Meiosis, Cell Cycle and Cancer (Lecture 2)

Question 1

Meiosis gives rise to which cells?

Answer 1

Haploid

Question 2

How much DNA does a haploid cell have compared to a diploid?

Answer 2

Haploid cell (n); (1⁄2 the amount of DNA as a diploid cell)

Question 3

How much DNA does a diploid cell have compared to a haploid?

Answer 3

Diploid cell (2n); 2X more DNA than a haploid cell.

Question 4

How many chromosomes do humans have?

Answer 4

Humans have 23 pairs of chromosomes, for a total of 46 chromosomes

Question 5

Click to see the mitosis/meiosis haploid vs. diploid

Answer 5

Question 6

How many interphases are there in meiosis?

Answer 6

There is only 1 interphase, similar to mitosis

Question 7

What does the first division do in meiosis that does not happen in mitosis?

Answer 7

The first division randomly separates homologous chromosomes. This does not happen in mitosis

Question 8

What does the second division of meiosis result in? (similar to mitosis)

Answer 8

The second division results in the splitting of sister chromatids, similar to mitosis.

Question 9

What is the end result of meiosis? (unlike mitosis)

Answer 9

The end result is 4 genetically unique daughter cells, unlike mitosis.

Question 10

In meiosis are the daughter cells haploid or diploid?

Answer 10

Each genetically unique daughter cell is haploid, unlike mitosis

Question 11

Mitosis occurs in the bodies _________, while meiosis occurs in the ______________

Answer 11

Mitosis occurs in the bodies stem cells (eg., colon)

Meiosis occurs in the mature germ (sex) cells

Question 12

Mitosis occurs in __________________ (to increase #’s)

Answer 12

Mitosis occurs in immature germ (sex) cells (to increase #’s)

Question 13

Mitosis results in two _____ daughter cells

Meiosis results in four ______ daughter cells

Answer 13

Mitosis results in two diploid daughter cells

Meiosis results in four haploid daughter cells

Question 14

What is different about the daughter cells produced in mitosis vs. meiosis?

Answer 14

In mitosis, each daughter cell is genetically identical

In meiosis, each daughter cell is genetically unique

Question 15

In meiosis, how many chromosomes does the daughter cell have?

Answer 15

Each daughter contains half the number of chromosomes as the parent

Question 16

What can be said about the continuity of mitosis and meiosis?

Answer 16

Mitosis can continue in perpetuity

Meiosis is a terminal event in vast majority of eukaryotes

Question 17

What is the chromosomal alignment in mitosis and meiosis?

Answer 17

In mitosis, all 46 chromosomes aligned in one plane

In meiosis, 23 pairs of homologous chromosomes aligned in one plane

Question 18

Where do mitotic spindles attach in mitosis and meiosis?

Answer 18

In mitosis, mitotic spindles attached to kinetochores orientated opposite each other on both sister chromatids

In meiosis, mitotic spindle attached to mono- orientated kinetochores on the sister chromatids

Question 19

Does recombination occur in mitosis and meiosis?

Answer 19

In mitosis, no recombination occurs

In meiosis, recombination occurs between homologous chromosomes

Question 20

What events occur in Prophase I of meiosis I?

Answer 20

1. Chromosomes first become visible as thin threads. DNA replication is already complete.
2. Homologous chromosomes continue to condense and undergo synapsis (gene-for- gene pairing).
3. When synapsis is complete, each pair of homologous chromosomes forms a bivalent. Each chromosome consists of two sister chromatids.
4. The chromosomes continue to shorten and thicken and the chiasmata between non-sister chromatids become apparent
5. The nuclear envelope begins to break down

Question 21

Explain the process of crossing over

Answer 21

Crossing over is the exchange of genetic material between non-sister chromatids of homologous chromosomes during meiosis, which results in new allelic combinations in the daughter cells

Question 22

What are paternal and maternal homologs?

Answer 22

One of these chromosomes is derived from the male parent (parental chromosome) and one from the female (maternal chromosome). The chromosomes in this pair are called homologs - there is one paternal and one maternal homolog

Question 23

What is bivalent?

Answer 23

During the prophase of meiosis I, homologous chromosomes pair and form synapses. The bivalent has two chromosomes and four chromatids, with one chromosome coming from each parent

Question 24

What is a chiasma?

Answer 24

The chiasma is a structure that forms between a pair of homologous chromosomes by crossover recombination and physically links the homologous chromosomes during meiosis

Question 25

What are recombinant chromatids?

Answer 25

Crossing over occurs between prophase I and metaphase I and is the process where two homologous non-sister chromatids pair up with each other and exchange different segments of genetic material to form two recombinant chromosome sister chromatids

Question 26

What events occur in Prometaphase I and Metaphase I?

Answer 26

Prometaphase I: Spindles attach to kinetochores on chromosomes Metaphase I: Homologous pairs line up in center of cell, with bivalents oriented randomly with respect to each other

Question 27

What is a kinetochore?

Answer 27

A complex of proteins associated with the centromere of a chromosome during cell division, to which the microtubules of the spindle attach

Question 28

What events occur in Anaphase I and Telophase I?

Answer 28

Anaphase I: Homologous chromosomes separate, but sister chromatids do not separate Telophase I and cytokinesis: Daughter cells are ready to move into prophase II

Question 29

Explain the process of Meiosis II?

Answer 29

Prophase II: The nuclear envelope breaks down and the chromosomes condense. Prometaphase II: Spindles attach to kinetochores on chromosomes. Metaphase II: Chromosomes align in center of cell. Anaphase II: Sister chromatids separate. Telophase II and cytokinesis: The nuclear envelope re- forms and the cytoplasm divides.

Question 30

Comparing Mitosis and Meiosis | (Information slide)

Answer 30

Question 31

What is cytoplasmic division?

Answer 31

Cytoplasmic division or Cytokinesis separates the original cell, its organelles and its contents into two more or less equal halves. While all types of eukaryotic cells undergo this process, the details are different in animal and plant cells.