GRE Subject Test: Biochemistry, Cell, and Molecular Biology : Help with Recombination

Study concepts, example questions & explanations for GRE Subject Test: Biochemistry, Cell, and Molecular Biology

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Example Questions

Example Question #1 : Help With Recombination

Which of the following methods results in no loss of information when repairing a double-stranded DNA break?

Possible Answers:

Recombination

Non-homologous end joining

Translesion synthesis

There is no way to prevent loss of information from a double-stranded break in DNA

Correct answer:

Recombination

Explanation:

Recombination between homologous chromosomes is one of the only methods for repairing double-stranded breaks in DNA without losing information. This method only works, however, if there is an extra copy of the same DNA in the cell (i.e. on a homologous chromosome). Recombination is not possible prior to the S phase of the cell cycle, during which DNA is replicated.

Non-homologous end joining results in the deletion of a few base pairs, which can be problematic if done in the coding region of a gene. Translesion synthesis actually has nothing to do with double-stranded breaks, and refers to a method of accurately synthesizing DNA over mutations (such as thymine dimers) by using specialized polymerases.

Example Question #2 : Help With Recombination

Genetic recombination occurs during __________ of meiosis I, and genetic information is exchanged between __________.

Possible Answers:

metaphase . . . crossover gametes

metaphase . . . non-sister chromatids

prophase I . . . non-sister chromatids

prophase I . . . sister chromatids

anaphase . . . sister chromatids

Correct answer:

prophase I . . . non-sister chromatids

Explanation:

Recombination occurs between homologous chromosomes, not the sister chromatids, and this happens in prophase I of meiosis. 

All GRE Subject Test: Biochemistry, Cell, and Molecular Biology Resources

1 Diagnostic Test 201 Practice Tests Question of the Day Flashcards Learn by Concept
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