Biochemistry Practice Test 5

1. SH₂ domain specifically binds to _____________

Phosphorylated tyrosine residues

GDP

Phosphorylated serine residues

Ca⁺²

2. When visual stimulus reaches receptors in retina of eye, first process involving absorption of physical energy by receptors is?

Coding

Transduction

Adaptation

Reception

3. Receptor proteins that indirectly activate enzymes that generate intracellular second messengers are _____________

Steroid receptors

Serpentine receptors

Adhesion receptors

Receptor enzymes

4. At which cell cycle checkpoint, cell cycle is halted if cell’s DNA is damaged?

G₁ - S

G₀ - G₁

S - G₂

G₂ - M

5. Which drug is used to terminate early pregnancies?

RU486

Glucophage

Metformin

Victoza

6. Which of the following statements is false about a ligand-gated ion channel receptor?

They consist of five glycoproteins

Differences in membrane potential affect whether the channel receptors are open or close

They are present in the cell membrane

Neurotransmitters can act as the chemical messengers for these channels

7. Programmed cell death is termed as ___________

Metastasis

Mitotic termination

Apoptosis

Proliferation

8. Which out of the following statements is true about gene regulation in bacteria?

Enhancers commonly regulate transcription

Activator proteins bind near promoters and increase the efficiency of transcription

Genes with related functions are often grouped together and have a single start codon

Repressor protein blocks transcription by binding to operator sequence

9. Scaffold protein in insulin signal transduction ___________

KSR

AKAP

MEKK1

IRS-1

10. Which of the following is not a downstream component?

MEK

ERK

PIP3

Ras