Biological Principles 1 -- HW#1

1.  Chromosomes are composed of sister chromatids at what stage of the cell cycle? G2

2. Prophase: chromosomes condense, become visible, nuclear membrane dissolves
    Metaphase: chromosomes line up in the center
    Anaphase: sister chromatids separate
    Telophase: chromosomes de-condense, 2 new nuclear membranes

3. Interphase: G1, G2, S

4. Cell prepares for cell division: G2

5. At what stage do the homologous chromosomes pair up? Prophase 1

6. At what point in meiosis does the chromosome number get reduced to haploid? Anaphase 1

7. At what stage do sister chromatids separate? Anaphase 2

8. At what stage do homologous pairs separate? Anaphase 1

9. At what stage in meiosis does crossing over occur? Prophase 1

10. If a cell containing 12 chromosomes undergo mitosis, the daughter cell will each have how many chromosomes? 12

11. If a cell containing 12 chromosomes undergo meiosis, the daughter cells will have how many chromosomes? 6

12. After a cell completes mitosis and cytokinesis, how many daughter cells will there be? 2

13. After a cell completes meiosis and cytokinesis, how many daughter cells will there be? 4

14. Cells derived from a meiotic division are NOT genetically identical.

15. Cells derived from a mitotic division are genetically identical.

16. Color blindness in humans show X linked recessive inheritance. If a color blind woman marries a man with normal vision, what would you expect? 50% normal female, 50% blind male

17. How many different gametes could a tri-hybrid make? 2^n : 2^3 : 8

18. How many different gametes could a tetra-hybrid make? 2^n : 2^4 : 16

19. Mabel's sister died of cystic fibrosis as a child. Mabel does not have the disease, neither the parents. Mabel's husband is normal. Frequency of cystic fibrosis allele is one in fifty. Mabel is pregnant with first child. What probability the child has cystic fibrosis?
Both parents are heterogenous. Sister is the 1/4 chance of homozygous recessive. Mabel is the 2/3 chance of heterozygous. Both Mabel and her husband are heterozygous. Child has 1/4 chance of cystic fibrosis.