Given the gene sequence ABCDE, crossing over should occur most frequently between_____.
a. A-B
b.) B-C
c.) A-E
d.) A-D
e.) A-C
PLEASE explain how you got the answer thanks!
To determine which crossover is most likely to occur, we need to understand the concept of crossing over during genetic recombination. Crossing over is the exchange of genetic material between paired chromosomes during meiosis.
In the given gene sequence ABCDE, we assume that each letter represents a different gene locus. During crossing over, chromosomes exchange segments of DNA at these loci.
To determine the crossover frequency, we need to observe the distribution of crossover events among the gene loci. In a given gene sequence, crossover frequency between two loci depends on the distance between them on the chromosome. The closer two loci are, the more likely they are to be involved in a crossover event.
Let's analyze the options to find the most likely crossover pair:
a) A-B: This option represents the crossover between locus A and locus B. Since these two loci are adjacent in the given gene sequence, it is reasonable to assume that crossing over between A and B may occur more frequently.
b) B-C: This option represents the crossover between locus B and locus C. Again, as B and C are adjacent in the sequence, this crossover is a possibility.
c) A-E: This option represents the crossover between locus A and locus E. However, there are multiple loci between A and E (B, C, and D). Since crossing over events generally occur more frequently between adjacent loci, this option is less likely.
d) A-D: This option represents the crossover between locus A and locus D. Similar to option c, there are multiple loci between A and D (B and C). Hence, this option is less likely.
e) A-C: This option represents the crossover between locus A and locus C. Since there is only one locus (B) between A and C, this crossover is a possibility.
Based on the analysis, option a (A-B) and option e (A-C) seem to be the most likely crossover events. However, since loci A and B are adjacent to each other, it is more probable that crossover would occur between these two loci (A-B). Therefore, the correct answer is a. A-B.
It is crucial to note that the actual frequency of crossovers depends on various factors such as the genetic distance between loci, the presence of recombination hotspots, and the specific biological context.