Chapter 13: Meiosis

Question 1

What is genetics?

Answer 1

The study of heredity and the variation of inherited characteristics

Question 2

What happens in asexual reproduction?

Answer 2

A single individual is the sole parent and passes copies of all its genes (DNA) to its offspring without the fusion of gametes (sex cells); an individual that reproduces asexually gives rise to a clone (a group of genetically identical individuals)

Question 3

What happens in sexual reproduction?

Answer 3

Two parents give rise to offspring that have unique combinations of genes inherited from the two parents; in contrast to a clone, offspring of sexual reproduction vary genetically from their siblings and both parents; they are variations on a common theme of family resemblance, not exact replicas

Question 4

Mitosis: Asexual or Sexual?

Answer 4

Asexual reproduction

Question 5

Meiosis: Asexual or sexual?

Answer 5

Sexual reproduction

Question 6

What are homologous chromosomes (or homologs)?

Answer 6

Is where both chromosomes of each pair carry genes controlling the same inherited characters

Question 7

In humans, how many chromosomes does a somatic cell have?

Answer 7

46 chromosomes (23 pairs)

Question 8

What are somatic cells?

Answer 8

Cells that are not sex cells

Question 9

What are the sex cells for humans?

Answer 9

Sperm=male

Ovaries=female

Question 10

What is a diploid?

Answer 10

A cell or organism that has paired chromosomes, one from each parent;
In humans, somatic cells are diploid and have 23 pairs of chromosomes

Question 11

What is a haploid?

Answer 11

Cells that contain a single set of chromosomes; human sex cells (egg and sperm cells)

Question 12

What happens in prophase 1 (meiosis part 1)?

Answer 12

• chromosomes condense
• nuclear envelope dissolves
• homologous chromosomes connect
• crossint over occur (a.k.a. recombination)

Question 13

What happens in metaphase 1 (meiosis part 1)?

Answer 13

• spindle fibers from opposing centrosomes connect to kinetochores on homologous chromosomes (at centromeres)
• alligns them along the middle of the cell (metaphase/equatorial plate)

Question 14

What happens in anaphase 1 (meiosis part 1)?

Answer 14

• spindle fibers contract and split the homologous chromosomes
• moves them to opposite poles of the cell

Question 15

What happens in telophase 1 and cytokinesis (meiosis part 1)?

Answer 15

• chromosomes decondense/unwound
• nuclear membrane reforms
• cell divides (in cytokinesis) to form two haploid daughter cells

Question 16

What happens in telophase 1 and cytokinesis (meiosis part 1)?

Answer 16

• chromosomes decondense/unwound
• nuclear membrane reforms
• cell divides (in cytokinesis) to form two haploid daughter cells

Question 17

What happens in prophase 2 (meiosis part 2)?

Answer 17

• chromosomes condense
• nuclear membrane disolves
• centrosomes move to opposite poles

Question 18

What happens in metaphase 2 (meiosis part 2)?

Answer 18

• spindle fibers from opposing centrosomes attach to chromosomes (at centromere)
• alligns them in the middle of the cell

Question 19

What happens in anaphase 2 (meiosis part 2)?

Answer 19

• spindle fibers contract and separate sister chromatids

- chromatids (now called chromosomes) move to opposite poles

Question 20

What happens in telophase 2 and cytokinesis (meiosis part 2)?

Answer 20

• chromosomes decondense/unwound
• nuclear membrane reforms
• cella divide (in cytokinesis) to form 4 haploid daughter cells