CELL DIVISION
MEIOSIS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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When the DNA of the diploid cell is copied
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When homologous chromosomes move to opposite ends of the dividing cell during Telophase I
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When spindle fibers move the chromosomes toward the midline of the dividing cell during Metaphase I
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When homologous chromosomes pair and portions of chromatids break off and are exchanged during Prophase I
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Detailed explanation-1: -When homologous chromosomes form pairs during prophase I of meiosis I, crossing-over can occur. Crossing-over is the exchange of genetic material between homologous chromosomes. It results in new combinations of genes on each chromosome.
Detailed explanation-2: -Crossing over is a cellular process that happens during meiosis when chromosomes of the same type are lined up. When two chromosomes-one from the mother and one from the father-line up, parts of the chromosome can be switched. The two chromosomes contain the same genes, but may have different forms of the genes.
Detailed explanation-3: -Crossing Over During prophase of meiosis I, the double-chromatid homologous pairs of chromosomes cross over with each other and often exchange chromosome segments. This recombination creates genetic diversity by allowing genes from each parent to intermix, resulting in chromosomes with a different genetic complement.
Detailed explanation-4: -Crossing over occurs only during prophase I. The complex that temporarily forms between homologous chromosomes is only present in prophase I, making this the only opportunity the cell has to move DNA segments between the homologous pair.
Detailed explanation-5: -When recombination occurs during meiosis, the cell’s homologous chromosomes line up extremely close to one another. Then, the DNA strand within each chromosome breaks in the exact same location, leaving two free ends. Each end then crosses over into the other chromosome and forms a connection called a chiasma.