1. Which of the following bond is not present in DNA?
a) Phosphate bond
b) Hydrogen bond
c) VanderWaal’s force
d) Disulphide bond
Explanation: Disulphide bond is not present in a DNA molecule. Phosphate bond is present between two deoxy-nucleotides (dNTPs) of DNA. The nitrogen bases on the two strands of DNA have hydrogen bonds between them. Adenine is connected Thymine by 2 hydrogen bonds, Guanine is bound to Cytosine by 3 hydrogen bonds. The base stacking in DNA is due to Vanderwaal’s force.
2. Which of the following amino acids may or may not be protonated at neutral pH?
a) Glutamate
b) Lysine
c) Histidine
d) Arginine
Explanation: The amino acids may be negatively charged, positively charged or neutral at a neutral pH. Here, Arginine and Lysine are positively charged or protonated at neutral pH, while Glutamate is negatively charged at neutral pH. However, Histidine may or may not be protonated at normal pH. The side chain of Histidine has a pKa of 6.5, which means only 10% of Histidine is protonated.
3. Heparin is an example of ___________?
a) Tertiary protein
b) Oligosaccharides
c) Glycoproteins
d) Glycosaminoglycan
Explanation: A more complex structures of polysaccharides is glycosaminoglycan (GAGs). Unlike other polysaccharides, they have an A-B-A-B where A and B represent two different sugars. An example of GAG is heparin, which is secreted by cells in lungs against tissue damage. Heparin prevents blood coagulation, enabling free flow of blood to heart or lungs.
4. Proteome is a ____________
a) A precursor of protein
b) Storehouse of proteins
c) An inventory of the total amount of proteins
d) None of the mentioned
Explanation: The entire inventory of proteins that is produced by an organism is known as that organism’s proteome. It may be also applied to the inventory of proteins in a particular tissue or cell. Proteomics is the field of protein biochemistry.
5. Which of the following is not a protein denaturant?
a) SDS
b) Phenol
c) DTT
d) Acetic acid
Explanation: Sodium dodecyl sulfate or SDS is a strong denaturant of protein and is used in SDS-PAGE technique. DTT is oftentimes used along with SDS to further denature proteins by reducing their disulfide bonds to allow for better separation of proteins during electrophoresis. Phenol is used as a protein denaturant during isolation of RNA from plants
6. Which of the following is untrue?
a) Protein folding occurs in Golgi bodie
b) Protein folding is assisted by a protein molecule called Chaperone
c) Transmembrane or organelle proteins contain a signal peptide
d) Proteins are present in cytoplasm and cell organelles of all cells
Explanation: The folding of proteins occurs in the lumen of the Endoplasmic Reticulum (ER). A newly synthesized protein undergoes a series of modifications in the ER with the help of a number of molecular chaperones and folding enzymes that all together assist its proper folding and subsequent release from ER. The majority of ER proteins are dedicated to the folding of proteins. Golgi bodies help in the proper packaging and transport of proteins.
7. RNA does not have the nitrogen base of _______
a) Uracil
b) Cytosine
c) Thymine
d) Adenine
Explanation: RNA does not have the pyrimidine Thymine and has Uracil instead while DNA has Thymine. In RNA, Adenine binds to Uracil with two hydrogen bonds while in DNA, Adenine binds to Thymine by two hydrogen bonds.
8. Which of the following is functionally the odd one out?
a) siRNA
b) miRNA
c) shRNA
d) snRNA
Explanation: micro RNA (miRNA) is a small non-coding RNA that helps in gene silencing. Small interfering RNA (siRNA) helps in gene silencing through the RNA interference pathway. Short hairpin RNA (shRNA) silences target gene via RNA interference. However, small nuclear RNA or snRNA helps in RNA splicing and processing.
9. Which of the following RNA is artificially made?
a) snRNA
b) scRNA
c) miRNA
d) siRNA
Explanation: siRNA, snRNA and miRNA are all produced naturally in the cell. Small cytoplasmic RNA (scRNA) is an engineered (artificial) RNA molecule that helps in in-vitro and in-vivo signal transduction.
10. In RNA transcription, which of the following is a part of TBP-associated factor (TAF)?
a) TFIID
b) TFIIB
c) TFIIF
d) TFIIH
Explanation: TFIID includes the TBP subunit which binds to the TATA box along with some other proteins, together known as the TBP-associated factors. TFIIB provides a binding site for RNA Polymerase. TFIIF contains a special subunit which is bound to the entering RNA Polymerase. TFIIH contains 10 subunits, 3 of which possess enzymatic activity.