Bio chapter 9 Meiosis

Question 1

Meiosis

Answer 1

Produces gametes. Four daughter cells which are haploid are produced from a single precursor cell. Chromosome number is reduced in half. Two chromosomal replications. Happens only in germ cells.

Question 2

Meiosis I

Answer 2

Reductive division, PMAT I and cytokinesis

Question 3

Prophase I

Answer 3

Homologous chromosomes align to their genes match up. Crossing over occurs. Synapsis or pairing of homologous chromosomes.

Question 4

Linkage

Answer 4

The tendency of genes on the same chromosome to stay together in the same gamete.

Question 5

Chiasmata

Answer 5

Evidence of crossover. Area shaped like an X. Homologous non sister chromatids exchanged their genetic material.

Question 6

Synaptonemal complex

Answer 6

Maintains the synapsis process in a fixed state until crossing over occurs. It is a protein that provides structural framework for crossing over to occur during Prophase I.

Question 7

Metaphase I

Answer 7

Synaptic pairs line up, microtubules are attached to the kinetochore.

Question 8

Anaphase I

Answer 8

Each pair of homologous chromosomes separate. No longer sister chromatids but separation homologues.

Question 9

Telophase I and cytokinesis

Answer 9

Two haploid cells form, two chromatid sister still make up a chromosome.

Question 10

Meiosis II

Answer 10

Similar to mitosis. Spindle apparatus forms to separate the two sister chromatids.

Question 11

Metaphase II

Answer 11

Double stranded chromosomes become attached to the spindle, each chromosome is aligned at spindle equator.

Question 12

Anaphase II

Answer 12

Each chromosome splits; sister chromatids are now on their own and migrate to opposite poles.

Question 13

Telophase II and cytokinesis

Answer 13

Four daughter nuclei; after cytokinesis each gamete has a haploid number of chromosomes.

Question 14

Mitosis vs Meiosis production

Answer 14

Mitosis produces clones- 2 daughter cells

Meiosis produces variation- only occurs in germ cells.

Question 15

Compare mitosis vs meiosis in synapsis and crossing over

Answer 15

Mitosis: no synapsis and no crossing over
Meiosis: Synapsis occurs and crossing over in prophase I

Question 16

Mitosis vs meiosis purpose

Answer 16

Mitosis: produces cells for growth and repair
Meiosis: produces gametes

Question 17

Chromosomes are photographed when most condensed in ____ for a karyotype

Answer 17

Metaphase

Question 18

Fertilization is also called __ ( Mitosis).

Answer 18

Syngamy

Question 19

Mitotic Phase Chromosome # vs Chromatid #

Answer 19

Through PMAT, chromatid # is always 92. From metaphase to anaphase chromosome # changes from 46 to 92.

Question 20

Meiosis I Chromosome # vs Chromatid #

Answer 20

PMAT I Chromosome #3 and chromatid # stays the same at 46 and 92. After End of Meiosis I then chromosome and chromatid # is divided by 2.

Question 21

Meiosis II

Answer 21

Chromatid # is 46 until end of Meiosis II, 23. Chromosome # changes Metaphase II 23 to anaphase 46 and halves at the end of meiosis II.

Question 22

Spermatogenesis

Answer 22

Seminiferous tubules of testes. Continuously be made. Meiosis and differentiation to yield 4 mature spermatozoa. LH and FSH work together.

Question 23

Primary spermatocyte vs secondary spermatocytes and spermatids

Answer 23

Primary 2N, Secondary and spermatids N.

Question 24

Sperm

Answer 24

Head of sperm is the acrosome. It contains hyaluronidase which breaks down the zone pellucida (outer membrane of ova), allowing for syngamy (fertilization).

Question 25

Oogenesis

Answer 25

Occurs in ovaries, early cells stop meiosis and stay in Prophase I until puberty. One follicle each month matures.

Question 26

Oogonia and primary ooctye have ___ # of chromosomes.

Answer 26

2N, all polar bodies, ooctye, ovum after are N

Question 27

Only if a sperm fertilizes the secondary occyte will it resume ______?

Answer 27

Meiosis II.

Question 28

Why is a polar body made?

Answer 28

The haploid cell cannot be fertilized. Polar bodies contain only a small % of cytoplasm. They eliminate half of the diploid chromosome set.

Question 29

Capacitation

Answer 29

Functional maturation of sperm. Must occur to render sperm competent for fertilization. May allow acrosomal reaction to take place.