1. Genes, Alleles, and meiosis
Study Guide

2. Compare and contrast mitosis and meiosis.
2 identical diploid cells
4 unique haploid cells
one duplication of DNA, one division
one duplication, two divisions
a form a asexual reproduction
1st stage in sexual reproduction

3. How are human egg cells similar to human sperm cells?
both are haploid

4. combinations different from the original
How many chromosomes does a cell have after meiosis (as compared to a parent cell)?
½ , with gene
combinations different from
the original

5. What happens during oogenesis in humans?
Meiosis in females producing 3 inactive polar bodies and one egg cell

6. What is the diploid number of chromosomes in a human cell?46

7. A sex cell (sperm cell or egg cell)
Define gamete.
A sex cell (sperm cell or egg cell)

8. Define zygote.
Single cell formed when the egg and sperm cell unite during fertilization

9. If an organism has 20 chromosomes for his normal diploid number, then how many chromosomes will it have after meiosis? 10

10. Describe the process of fertilization.
Sperm cell and egg cell unite to form a zygote

11. What happens in the process of “crossing over?”
chromatids of the homologous chromosomes cross over one another and crossed sections exchange

12. Define Heredity:
passing of characteristics from parent to offspring

13. What happens to the diploid number of chromosomes that an organism has after it undergoes meiosis?
It is cut in half

14. What is the chromosome arrangement for the picture above?
(n + n  2n) Fertilization

15. Complex organisms produce gametes (egg and sperm) that unite during fertilization, forming a single cell known as _______.
Zygote

16. The picture above demonstrates what concept?
fertilization

17. The picture above demonstrates what concept?
Crossing-over

18. The picture shown above demonstrates what concept?
meiosis

19. Different forms of a gene that determine traits
What is an allele?
Different forms of a gene that determine traits

20. How is prophase I of meiosis different from prophase of mitosis?
Prophase I of meiosis has:
crossing over, which shuffles chromosomes between homologs
Formation of tetrads(pairs of homologous chromosomes)

21. Separating paired homologous chromosomes occurs during what phase?
Anaphase1

22. In meiosis I, what happens to the total number of chromosomes in the cell?
It is cut in half

23. Which stage of meiosis, I or II, is more similar to mitosis
Which stage of meiosis, I or II, is more similar to mitosis? How is it different?
Meiosis II is more similar to mitosis- both separate duplicated chromosomes

24. Crossing over in prophase I shuffles chromosomes between homologs
How is the genetic variation seen in gene pools of various organisms best explained?
Crossing over in prophase I shuffles chromosomes between homologs
anaphase II separates duplicated chromosomes to 4 cells which then contain unique combinations of alleles

25. In mitosis, duplicated chromosomes divide and each of the two cells produced contain a full set of the duplicated genetic material. What is contained in the two cells produced at the end of meiosis I? Meiosis II?
Meiosis I- half of the homologous chromosome pairs that are now unique are randomly sorted to the two cells produced; the chromosomes remain duplicated Meiosis II- duplicated chromosomes are separated to produce 4 cells containing unique allele combinations

26. Sister chromatids separate to different daughter cells at the end of meiosis II. Does this change the chromosome number from the number in each cell at the end of meiosis I?
No, chromosome number is the same because it is duplicated chromosomes that are separated