Gametogenesis overview

Question 1

What are the 5 phases in prophase 1 of meiosis?

Answer 1

Leptotene
Zygotene
Pachytene
Diplotene
Diakinesis

Question 2

What happens in the leptotene phase of meiosis 1?

Answer 2

Chromosomes condense, DNA replication is finished

Question 3

What happens in the zygotene phase of meiosis 1?

Answer 3

Synapsis

Question 4

What happens in the pachytene phase of meiosis 1?

Answer 4

Crossing over

Question 5

What happens in the diplotene phase of meiosis 1?

Answer 5

Homologous chromosomes separate

Question 6

What happens in the diakinesis phase of meiosis 1?

Answer 6

Transition into metaphase

Question 7

What are germ cells?

Answer 7

Cells destined to become gametes, will reside in the gonad tissue but don’t form the gonad tissue

Question 8

What happens to the germ cells once they are specified?

Answer 8

They stop dividing and are segregated away from the somatic cells until they are ready to move into the gonads

Question 9

What are the 5 things that regulate cell identity?

Answer 9

Gene expression, membrane components, proteins, mRNA localization, transcription factors

Question 10

What was Louis Bounoure’s experiment? What did he find and conclude?

Answer 10

Let an amphibian zygote grow into the 2, 4 and 8 cell stages, then split the cells apart. The cells lived and grew into two new individuals in the 2 cell stage, but none of the cells lived after being split from the 8 cell stage. Concluded there were things in the cytoplasm required for a new individual to be produced, and not every cell in the 8 cell stage had all that info

Question 11

What is the germ plasm?

Answer 11

A particular area of the egg cytoplasm that has the mRNA and proteins localized to set the fate of the germ cells

Question 12

Why are germ cells set aside so early in development?

Answer 12

Keep all information intact, since every cell division can produce errors. The germ cells become a library for the genetic information

Question 13

What are the 2 important genes associated with germ cell specification?

Answer 13

Vasa and nanos

Question 14

Where do the Vasa and Nanos transcripts come from?

Answer 14

Maternal genes that already exist in the egg as mRNA, localized in the germ plasm

Question 15

What do Vasa and Nanos do?

Answer 15

Block transcription and translation to stop cell division

Question 16

What are the 3 stages of gametogenesis?

Answer 16

Gonial, gonocyte, gonotid

Question 17

What is a gonial cell?

Answer 17

The diploid product of a germ stem cell

Question 18

What are 2 things that could happen to a gonial cell?

Answer 18

Either keeps dividing through mitosis or enters meiosis

Question 19

What is the gonial stage of spermatogenesis called?

Answer 19

Spermatogonia

Question 20

What is the gonial stage of oogenesis called?

Answer 20

Oogonia

Question 21

What is happening in the morphogenesis example in C. elegans gametogenesis?

Answer 21

Gonad cells produce a signalling protein called Delta that inhibits meiosis and encourages mitosis in germ cells by interacting with the Notch receptor. The germ cells keep undergoing mitosis and eventually start to crowd each other out. Some cells get pushed away from the cells producing Delta, and will start meiosis once they are out of range.

Question 22

What is a gonocyte?

Answer 22

A gonial cell that has entered meiosis

Question 23

What is the gonocyte stage of spermatogenesis called?

Answer 23

Spermatocyte

Question 24

What is the gonocyte stage of oogenesis called?

Answer 24

Oocyte

Question 25

What is a gonotid?

Answer 25

Specialized haploid gonocyte, only applies to sperm

Question 26

What is spermiogenesis?

Answer 26

The specialization of a spermatocyte into a spermatid, which includes development of the flagella, reduction of the cytoplasm, condensation of the chromosomes into toroids

Question 27

What do the germ stem cells in Drosophila oogenesis divide into with every round of mitosis?

Answer 27

One GSC and one oogonium

Question 28

What does the Drosophila oogonia become once it starts dividing?

Answer 28

Cystoblast

Question 29

What sort of development does a Drosophila cystoblast undergo?

Answer 29

Syncytial. The cells stay connected through the cytoplasm

Question 30

Does every cell in a Drosophila cystoblast become an oocyte?

Answer 30

No. Only one enters meiosis and the rest become nurse cells

Question 31

What do follicle cells do in Drosophila oogenesis? Where do they come from?

Answer 31

They surround the egg and help determine body axises. They come from the gonad and not the cyst

Question 32

What is Drosophila germ stem cell renewal an example of?

Answer 32

Morphogenesis

Question 33

How do Drosophila germ stem cells renew themselves?

Answer 33

The GSC are anchored to the Cap cells and are receiving BMP secreted by the Cap cells, which turns off the Bam gene. When the GSC divides, mitosis is oriented so that one cell is further away and moves out of the range of BMP. Without the signal, Bam turns out and the cell becomes an oogonium and starts forming a cystoblast

Question 34

Does formation of a cystoblast occur in mammalian oogenesis?

Answer 34

No, all mitotic divisions are completed before birth in the fetus

Question 35

What happens to the oogonia after mitotic divisions are finished?

Answer 35

Held in stasis in follicles until sexual maturity

Question 36

What is a primary oocyte?

Answer 36

Product of meiosis 1

Question 37

What is a secondary oocyte?

Answer 37

A more mature oocyte that is undergoing meiosis 2 and getting ready to be ovulated

Question 38

What are the two types of cells that make up the follicle?

Answer 38

Granulosa and thecal cells

Question 39

Where are granulosa cells found?

Answer 39

Tightly packed around the oocyte in a follicle

Question 40

Where are thecal cells found?

Answer 40

Loosely packed around the oocyte in a follicle

Question 41

What is the purpose of the follicle structure?

Answer 41

Support, nutrients, secretes hormones

Question 42

What is the Zona pellucida?

Answer 42

A thick extracellular matrix made of proteins and carbs that surrounds the oocyte

Question 43

What is the corona radiata?

Answer 43

The granulosa cells that maintain very tight association with the oocyte

Question 44

What is the antrum?

Answer 44

A space in the follicle structure between the corona radiata and the granulosa cells

Question 45

Which parts of the follicle are ovulated with the egg?

Answer 45

Zona pellucida and corona radiata

Question 46

What is the spermatogenesis equivalent of the cap cells in Drosophila oogenesis?

Answer 46

Hub cells

Question 47

What is the function of the hub cells?

Answer 47

Tell GSC when to divide

Question 48

Are cysts formed in insect spermatogenesis?

Answer 48

Yes

Question 49

What is the signal secreted by the hub cells?

Answer 49

Unpaired

Question 50

What does unpaired do to spermatogonia?

Answer 50

Causes movement of the centrosome so cytokinesis happens in a particular location

Question 51

Where are sperm produced in mammals?

Answer 51

Seminiferous tubules

Question 52

Which stage in spermatogenesis is located around the periphery of the seminiferous tubules?

Answer 52

Spermatogonia

Question 53

Are cells closer to the central channel of the seminiferous tubules more or less mature?

Answer 53

More. They go through meiosis as they approach the centre

Question 54

What are Sertoli cells?

Answer 54

Cells that maintain the endocrine environment in the testes