Question

1. Are sister chromatids identical anymore after crossing over? Explain. 2. Could a karyotype determine if a person will have brown hair?! 3. Why is it so problematic if nondisjunction occurs during meiosis? Think of what would result. 4. You isolate a cell from the liver of a lab animal. After running a diagnostic test, you dis- cover there are 18 chromosomes in the cell. How many gamete combinations could that organism make from random alignment? 5. Would you expect to observe crossing over in the male 23rd pair? Explain. 6. You make a karyotype from a cell and observe that the cell has 10 chromosomes in it. However, upon further observation you are unable to find any homologous pairs. What kind of cell did you likely run a karyotype on? Explain what stage of cell division it likely could be in. 7. Is the 12th chromosomes that you received at conception the same as your great- grandmother's chromosome 12? Use your knowledge from this chapter to answer the question.

Biology 108 Laboratory Manual: Fourth Edition. Follow-Up Questions for Chapter 5 (pg. 87-88)

Answer 1

1. No, the sister chromatids are not identical anymore after crossing over. After crossing over the allele between different chromosome are exchanges and form a different allele in sister chromatids.

2. No, karyotype does not determine the person have brown hair. Karyotype is used to determine the species number and size of the chromosome present in that species. The hair color is determined by gene experssion level not by karyotyping.

3. During meiosis the certain pair of homologous chromosome not able to segregate leads to Non disjunction. So both chromosome pair moves to the same daughter cells and results in a aneuploidy.
Example trisomy 21 (Down syndrome) and monosomy X (Turner syndrome).

4. 2^18 possibilites

5. No, the 23rd chromosome in male is Y chromosome they only have one copy of that.