Meiosis and Genetic Variation
Meiosis occurs in a series of different phases and creates genetically unique reproductive cells. One of the advantages of meiosis is that it results in genetic variation, thus creating genetically unique reproductive cell types. Genetic variation occurs due to the process of crossing over in which homologous chromosomes exchange genetic materials through the chiasmata. It involves the exchange of segments of chromosomes between non-sister chromatids.
Which process helps make meiotic cells genetically different and occurs during prophase I, but not during prophase II?
A. Fertilization
B. Independent assortment
C. Crossing over
D. Chromosome replication
Which process helps make meiotic cells genetically different and occurs during prophase I, but not during prophase II? Answer: Crossing overExplanation: Meiosis is the type of cell division that originates haploid gametes from a diploid germline cell. Daughter cells not only possess half of the chromosomes than the mother cell but also the genetic composition of the chromosomes is different. The above is a consequence of the crossing over that generates recombination of DNA. Crossing over occurs when two homologous chromosomes break and exchange fragments of genetic material. This process occurs within the prophase 1 in meiosis 1, specifically in the pachytene phase. The exchange of genetic material between homologous chromosomes generates recombination of alleles. This causes that the genetic composition of the daughter cells chromosomes is different from the genetic composition of the mother cell chromosomes. In other words, a chromosome that initially (in the mother cell) has alleles inherited exclusively from the father, will have alleles from the mother in the gamete.