
1.10 Topoisomerase or _____
unwinds and rewinds DNA strands to prevent
the DNA from becoming tangled or supercoiled.
(1)
a) DNA ligase.
b) DNA polymerase.
c) DNA helicase.
d) DNA gyrase.
QUESTION2: TRUE/FALSEQUESTIONS
[10 MARKS]
Evaluate the statements and select whether the statement is true or false. Write the
word 'True' or 'False' next to the corresponding number in your ANSWERBOOK.
Correct the incorrect word(s) in each false statement.
[10]
2.1 Transfer RNAs, or tRNAs, are molecular "bridges" that connect mRNA codons to
the amino acids they encode.
2.2 Ribosomes are made up of carbohydrates and RNA (ribosomal RNA, or rRNA).
2.3 There are 3x4x4=48 possible combinations in the genetic code.
2.4 Transcription is the second step in gene expression.
2.5 DNA sequence that indicates where a genetic sequence can be read and decoded
(promoter region) is known as the TATA box.
2.6 DNA polymerase is the main enzyme involved in transcription.
Cell and Molecular Biology (CMB521S)
2nd Opportunity January 2025
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Pleaseanswer ALL of the questions in this section.
QUESTION 3:
3.1 Briefly explain the process of signal transduction in cell communication.
[18 MARKS]
(5)
3.2 With an aid of a diagram, explain the concept of ligand and receptor binding
in cell communication. (Three (3) marks for the diagram and five (5) marks
for the explanation.)
(8)
3.3 Name five (5) important aspects related to cell-cell adhesion that are significant to
cell biology.
(5)
QUESTION 4:
[30 MARKS]
4.1 What is the biological significance of the function of membrane carbohydrates
found in the cell membrane?
(6)
4.2 Demonstrate your understanding of how vesicular transport takes place
in your own words.
(12)
4.3 Explain how normal cell growth occurs in the human body, using the skin as
an example.
{12)
SECTION C: LONG ANSWER QUESTIONS
[32 MARKS]
Pleaseanswer ALL of the questions in this section. Give your answers in point form.
QUESTION 5:
[14 MARKS]
Detail the 2nd and 3rd steps involved in DNA replication. Give your answer(s) in point
form. {One {1} mark for naming the correct step and nine (6) marks for detailing each
step.)
Cell and Molecular Biology (CMB521S)
2nd Opportunity January 2025
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QUESTION 6:
[18 MARKS]
Study the normal strand below and compare with mutations indicated from 6.1.1- 6.1.3.
For each diagram, identify the type of mutation, explain where the mutation occurred
and interpret which amino acids have been coded for on the entire strand using the
attached genetic code table. (One (1) mark for identifying mutation type, one (1) mark
for the explanation and four (4) marks for interpreting (may give abbreviations) the coded
amino acids on each strand.)
(18)
DN/1, A A A;
mRNA~~
Normal:
T IT
I
AM~QQ~QQ
6.1.1
6. 1.2
"'\\
iQG mRNAm[grGg ]Q~
Cell and Molecular Biology (CMB521S)
2nd Opportunity January 2025
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6.1.3
lJ u
Second base
C IA
G I,~,
ucu} uuu}Phe
U'UC UCC
Ser
UUAAUC } Tyr
UUGGUC}cys
u
C
UUUUGA}Leu
UCA
UCG
UAA Sto G S o A
UAGSto~ UGG Trp G
cuu}CCU} Q)
00
(0
..Cl
C
CCUUAC
CUG
L
eu
CCC
CCA
CCG
Pro CCAAUC}His
. CCAAAG}Gln
CCGGC U}
u
C
CGA Arg
A
Q)
(f)
CGG
G
(0
..Cl
+..J
"O
(f)
L
.,--
Ll..
ACU} AUU
AUC Ile
u ACC Thr
AAAACU}Asn 'AAGGCU}Ser
L
.,--
C
.£:
I-
A
ACA
ACG
AAAAGA}Lys
AAGGAG} Arg
A
G
GUU}GCU} GGU} G
GUC
GUA
Yal
GUG
GCC
GCA Ala
GCG
GGAACU}Asp GGC Gly
GGAAAG}Glu
GGA
GGG
u
C
A
G
END OF QUESTION PAPER.
Cell and Molecular Biology (CMB521S)
2nd Opportunity January 2025
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