2. Differences between asexual and sexual reproduction.
3. What are the sexual sources of genetic variations?
1. Meiosis produces cells there differ genetically from their parent cells. Mitosis produces daughter cells that are genetically identical to their parent cell.
Synapsis and crossing over just occur in meiosis, meiosis 1.
At metaphase 1, chromosomes are positioned on the metaphase as pairs of homologs, rather than individual chromosomes, as in metaphase of mitosis.
At anaphase 1 of meiosis, the replicated chromosomes of each homologous pair move toward opposite poles, but the sister chromatids remain attached. In anaphase of mitosis, by contrast, sister chromatids separate.
2. Individuals reproducing asexually transmit %100 of their genes to their progeny, whereas individuals reproducing sexually transmit %50.Single parent/two parents. Asexual reproduction requires only mitosis, but sexual reproduction is involved by meiosis.
3.Independent assortment = The random distribution of maternal and paternal homologues to the gametes. Crossing over is another mechanism that increases genetic variation is the process of crossing over, during which homologous chromosomes exchange genes. Random fertilization is another source of genetic variation in offspring.
5 main facts on this chapter :
. Normal human somatic cells are diploid. They have 46 chromosomes made up of two sets of 23.
. 22 homologous pairs of autosomes, each with maternal and paternal homolog. The 23rd pair is the sex chromosome, determines the sex of the person.
. Three events in sexual reproduction contribute to genetic variation in a population..
. Independent assortment happens in meiosis, crossing over during meiosis I, and random fertilization of egg cells by sperm.
. Meiosis I separates homologous chromosomes, while meiosis II separates sister chromatids.
In this chapter, we learnt about meiosis, its different stages, and differences between meiosis and mitosis. We studied origins of genetic variation among offsprings.
No comments:
Post a Comment