991. In a native PAGE, proteins are separated on the basis of
A. net negative charge
B. net charge and size
C. net positive charges size
D. net positive charge

992. The subunit molecular weight as well as the number of subunits in the quaternary structure can be determined by
A. SDS-PAGE electrophoresis
B. gel filtration chromatography
C. combining information from (a)and (b)
D. isoelectric focusing

993. Proteins are separated in an SDS-PAGE experiment on the basis of their
A. positively charged side chains
B. molecular weight
C. negatively charged side chains
D. different isoelectric points

994. Small charged molecules, often biogenic amines function as
A. hormones
B. neurotransmitters
C. both (a) and (b)
D. none of these

995. SH2 domains specifically bind to
A. phosphorylated serine residues
B. phosphorylated tyrosine residues
D. Ca2+

996. In paracrine signaling, the signaling molecules affects only
A. target cells close to the cell from which it was secreted
B. target cells distant from its site of synthesis in cells of an endocrine organ
C. both (a) and (b)
D. none of the above

997. Simple nerve reflexes use signaling molecules called
A. neurotransmitters
B. nitric oxides
C. G proteins
D. proteases

998. Which of the following is not a type of signaling molecule?
A. Testosterone
B. Insulin
C. Thyroxin
D. Adenylate cyclase

999. Reverse transcripase from HIV does not
A. uses RNA as a template
B. has a 5′ to 3′ polymerase activity
C. has a 3′- 5′ exonuclease activity
D. requires a primer

1000. Which of the following amino acids can interact with the DNA or RNA nucleotide bases via hydrogen bonding?
A. Asn and Gln
B. Cys and Met
C. Lys and Leu
D. Ile and Val