Meiosis Review
Define the following words:
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Homologous: Chromosomes same size and shape and same genes but different alleles
(versions of genes).
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Haploid: Half the original chromosomes found in a sperm or egg (gamete) one of the
homologous chromosome
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Diploid: Full amount of chromosomes/both homologous chromosomes
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Crossing Over: exchange of segments of dna between homologous chromosomes
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Law of Independent Assortment: homologous chromosomes line up randomly and go to
different sides each time a cell divides
Describe what happens during each of the phases below:
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Interphase: Chromosomes replicate
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Prophase I: Chromosomes condense
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Metaphase I: Homologous chromosomes line up at the equator next to one another
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Anaphase I: Homologous chromosomes get pulled to the poles
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Telophase I: Cleavage begins to occur
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Prophase II: Two daughter cells are formed
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Metaphase II: Chromosomes line up in the middle
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Anaphase II: Sister chromatids separate and move towards poles
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Telophase II: Cleavage begins
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Cytokenesis II: 4 genetically unique gametes (sperm or egg) are formed
In the space below, draw what is happening based on the description provided.
Interphase: Each chromosome
makes a copy of itself
Prophase I: Homologous
chromosomes cross-over at
the A/a gene and the E/e
gene.
End of Cytokenesis I:
Two new cells are
made, having
different
chromosomes
compared to the
original cell.
End of Cytokenesis
II: Each cell
contains half the
amount of
chromosomes
compared to the
original cell and all
4 cells are
genetically unique.
_______ 1. In humans, body cells have ____ total chromosomes and sex cells have ____ total
chromosomes.
a. 46, 46
b. 23, 46
c. 23, 23
d. 46, 23
_______ 2. What are homologous chromosomes? Choose all that apply.
a. Chromosomes of the same size.
c. A pair of chromosomes with different genes.
b. Chromosomes of the same shape.
d. A pair of chromosomes, one from each parent.
_______ 3. At the end of meiosis, how many cells are created?
a. 1
b. 2
c. 3
d. 4
_______ 4. What kind of sex cells do males and females make?
a. Males make eggs, females make sperm c. Males and females both make egg cells
b. Males make sperm, females make eggs d. Males and females both make sperm cells
5. Explain why crossing over is so important for sex cells.
Because it creates genetically unique sex cells
6. What is the difference between diploid and haploid cells?
Diploid have both sets of homologous chromosomes and haploids have only one set of
chromosomes. Diploid has a full set of chromosomes. Haploid has only half the chromosomes.
Write the stage each cell is in below. Do not forget to write I or II.
7. _________Telophase 1________________
8. ___Metaphase 2___
9. _____prophase 2
Write the name of the stage that matches the description below. Do not forget to write I or II.
10. ____________Anaphase 1_ Homologous chromosomes move towards opposite sides of the cell.
11. _______Telophae 2/cytokinesis Four new daughter cells form.
12. What type of cell undergoes meiosis?
Sperm or Egg
13. Define homologous chromosomes? Same size same shape same genes but different allele
(version)
14. For each of the following state if the cell is haploid or diploid.
Sperm cell =
Liver cell =
Egg cell =
Stomach cell =
15. If the diploid number in a liver cell is 52, how many chromosomes are there in the egg of this
organism? _________26
16. During meiosis, the chromosome number:
a) is doubled
b) is reduced
c) remains the same
d) becomes diploid
17. Cells starting mitosis & meiosis begin with a (haploid or diploid) set of chromosomes.
Diploid
18. How many times do cells divide during meiosis? _______
twice
19. What are the stages of meiosis called?
Meiosis I:interphase prophase 1 anaphase 1 metaphase 1 telophase 1 cytokinesis
Meiosis II: prophase 2 anaphase 2 metaphase 2 telophase 2 cytokinesis
20. Draw a tetrad: What phase do you first see this in?
21. Which of the following best describe the term “crossing over”?
a.) An exchange of information between two homologous chromosomes
b.) A molecular interaction between two sister chromatids
c.) A molecular interaction between two non-sister chromatids
d.) A separation of two sister chromatids
Figure 2
22. Crossing-over can be found in the stage of
a.) Prophase I
b) Prophase II
c) Anaphase I
d) Anaphase II
23. Which letter in figure #2 represents meiosis? Why?
d
24. Which letter in figure #2 represents mitosis? Why?
a
25. Is DNA copied before Meiosis II? no
26. How many cells form at the end of Meiosis II and how many chromosomes do they contain?
4 cells and half of the original
27. A sperm cell is a (gamete, zygote), and is (haploid, diploid).
haploid
28. When a sperm cell and an ovum/egg merge, they undergo the process of fertilization, and give rise
to a (gamete, zygote), which is (haploid, diploid).
Zygote diploid
29. What is the ultimate goal/purpose of mitosis? What term do we use to describe the new cells?
Make new cells called daughter cells
30. What is the difference between chromosomes, chromatids, and homologous chromosomes? You
may draw a picture as your answer.
31. How are DNA and chromosomes related?
Chromosomes are DNA
32. What is the difference between a haploid, diploid, and zygote?
Haploid: Half the chromosomes/one homologous chromosome
Diploid: All the chromosomes/ both homologous chromosomes
Zygote: Fertilized Egg
33. How does Meiosis differ from Mitosis?
Two divisions in meiosis 1 in mitosis, 4 cells at the end in meiosis 2 cells and the end of
mitosis, homologous chromosomes line up next to one another in meiosis and in a line during mitosis
34. What does Meiosis create? Haploids or Diploid? Somatic cells or gametes?
Haploid Gametes
35. What is a gamete? How do we represent the chromosome number: 2n or n?
n
36. What is crossing over? When does it happen? Draw a picture.
Crossing over is when segments of DNA get exchanged from homologous chromosomes causing
genetic diversity.