Final Molecular Biology Exam Review

Cyclic AMP (cAMP) is a small molecule that associates with its binding site with a high degree of specificity. Which types of noncovalent interactions are the most important for providing the

"hand in a glove" binding of CAMP?

A. hydrogen bonds

B. electrostatic interactions

C. van der Waals interactions

D.hydrophobic interactions

A. hydrogen bonds

Which of the following best describes the mechanism by which chromatin-remodeling complexes "loosen" the DNA wrapped around the core histones?

a. They remove histone H1 from the linker DNA adjacent to the core histone octamer.

b. They chemically modify core histones to alter the affinity between the histone octamer and the DNA.

c. They chemically modify the DNA, changing the affinity between the histone octamer and the DNA.

d. They use energy derived from ATP hydrolysis to change the relative position of the DNA and the core histone octamer.

d. They use energy derived from ATP hydrolysis to change the relative position of the DNA and the core histone octamer.

The chromosomes we typically see in images are isolated from mitotic cells. These mitotic chromosomes are in the most highly condensed form. Interphase cells contain chromosomes that are less densely packed and

A. share the same nuclear territory as their homolog.

B. are completely tangled with other chromosomes.

C. are restricted to the nucleolus.

D. occupy discrete territories in the nucleus.

D. occupy discrete territories in the nucleus.

The Figure shows a ribose sugar. The part of the ribose sugar that is different from the deoxyribose sugar used in DNA is pointed to by which arrow?

A.1

B.6

C.4

D.5

D.5

G-proteins are regulated by binding vs. hydrolysis of GTP. What protein will bind to G-proteins and get them to exchange GDP for GTP.

A. GEF

B. G-protein kinase

C. G-protein phosphatase

D. GAP

A. GEF

Which of the following statements is true?

A. The difference in proton concentration across the inner mitochondrial membrane has a much larger effect than the membrane potential on the total proton-motive force.

B. The pH in the mitochondrial matrix is higher than the pH in the intermembrane space.

C. The proton concentration gradient and the membrane potential across the inner mitochondrial membrane tend to work against each other in driving protons from the intermembrane space into the matrix.

D. The NADH dehydrogenase complex does not pump protons across the membrane.

B. The pH in the mitochondrial matrix is higher than the pH in the intermembrane space.

In step 4 of the citric acid cycle, the reduction of NAD+ to NADH is coupled to the generation of CO2 and the formation of a high-energy thioester bond. Which molecule provides the sulfhydryl group necessary to form the thioester bond?

A. acetyl CoA

B. pyruvate

C. CoA

D. cysteine side chain in the catalytic pocket

C. CoA

Active transport requires the input of energy into a system so as to move solutes against their electrochemical and concentration gradients. Which of the following is NOT one of the common ways to perform active transport?

A. K+-coupled

B. ATP-driven

C. light-driven

D. Na+-coupled

A. K+-coupled

What category of membrane transport are channels a part of?

A. facilitated diffusion

B. diffusion

C. secondary active transport

D. active transport

A. Facilitated Diffusion

Which of the following situations would facilitate the process of exon shuffling?

A. shorter introns

B. exons that code for more than one protein domain

C. introns that contain regions of similarity to one another

D.a haploid genome

C. Introns that contain regions of similarity to one another

Your friend works for a biotechnology company and has discovered a drug that blocks the ability of Ran to exchange GDP for GTP. What is the most likely effect of this drug on nuclear export?

a. Nuclear export receptors would interact irreversibly with the nuclear pore fibrils.

b. Nuclear export receptors would be unable to release their cargo in the nucleus.

c. Nuclear export receptors would be unable to bind cargo.

d. Nuclear export receptors would be unable to enter the nucleus.

C. Nuclear export receptors would be unable to bind cargo.

Which of the following statements about nuclear transport is true?

A. Nuclear pores contain proteins with disordered segments that fill the channel and allow small water-soluble molecules to pass through in a nonselective fashion.

B. Nuclear import receptors bind to proteins in the cytosol and bring the proteins to the nuclear pores, where the proteins are released from the receptors into the pores for transit into the nucleus.

C. Nuclear pores are made up of many copies of a single protein.

D. mRNAs and proteins transit the nucleus through different types of nuclear pores.

A. Nuclear pores contain proteins with disordered segments that fill the channel and allow small water-soluble molecules to pass through in a nonselective fashion.

A cargo molecule is brought into a cell via receptor-mediated endocytosis. Which of the following factors causes the receptor to release its cargo molecule into the lumen of the endosome?

A. proteolytic digestion of the receptor

B. competitive inhibitors

C. high salt concentrations

D. acidic pH

D. Acidic pH

Which of the following statements about molecular switches is

FALSE?

A. Protein kinases transfer the terminal phosphate from ATP onto a protein.

B. Serine/threonine kinases are the most common types of protein kinase.

C. Phosphatases remove the phosphate from GTP on GTP-binding proteins, turning them off.

D. A GTP-binding protein exchanges its bound GDP for GTP to become activated.

C. Phosphatases remove the phosphate from GTP on GTP-binding proteins, turning them off. (False)

In which cellular location would you expect to find ribosomes translating mRNAs that encode ribosomal proteins?

A. the nucleus

B. on the rough ER

C. in the cytosol

D. in the lumen of the ER

C. In the cytosol

In photosynthetic bacteria, where are chlorophyll-like pigments located?

a. in folded regions of the cell wall

b.in the chloroplast membranes

c.in the central vacuole

d.in in-folded regions of the plasma membrane

D. In in-folded regions of the plasma membrane

Which of the following components would be most likely to enhance the assembly of the nuclear lamina?

a. a concentrated salt solution that is 10 times the concentration normally found in the nucleoplasm

b. protein kinase inhibitors

c. ATP

d. phosphatase inhibitors

B. Protein Kinase Inhibitors

Which of the following descriptions is consistent with the behavior of a cell that lacks a protein required for a checkpoint mechanism that operates in G2?

a. The cell would be unable to enter G2.

b. The cell would pass through M phase more slowly than normal cells.

c. The cell would enter M phase under conditions when normal cells would not.

d. The cell would be unable to enter M phase.

C. The Cell would enter M Phase under conditions when normal cells would not.

Sister chromatid separation occurs because __________ are destroyed by the APC/C.

a. cohesins

b. kinetochores

c. securins

d. condensins

C. Securins

Which of the following genetic changes would not convert a proto-oncogene into an oncogene?

A. A mutation that introduces a stop codon immediately after the codon for the initiator methionine.

B. A mutation within the coding sequence that makes the protein hyperactive.

C. An amplification of the proto-oncogene, causing overproduction of the normal protein.

D. A mutation in the promoter of the proto-oncogene, causing the normal protein to be expressed at an abnormally high level.

A. A mutation that introduces a stop codon immediately after the codon for the initiator methionine.

Which of the following statements about tumor suppressor genes is false?

A. Gene amplification of a tumor suppressor gene is less dangerous than gene amplification of a proto-oncogene.

B. Cells with one functional copy of a tumor suppressor gene will usually proliferate faster than normal cells.

C. Homozygous inactivation of a tumor suppressor gene leads to enhanced cell survival and proliferation.

D. Individuals with only one functional copy of a tumor suppressor gene are more prone to cancer than individuals with two functional copies of a tumor suppressor gene.

B. Cells with one functional copy of a tumor suppressor gene will usually proliferate faster than normal Cells.