ESSENTIAL/INTRODUCTORY CELL BIOLOGY AND BIOCHEMISTRY
2012-2013
SAMPLE QUESTIONS ON NUCLEIC ACIDS AND MACROMOLECULES
1. Which of the following statements about the structure of DNA shown in the figure on the right is false?
The width of the DNA molecule is variable since it can accommodate nucleotides containing varying numbers of nitrogen-based "rings."
Hydrogen bonds determine which nitrogenous bases can pair together.
A total of 10 pairs of nucleotides are included in each complete "turn" of the double helix.
The outer surface contains two sugar phosphate backbones
The distance between the nitrogenous base pair "rungs" of the helix is about 0.34nm.
2. In the Meselson-Stahl experiment bacteria grown in heavy nitrogen (N15) were transferred to light nitrogen (N14) and the density of the DNA monitored over successive rounds of replication. After two rounds of replication both light DNA and hybrid (light/heavy) DNA was present. What result would you expect if the bacteria were allowed to undergo one more round of replication?
One band of heavy DNA One band of hybrid DNA
One band of hybrid DNA
One band of light DNA One band of light DNA and one band of hybrid DNA
One band of light DNA and a second band between light and hybrid DNA
3. Put the following events in protein synthesis in chronological order.
1 After peptide linkage, the empty P site tRNA prepares to leave the ribosome 2 The ribosome releases the empty tRNA as it translocates the length of one codon 3 The next tRNA binds to the A site 4 A tRNA is positioned at the UAG start codon 5 The amino acid at the P site is transferred to the amino acid attached to the tRNA at the A site 6 The A site is now free for the next incoming tRNA
4,1,5,3,6,2
4,6,1,2,3,5
4,1,5,2,3,6
4,3,5,1,2,6
4,2,5,1,3,6
4. Which one of the following is correct for Trehalose
Glucose linked to glucose by an (-1,1 glycosidic linkage
Glucose linked to glucose by an (-1,6 glycosidic linkage
Glucose linked to glucose by an (-1,4 glycosidic linkage
Glucose linked to glucose by a β-1,6 glycosidic linkage
None of the above are correct
5. A region of the template (non-coding/non-sense) strand of a DNA molecule has the following sequence, 3’ –CGATTA- 5’. What is the sequence of RNA transcribed from this DNA?
3’ –GCTUUT- 5’
3’ –CGAUUA- 5’
5’ –CGATTA- 3’
5’ –GCUAAU- 3’ None of the above
6. Which one of the following is the correct general formula for an L-amino acid?
COOH COOH CH2OH COOH CHO
H CH2 NH2 H NH2 H NH2 OH NH2 H
NH2 R R R R
(A) (B) (C) (D) (E)
7. The side chain of leucine is a hydrocarbon. In a folded protein, where would you expect to find leucine?
In the interior of a cytoplasmic enzyme
On the exterior of a protein embedded in a membrane
On the exterior of a cytoplasmic enzyme
A and B
A and C
8. Which of the following illustrates the idea that the primary structure of a protein determines its tertiary structure?
A. In sickle cell haemoglobin a glutamic acid is changed to a valine and this causes a change in the shape of the haemoglobin polypeptide.
B. Haemoglobin has a structure containing four subunits.
C. Binding of oxygen to haemoglobin causes a shift in the relative positions of the four subunits
D. All of the above
E. None of the above
9. Choose the correct statement regarding nucleosomes.
A. Nucleosomes are made of chromosomes
B. Nucleosomes consist entirely of DNA
C. Nucleosomes consist of DNA wound round a histone core
D. Nucleosomes are present only during mitosis
E. Nucleosomes stop DNA strands from separating
10. Which one of the following is correct for maltose
A. Glucose linked to glucose by a β-1,4 glycosidic linkage
B. Glucose linked to glucose by an ((1,6 glycosidic linkage
C. Glucose linked to glucose by an ((1,4 glycosidic linkage
D. Glucose linked to glucose by a β-1,6 glycosidic linkage
E. None of the above are correct
Which of the following statements about neutrophils is untrue?
They are the most abundant white blood cells
They are approximately twice the size of red blood cells
They are phagocytic
They are classed as agranulocytes
E. They represent the initial cellular response to bacterial infection
Which of the following types of tissue lines the inside of the gastrointestinal tract?
Connective
Smooth muscle
Nervous
Epithelial
Adipose
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