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This is done by one of Mum's chromosomes swapping a segment of DNA with one of Dad's chromosomes. In the first prophase of meiosis (prophase I) each chromosome contains two molecules of DNA. You can see these as the two sister-chromatids of each chromosome. During this prophase, each chromosome pairs with the corresponding chromosome from the other set. In other words, the chromosome 1 from the male parent aligns itself beside chromosome 1 from the female parent, the two copies of chromosome 2 do likewise, and so on. The two copies of one chromosome are called homologous chromosomes.
Each pair of chromosomes is called a bivalent, and consists of four chromatids twisted around each other. At various points along this bivalent, two non-sister chromatids will break at the same locus (point along the DNA) and recombine, so that now a stretch of DNA from Mum has attached to a stretch from Dad, and vice versa. On average, this crossing-over happens three or four times along the length of a chromosome, so that one DNA molecule now consists of alternating segments from each parent. Because no two parents are genetically identical, the recombined DNA has a base sequence that is different from that supplied by either parent. It is like a linear mosaic. The positions of crossing-over are pretty well random, so every time meiosis takes place in one individual novel base sequences are generated.
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What is the exchange of DNA between homologous chromosomes during pro phase of meiosis?
Crossing over or chromosomal crossover.
What happens during meiosis that results in a defect characterized by the deletion of a chromosome?
what happens during meiosis that results in a defect characterized by the deletion of chromosomes
What two factors introduce genetic variation during the process of meiosis?
The two factors that introduce genetic variation during the process of meiosis are independent assortment and chromosomal crossover. These occur during prophase 1 and anaphase 1 of meiosis.
What happens during meiosis during anaphase 1?
The tetrads are pulled apart.
How many times do chromosomes make copies of themselves during meiosis?
Chromosomes make copies of themselves once during meiosis. This occurs during the S phase of interphase, which happens before meiosis I.
Do chromosomes undergo crossover during mitosis?
No, chromosomes do not undergo crossover during mitosis. Crossover, also known as genetic recombination, occurs during meiosis, not mitosis.
How does mitosis involve crossover?
Mitosis does not involve crossover. Crossover, also known as genetic recombination, occurs during meiosis, not mitosis. In meiosis, crossover is the exchange of genetic material between homologous chromosomes, leading to genetic diversity in offspring.
During which phase of meiosis does crossover occur?
Crossover occurs during the prophase I stage of meiosis. This is when homologous chromosomes pair up and exchange genetic material, leading to genetic diversity among the resulting gametes.
Do sex chromosomes crossover during meiosis?
Yes, sex chromosomes can undergo crossover during meiosis, which is the process of genetic recombination that occurs during the formation of gametes. This can result in the exchange of genetic material between homologous chromosomes, leading to genetic diversity in offspring.
What is the exchange of DNA between homologous chromosomes during pro phase of meiosis?
Crossing over or chromosomal crossover.
What happens during meiosis that results in a defect characterized by the deletion of a chromosome?
what happens during meiosis that results in a defect characterized by the deletion of chromosomes
What happens during synapsis meiosis?
Tetrads form
What two factors introduce genetic variation during the process of meiosis?
The two factors that introduce genetic variation during the process of meiosis are independent assortment and chromosomal crossover. These occur during prophase 1 and anaphase 1 of meiosis.
What happens during meiosis during anaphase 1?
The tetrads are pulled apart.
How many times do chromosomes make copies of themselves during meiosis?
Chromosomes make copies of themselves once during meiosis. This occurs during the S phase of interphase, which happens before meiosis I.
Genes that r closer together are more likely to be separated by a crossover event in meiosis is that falso?
Yes, that statement is false. Genes that are closer together on a chromosome are actually less likely to be separated by a crossover event during meiosis, while genes that are farther apart are more likely to undergo crossing over.
Occurs during prophase 1 of meiosis?
Crossing over between homologous chromosomes occurs during prophase 1 of meiosis. This process involves the exchange of genetic material between homologous chromosomes, leading to genetic diversity among the offspring.
