For crossing over to occur, homologous chromosomes must align precisely early in prophase I so that nonsister chromatids can exchange corresponding segments of DNA. … As a result of crossing over, sister chromatids are no longer identical to each other.
Are sister chromatids still identical after crossing?
Explanation: When chromatids “cross over,” homologous chromosomes trade pieces of genetic material, resulting in novel combinations of alleles, though the same genes are still present. … If crossing over did not occur until sometime during meiosis II, sister chromatids, which are identical, would be exchanging alleles.
Is it true that crossing over occurs at the ends of chromosomes rather than near the centromeres?
Individual chromosomes, each composed of sister chromatids, align in the center of the cell. … Crossing over occurs at the ends of chromosomes, rather than near the centromeres, because segments of DNA near the centromeres cannot break and rejoin easily. 3.
What would happen if crossing over occurred between sister chromatids?
What would happen if crossing over occurred between sister chromatids? Nothing would happen because sister chromatids are genetically identical or nearly identical. … Daughter cells would not be genetically identical, and they could contain two copies of the same allele.
Do sister chromatids separate during meiosis?
Meiosis II is the second division of meiosis. It occurs in both of the newly formed daughter cells simultaneously. Meiosis II is similar to Mitosis in that the sister chromatids are separated.
How does crossing over affect the observed outcomes?
How does crossing-over affect the observed outcomes? … (1 point) Through the process of crossing over, the vestigial wings and black body traits are able to be inherited individually or together. The closer the two genes are on the chromosome, the more likely that they will be inherited together.
Does crossing over increase genetic variation?
Genetic variation is increased by meiosis
Recombination or crossing over occurs during prophase I. Homologous chromosomes – 1 inherited from each parent – pair along their lengths, gene by gene. … Independent assortment is the process where the chromosomes move randomly to separate poles during meiosis.
When can Nondisjunction occur choose the best answer?
When can nondisjunction occur? Choose the best answer. Nondisjunction errors can occur in meiosis I, when homologous chromosomes fail to separate, or in either mitosis or meiosis II, when sister chromatids fail to separate.
Are gametes different in identical twins?
The gametes produced in meiosis aren’t genetically identical to the starting cell, and they also aren’t identical to one another. … This diversity of possible gametes reflects two factors: crossing over and the random orientation of homologue pairs during metaphase of meiosis I.
Do identical twins go through mitosis?
Identical twins is where the already-fertilized embryo splits into two, each becoming a separate individual, growing by mitosis.