B is the correct answer Crossing over does not occur between genes
Scientists know that a mutation - or alteration - in a particular gene's DNA may contribute to a certain disease. However, it can be very difficult to develop a test to detect these mutations, because most large genes have many regions where mutations can occur. For example, researchers believe that mutations in the genes BRCA1 and BRCA2 cause as many as 60 percent of all cases of hereditary breast and ovarian cancers. But there is not one specific mutation responsible for all of these cases. Researchers have already discovered over 800 different mutations in BRCA1 alone.
The DNA microarray is a tool used to determine whether the DNA from a particular individual contains a mutation in genes like BRCA1and BRCA2. The chip consists of a small glass plate encased in plastic. Some companies manufacture microarrays using methods similar to those used to make computer microchips. On the surface, each chip contains thousands of short, synthetic, single-stranded DNA sequences, which together add up to the normal gene in question, and to variants (mutations) of that gene that have been found in the human population.
Condensation is the answer. Hope that helps, happy holidays!
Answer:
The correct answer is genetic drift.
Explanation:
The phenomenon of changing the frequency of an allele in a specific population with time is known as genetic drift. The mentioned gene variation or the modification in the frequency of the allele is required to take place abruptly so that the phenomenon of genetic drift can take place. The environmental factors do not play an essential role in the phenomenon of genetic drift to take place.
The process of genetic drift occurs generally due to random sampling of organisms, it illustrates the random change in the number of gene variants within a population. When the existence of the different forms of a gene, that is, alleles, enhances or reduces by chance with time within a population, the phenomenon of genetic drift occurs. Thus, the mentioned case is an illustration of genetic drift.
CROSSING OVER
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