d3.1 (reproduction) Flashcards
parts of a plant’s reproductive system & functions x9
Sepal: Protects developing flower inside bud
Petal: Colourful, attracts pollinators
Anther: Produces pollen
Pollen: Contains male nuclei for fertilization
Filament: Stalk that holds up anther
Stigma: Sticky part of carpel, where pollen lands
Style: Part of carpel that supports Stigma
Ovary: Base of carpel, contains ovule. Sometimes a fruit.
Ovule: Chamber within ovule where female nuclei develops
hermaphroditic definition
contain both male and female structures
key features of insect-pollinated flowers x5
bright colours
sweeter scent
sugary nectar
visible landing platforms
sticky pollen
pine trees produce two types of cones: male cones and female cones. male cones are smaller and produce pollen, while female cones are larger and contain seeds.
how have some species of conifer cones adapted to avoid self-pollination?
female cones grow on higher branches, and male cones on lower branches. this is thought to prevent self-pollination as the wind will carry pollen from male cones away from drop site.
define heterostyly. how do primrose flowers exhibit this?
where there are different floral forms within the same species to facilitate cross-pollination
pin eyed: style is long, and the stigma is positioned farther out in the flower. anthers are closer to the base of the flower. pollen is positioned lower down in the flower
thrum: style is shorter, and the stigma is positioned closer to the base of the flower. anthers are located nearer to the top of the flower. pollen is placed higher up.
this encourages cross pollination within the species
define dioecious plants (give 2 examples)
plants that have separate male and female plants (i.e. willows & cannabis)
incompatibility mechanisms present in some plants aims to reduce self-pollination. what are 4 examples of this?
pollen grain lands on stigma, fails to grow pollen tube
pollen grain grows pollen tube, but it doesn’t enter style
pollen tube grows and enters ovule, but pollen nuclei degenerate before fertilization
fertilization occurs but plant embryo degenerates
what is gametophytic self-incompatibility (GSI) mechanism (how does it work)?
the pollen grain itself carries the self-incompatibility (SI) allele, and the pollen is rejected if it shares the same allele as the pistil (female part of the flower)
how is sporophytic self-incompatibility (SSI) different from gametophytic self-incompatibility (GSI)?
self-incompatibility is determined by the alleles in the pollen parent’s tissues (sporophyte), rather than in the pollen itself
(stigma identifies the incompatibility based on the pollen’s genetic makeup, not the allele carried by the pollen grain itself, if the pollen grain has one or more of the same alleles as the pistil, the pollen will be rejected)
example species of gametophytic self-incompatibility (GSI) and sporophytic self-incompatibility (SSI) (1 each)
GSI = brassica
SSI = roses
what is hybrid self-incompatibility (HSI)? when can it be observed?
a combination of both GSI and SSI mechanisms, often found in hybrid species. it prevents self-pollination in hybrids
5 ways of seed travel
wind, animals, water, bursting, humans
what is the point of a seed going dormant?
allows seeds to wait until environmental conditions are favourable
define imbibition, what does it do?
process of seed absorbing water. activates biochemical processes in seed
define radicle (in relation to seed growth)
first plant structure to grow, turns into the root
define hypocotyl
first above ground structure
where is meristem tissue found? what is it the site of?
present at tips of roots and shoots. it is where plant growth occurs
at fertilization, two ______ _________ fuse to form a _______ __________
haploid gametes, diploid zygote
to maintain the correct number of chromosomes in each generation, there must be a reduction in the number of chromosomes in the forming of eggs and sperm– why?
by uniting two gametes with half the number of chromosomes, the full chromosome number is restored each generation
define gametogenesis
the process of the production of gametes
4 general steps of gametogenesis
mitosis of germ cells to create a supply of cells that can divide to become gametes
growth of the germ cell prior to dividing to ensure it has the materials and nutrients it will need for division
two divisions of meiosis to create four haploid daughter cells.
differentiation of the haploid daughter cells to create specialized gametes (oocytes or spermatozoa)
what is a germ cell?
stem cells within the gonads (testes or ovaries) that can divide and differentiate to become gametes (a cell that develops into a reproductive cell)
testes are composed largely of seminiferous tubules (coiled tubes). what do the walls contain?
cells that produce sperm
spermatogenesis cell names for each step x5
spermatogonia
primary spermatocytes
secondary spermatocytes
spermatid
spermatozoa
what do sertoli cells provide to primary spermatocytes?
nourishment to the primary spermatocytes as they grow
watch a video on spermatogenesis
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once the sperm has differentiated, it is transported through the ________________ and stored in the _______ of the testes until it is ready to leave the male body
long seminiferous tubules, epididymis
watch a video on oogenesis
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from the end of prenatal development through childhood, the primary oocytes remain at what stage?
prophase I
influenced by FSH from the pituitary, each month an ovarian follicle will grow. just before ovulation, the primary oocyte within the follicle will complete what?
meiosis I
the secondary oocyte (larger haploid cell), is still in the follicle. it will begin meiosis II but stop at what stage?
metaphase II
if fertilization occurs, the secondary oocyte will complete meiosis II and another what will be created?
polar body
what causes ovulation?
influenced by LH from the pituitary, each month a follicle will rupture, causing ovulation
how long can sperm live within the female reproductive tract?
~5 days
after ejaculation, sperm moves through the ___, into the ___ and swim towards the ___ within the ___
cervix, uterus, egg, oviduct
sperm are able to direct their movement towards an egg using thermotaxis and chemotaxis. what are these two processes?
in thermotaxis, sperm change their swimming direction according to a temperature gradient, swimming towards a warmer temperature
in chemotaxis, the sperm move in response to a chemical gradient. sperm plasma membranes have receptors that detect chemicals released by the egg
what are corona cells? what do they secrete?
cells that form around a developing egg in the ovary and remain with it upon ovulation
hormones that trigger the acrosomal reaction in the sperm
what is the acrosome reaction?
an reaction where enzymes (triggered by zona pellucida & released by exocytosis) in the sperm’s head (acrosome) digest the zona pellucida of the egg (a glycoprotein matrix surrounding the egg cell membrane)
goes from this shape ⋂ to Ʊ (without concaving inward near base, also not upside down)
what is the zona pellucida?
a glycoprotein matrix surrounding the egg cell membrane
fertilization occurs with the fusion of the sperm plasma membrane with the egg plasma membrane. after the membranes fuse, what happens?
the sperm nucleus enters the egg cell
upon fusion of the sperm and egg membranes, what does the zona pellucida do?
hardens to prevent entry of more sperm (ensures that the egg is not fertilized by multiple sperm and that the zygote will have the correct number of chromosomes)
define polyspermy, what does it lead to?
fertilization by multiple sperm
leads to incorrect numbers of chromosomes and is lethal to the developing fetus
aside from preventing polyspermy, what else is zona pellucida glycoproteins responsible for?
species-specific recognition of sperm, ensuring that sperm from one species cannot fertilize the egg of another
define cortical granules, what happens to them after fertilization?
thousands of vesicles near the membrane of the egg which contain various enzymes & change the structure of the zona pellucida
a signaling pathway is activated which causes the granules to fuse with the egg cell membrane and release their contents via exocytosis (called cortical reaction)
typical human female reproductive system components x6
ovary
oviduct
uterus with endometrium
cervix
vagina
vulva
ovaries functions x2
produce, store and release eggs
make hormones that control the menstrual cycle and pregnancy
define scrotum & purpose
a sac protecting the testes, keeps @ body temperature
testes function x2
making sperm
producing testosterone
define epididymis (with its location & function)
long, coiled tube on top of each testis
sperm mature here
define vas deferens (AKA sperm duct) (with its location & function)
long, muscular tube
travels from the epididymis into the pelvic cavity, & merges with the urethra near bladder
transports mature sperm to the urethra in preparation for ejaculation
seminal vesicles function
glands that produce a fluid that is high in fructose, a sugar that provides nutrients for sperm cells, as well as other proteins, enzymes, and mucus. (this fluid is the major component of semen)
what does the prostate gland do? why does it do this?
adds an alkaline fluid to the semen
this fluid neutralizes the slightly acidic pH of the vagina
what happens during follicular phase? (ovarian cycle)
a follicle develops within the ovary to eventually release the egg at ovulation
what is a follicle?
a fluid filled sac with an immature egg cell
what happens during luteal phase? (ovarian cycle)
walls of the ruptured follicle develop into the corpus luteum
(if a pregnancy does not occur, the corpus luteum breaks down and the ovary returns to the next follicular phase)
what is the corpus luteum?
a temporary mass of cells within the ovary
the follicular phase of the ovarian cycle is activated by follicle stimulating hormone (FSH). what is it triggered by? what does it cause?
triggered by gonadotropin releasing hormone (GnRH) from the hypothalamus, FSH is released from the pituitary and travels through the blood to the ovaries
causes the development of the follicle and the production of oestradiol (estrogen)
what is ovulation? what is it triggered by? what does it cause?t
the rupture of a developed follicle to release the egg into the oviduct
triggered by a rapid rise in luteinizing hormone (LH) (also triggered by GnRH from the hypothalamus, LH is released from the pituitary and travels through the blood to the ovaries)
causes partial digestion of the follicle wall, allowing it to burst open & release the egg
cells of the corpus luteum secrete what 2 things? what does this cause?
oestradiol and progesterone
causes the thickening of the uterus endometrium
the corpus luteum will be broken down if fertilization does not occur, causing what?
a drop in the levels of oestradiol and progesterone
look at d3.1 slide 100
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example of ovarian cycle negative feedback
oestradiol provides negative feedback to the hypothalamus, which lowers the levels of FSH and LH being secreted and subsequently, the levels of oestradiol produced
example of ovarian cycle positive feedback
(days 12-14 of the ovarian cycle) oestradiol switches to provide positive feedback to the hypothalamus. this causes an increase in the level of LH being secreted which leads to ovulation
define menses (uterine cycle)
low levels of oestradiol and progesterone trigger shedding of the endometrium from the uterus (period)
define proliferation (uterine cycle)
rising levels of oestradiol and progesterone from the ovary follicle and then corpus luteum cause growth of the endometrium in anticipation of implantation of an embryo
define secretory (uterine cycle)
dropping levels of oestradiol and progesterone from the degradation of the corpus luteum cause the endometrium lining to begin to weaken and degrade
steps in IVF process x6 (semi detailled)
down regulation: injections of medications which stop the pituitary from secreting FSH & LH, which suspends the normal menstrual cycle
ovarian stimulation: administration of high doses of FSH to trigger development of multiple follicles
egg retrieval: eggs are retrieved from the ovaries (oocyte retrieval, procedure in which a needle with a vacuum suction is used to draw eggs out of the ovarian follicles)
fertilization: each egg is mixed with a sample of sperm in a shallow dish, incubated for 1-2 days to see if a zygote forms
endometrial prep: oestradiol and progesterone are prescribed to prepare uterus for an IVF embryo (thickening of the endometrium)
embryo transfer: 1+ embryo (2-6 days old) placed into uterus for continued growth
how does puberty start?
hypothalamus sends out GnRH, which binds to its receptor within the pituitary cell, which activates synthesis and secretion of two hormones (FSH & LH)
this hormones travel via blood to gonads (testes or ovaries), where they bind to cells with complementary transmembrane receptors where a signalling cascade is triggered & effects of puberty are seen
FSH in male puberty (binding & what it leads to)
binds to a transmembrane receptor on sertoli cells
leads to activation and maintenance of spermatogenesis
LH in male puberty (binding & what it leads to)
binds to a transmembrane receptor on leydig cells
leads to the production of testosterone
what happens in response to testosterone (puberty)? x6 changes
enlargement of the penis and testes
deepening of the voice
growth of facial and public hair
increase in muscle size and strength
bone growth
increased sex drive
FSH in female puberty (binding & what it leads to)
binds to a transmembrane receptor on granulosa cells in a follicle
leads to the development of the follicle and the production of oestradiol
LH in female puberty (binding & what it leads to x3)
binds to a transmembrane receptor on cells in the follicle and corpus luteum
leads to: ovulation, development of the corpus luteum, production of progesterone
what happens in response to estrogen (puberty)? x4 changes
enlargement of vagina and uterus
development of breasts
beginning of menstrual cycles
change in body shape and fat deposition
what happens in response to progesterone (puberty)? x1 main change
development of breasts
how does a zygote turn into an embryo?
zygote begins to divide by mitosis to form an embryo composed of genetically identical cells
embryonic cell proliferation is rapid, with cells omitting gap phases of interphase. what results from this?
the number of cells increases, but the size of the individual cells gets smaller as the cytoplasm is split between them
initially, the embryo divides to create a ball of cells called what?
after ~5 days after fertilization, the cells of this changes into a what? where does this occur?
a morula
blastocyst
occurs in oviduct
the “inner cell mass” of the blastocyst will develop into the ___ and the outer layer of cells will develop into the ___ and _____
fetus, amniotic sac & placenta
about seven days after fertilization, the blastocyst undergoes implantation. what does this look like?
embedding into the endometrium of the uterine wall
human chorionic gonadotropin (hCG) is a glycoprotein hormone. when is it produced? & what is it produced by (x2)?
produced only during pregnancy
produced by the outer ring of cells of the embryo and from the placenta after it has developed
what is the function of human chorionic gonadotropin (hCG)?
stimulate the corpus luteum and placenta to continue to produce progesterone during the pregnancy
why is progesterone essential for pregnancy?
to maintain the endometrium of the uterus (preventing menstruation during the pregnancy)
watch this http://www.youtube.com/watch?v=aOfWTscU8YM
(if a full idea is not obtained, look over slides 139 to 141 of d3.1)
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monotremes vs marsupials vs placentals
monotremes: egg-laying mammals strictly found in Australia and New Guinea (such as platypus and echidna)
marsupials: give birth to underdeveloped offspring that climb into the mother’s pouch to complete development (such as kangaroos, koalas, opossums)
placentals: mothers carry the fetus in their uterus where it is nourished via the placenta (such as cats, rodents, elephants, whales, humans)
the placenta is composed of a combination of fetal and maternal tissues.
fetal half: blood from the fetus arrives at the placenta via blood vessels in the umbilical cord. within the placenta, the blood vessels branch into structures called chorionic villi.
what is the purpose of cells that line the chorionic villus?
what is a benefit of the structure of the chorionic villi?
separate the maternal from fetal blood, creating a selectively permeable barrier between the fetal and maternal blood supplies
increases the surface area through which nutrients and waste can be exchanged between fetal and maternal blood
the placenta is composed of a combination of fetal and maternal tissues.
maternal half: blood from the mother flows to and from the spaces surrounding the villus.
what 2 main flows between fetal blood and maternal blood occur?
nutrition and oxygen in the mother’s blood moves into the chorionic villi and into the fetal blood supply
waste products and carbon dioxide from the fetus are passed from the fetal blood in the chorionic villi into the mother’s blood
look at d3.1 slide 148
purpose of human chorionic gonadotropin during pregnancy x2
maintains the ovarian corpus luteum for first weeks of pregnancy to ensure a new follicle doesn’t mature and another egg is not ovulated
suppresses the mother’s immune system so the embryo is not rejected
purpose of estrogen & progesterone during pregnancy x2
maintains the endometrium during pregnancy
stimulates mammary gland development
the placenta facilitates nutrient, gas and waste exchange between the physically separate maternal and fetal circulations.
what travels from mother to fetus? x8
glucose
amino acids
lipids
oxygen
water
antibodies
horomones
ions
the placenta facilitates nutrient, gas and waste exchange between the physically separate maternal and fetal circulations.
what travels from fetus to mother? x4
carbon dioxide
water
ions
waste products (i.e. urea)
movement of gasses (O2 and CO2) between the mother and fetus occurs by what?
simple diffusion
movement of simple carbs (i.e. glucose) between the mother and fetus occurs by what? specify how this is done for glucose particularily
facilitated diffusion
through glucose transport channel proteins (GLUTs) in the cells of the chorionic villi
movement of amino acids between the mother and fetus occurs by what?
active transport via amino acid transporter proteins
movement of antibodies between the mother and fetus occurs by what?
bulk transport (endo/exocytosis)
during the first 10 weeks of pregnancy, progesterone is secreted by the _______. after those initial weeks, the _____ takes over producing progesterone
corpus luteum, placenta
progesterone levels rise until near the end of the pregnancy. progesterone is important in maintaining the pregnancy because it: x4
suppresses the mothers immune response so it will tolerate the presence of fetal cells and DNA
prevents ovulation of eggs from the ovaries
maintains the uterus endometrium, preventing menses (uterine wall shed) while the mother is pregnant
inhibits secretion of oxytocin by the pituitary, thereby keeping the uterus muscle relaxed, preventing onset of early labor
what is childbirth triggered by?
a drop in progesterone levels
what does oxytocin do?
stimulates contractions of the muscles of the uterus during childbirth
how is oxytocin representative of a positive feedback loop?
oxytocin released during a contraction of the uterus at the start of childbirth stimulates the production and release of more oxytocin, which makes contractions become more frequent and intense allowing the baby to be born
symptoms of menopause x4
hot flashes
night sweats
reduced sex drive
vaginal dryness
why may women be prescribed medications of oestradiol and progesterone? what can it treat & what may it reduce the risk of?
a way to treat menopause symptoms
reduced risk of coronary heart disease in postmenopausal women
what is coronary artery disease caused by?
plaque (cholesterol deposits) buildup in the wall of the arteries that supply blood to the heart
define spurious correlation
a correlation in which two variables are associated but not causally related, due to either coincidence or the presence of a certain third, unseen factor
