D3.1 Reproduction Flashcards
sexual vs asexual reproduction
- gametes fertilized vs organism replication
- 2 vs 1 parent
- genetically unique vs identical offspring
types of asexual reproduction
binary fission, mitosis, budding, fragmentation, vegetative reproduction (new plants from roots, etc.), parthenogenesis (developing egg without sperm)
draw and label the female reproductive system
vagina, cervix, uterus, oviduct/Fallopian tubes, ovaries (front and side view)
gonad
organ producing gametes (ovary and testis)
function of ovaries
produce oestradiol and eggs as secondary oocytes, ovulation in corpus luteum temporarily produces progesterone
function of Fallopian tube
carry egg from ovary to uterus
function of uterus
embryo implantation and development
function of endometrium
vascular inner lining of uterus
draw and label the male reproductive system
testis, scrotum, epididymis, vas deferens, urethra, seminal vesicle, bladder, prostate gland, Cowper’s gland, penis/erectile tissue, anus (side view)
function of testes
produces sperm in seminiferous tubules
function of epididymis
where sperm are stored and mature
function of scrotum
protects testes and sperm grow at cooler temperature
function of vas deferens
carries sperm to urethra
function of seminal vesicle
produces seminal fluid
function of prostate gland
produces most of the semen, used to neutralize vaginal fluid
function of Cowper’s gland
produces lubricating mucus
menstrual cycle
- hypothalamus produces gonadotropin-releasing hormone (GnRH)
- GnRH stimulates pituitary gland to produce follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
- FSH and LH stimulate ovaries to produce oestradiol
- Oestradiol stimulates endometrium to increase vessels and pituitary gland to increase production of FSH and LH (positive feedback)
- Increase in FSH and LH stimulates arrangement of follicle cells in two rings around oocytes, producing Graafian follicles
- Single follicle enters Fallopian tube after ovulation, outer ring stays in ovaries
- Outer follicles form corpus luteum, producing progesterone to maintain endometrium and dividing to heal would from ovulation
- Corpus luteum produces progesterone for 10-12 days, signalling to hypothalamus no GnRH (negative feedback)
- When corpus luteum diminishes, no more endometrium vessels, low levels oestradiol and progesterone result in menstruation and new cycle
function of luteinizing hormone
stimulates follicles to mature and release eggs
2 components of menstrual cycle
ovarian and uterine cycle
process of fertilization
- sperms release enzymes from acrosome penetrates follicle layer, then zona pellucida (glycoprotein gel), then plasma membrane
- egg releases vesicles to destroy sperm flagellum and mitochondria, leaving male nucleus with female in egg (pronuclei)
- pronuclei replicate DNA then fuse, prepare for mitosis (chromosomes and spindles form, nuclear membrane dissolves)
- first mitosis 30 h later, 16 cells after 3 days
reasons for infertility
low sperm count, impotence, abnormal ovulation, blocked Fallopian tubes
process of in vitro fertilization
- woman takes drugs to stop hormones of menstrual cycle
- woman injected with FSH to produce more Graafian follicles (superovulation), and hCG to maintain endometrium
- eggs harvested surgically, sperm from ejaculation
- eggs and sperm mixed in multiple dishes, 1-3 healthy embryos implanted into uterus (unused embryos are frozen)
what plant structures produce gametes?
ovules and pollen grains
how do ovules and pollen grains reproduce, in contrast to plant gametes?
meiosis vs mitosis
how are flowering plants capable of self-fertilization?
many have hermaphroditic flowers, with male and female structures
process of cross-fertilization
- pollinators attracted to nectar, come into contact with pollen in anther and bring to other plants
- pollen sticks to stigma of other plant, becomes pollen tube growing down style to take male nuc to ovule
- each tube has 2 male nuclei (double fertilization) and ovule has 3 female nuclei; 1 male fertilizes 1 female to form zygote, other male fertilizes other 2 females to form triploid endosperm (nourishes embryo)
draw and label an insect-pollinated flower
petals, anthers on filaments (stamen), ovule and ovary connected to stigma through style in middle (carpel), sepal, nectar drops
function of sepal
protects developing flower in bud
function of anther
produces pollen
function of stigma
sticky for pollen to attach
function of ovaries in plants
contains ovules, where female nuclei develop
methods of promoting cross-pollination and preventing self-pollination
- different maturation for pollen vs ovules
- chemical self-incompability mechanisms
- flowers with only male/female parts
- plants with only one sex of flowers
- pollen transferred away by wind
types of self-incompatability mechanisms
- pollen tube isn’t formed
- pollen grain doesn’t enter stigma
- pollen nuclei degenerate before fertilization
- embryo degenerates early
benefits of cross-pollination
increased variation and vigour
vigour
healthy growth of new plant
methods of seed dispersal
fruits that animals eat and defecate seeds, some float on water or wind, some have pods that dry then release explosively
describe the process of germination
- seeds stay dormant until good water, nutrients, O, temperature
- seeds’ endosperm tissue has food transferred to embryo through cotyledons until can do photosynthesis
- imbibition increases respiration and protein synthesis
- radicle (main root) first part of embryo to emerge from seed coat
- hypocotyl (shoot that supports coyledons) first structure above ground
- first leaves develop as endosperm depleted
- secondary roots and root hairs develop
- growth continues from meristem tissue
imbibition
absorption of substance, esp of water by plant
physiological changes from puberty in women
increased height and mass, underarm and pubic hair, breasts, menstruation, acne, widened hips, fat deposits
physiological changes from puberty in men
increased height and mass, underarm, facial, chest, and pubic hair, acne, deeper voice, enlarged testes and penis, erections
describe the process of spermatogenesis
- spermatogonia in seminiferous tubules replenish with mitosis and develop into primary spermatocytes, which become spermatozoa through meiosis
- spermatozoa stay in tubule to form flagellum and acrosome, using nutrients from sertoli cells
- stages of meiosis move spermatozoa closer to interior of tubule, eventually detaching from sertolis and moving through lumen to epididymis for storage
describe the process of oogenesis
- oogonia in ovaries undergo mitosis and develop into primary oocytes during foetal development
- follicle cells undergo mitosis and surround each primary oocyte, forming primary follicle
- after puberty, some primary follicles undergo meiosis 1, making small first polar body and large secondary oocyte
- follicle cells divide and form 2 rings around oocyte with fluid between, forming Graafian follicle
- fluid makes ovaries bulge, stimulating ovulation, where secondary oocyte with only inner ring is released
- if fertilized, meiosis 2 occurs, forming second polar body and zygote
differences between spermatogenesis and oogenesis
- millions of sperm daily vs thousands of eggs at birth
- 4 gametes vs 1 gamete and 2 polar bodies produced
- smallest vs biggest cells
- minimal organelles vs many organelles and nutrients
- motile vs non-motile
polyspermy
when more than 1 sperm fertilizes ovum, resulting in ovum not developing
how is polyspermy prevented?
upon penetration, sperm set off cortical reaction, where corticle granules on interior of egg plasma membrane fuse and release enzymes, causing a chemical change and making zona pellucida impenetrable
describe embryo development into blastocyst
embryo divides while moving through Fallopian tube, 100 cells upon reaching uterus ready to implant in endometrium, becoming blastocyst
components of a blastocyst
- trophoblast: surrounding cells forming placenta, umbilical cord
- inner cell mass
- fluid-filled cavity
how does pregnancy testing work?
antibodies are bonded to enzyme that changes colour when exposed to hCG, found in pregnant women
hCG
human chorionic gonadotropin, produced by trophoblast layer then placenta, allows continuation of corpus luteum, progesterone production, and endometrium maintenance in mom
B-lymphocytes
white blood cells producing monoclonal antibodies, such as hCG-detecting ones
monoclonal antibody
antibody from culture that only produces 1 antibody
umbilical cord
develops from placenta, protects 3 blood vessels: 2 carrying deoxygenated fetal blood to placenta to exchange materials with mom’s blood, 1 carrying oxygenated blood to provide foetus with nutrients
where do fetal blood vessels and maternal blood vessels exchange materials?
intervillous space where mom’s blood is dumped
how do fetal blood vessels increase surface area?
division into placental villi
do all mammals form placentas?
only placental mammals; marsupials and monotremes don’t
advantage of placental mammals
can keep foetus in uterus longer, increased survival rate
process of parturition
positive feedback loop that increases frequency of uterine contractions:
1. foetus reaching full term stimulates decreased progesterone secretion
2. decreased progesterone stimulates pituitary gland to release oxytocin
3. oxytocin receptors in uterus respond with contraction
4. contraction signals more oxytocin, repeats until birth when there’s nothing to contract upon anymore
pitocin
body recognizes as oxytocin; sometimes given to women past term to induce labour
menopause
usually after 45-55 years old when oestradiol and progesterone production (from menstrual cycle) stops
what is used to mitigate symptoms of menopause?
hormone replacement therapy (with oestradiol)
