Which one of the following statements about chromatin is NOT true?
DNA winds approximately 1.65 times around the nucleosomes.
H2A-H2B binds to both the entry and exit ends of DNA in nucleosomes.
Covalent modification of histones influence chromatin compaction.
Non-histone proteins are part of mitotic chromosomes.
B.
H2A-H2B binds to both the entry and exit ends of DNA in nucleosomes.
Among the given statements, a statement that is not true is that H2A-H2B binds to both the entry and exit ends of DNA in nucleosomes. It can be corrected as it binds DNA in two planes perpendicular to the DNA superhelical axis.
What is the effect of sudden increase in the levels of ATP and citrate on an erythrocyte undergoing glycolysis?
It inhibits glycolysis.
It stimulates glycolysis.
The rate of glycolysis remains unaltered.
The rate of glycolysis increases gradually.
During eukaryotic cell division, metaphase to anaphase transition is regulated by degradation of
Cyclin B1
CDK1
Aurora A kinase
Polo-like kinase
One of the mechanisms used by bacteria for adaptation to changed environment is altering the transcription of their genes. In this regard, which one of the following responses is NOT found in bacteria?
A gene with two different promoters for expression in different conditions.
use of different sigma factors for transcription of genes.
Expression of alternate α, β and β' subunits.
Expression of anti-sigma factors.
In a signalling event, binding of an extracellular ligand activates G-protein coupled receptor (GPCR) that eventually activates phospholipase C-β. Which one of the following statements truly reflects the function of phospholipase C-β?
Phospholipase C-β converts PI (3, 4, 5)P3 to PI (4, 5)P2.
Phospholipase C-β converts PI (4)P to PI (4, 5)P2.
Phospholipase C-β converts PI (4, 5)P2 to diacylglycerol and IP3.
Phospholipase C-β converts PI (5) to PI (4, 5)P2.
Which one of the following λ proteins acts both as an activator and repressor of transcription?
cI protein
N protein
cII protein
Q protein
Indicate the INCORRECT statement from the following:
Allosteric enzymes function through reversible noncovalent binding of allosteric modulators or effectors.
Monoclonal antibodies that catalyze the hydrolysis of esters or carbonates can be produced.
Enzymes are not inhibited irreversibly by heavy metals such as Hg2+, Ag+.
Acid phosphates hydrolyze biological phosphate esters at ∼ pH 5.0
The φ and ψ of a β-strand composed of all D-amino acids will mainly occupy which quadrant in the Ramachandran plot?
upper left
upper right
lower left
lower right
Choose the correct statement from the following:
Disulfide bonds in a 20-residue peptide can be formed only if the cysteines are adjacent to each other.
The amino acid isoleucine has only one chiral centre.
Both bases and sugar contribute to the chirality of nucleic acids.
The pI of aspartic acid is less than that of glutamic acid.
Select a cellular body which is NOT a part of the nuclear bodies:
P bodies
Nucleolus
Cajal bodies
Interchromatin granule clusters