Meiosis

Question 1

What is gametogenesis?

Answer 1

Making of oocytes and sperm

Question 2

Are gametes haploid or diploid?

Answer 2

Haploid due to meiosis

Question 3

What are sex cells called when they enter meiosis I?

Answer 3

Primary oocyte or primary spermatocyte

Question 4

Define ploidy.

Answer 4

Origin of an individual chromosome’s DNA

Question 5

What is euploid?

Answer 5

An extra full set of chromosomes usually due to polyspermy (triploidy)

Question 6

What is aneuploid?

Answer 6

Extra single chromosome due to nondisjunction (trisomy)

Question 7

What is “N”?

Answer 7

Total # of DS DNA copies of each chromosome

Question 8

What kind of ploidy and N does a gamete have?

Answer 8

Haploid and 1N

Question 9

Define homologues.

Answer 9

Identical chromosomes originating from different parents

Question 10

Define sister chromatids.

Answer 10

Duplicated copy of each chromosome following S phase; connected centromere

Question 11

Define bivalents or tetrads.

Answer 11

Pair of duplicated homologues… 2 pairs of sister chromatids

Question 12

Define chiasmata.

Answer 12

Regions where bivalents crossover and recombine during prophase I of meiosis

Question 13

What are the male and female versions of the primordial germ cell?

Answer 13

Spermatogonium

Oogonium

Question 14

What are the male and female versions of cells committed to Meiosis I?

Answer 14

Primary Spermatocyte

Primary Oocyte

Question 15

What are the male and female versions of Completed meiosis I/Committed to Meiosis II cells?

Answer 15

Second Spermatocyte

Secondary Oocyte

Question 16

What are the male and female versions of completed meiosis I/Immature gamete cells?

Answer 16

Spermatid

No female version

Question 17

What are the female and male versions of a mature gamete cell?

Answer 17

Spermatozoa

No female version (fertilized egg or zygote)

Question 18

When do males and females begin begin meiosis?

Answer 18

Males begin at puberty

Females begin in utero

Question 19

Is meiosis continuous or arresting in males and females?

Answer 19

Continuous in males

Arrests twice in females

Question 20

How many haploid gametes are produced in males and females?

Answer 20

4 haploid gametes in males

1 haploid gamete in females

Question 21

What is another name for the 1st meiotic division?

Answer 21

Reduction division or diploid to haploid

Question 22

In meiosis I do sister chromatids stay together or separate?

Answer 22

Stay together

Question 23

What happens in Meiosis I: Prophase I?

Answer 23

Oocytes are arrested at diplotene stage until ovulation; this prolonged female diplotene is called dictyotene

Question 24

What occurs during Prophase I?

Answer 24

Crossing over

Question 25

What happens in Meiosis I: Metaphase I?

Answer 25

Nuclear membrane disappears Spindle forms Paired chromosomes align at equatorial plane Centromeres orient toward opposite poles

Question 26

How do sister chromatid kinetochores behave in Metaphase I?

Answer 26

They behave as one and orient toward a single pole

Question 27

What is the most error prone step of meiosis?

Answer 27

Meiosis I: Anaphase I

Question 28

What happens in Meiosis I: Anaphase I?

Answer 28

Bivalents disjoin and sister chromatid pairs are drawn to opposite poles of the cell; thus, chromosome number is halved.

Question 29

When does nondisjunction occur?

Answer 29

When homologous chromosomes fail to separate during meiosis.

Question 30

What does nondisjunction result in and when may it occur?

Answer 30

Results in some gametes with 24 chromosomes, some with 22 | May occur at meiosis I or meiosis II

Question 31

In Meiosis I: Telophase I and Cytokinesis what happens?

Answer 31

Decondensation of chromosomes Reformation of nuclear membrane 2 Haploid daughter cells made Cells enter a brief interphase

Question 32

Do cells going through Meiosis enter S phase before going on to the next division?

Answer 32

Nope they do not

Question 33

What happens in cytokinesis in the spermatocyte?

Answer 33

Spermatocytes divide their cytoplasm approximately equally to yield two secondary spermatocytes

Question 34

What happens in cytokinesis in the primary oocyte?

Answer 34

Oocytes divide very unevenly to yield one secondary oocyte and the first polar body

Question 35

What has oocyte biopsy been found to help with?

Answer 35

Oocyte biopsy of a polar body could possibly be used to determine which eggs have the best chance to produce a viable embryo.

Question 36

What is another name for 2nd meiotic division?

Answer 36

Equational division or 2N to 1N

Question 37

Are sister chromatids separated or together in Meiosis 2?

Answer 37

Separated

Question 38

What is the end result of the 2nd meiotic division?

Answer 38

4 haploid secondary (1N) spermatocytes | 1 secondary oocyte + 2nd polar body

Question 39

When does an oocyte complete meiosis 2?

Answer 39

Only if the egg is fertilized.