SEXUAL REPRODUCTION IN ANIMALS Flashcards
What is a zygote? (1)
the cell formed by the fusion of two gametes.
what are the differences between oogenesis and spermatogenesis? (7)
-time of arrival
-development
-timing
-number of gametes
-release
-process of meiosis
-structure
what is fertilisation? (1)
the fusion of the nuclei of two gametes to form the nucleus of a zygote, contains the chromosomes from both gametes.
what is the karyotype of a female? (1)
XX
What is meant by the sex? (2)
the sex of an organism has a genetic basis in mammals, it depends on the absence or presence of a activated gene, SRY, located on the Y chromosome.
what happens in the growth stage in terms of oogenesis? (1)
cells develop from oogonia to primary oocytes.
what process are sperm cells produced by? (1)
spermatogenesis
what are the female gonads? (2)
gonads; ovaries
and produce gametes called ova (singular ovum)
what are the male gonads? (2)
gonads; testes
produce gametes called spermatoza (singular spermatozoon)
what is a gonad? (1)
an animal organ that produces gametes.
what are the sequences of both the male and female processes of gametogenesis? (3)
-multiplication (proliferation)
-growth
-maturation
what is the germinal epithelium? (1)
a single layer of cells (epithelium) that undergoes regular mitosis, producing other cells.
what occurs during the second round of meiosis in oogenesis? (1)
meiosis 2 of the secondary oocyte produces a large ovum and a smaller polar body which is lost.
what happens in the growth stage, in terms of spermatogenesis? (1)
cells develop from the spermatogonia to primary spermatocytes.
what occurs during the first round of meiosis in oogenesis? (1)
the primary oocyte produces one haploid secondary oocyte and a smaller, haploid polar body which is lost.
what occurs during the second round of meiosis in spermatogenesis? (1)
both secondary spermatocytes undergo meiosis 2 to produce 4 gametes.
what occurs during the first round of meiosis in spermatogenesis? (1)
the primary spermatocyte produces haploid secondary spermatocytes that are the same size.
how are oogenesis and spermatogenesis different, in terms of time of arrival? (2)
oogenesis - oogonia formed in the embryonic ovaries long before birth.
spermatogenesis - spermatogonia formed from the time of puberty throughout adult life.
how are oogenesis and spermatogenesis is different, in terms of development? (3)
oogenesis - oogenesis becomes surrounded by follicle cells forming tiny primary follicles and remain dormant within the ovary cortex. most fail to develop further, they degenerate.
spermatogenesis - all spermatogonia develop into sperm, nurtured by the Sertoli cells in the seminiferous tubules of the testes.
how are oogenesis and spermatogenesis different, in terms of release? (2)
oogenesis - the graafian follicle releases a secondary oocyte into the oviduct at ovulation.
spermatogenesis - sperm are released from the body by ejaculation.
what is meant by maturation in terms of the process by gametogenesis? (1)
which involves meiosis and results in formation of haploid gametes.
what is a gamete? (1)
cells carrying half the number of chromosomes.
how are oogenesis and spermatogenesis different, in terms of the number of gametes? (2)
oogenesis - one ovum is formed from each oogonium
spermatogenesis - four sperm are formed from each spermatogonium
how are spermatogenesis and oogenesis different, in terms of the process by meiosis? (2)
oogenesis - meiosis 2 reaches prophase and then stops until a male nucleus enters the secondary oocyte, triggering completion of meiosis 2.
spermatogenesis - meiosis 1 and 2 go to completion during sperm production
how are oogenesis and spermatogenesis different, in terms of timing? (3)
oogenesis - each month from puberty until the menopause, a few primary oocytes undergo meiosis 1 to become secondary oocytes. only one of these forms a graafian follicle, the others degenerate.
what is meant by proliferation, in terms of the process of gametogenesis? (2)
in which cells present in a layer called the germinal epithelium divide by mitotic cell division. this division is repeated to reproduce many cells capable of becoming gametes.
where are sperm made? (1)
seminiferous tubules
what does the outer trophoblasts of the blastocysts become? (1)
become a membrane (the amnion) that helps to nourish the embryo.
what coats the head of the sperm? (2)
the head of the sperm is coated with glycoproteins picked up from the epididymis, these have to be removed to make sperm capable of fertilisation.
what is the endometrium? (1)
the lining of the uterus.
what does the inner mass of the blastocyst become? (1)
destined to become the embryo.
what occurs after the blastocyst is fertilised is implanted? (1)
cells differentiate to form a different type of cell.
what are the two processes that allow capacitation? (2)
the cell surface membrane of the sperm head is stripped of the glycoproteins it acquired in the epididymis, the acrosome reaction occurs.
what is the tail of the sperm? (1)
containing microtubules in an arrangement similar to that of a cilium.
what does the acrosome contain? (1)
contains hydrolytic enzymes.
what process are egg cells produced by? (1)
oogenesis
what are the first and second stages of fertilisation in the ovum? (2)
1) oogonia grow to become oocytes
2) primary follicle (oocyte surrounded by a layer of follicle cells)
what are the third stage of fertilisation in the ovum? (2)
each menstrual cycle a few primary follicles start to develop (meiosis 1) is completed forming a secondary oocyte and a first polar body.
what are the fourth stage of fertilisation in the ovum? (2)
secondary oocyte in mature ovarian follicle with layers of follicle cells and fluid early in prophase of meiosis 2.
what are the fifth stage of fertilisation in the ovum? (2)
follicle bursts at ovulation and egg cell (secondary oocyte) released (surrounded by follicle cells)
what are the sixth stages of fertilisation in the ovum? (2)
remains of follicle now develops into endocrine gland (corpus luteum)
what is gametogenesis? (1)
the process by which gametes are produced.
what is the karyotype for a male? (1)
XY
what are the separate structures of an individuals sperm? (3)
-a head
-a middle part
-a tail
what is the middle part of a sperm? (1)
packed with mitochondria - the organelles that produce ATP.
what is the head of the sperm? (10
contains a haploid nucleus and an acrosome.
how are oogenesis and spermatogenesis different, in terms of structure? (2)
oogenesis - the fertilised ovum is non-motile and becomes lodged in the endothelium of the uterus where cell divisions (cleavage) lead to embryo formation.
spermatogenesis - sperm are small motile gametes.
what is a graafian follicle? (1)
each follicle starts as a layer of cells around the oocyte but eventually develop into a fluid filled sac, the graafian follicle.
what is a blastocyst? (1)
a fluid - filled ball of cells (called blastomeres) formed by a repeated cell division of a zygote (formed 4-5 days after fertilisation)
what is reproduction? (1)
the production of new individuals by an existing member of members of the same species.
what occurs in the first stage of fertilisation? (1)
sperm passes between the follicle cells and arrives at the jelly coat surrounding the secondary oocyte.
what occurs in the second stage of fertilisation? (1)
‘capacitation’ changes to the surface of the head of the sperm, releasing hydrolytic enzymes (acrosome reaction)
what occurs in the third stage of fertilisation? (1)
enzyme digestion creates a tiny path for sperm to reach the cell surface membrane of the secondary oocyte.
what occurs in the fourth stage of fertilisation? (1)
fusion of the cell surface membrane of secondary oocyte and sperm.
what occurs in the fifth stage of fertilisation? (1)
cortical granules in outer layers of cytoplasm of secondary oocyte pass across the cell membrane by exocytosis, preventing entry of a second sperm (cortical reaction)
what is capacitation? (1)
changes to the head of a sperm cell, making it fully capable of fertilisation.
