- Hits: 4910
1. Factors responsible for a water molecule being a dipole include one of the following :
(A) The similarity in electron affinity of Hydrogen and Oxygen.
(B) The tetrahedral structure of liquid water.
(C) The magnitude of H-O-H bond angle.
(D) The ability of water to hydrogen bond to various chemical structures.
2. For the ion product of water; which one of the following is correct ?
(A) Is independent of temperature
(B) Has a numerical value of 1 × 10–14 at 25ºC.
(C) Is the equilibrium constant for the reaction HOH ↔H+ + OH–
(D) Is an approximation that fails to take into account the presence of the hydronium ion. H3O+
3. Mitochondria are associated with all of the following except one :
(A) ATP Synthesis
(B) DNA Synthesis
(C) Protein Synthesis
(D) Hydrolysis of macromolecules at very low pH.
4. Which one of the following carries out the oxidation of very long chain fatty acids ?
(A) Peroxisomes (B) Nucleus
(C) Cytoskeleton (D) Endoplasmic reticulum
5. A polynucleotide is a polymer in which :
(A) The two ends are structurally equivalent
(B) The monomeric units are joined together by phosphodiester bonds.
(C) There are at least 20 different kinds of monomers that can be used.
(D) Purine and pyrimidine bases are the repeating units.
6. A palindrome is a sequence of nucleotides in DNA that :
(A) Is highly reiterated
(B) Is part of the introns of eukaryotic gene
(C) Is a structural gene
(D) Has local symmetry and may serve as a recognition site for specific proteins/enzymes.
7. Ribozymes :
(A) Are any nucleic acids.
(B) Are enzymes whose catalytic function resides in RNA subunits.
(C) Carry out self processing reactions but cannot be considered true catalysts.
(D) Require a protein co factor to form a peptide bond.
8. Another approach to cancer treatment is drugs that inhibit topoisomerases which :
(A) Regulate the level of superhelicity of DNA in cells.
(B) Always break only one strand of DNA.
(C) Can create but not break supercoils in DNA.
(D) Hydrolyse all types of RNA.
9. A nucleosome :
(A) Is a regularly repeating structure of DNA and histone proteins
(B) Has a core of DNA with proteins wrapped around the outside
(C) Uses only one type of histone per nucleosome
(D) Is separated from a second nucloeosome by nonhistone proteins.
10. The Z DNA helix :
(A) Has fewer base pairs per turn than the B DNA
(B) Is favoured by an alternating GC sequence
(C) Tends to be found at the 3' end of genes
(D) Is a permanent conformation of DNA.
11. Which interaction is not formed when protein subunits combine to form a quaternary structure ?
(A) Disulfide bond formation (B) Hydrogen bonding
(C) Hydrophobic interactions (D) van der Waals’ forces
12. Proteins may be separated according to size by :
(A) Isoelectric focussing (B) Polyacrylamide gel electrophoresis
(C) Ion exchange chromatography (D) Molecular exclusion chromatography
13. Changes in protein conformation can be detected rapidly by all of the following except one :
(A) Ultraviolet absorbance spectroscopy (B) Fluorescence emission spectroscopy
(C) Optical rotator dispersion (D) Visible light absorption spectroscopy
14. Lipoproteins in the blood have the same general architecture, which includes :
(A) Neutral core of triacylglycerols and cholesteryl esters
(B) Amphipathic lipids oriented with their polar head groups at the surface and their hydrophobic
chains oriented towards the core
(C) Most surface apoproteins containing amphipathic helices
(D) Metal ions are always associated with lipoproteins to make them stable.
15. Chaperone proteins :
(A) All require ATP to exert their effect
(B) Cleave incorrect disulfide bonds, allowing correct ones to subsequently form
(C) Guide the folding of polypeptide chains into patters that would be thermodynamically unstable without the presence of chaperones
(D) Of the hsp 70 class are involved in transport of proteins across mitochondrial and ER membranes.
M.Sc. (Hons. School) Biochemistry/210101/DNB-11701 2
16. Both strands of DNA serve as templates concurrently :
(A) Replication (B) Transcription
(C) Translation (D) Reverse transcription
17. The discontinuous nature of DNA synthesis :
(A) Leads to the synthesis of Okazaki fragments
(B) Leads to the synthesis of RNA
(C) Leads to the synthesis of proteins
(D) Leads to the synthesis of leading strand
18. All of the following statement about telomerases are correct except :
(A) The RNA component acts as a template for the synthesis of a segment of DNA
(B) It adds to the 5' ends of the DNA strands
(C) It provides a mechanism for replicating the ends of linear chromosomes in most eucaryotes
(D) It is a reverse trancriptase.
19. A transition mutation :
(A) Occurs when a purine is substituted for a pyrimidine, or vice versa
(B) Results from the insertion of one or two bases or base analogues into the DNA chain
(C) Decreases in frequency in the presence of base analogues such as 2-amino purine
(D) Results from the substitution of one purine for another or of one pyrimidine for another.
20. All of the following are the factors in the unwinding and separation of DNA strands for replication except :
(A) The tendency of negative superhelices to partially unwind
(B) Destabilization of complementary base pairs by helicases
(C) The action of topoisomerases
(D) The enzymatic activity of SSB proteins.