2. Consider a diploid organism with a haploid complement of 4 chromosomes in its gametes. At meiotic prophase I, how many total chromosomes copies will be present in a cell? a. 16; 4 pairs of homologous chromosomes and 2 sister chromatids per chromosome b. 8; 4 pairs of homologous chromosomes c. 12; 4 pairs of homologous chromosomes and their haploid complement d. 4; 1 complete set of chromosomes
Q1) During Anaphase I, homologous chromosomes (one from each pair) are pulles to opposite poles and during Anaphase II, the sister chromatids of each chromosome are pulled towards opposite poles. Crossing over occurs during prophase I and synapsis also occurs during prophase I. therefore option and b are correct.
Q2) The haploid complement (n) of the organism is 4.
Therefore the number of chromosomes in its diploid cell = 2n = 2 x4 = 8
At meiotic prophase I, the number of chromosomes in the cell = 8
Since each chromosome has replicated, therefore 16 chromosome copies will be present
4 pairs of homologous chromosomes and two sister chromatids per chromosome.
therefore option a is correct.
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