Problem:

Question 1: Which of the following is NOT involved in cell signalling?

A) phospholipids

B) calcium ions

C) sugar phosphates

D) magnesium ions

E) cyclic nucleotides

Question 2: Which of the following molecules can convey a signal from certain hormone receptors to an effector enzyme?

A) tyrosine kinase

B) adenyl cyclase

C) G protein

D) glycogen phosphoylase

E) arrestin

Question 3: Which of the following biochemical activities is involved in the control of the cell cycle?

A) protein phosphorylation

B) mRNA processing

C) protein glycosylation

D) ATP hydrolysis

E) protein folding

Question 4: An electron micrograph shows cytoplasmic filaments that converge on a localized, darkened region of the plasma membrane. This structure probably:

A) is involved in transport of secretory vesicles

B) regulates traffic in and out of the nucleus

C) is involved in cell-cell interaction

D) is responsible for contraction of the cell

E) is involved in cell division

Question 5: You've discovered a novel protein that is associated with cylindrical filaments in the cytoplasm. Inhibition of this protein with antibody resulted in fragmentation of the golgi body. From this you conclude that the protein is probably:

A) similar to myosin

B) a protein in phosphatase

C) a motor protein of microtubules

D) a regulator intermediate filament assembly

E) a G protein

Provide the correct answer and justification for your choice.