Multiple Choice
During which phase of meiosis does crossing over between homologous chromosomes occur?
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4. Genetic Mapping and Linkage
Crossing Over and Recombinants
Multiple Choice
During meiosis I, what exactly is exchanged during crossing over between homologous chromosomes to produce recombinant chromatids?
A
Segments of DNA between non-homologous chromosomes
B
The spindle fibers attached to kinetochores
C
Corresponding segments of DNA between non-sister chromatids of homologous chromosomes
D
Entire sister chromatids between the two chromatids of the same chromosome
Verified step by step guidance1
Understand that crossing over occurs during prophase I of meiosis, where homologous chromosomes pair up closely in a process called synapsis.
Recognize that each homologous chromosome consists of two sister chromatids, so there are four chromatids in total (a tetrad) involved in crossing over.
Identify that crossing over involves the exchange of genetic material between non-sister chromatids of homologous chromosomes, not between sister chromatids or non-homologous chromosomes.
Note that the exchanged material consists of corresponding segments of DNA, meaning the same loci are involved on each chromatid, ensuring genetic information is swapped accurately.
Conclude that this exchange produces recombinant chromatids, which have a new combination of alleles different from the original chromatids, increasing genetic diversity.
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