All histones undergo post-translational modification of specific amino acids. These modifications
P. Alter the charge of the histone molecule
Q. Are permanent
R. Occur on the N-terminal tail of the histones, which are thought to extend out from the core
S. Occur at specific times during the cell cycle

Which of the following is a prime example of a ribonucleoprotein enzyme, the catalytic activity of which (under non-physiological conditions), resides solely in its RNA component

A. Reverse transcriptase

B. Cytochrome c

C. Bacterial RNA polymerase

D. RNase P

Main functions of baffles in a bioreactor are
P. To prevent a vortex.
Q. To increase aeration.
R. To reduce interfacial area of oxygen transfer.
S. To reduce aeration rate.

A. P, Q

B. Q, R

C. R, S

D. P, S

All the following may be methods for the inhibition of microbial growth by antibiotics except

A. Antibiotics disrupt cell wall synthesis

B. Antibiotics interfere with cell membrane function

C. Antibiotics prevent the release of energy from ATP

D. Antibiotics inhibit the synthesis of protein

A feature common to almost all transmembrane proteins is

A. A phosphorylated exterior domain

B. A structure consisting almost exclusively of beta-sheets

C. An amino acid sequence rich in acidic residues

D. An alpha-helical region of about 20 to 25 hydrophobic amino acids