Final answer:
Crossing-over, a key process during meiosis, involves homologous chromosomes exchanging genetic material to form recombinant chromosomes. This process enhances genetic diversity among offspring, giving rise to unique genetic combinations in gametes. The outcome of meiosis is four genetically distinct haploid cells from one diploid cell.
Step-by-step explanation:
Process of Crossing-Over During Meiosis
Crossing-over is a crucial event in meiosis, specifically during prophase I, which is the first stage of the first meiotic division. During prophase I, homologous chromosomes (each comprising two sister chromatids) pair up closely in a process known as synapsis. At this point, non-sister chromatids from each homologous pair might exchange segments of genetic material. This exchange occurs at points called chiasmata (singular: chiasma) and results in genetic recombination. The outcome of crossing-over is recombinant chromosomes that have a mix of alleles from both parents.
Importance of Crossing-Over
The importance of crossing-over cannot be understated. It serves as a source of genetic diversity among offspring. Because the chromatids after crossing-over are not identical, when they go on to Meiosis II and separate into different gametes, they carry different combinations of alleles. This ensures that the offspring resulting from sexual reproduction have a unique set of genetic information, distinct from their parents and siblings. This genetic variation is fundamental to the process of evolution and the ability of populations to adapt to changing environments.
Outcome of Meiosis
Meiosis culminates in the production of four haploid cells from one diploid cell. Each haploid cell has half the number of chromosomes as the original diploid cell and is genetically unique due to the events of crossing-over and independent assortment.
Complete question is as follows :
a. Describe the process of crossing-over during meiosis.
b. Explain the importance of crossing-over.