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What aspects separate single-crossover events from double-crossover events?
A)Single-crossover events result in one-way displacement of chromosomal content from one chromosome to another, while double-crossover events reverse this one-way displacement resulting in chromosomes identical to the pre-crossover chromosomes.
B)Single-crossover events occur during mitosis when a cell splits into two cells, while double-crossover events occur during meiosis when a cell splits into four cells.
C)Single-crossover events affect only the ends of chromosome arms, while double-crossover events affect segments in the middle of chromosome arms.
D)Single-crossover events affect one arm of each chromosome, while double-crossover events affect two arms of each chromosome.
Answer Explanation:
C is correct. A double-crossover event is one in which chromosomal arms of homologous chromosomes cross over in two different places along the arm. This results in a section in the middle of each chromosome being exchanged.
A: A double-crossover event occurs in two different places along the chromosome arm, resulting in a segment exchange, not a reversal of the original crossover.
B: Crossover events only occur during meiosis, not during mitosis.
D: Both single- and double-crossover events will only affect one arm of each chromosome.
I am a little confuse as to why A could not be the correct answer. If someone could help that would be appreciated.
Thanks!!!!
A)Single-crossover events result in one-way displacement of chromosomal content from one chromosome to another, while double-crossover events reverse this one-way displacement resulting in chromosomes identical to the pre-crossover chromosomes.
B)Single-crossover events occur during mitosis when a cell splits into two cells, while double-crossover events occur during meiosis when a cell splits into four cells.
C)Single-crossover events affect only the ends of chromosome arms, while double-crossover events affect segments in the middle of chromosome arms.
D)Single-crossover events affect one arm of each chromosome, while double-crossover events affect two arms of each chromosome.
Answer Explanation:
C is correct. A double-crossover event is one in which chromosomal arms of homologous chromosomes cross over in two different places along the arm. This results in a section in the middle of each chromosome being exchanged.
A: A double-crossover event occurs in two different places along the chromosome arm, resulting in a segment exchange, not a reversal of the original crossover.
B: Crossover events only occur during meiosis, not during mitosis.
D: Both single- and double-crossover events will only affect one arm of each chromosome.
I am a little confuse as to why A could not be the correct answer. If someone could help that would be appreciated.
Thanks!!!!