| What is gametogenesis? | how gametes are made in gonads (testes / ovary) |
| what are gonads? | testes and ovaries were gametes are made |
| what are the 3 processes in gametogenesis? | mitotic divisions and cell growth
meiosis
differentiation |
| Outline the process of spermatogenesis (5) | in seminiferous tubules the germline epithelium do mitosis
spermatogonia produce spermatocytes w cell growth
spermatocytes undergo meiosis (2 divisions) = spermatids
differentiates into 4 sperm cells |
| what are the support cells for sperm called? | sertoli cells |
| what does spermatogenesis depend upon? | Testosterone levels made in the leydig cells |
| outline the process of oogenesis (6) | produced in the ovaries
oogonia + granulosa cells undergo mitosis
oocyte 1 (prophase 1) till puberty
oocyte 2 (meiosis 1) + 3 polar bodies (met 2) in puberty
meiosis 2 done if oocyte is fertilised = ovum + polar body
unequal cytoplasm division |
| What are the differences between spermatogenesis and oogenesis? (3) | number of cells = sperm (4) ovum (1)
size = sperm (equal size), ovum (only 1 has all cytoplasm)
timing = sperm (continuous production till death), ovum (limited and staggered) |
| list the order of stages in spermatogenesis using a seminiferous tubule diagram (6) | germline epithelium + sertoli cells
spermatogonia (mitosis and growth)
1 spermatocyte (meiosis 1)
2 spermatocyte (meiosis 2)
spermatid (differentiation)
4 sperms |
| label a sperm (6) | acrosome = hydrolytic enzyme to penetrate jelly
nucleus = genetic info
centriole = so zygote can divide
Mitochondria = ATP for movement
flagellum = movement
axonome = bends for movement |
| List the order of stages in oogenesis using a ovary diagram (6) | primordial follicles (P1) primary oocytes
each month = primary follicle
secondary follicle
mature follicle = ruptures and released secondary oocyte
corpus leutum = produces estrogen and progesterone
corpus albicans |
| What does external fertilisation involve? example? (3) | fuse outside and is influenced by the environment (predators and pH) = release a large amount to make up for loss. Aquatic animals
Eg: Spawning |
| What does internal fertilisation involve? (2) | gametes formed inside (copulation) prevent exposure + more protection but there is a survival cost to parent |
| What is it called when gametes are formed inside? | copulation |
| What are the biochemical changes to egg and sperm during fertilisation? (3) | capacitation
acrosome reaction
cortical reaction |
| What is capacitation? (2) | improves sperm mobility by destabilising acrosome cap and cholesterol coat is removed |
| What is acrosome reaction? (3) | sperm binds to jelly and enzymes are released from acrosome
digests jelly so sperm nucleus can enter
binds to docking proteins |
| What is cortical reaction?(4) | cortical granule in ovary releases enzyme into jelly to destroy sperm binding sites
hardens jelly coat
prevents polyspermy |
| label an ovary (4) | nucleus = forms after fertilisation
cortical granule = releases when fertilised to prevent polyspermy
Zona pellucida (jelly)
corona radiata (follicular cells to support and nourish) |
| What are the stages of embryo development? (3) | zygote = influx of Ca2+ completes meiosis
mitosis = morula
differentiates blastocyst = outer
outer is trophoblast= placenta |
| How is the blastocyst implanted? also include the stages of embryo development (5) | Day 0 = zygote
Day 4 = Morula
Day 7 = Blastocyst
digestive enzymes released degrade lining and autocrine hormones triggers implantation
when implanted blastocyst gets nutrients from endometrial lining |
| What is HCG? what is its main purpose? | Human chorionic gonadotrophin maintains the corpus leutum |
| which hormones do corpus leutum produce? | estrogen and progesterone |
| what does estrogen do? (2) | inhibits PSH + LH production = prevents release of more eggs |
| what does progesterone do? (2) | maintains endometrium lining
thickens cervix |
| How long is HCG maintained for? | 8-10 weeks |
| what replaces the job of HCG after it stops being produced? (2) | placenta does progesterone secretion and nourishes embryo
HCG levels decrease so corpus leutum degenerates |
| what does the placenta develop from? | from trophoblast after implantation |
| What are the two main jobs of the placenta? | exchanges materials bw mom and fetus
secretes hormones to maintain pregnancy after corpus leutum degenerates |
| What are the different parts of the placenta? (5) | umbilical cord
fetal vein and artery
maternal vein and artery
chorionic villus
intervillous space (lacunae) |
| What does chorionic villus do? | moderates material exchange |
| What are the features of chorionic villus to aid diffusion? | microvilli = increase surface area
close to surface = less distance |
| what gets transferred to the fetal cappillaries? | oxygen, water and nutrients |
| what gets transferred out of the fetal capillaries? | CO2 and urea |
| when does estrogen and progesterone levels peak? | 3rd trimester |
| What does estrogen do in 3rd trimester? (2) | grows uterine muscles
develops mammary glands |
| What does progesterone do in the 3rd trimester? (2) | maintains endometrium
decreases contraction |
| What is the birth process called? | parturition |
| which hormones are involved in the birth process? | estrogen and oxytocin |
| what is the positive feedback loop of the birth process? (5) | baby stretches cervix by pushing
nerve impulses causes posterior pituitary to release oxytocin
oxytocin causes smooth muscle lining to contract
less space causes more stretching
loop repeats |
| which hormone is released from the fetus? what does it do? | prostaglandin causes more contractions |
| what does estriol do? (2 oppsites) | promotes release of oxytocin from posterior pituitary
inhibits progesterone because it prevents contractions |
| What does oxytocin do? (2 opposites) | promotes contractions
and inhibits progesterone |
| what is gestation period? | Time taken for fetus to develop and depends on animal size and development level |
| what is altricial and precocial? | undeveloped and developed |
