Lecture 6: Meiosis, germ cells and fertilization

Question 1

Diploid

Answer 1

two sets of chromosomes, one from each parent

Question 2

Haploid

Answer 2

One set of chromosomes

Question 3

Gamete

Answer 3

Specialized reproductive cells; sperm or eggs generated through meiosis

Question 4

Fertilization

Answer 4

Haploid gametes fuse to form diploid cell (zygote)

Question 5

Zygote

Answer 5

Divides by mitosis to become multicellular organism

Question 6

Germline cells

Answer 6

Gametes and their precursors

Question 7

Somatic cells

Answer 7

form the rest of the body and leave no progeny

Question 8

4 chromatid structure name

Answer 8

Bivalent

Question 9

Stable pairing requires ____

Answer 9

Crossing over-form chiasma

Question 10

Synaptonemal complex

Answer 10

Structure of two paired homologs, important for crossing over

Question 11

Pseudoautosomal region

Answer 11

Small region of homology between x and y allowing them to pair

Question 12

5 phases of prophase

Answer 12

Leptotene
Zygotene
Pachytene
Diplotene
Diakineses

Question 13

Leptotene

Answer 13

Homologs begin to condense/pair

Question 14

Zygotene

Answer 14

Homologs pair and synaptonemal complexes form

Question 15

Pachytene

Answer 15

Synapsis complete, crossing over occurs

Question 16

Diplotene

Answer 16

Synaptonemal complex begins to break down; homologs begin to separate but remain attached at chiasma

Question 17

Diakinesis

Answer 17

Reach maximum condensation; separation of homologs and transition into metaphase

Question 18

Non-disjunction

Answer 18

Homologs fail to separate properly. Common during egg development, more common with higher age

Question 19

Aneuploid

Answer 19

Cells with abnormal chromosome number

Question 20

Female eggs first arrest at

Answer 20

Prophase 1 of Meiosis 1, completed at ovulation

Question 21

Femalge eggs second arrest

Answer 21

Metaphase 2 of meiosis 2, complete meiosis after fertilization

Question 22

Male meiosis begins

Answer 22

At puberty and proceeds without arrest

Question 23

What dictates which cells become primary germ cells

Answer 23

Signaling from neighboring cells

Question 24

What determines if gonad is ovary or testes

Answer 24

Sex cells at genital ridge, not sex chromosome in PGC
Y chromosome in sperm directs genital ridge to develop into testis.
Default pathway is female

Question 25

Sry gene

Answer 25

Sex determining region on Y chromosome. Necessary and sufficient for testis development

Question 26

Expression of Sry causes

Answer 26

Cells to differentiate into sertoli cells and leydig cells (testis support cells)

Question 27

Sertoli cells secrete

Answer 27

Anti-mullerian hormone which suppresses female development

Question 28

Leydig cells secrete

Answer 28

Testosterone

Question 29

In absence of Sry

Answer 29

Genital ridge become ovary, PGC becomes egg

Somatic cells become follicle cells and theca cells

Question 30

Which hormones trigger ovulation and allow primary oocyte to complete M I

Answer 30

FSH + LH

Question 31

Syncitium

Answer 31

Progeny of spermatogonium don’t complete cytokineses, they remain connected through cytoplasmic bridges
This gives them access to diploid genome for their development

Question 32

Capacitation

Answer 32

Process required for a sperm to acquire capacity to fertilize an egg

Question 33

Fertilization

Answer 33

Sperm binds to zona pellucida, undergo acrosome reaction (allows penetration of zona pellucida)

Question 34

Cortical reaction

Answer 34

Egg fuses with sperm, cortical granules are released, other sperm can no longer bind

Question 35

Sperm contribute ____ & _____ for meiosis

Answer 35

Centrioles and centrosomes

Question 36

In polyspermy, extra ____ are present, causing what

Answer 36

Extra mitotic spindles are present, causing faulty segregation and aneuploidy