Mitosis & Meiosis

Question 1

chromosomes are at their greatest elongation (not visible)

[mitosis stages]

Answer 1

prophase

Question 2

begin to coil, become more condensed.

[mitosis stages]

Answer 2

prophase

Question 3

nuclear membrane disappears.

[mitosis stages]

Answer 3

prometaphase

Question 4

spindle fibers : begin to appear

[mitosis stages]

Answer 4

prometaphase

Question 5

chromosomes attach to the spindle fiber at their kinetochores.

[mitosis stages]

Answer 5

prometaphase

Question 6

mitotic spindle completed

[mitosis stages]

Answer 6

metaphase

Question 7

centrioles: divide and move to opposite poles.

[mitosis stages]

Answer 7

metaphase

Question 8

chromosomes: line up on the equatorial plate, reach their maximum state of contraction.

[mitosis stages]

Answer 8

metaphase

Question 9

centromeres: divide longitudinally.

[mitosis stages]

Answer 9

anaphase

Question 10

chromatids: separate and migrate to opposite poles as anaphase progresses.

[mitosis stages]

Answer 10

anaphase

Question 11

chromosomes: uncoil, become indistinguishable again.

[mitosis stages]

Answer 11

telophase

Question 12

nucleoli: reform

[mitosis stages]

Answer 12

telophase

Question 13

nuclear membrane: reconstructed

[mitosis stages]

Answer 13

telophase

Question 14

followed by cytokinesis, or cytoplasmic division.

[mitosis stages]

Answer 14

telophase

Question 15

It takes place only in the ovaries and testes.

Answer 15

Meiosis

Question 16

Each gamete produced contains only one copy of each what?

Answer 16

chromosome

Question 17

Fertilization restores the diploid number in what?

Answer 17

zygote

Question 18

4 several substages of Meiosis I.

Answer 18

Prophase I
Metaphase I
Anaphase I
Telophase I

Question 19

longest.

[meiosis substages]

Answer 19

Prophase I

Question 20

5 complex stage of Prophase I

Answer 20

LEPTOTENE
ZYGOTENE
PACHYTENE
DIPLOTENE
DIAKINESIS

Question 21

There are 46 chromosomes, each comprised of two chromatids.

[prophase I stages]

Answer 21

Prophase I — Leptotene

Question 22

Chromosomes begin to condense but are not visible by light microscopy.

[prophase I stages]

Answer 22

Prophase I — Leptotene

Question 23

Once leptotene takes place, the cell is committed to meiosis.

[prophase I stages]

Answer 23

Prophase I — Leptotene

Question 24

Homologous chromosomes (long threadlike structures) pair locus for locus. — SYNAPSIS: paring locus for locus.

[prophase I stages]

Answer 24

Prophase I — Zygotene

Question 25

A tripartite structure, the synaptonemal complex, can be seen in electron microscopy — necessary for the phenomenon of crossing over that will takes place later in prophase I. [prophase I stages]

Answer 25

Prophase I — Zygotene

Question 26

Synapsis of X and Y chromosomes in males occurs only at the pseudoautosomal regions. [prophase I stages]

Answer 26

Prophase I — Zygotene

Question 27

These regions are located at the distal short arms and are only segments of the X and Y chromosomes containing homologous loci. [prophase I stages]

Answer 27

Prophase I — Zygotene

Question 28

The nonhomologous proportions of these chromosomes condense to form the sex vesicle. [prophase I stages]

Answer 28

Prophase II — Zygotene

Question 29

Crossing over of genetic material chromosome becomes short and thick and divide into four distinct chromatids. [prophase I stages]

Answer 29

Prophase I — Pachytene

Question 30

Chromosomes continue to shorten and thicken. [prophase I stages]

Answer 30

Prophase I — Diplotene

Question 31

Homologous chromosomes begin to repel each other. [prophase I stages]

Answer 31

Prophase I — Diplotene

Question 32

Repelling continues until the homologous chromosomes are held together only at points where crossing over took place — CHIASMATA [prophase I stages]

Answer 32

Prophase I — Diplotene

Question 33

In males, the sex vesicles disappears and the X chromosomes associate end to end. [prophase I stages]

Answer 33

Prophase I — Diplotene

Question 34

Chromosomes reach their greatest contraction during this last stage of prophase. [prophase I stages]

Answer 34

Diakinesis - Prophase I — Diplotene

Question 35

Disappearance of the nuclear membrane and formation of the mitotic spindle. The bivalents line up on the equatorial plate with their centromeres randomly oriented toward opposite poles. [meiosis]

Answer 35

Meiosis I — Metaphase I

Question 36

The centromeres of each bivalent separate and migrate to opposite poles. [meiosis]

Answer 36

Meiosis I — Anaphase I

Question 37

Two haploid sets of chromosomes reach opposite poles and cytoplasm divides. [meiosis]

Answer 37

Meiosis I — Telophase I

Question 38

The result is two cells containing 23 chromosomes, each composed of two chromatids. [meiosis]

Answer 38

Meiosis I — Telophase I

Question 39

contain 23 chromosomes each consisting a single chromatid.

Answer 39

Spermatids

Question 40

the spermatids differentiate to become spermatozoa

Answer 40

— a mature sperm.

Question 41

In females: oogenesis begins in what?

Answer 41

prenatal life.

Question 42

Ova develop from oogonia within the follicles in?

Answer 42

ovarian cortex

Question 43

This suspended diplotene is referred to as

Answer 43

dicytotene

Question 44

The chromosomes of the egg and sperm produced in Meiosis II are each surrounded by a nuclear membrane within the cytoplasm of the ovum.

Answer 44

Fertilization

Question 45

The pro-nuclei fuse to form the diploid nucleus of the zygote and the first mitotic division begins.

Answer 45

Fertilization

Question 46

Begins with sexual maturity and occurs throughout the post-pubertal life of a man.

Answer 46

Spermatogenesis

Question 47

SITE: seminiferous tubules of the male testes

Answer 47

Spermatogenesis

Question 48

Process is continuous and each cycle results in the formation of four non-identical spermatozoa.

Answer 48

Spermatogenesis

Question 49

Proceed much like mitotic cell division except that each cell contains only 23 chromosomes.

Answer 49

Meiosis II

Question 50

The spermatogonia contain how many chromosomes?

Answer 50

46