Gametogenisis

Question 1

what is gametogensis

Answer 1

the process where specialsied cells, or gametes are produced. occurs in the gonads, for sexual reproduction.

Question 2

gemetogensis in females

Answer 2

oogenesis

Question 2

what are gonads

Answer 2

glands that produce hormones involved in reproduction.
testes - in males
ovaries - in females.

Question 3

gemetogensis in males

Answer 3

Spermatogenesis

Question 4

components of the testes

Answer 4

includes the twisted and coiled - seminiferous tubules, where sperm is made and the epididymis, where the sperm further matures (longer flagella and more mitochondria), and get ready for ejaculation.

Question 5

what are the components of the seminiferous tubules

Answer 5

has a smooth muscle layer - to help propel the sperm from the tubules into the epididymis.
and many sertoli cells,

Question 6

what is the process, of movements of the sperm from tubules into the epididymis.

like squeezing toothpaste from bottle.

Answer 6

peristalis. l=wave like muscle contraction.

Question 7

where is the sperm made in the seminiferous tubules

Answer 7

in between 2 sertoli cells.

Question 8

what is the precursor of the sperm cell, or the intial cell where all the sperm comes from.

Answer 8

the Spermatogonium, they are the undifferentiated germ cells in the testes.

Question 9

where is the tight junction found, and what is its function

Answer 9

found near the far ends of the sertoli cells, which seperates the basal compartment (outside area of the tubules) and the lumenal compartments.
- it opens up to let the primary spermocytes through, and closes up immediately, to prevent leakege and maintain optimum environments.

Question 10

what is the primary spermocyte formed from, and how.
how many chromoseoms does it have.

Answer 10

formed from the intial spermatogonium. formed by mitosis and then differentiation.

A diploid cell with 46 chromosomes.

Question 11

what 2 cells does the mitosis of spermatogonium, result in.

Answer 11

1 cell undergoes differentiation, to form the priamry spermatocyte, and the other cell essentially reverts back to reform another spermatogonium.

Question 12

the (diploid) primary spermocyte’s cytoplasm grows in size, what happens after.

Answer 12

the primary spermocyte undergoes corssing over in prophase 1, and then
dividies into 2 secondary spermocytes, by meiosis 1.
now the secondary spermocytes are haploid cells with 23 chromosomes, still with 2 sister chromatids.

Question 13

what do the secondary spermocytes divide into,
how many chromosomes, do the products have

Answer 13

each secondary spermocytes, divides into 2 spermatids each, during meiosis 2. here the sister chromatids have seperated.
results in each spermatid being a haploid - having 23 chromosomes, and one sister chromatid each.

Question 14

How is the spermatozoa formed.

Answer 14

spermatids are differentiated into spermatozoa, through the process of speriogenesis.

Question 15

where does further maturation (spermoiogenesis) of the formed spermatozoa occur and what is included.

Answer 15

At the border of them lumen,

• the removal of excess cytoplasm and organelles including ribosomes and endoplasmic reticulum.
• Forming a streamlined, motile cell
• further condensation of chromatin.
• acrosome matures from the golgi complex, acrosin enzymes and other polysaccharides.

all allowing them to become functional cells.

Question 16

how long does maturation of the spermatozoa take

Answer 16

usually 2-3 weeks.

Question 17

how many spermatozoa are formed by a single diploid spermatogonium

Answer 17

4

Question 18

when does spermatogenesis occur in males

Answer 18

at around ages 10-14, when puberty starts

Question 19

describe a timeline of how spermatogenesis starts from fetal developments until puberty.

Answer 19

fetal development = spermatogenia under mitosis, increasing in number.

start of puberty (10-14 years) - meiosis starts.
- under the influence of hormonal changes, differentiation occurs and other processes result in spermatozoa forming.

Question 20

what does the head of a sperm cell consist of

Answer 20

the nucleus, cell membrane and acrosome cap.

Question 21

describe the acrosome cap -
- how it is formed
- structure
- function

Answer 21

made from the goli complex during spermiogenesis.
consists of the acrosin enzyme, and other polysaccharides.
- has its own acrosomal membrane.
- involved in the recognition of te oocyte based on it’smolecule composition = chemotaxis,

Question 22

describe the midpiece -
main characterisitic of it.

Answer 22

contains tightly packed mitochondira = energy for swimming and apoptosis.

Question 23

where is the centriole found in a sperm cell.

main function?

Answer 23

between the head and the midpiece, refrerred to as the centrole-centrosome complex.

essential for movement, and production of mitotic apparatus for seperating chromsomes, whilst being a template for all subsequent centrioles.

Question 24

what % does the tail make up of the sperm cell

Answer 24

about 80%

Question 25

what is the main germ cell that starts oogenesis

Answer 25

the oogenium

Question 26

what happens to the oogonium first, in oogenesis

Answer 26

it undergoes mitosis, increasing no. of cells, forming the primary oocyte. (upto 1-2 mill).

Question 27

what cell division phase are primary oocytes arrested in

Answer 27

prophase 1.

Question 28

where does the mitosis of the ooogonium to form primary oocyte occur

Answer 28

in the utero - before birth. (the womb).

Question 29

when does the primary oocyte leave the prophase 1 arrest, and what happens after.

Answer 29

leaves after puberty, undergoes meiosis 1, to form the secondary oocyte with 23 chromosomes (1n) and the 1st polar body.

Question 30

how are polar bodies formed and what are they

Answer 30

they are formed, by unequal division of a cell, the (primary and secondary) oocyte being the larger and more important of the two. the polar body has less of the cytoplasm, but equal chromosomal content. - later dies.

Question 31

what meiotic phase is the secondary oocyte arrested at

Answer 31

metaphase 2.

Question 32

what triggers the meiotic division of the primary oocyte into the secondary oocyte.

Answer 32

at adolescence, the aterior pituirty hormones cause the development of many follicles in the ovary. which finishes the first meiotic division = secondary oocyte

Question 33

what happens to the seoncdary oocyte during ovulation, (if no sperm enters)

Answer 33

the secondary oocyte travels through the fallopian tubes, on its way to the uterus, without every finishing meiosis 2. - gets disingrated there and later any remaining material will be shed from the body in the next period.

Question 34

where does the sperm meet the egg cell. for fertilisation to occur.

Answer 34

the sperm travels from the uterus into the fallopian tubes where fertilisation with the ovum occurs.

Question 35

when is the egg oficially called the ovum in oogenesis

Answer 35

called the ovum, only after the egg has been fertilised.

Question 36

what processes happen for the second oocyte to become the ovum, and another polar body.

Answer 36

meiosis 2 continues and obvs fertilisation.

Question 37

what does the genetic makeup of the fertilised egg consist of

Answer 37

a diploid cell with - 23 chromosomes from the father and 23 chromosomes from the mother.

Question 38

what happens during ovulation

Answer 38

the secondary oocyte is released into the uterus (still in metaphase 2) through the oviduct.

Question 39

in what process does the sperm and egg cell nuclei fuse

Answer 39

during syngamy, which occurs after the sperm penetrates the egg, during fertilisation.

Question 40

when does ovum become a zygote

Answer 40

after fertilisation

Question 41

what is the difference in terms of of number of gametes produced during oogeneis and spermatogenesis

Answer 41

spermatogenesis = 4 functional sperm cells from 1 speratogonium oogenesis = 1 egg and 2 polar bodies from each oocyte.