Recombination frequencies
a. arise from completely random genetic exchange.
b. are the same for all genes.
c. decrease with distance.
d. are the same for cis and trans heterozygotes.
That doesn't help.
To determine the correct option among a, b, c, and d for the question about recombination frequencies, we need to understand what recombination frequencies are and how they behave.
Recombination frequencies, also known as genetic recombination, refer to the likelihood of two specific genes on the same chromosome undergoing a genetic exchange during cell division. This phenomenon is the result of crossing over, where sections of DNA are exchanged between homologous chromosomes.
Now, let's go through each option to evaluate its accuracy:
a. Arise from completely random genetic exchange:
This option is partially correct. Recombination frequencies do arise from genetic exchange, but it is not completely random. The exchange occurs between specific genes during the formation of gametes. Therefore, option a is incorrect.
b. Are the same for all genes:
This option is incorrect. Recombination frequencies vary among different genes. The likelihood of recombination is influenced by factors such as the distance between genes and the presence of genetic markers. Therefore, option b is incorrect.
c. Decrease with distance:
This option is correct. Recombination frequencies generally decrease with increasing physical distance between genes on a chromosome. This phenomenon is known as the genetic linkage. Genes that are closer together have a lower chance of being separated during crossing over. Therefore, option c is correct.
d. Are the same for cis and trans heterozygotes:
This option is incorrect. Cis and trans heterozygotes refer to two different arrangements of alleles on homologous chromosomes. Recombination frequencies can vary depending on these arrangements. Therefore, option d is incorrect.
In summary, the correct answer is option c: Recombination frequencies decrease with distance.