Chapter 43: Animal Reproduction Flashcards
What are the four sex steroids?
- Cholesterol
- Oestrogen
- Progesterone
- Testosterone
What happens to sex hormones before puberty?
held at low level due to negative feedback
What happens to sex hormones during puberty?
feedback loop is down regulated (Hypothalamic receptors for sex-hormones will become less sensitive.)
Gametes
eggs, sperm produced by meiosis
zygote
formed from the fusion of male and female gametes during fertilization (diploid)
What processes in sexual reproduction lead to diversity?
gametogenesis and fertilization, through independent assortment and the recombination of alleles of chromosomes
Haploid
one set of chromosomes
Diploid
two sets of chromosomes
Gametogenesis
produces gametes in meiosis from the germ cell one
What are the two types of gametogenesis?
- Spermatogenesis
2. Oogenesis
What do the primary sex organs produce?
haploid cells via gametogenesis
What is the path of male sex organs to produce gametes?
testis–>spermatogonia–>sperm
What is the path of female organs to produce gametes?
ovary–>oogonia–>egg
What are the functions of the accessory sex organs?
facilitate fertilization (penis and vagina)
What is spermatogenesis and where does it occur?
it is the process of sperm production; occurs in the seminiferous tubules of the testes.
How does spermatagonia proliferate, what type of division?
mitosis; throughout a male’s lifespan
How many sperm does a primary spermatocyte produce?
four haploid sperm: 2 with X and 2 with Y
Oogenesis: describe the pathway
female germ cell–>mitosis–>oogonium–>mitosis–>primary oocyte–>first meiotic division–>secondary oocyte(n) & first polar body–>second mitotic division–>ootid(n) & second polar body–>ovum(n) & polar bodies degrade
How many eggs does each oogonium produce?
one
In what form are the female sex cells stored and for how long?
primary oocyte stored in prophase for up to 50 years
When does the second mitotic division occur in oogenesis?
after fertilization.
Where does oogenesis occur
in fetal ovaries during gestation
how many primary oocytes exist at puberty?
~200,000
How many primary oocytes will mature during a woman’s fertile years?
~450