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Genetics problem set

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1. Diagram the process of meiosis using the four chromosomes given below.

2. A father has dimples, the mother does not have dimples, and one of their three children have dimples but the other two do not. Dimples (D) are dominant over no dimples (d). Give the probable genotypes of all five persons concerned.

3. Explain the process you would use to tell if an F2 seed that appeared to have the dominant phenotype was homozygous dominant or heterozygous.

4. Both the husband and wife have normal vision. The wife gives birth to a color-blind daughter. What can you deduce about the girl's parentage? Explain why.

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1. Diagram the process of meiosis using the four chromosomes given below.

Meiosis is the process by which gametes are formed. Unlike in mitosis 4 haploid cells are produced. However, the parts of the cycle are the same albeit slightly different. In our imaginary cell with 4 chromosomes (A1, A2, B1, B2) the letters indicate homologous chromosomes.

Meiosis I
S phase- the DNA content of the cell is duplicated.
A1,A2,B1,B2 -----> A1,A1,A2,A2,B1,B1,B2,B2

Prophase I- nuclear envelop break down occurs and chromosomes condense.

Metaphase I- homologous chromosomes line up on the metaphase plate.

Anapahse I- homologous chromosomes move towards opposite poles.
A1A1 A2A2
B1B1 B2B2

Telophase I- homologous chromosomes are segregated to opposite poles.
A1A1 A2A2
B1B1 B2B2

Cytokinesis I- cell division occurs.

Meiosis II
Daughter cells divide again ...

Solution Summary

Detailed answers with references for 4 questions regarding inheritance of dominant negative alleles.