Chapter 2 Self-check questions

. Although most cancers result from the accumulation of mutations over time, evidence suggests that a single catastrophic event may account for a small number of cancers. Which statement below is false?

Such an event is called chromothripsis.

Evidence for this event includes the identification of a characteristic translocation between two particular chromosomes in a cancer cell.

This event is fairly common for bone cancer.

Three possible mechanisms for this event include ionizing radiation, telomere dysfunction, and/or aborted apoptosis.

. Which of the following intermediates is not formed during radiolysis?

Hydrogen peroxide.

Superoxide radical.

Hydroxyl radical.

Water

. Which one of the following statements is true?

Alkylating agents are commonly created during the cooking of meat.

The hydroxyl radical is a very unreactive molecule.

A short electromagnetic wavelength correlates with low energy radiation.

The depth of transmission of UV light is dependent on the wavelength.

. What unit is used to indicate the amount of biological damage by radiation?

Sieverts.

Grays.

Ionizing potential.

Wavelength.

. Which one of the following pairs of a class of chemical carcinogen and a corresponding example is not correct?

Nitrosamines: created by the reaction of preservatives during the smoking of food.

Polyphenol: epigallocatechin-3-gallate (EGCG).

Alkylating agents: mustard gas.

Aromatic amines: benzo[a]pyrene.

. Which one of the following cancer drugs mimics an endogenous metabolite and interferes with nucleic acid synthesis?

Methotrexate.

Cyclophosphamide.

Doxorubicin.

Vincristine.

. Which of the following DNA repair mechanisms are incorrectly matched to the type of damage they repair?

One step repair: damage caused by alkylating agents.

Base excision repair: bases chemically altered by endogenous mechanisms.

Nucleotide excision repair: replication errors that have escaped editing by polymerases.

Mismatch repair: replication errors that have escaped editing by polymerases.

. UV from the sun is carcinogenic and is the principal cause of skin cancer. Which type of UV light is the most effective carcinogen and what is the most common UV photoproduct?

UVA (W.L. 320-380nm) and pyrimidine-pyrimidone photoproducts.

UVB and pyrimidine-pyrimidone photoproducts.

UVC and cyclobutane pyrimidine dimers.

UVB and cyclobutane pyrimidine dimers.

. Which of the following statements about kataegis is false?

It may be caused by the shattering of a chromosome or chromosomes due to radiation.

The observation of kataegis shakes the conventional view that cancer is caused by the accumulation of mutations over time.

It is small localized regions of hypermutation.

It may be caused by deamination of cytosines to form uracil by a family of cytidine deaminases, called APOBECs.

. Which statement about "synthetic lethal" combinations is false?

Poly (ADP-ribose) polymerase (PARP) inhibitors and tumors with BRCA1/2 mutations is a synthetic lethal combination being tested in clinical trials.

Poly (ADP-ribose) polymerase (PARP) inhibitors block a pathway involved in breast cell proliferation and can be used to treat breast cancer.

Each of the components in a "synthetic lethal" combination alone does not cause a cytotoxic effect. Healthy cells treated with PARP inhibitors are viable because these cells contain a functioning homologous recombination DNA repair pathway.

Olaparib is a poly-(ADP-ribose) polymerase (PARP) inhibitor that has been approved for the treatment of ovarian cancer patients with BRCA1 or BRCA2 mutations.

. Which one of the following is not a risk factor for breast cancer?

Early menarche and late menopause.

Alcohol consumption.

Unprotected sex.

Obesity in postmenopausal women.

. Which of the following is a drug strategy used to target estrogen action for breast cancer?

Monoclonal antibodies such as Herceptin

PARP inhibitors

Alkylating agents

Aromatase inhibitors

. The genome of some cancer cells may contain extrachromosomal DNA (ecDNA) that is characterized by all of the following EXCEPT:

Circular shape

Presence of a centromere

Large size of 100Kb-1.3 Mb

Ability to integrate into the host linear chromosome

. People who have a germline mutation in the hMLH1 gene, have Lynch syndrome and a predisposition to colon cancer. What type of DNA repair is defective?

Mismatch repair

Nucleotide excision repair

Base excision repair

Recombination repair

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