Gametogenesis II

Question 1

What is the first PGC division in the gonads?

Answer 1

A mitotic one

Question 2

Result of mitotic division of PGCs in the gonads?

Answer 2

Diploid (2n), two chromosome sets

Question 3

What follows the mitotic PGC division in the gonads?

Answer 3

Meiotic division

Question 4

Result of the meiotic division of the PGCs in the gonads?

Answer 4

1n–> haploid–> 1 set of chromosomes

Question 5

How many S phases do cells undergo in meiosis?

Answer 5

One

Question 6

Which type of cell division involves genetic recombination between homologous chromosomes from diff parents?

Answer 6

Meiosis

Question 7

Why is there no parthenogenic or androgenetic humans?

Answer 7

Needs to be a balance in the epigenetic influences of maternal and paternal

Question 8

Main stages in Meiosis I?

Answer 8

Prophase I, metaphase I, anaphase I, telophase I

Question 9

Main stages in meiosis ii

Answer 9

Prophase II, metaphase II, anaphase II, telophase II

Question 10

Stages of prophase I in meiosis?

Answer 10

Leptotene, Zygotene, pachytene, diakinesis

Question 11

What occurs in leptotene?

Answer 11

DNA rep finished, sis chromatids and closely associated, chromosomes start to condense

Question 12

What occurs in zygotene?

Answer 12

Synapsis, tripartite structure, cohesin tetheres chromosomes

Question 13

What is synapsis?

Answer 13

Pairing of homologous chromosomes
Requires synaptonemal complex

Question 14

What is the synaptonemal complex?

Answer 14

a protein structure that forms between homologous chromosomes during meiosis, specifically during prophase I

Question 15

What are the major synaptonemal structural proteins in humans?

Answer 15

SYCP-1, 2 and 3

Question 16

What sort of structure does the synaptonemal complex (SC) have?

Answer 16

Tripartite–> central and two parallel lateral elements

Question 17

What occurs in pachytene?

Answer 17

Condensation continues, chromosomes thicken
SC breaks down
Crossing over (recombination)

Question 18

What happens if there is a failure of SC formation?

Answer 18

Pachytene arrest and chromosome fragmentation

Question 19

What occurs in diplotene?

Answer 19

Chiasmata are visible at cross-over points
SC break down completion
Homologous chromosomes separate

Question 20

Where are lampbrush chromosomes found?

Answer 20

Growing oocytes of most animals except mammals

Question 21

Role of lampbrush chromosomes?

Answer 21

synthesizing large quantities of mRNA and other non-coding RNAs during oogenesis and early embryogenesis

Question 22

When do lampbrush chromosomes appear?

Answer 22

Diplotene

Question 23

What happens in diakinesis?

Answer 23

Kinetochores move away from each other
CHromosomes remained joined at tips

Question 24

What is the kinetochore?

Answer 24

Joins the chromosomes to the microtubules

Question 25

What occurs in metaphase I?

Answer 25

Nuclear membrane breakdown Chromosomes assemble on metaphase plate Spindle assembly checkpoint

Question 26

Role of cyclin B in metaphase I?

Answer 26

Prevents cohesin degradation until MI is complete

Question 27

Role of cohesin?

Answer 27

Binds sister chromatids together

Question 28

What happens in anaphase I?

Answer 28

Chromosomes separate

Question 29

What happens in telophase I?

Answer 29

Formation of two cytokinetic products, each w/ a full set of homologous partners

Question 30

Result of telophase I in males?

Answer 30

Two cells

Question 31

Result of telophase I in females?

Answer 31

one cell and 1st polar body

Question 32

what is interkinesis?

Answer 32

A gap between meiosis I and meiosis II

Question 33

Is meiosis completed in males?

Answer 33

YEs

Question 34

Is meiosis II completed in females?

Answer 34

No, they arrest at metaphase II

Question 35

When is the metaphase II arrest in females maintained until?

Answer 35

Fertilisation

Question 36

What can failure to separate in meiosis lead to?

Answer 36

Non-dysjunction, and thus aneuploidy