From a piece of blank paper, cut out three sets of four cigar-shaped structures (a total of 12 structures). These will represent chromatids. Be sure each member of a set of four chromatids has the same length and girth. In set one, label two chromatids 'A' and two chromatids 'a.' Cut each of these chromatids about halfway across near their midpoint and slide the two 'A' chromatids together at the cuts to form a single set of attached sister chromatids. Do the same for the 'a' chromatids. In the second set of four chromatids, label two 'B' and two 'b.' Cut and slide these together as you did for the first set, joining the 'B' chromatids together and the 'b' chromatids together. Repeat this process for the third set of chromatids, labeling them as 'D' and 'd.' You now have models for three pairs of homologous chromosomes, for a total of six chromosomes. What are the genotypes of the daughter cells?

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Accepted Answer

Hey, everyone. Let's take a look at this question together. A cell consisting of a homologous pair of chromosomes having the genotype that is heterozygous. For all three genes undergoes meiosis. During meiosis, the cell undergoes two rounds of division resulting in the production of four haploid daughter cells with half the number of chromosomes as the parent cell. Which of the following could be a possible gammy produced by the parent cell. Is it answer choice. A dominant X dominant Z dominant, Z answer choice B, recessive, X, recessive Y, recessive Y answer choice C dominant X, recessive Y dominant Z or answer choice D, recessive X dominant Z dominant Z. Let's work this problem out together to try to figure out which of the following answer. Choices could be a possible gammy produced by the parent cell. So we have that phenotype where we have a dominant and recessive allele or X Y and Z since it is heterozygous for all three genes, and since it undergoes division where we have those daughter cells that receive one copy of each chromosome from that parent cell, that means that each daughter cell gets one of each allele. So each daughter cell can either have that dominant X or the recessive X A, dominant Y or a recessive Y and a dominant Z or a recessive Z. So each daughter cell gets one X allele, one Y allele and one Z allele. And they also cannot have two of the same type of A. They can only have one of each type, which means they cannot have more than one X Y or Z and they can only have one type of X, one type of Y and one type of Z, which means that answer choice is A B and D can all be eliminated. Since answer choice A has two Z S answer choice B has two Ys and answer choice D has two Zs. So that means that answer choice C dominant, X recessive, Y dominant Z is the correct answer. Since that gammy receives one of each allele and not more than one of each type. Making answer choice C the correct answer. And the only possible Gammy that could be used by the parent cell since each daughter cell gets one copy of the X allele, the Y allele and the Z allele. And they cannot have two of the same types of allele, meaning they cannot have more than one of each type and they only have one X, one Y and one Z, whether it is a dominant or recessive allele. So answer choice C is the correct answer. I hope you found this video to be helpful. Thank you and goodbye.

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Key Concepts

Chromatids and Chromosomes

Homologous Chromosomes

Genotype and Alleles