Chapter 10 Meiosis

Question 0

Gametes

Answer 0

The male or female reproductive cell that contains half the genetic material of the organism

Question 1

Meiosis

Answer 1

• A specialized type of cell division which reduces the chromosome number by half
• Meiosis occurs in all sexually reproducing eukaryotes (both single-called and multicellular) including animals, plants, and fungal

Question 2

Somatic cells

Answer 2

Any cell of a living organism other than the reproductive cells
-one of the cells that take part in the formation of the body, becoming differentiated into the various tissues, organs, etc

Question 3

Diploid chromosome number (2n)

Answer 3

The number of chromosomes present on each somatic cell, which is constant for any one species of plant or animal

Question 4

Haploid chromosome number (n)

Answer 4

The number of chromosomes in a sperm or egg cell

-half the diploid number

Question 5

Meiosis I phases

Answer 5

• prophase I
• metaphase I
• anaphase I
• telophase I

Question 6

Meiosis II phases

Answer 6

Prophase II
Metaphase II
Anaphase II
Telophase II

Question 7

Crossing over (a form of genetic recombination)

Answer 7

• the exchange of genetic material between homologous chromosomes that results in recombinant chromosomes
• one of the final phases of genetic recombination, which occurs during prophase I of meiosis during a process called synapsis

Question 8

Tetrad

Answer 8

A group of four chromatids formed from each pair of homologous chromosomes that split longitudinally during the prophase of meiosis

Question 9

Independent assortment

Answer 9

The process of random segregation and assortment of chromosomes during anaphase 1 of meiosis resulting in the production of genetically unique gametes

Question 10

Sex chromosomes

Answer 10

• either of a pair of chromosomes that determine whether an individual is male or female
• the sex chromosomes of human beings and other mammals are designated by scientist as X and Y
• XX = female; XY = male

Question 11

Oogonia

Answer 11

Any of the cells that give rise through mitosis to the oocytes and are found in the ovaries of vertebrates

Question 12

Spermatagonia

Answer 12

Any of the cells that give rise through mitosis to the spermatocytes and are found in the testes of vertebrates

Question 13

Primary oocytes

Answer 13

An oocyte that has begun but not completed the first meiotic division
-it has derived from an oogonium by differentiation near the time of birth

Question 14

Primary spermatocytes

Answer 14

A diploid cell that undergoes meiosis to form four spermatocytes
-a primary spermatocye divides into two secondary spermatocytes, which in turn divide to form the spermatids

Question 15

Polar bodies

Answer 15

Either of two small cells produced during the first and second meiotic divisions in the development of an oocyte, containing little cytoplasm and eventually degenerating

Question 16

Sexual reproduction

Answer 16

A biological process in eukaryotes that creates a new organism by combining the genetic material of two organisms in a process that starts with meiosis

Question 17

Asexual reproduction

Answer 17

A mode of reproduction in prokaryotes by which offspring arise form a single organism, and inherit the genes of that parent only

Question 18

Fundamentally, how does mitosis differ from meiosis?

Answer 18

• in mitosis (asexual), two genetically identical daughter cells each develop from a single parent cell
• in meiosis (preparing for sexual reproduction), the division of a germ cell involving two fissions of the nucleus and giving rise to four gametes, or sex cellsX each possessing half the number of chromosomes of the original cell

Question 19

What is meant by the terms meiosis I and meiosis II?

Answer 19

• Meiosis I produces two identical daughter (diploid) cells

- During meiosis II, these cells divide and produce four haploid cells

Question 20

Summarize the events of meiosis I

Answer 20

• prophase I: homologous chromosomes link as they condense, forming tetrads; crossing over May occur
• metaphase I: microtubules move homologous chromosomes to a metaphase plate; independent assortment may occur
• anaphase I: microtubules separate homologous chromosomes (sister chromatids stay together)
• telophase I: two haploid daughter cells result from cytokinesis

Question 21

Summarize the events of meiosis II

Answer 21

• prophase II: brief period
• metaphase II: sister chromatids line up at new metaphase plate
• anaphase II: sister chromatids separate
• telophase II: four haploid cells result

Question 22

Why is meiosis I also called “reduction division”?

Answer 22

Because meiosis I reduced the number of chromosomes by 50% (in humans from 46 to 23, resulting in a haploid cell)

Question 23

What are three key way meiosis differs from mitosis?

Answer 23

1) meiosis results in haploid cells while mitosis results in diploid cells
2) in meiosis homologous chromosomes line up on opposite sides of the metaphase plate, in mitosis, one sister chromosome lines up on each side
3) meiosis results in 4 different cells, mitosis results in 2 identical cells