Lesson 6 - Fertilization Flashcards
(108 cards)
1
Q
what do biologists use to study development
A
model organisms
2
Q
- process that begins when a sperm cell first makes contact with the covering of the egg
- ends with the intermingling of maternal and paternal chromosomes at the metaphase plate prior to first cleavage
- formation of a diploid zygote from haploid egg and sperm
- reaction of three bodies: sperm, egg, and secretion
A
fertilization
3
Q
when does fertilization begin
A
sperm cell first makes contact with the covering of the egg
4
Q
when does fertilization end
A
intermingling of maternal and paternal chormosomes at metaphase plate prior to first cleavage division
5
Q
three bodies that react during fertilization
A
sperm, egg, secretion
6
Q
types of fertilization
A
- exteral
- internal
7
Q
gametes released and fertilized outside of the female body
A
external fertilization
8
Q
sperm cells are deposited into the female reproductive tract
A
internal fertilization
9
Q
sperm filled reproductive gland of male fish
A
milt
10
Q
examples of external fertilization
A
- paired spawning in fishes
- amplexus in amphibians
11
Q
packt of sperms that is deposited by salamanders
A
spermatophore
12
Q
- male copulatory organ
- usually held inverted within the body
- everted for reproduction
- found lateral to the cloaca
- surface often have folds, papillae or spines to anchor the male within the female
A
hemipenis
13
Q
what does the surface of the hemipenis often have
A
folds, papillae, or spines to anchor
14
Q
copulation in birds
A
cloacal kiss
15
Q
mating behovior in whales
A
3rd party male props the female against the mating male
16
Q
courtship in humpback whales
A
pairs surfacing vertically face to face
17
Q
have the most extreme mating
A
anglerfish
18
Q
reproductive variation and terminologies
A
- parthenogenesis
- hermaphroditism
19
Q
- development of an egg into new individuals without fertilization
- “virgin bith”
- eg. honeybees, nematodes, lizard
A
parthenogenesis
20
Q
- condition werein an animal posses both male and female reproductive organs
- monoecious
- eg. flatwords, clams, some fish
A
hermaphroditism
21
Q
variation in hermaphroditism
A
- sequential hermaphorditism
- simultaneous hermaphroditism
22
Q
two types of sequential hermaphroditism
A
- protogynous
- protandrous
23
Q
female first, male later
A
protogynous
24
Q
male first, female later
A
protandrous
25
meiosis in parthenogenesis
first division is abortive, reduction never takes place
26
different types of parthenogenesis
1. arrhenotoky
2. thelytoky
3. amphitoky or deuterotoky
4. automixis
27
parthenogenesis that gives rise to males
arrhenotoky
28
parthenogenesis that gives rise to females
thelytoky
29
parthenogenesis that gives rise to both sexes
amphitoky or deuterotoky
30
two of the ova produced by a female in one meiosis fuse and then develop
automixis
31
parthenogenetic lizard
Komodo dragon
32
deliver the other half of the genome
sperm
33
prevent polyspermy and start development of new organism
egg
34
where is the nucleus located
animal pole
35
large, transcriptionally active chromosomes found in the germinal vesicle of oocytes (egg cells) of many animals, characterized by lateral loops that are sites of intense RNA synthesis
Lampbrush chromosomes
36
birds: place for reception of the ovulated egg cell and for fertilization
infundibulum
37
birds: synthesis and deposition of proteins (albumin)
magnum
38
birds: synthesis of two shell membranes
isthmus
39
birds: where synthesis of the shell happen
uterus
40
birds: storage of sperm cells and has no function in the synthesis of the egg
vagina
41
birds: opening
cloaca
42
size of human sperm cells
50-70μm
43
contains the half of the genome and acrosome containing the enzymes
head
44
contains enzymes
acrosome
45
contains the mitochondira which provides the ATP for its journey to the egg
middle piece
46
for locomotion of sperm
tail or flagella
47
important components in fertilization
1. initial membrane contact between egg and sperm
2. entry of sperm cell into the egg
3. prevention of polyspermy by the egg
4. metabolic activation of the egg
5. completion of meiosis by the egg
6. formation and fusion of male and female pronuclei
48
hours within the female reproductive tract
7 hours
49
play a crucial role in sperm maturation and function by modifying sperm surface glycoproteins during epididymal transit, influencing sperm binding and fertilization.
Glycosyltransferases
50
what must the spermatozoa pervade before reaching the ovum proper
- corona radiata
- zona pellucida
51
enzymes released by the acrosome
1. hyaluronidase
2. acrosin
52
corona-penetrating enzyme
hyaluronidase
53
trypsin-like protease which digests the zona pellucida
acrosin
54
- primary receptors
- N-acetyluglucosamine, galactose and zona receptor kinase
ZP3
55
- maintains binding of the sperm
- inner acrosomal membrane
ZP2
56
cross link the ZP3 and ZP2
ZP1
57
binding of the sperm to the zona pellucida
1. sperm adhesion proteins
2. ZP-3 receptors
3. cascade of transduction pathways
4. G-protein and kinase
5. IP3 synthesis and release of calcium ions from sarcoplasmic reticulum
58
acrosome acts as what
enzymatic drill to allow passage of sperm into the egg cytoplasm
59
what triggers acrosomal reaction
when sperm meets the egg
60
what happens during gamete contact and/or fusion
- depolarizes egg cell membrane
- sets up a fast block to polyspermy
61
what is also initiated when there is fusion of egg and sperm
cortical reaction
62
what is the cortical reaction
1. calcium-dependent exocytotic process triggered by fertilization
2. egg releases contents of cortical granules into the perivitelline space, preventing polyspermy (multiple sperm fertilizing one egg)
63
what does the fertilization envelope act as in cortical reaction
slow block to polyspermy
64
what does the cortical reaction require
high conc. of Ca2+ ions
65
triggers cortical reaction
change in Ca2+ concen.
66
- create osmotic graident
- water enters, swelling of space between plasma membrane and vitelline membrane
GAGs
67
cleave protein link beta plasma membrane and vitelline membrane
proteases
68
promotes hardening of zona pellucida and inactivation of the receptors
peroxidase
69
increases the rates of cellular respiration and protein synthesis by the egg cell
rise in Ca2+ in cytosol
70
fusion of pronuclei
amphimixis
71
amphimixis
1. entry of the sperm into the egg activates the egg to resume its second meiotic division -> 2nd polar body
2. sperm nucleus enlarges and undergoes decondensation of chromatin materials
3. approximation of sperm and egg pronuclei
4. fusion and breakdown of their nuclear membranes
5. recondensation of chromosomes in mitotic spindle
6. true diploid nucleus appeared in the 2 cell stage, not in zygote
72
when does a true diploid nucleus first appear
2-cell stage, not in zygote
73
30 degree movement of the cortical cytoplasm that leads to the appearance of gray crescent
cortical rotation
74
why is the gray crescent an important landmark
1. site of gastrulation
2. region opposite the sperm entry
3. turns into Spemann's organizer, a signaling center
75
how does mammalian fertilization differ from that of the sea urchin and frog
frog fertilization has coritcal rotation, leading to the appearance of the gray crescent
76
do the sperms always enter at the animal pole?
- in amphioxus, sperms enter in the vegital pole
- in fishes and insects, micropyle
77
what are the results of fertilization
1. restores diploid condition of species
2. determines genetic sex of embryo
3. activates egg to undergo development
4. establishes 2ndary polarity of the embryo
78
site of sperm entry
anterior and ventral region
79
opposite region of sperm entry
posterior and dorsal region
80
alter sperm motility and structure in mammals
secretions in mammalian female reproductive tract
81
physiological process where sperm undergo changes in the female reproductive tract, enabling them to penetrate and fertilize an egg, including increased motility and the ability to undergo the acrosome reaction
Sperm capacitation
82
extracellular matrix of the egg
zona pellucida
83
what kind of block is triggered when sperm binds to zona pellucida in mammals
slow block to polyspermy
84
when does the first cell division occur in mammals
12-36 hours after sperm binding
85
sea urchin vs mammals:
fertilization
sea urchin: external
mammals: internal
86
sea urchin vs mammals:
covering
sea urchin: noncellular jelly coat
mammals: cellular layer
87
sea urchin vs mammals:
completion of 2nd meiotic division
sea urchin: before entry of spermatozoon
mammals: before union of maternal and paternal genetic material
88
fertilization in mammals
1. release of cortical granules causing the zona reaction, preventing further sperm penetration
2. completeion of 2nd meiotic division and extrusion of 2nd polar body
3. formation of female pronucleus
89
covers the egg of sea urchin
thick jelly coat composed of small peptides, glycoproteins, and polysaccharide containing fucose sulfate units
90
increases motility of sea urchin spermatozoa
cluster together
91
responsible for increased motility and activated respiration that occur when sperm contacts the jelly coat
speract (decapeptide)
92
stimulates the acrosome reaction which is stimulated by an exchange of extracellular Ca with intracellular K
fucose sulfate polysaccharide or a glycoprotein
93
pH that begins localized fusion of outer acrosomal membrane with plasma membrane resulting to breakdown
intracellular pH . 7.2
94
what happens with acrosome reaction in _Arbacia_ sea urchin
- release of soluble enzymes located within acrosome vesicle
- polymerization of g-actin (globular) to f-actin (filamentous)
95
forms the basis of acrosomal process or filament
f-actin
96
protein that mediates sperm binding to the surface of the egg
bindin
97
help the sperm to digest the vitelline envelope
lysins
98
ensure only one sperm of the same species fertilizes the egg
extracellular region
99
- remains constant among different species
- serve to stimulate a signal transduction event that initiate changes that affect the egg after sperm-egg membrane fusion
intracellular region
100
after sperm-egg fusion, what engulf the head of sperm
group of microvilli
101
bulge due to microvilli engulfing head of sperm after sperm-egg fusion
fertilization cone
102
seconds in fast block
2-3 seconds and lasts for 60 seconds
103
Steps in slow block to polyspermy in sea urchins
1. plasma membrane generates a resting membrane potential = egg no longer permits the fusion of other sperm to its plasma membrane
2. Mobilization of Ca bound within the egg = wave of free Ca released initiates cortical reaction -> rupture of cortical granules and the release into the perivitelline space
3. release of ovoperoxidase from the cortical granules
104
Cortical granules move to inner surface of plasma membrane ->
fusion -> doubles the surface membrane of egg
105
what does the hydrated mucopolysaccharide form
hyaline layer between plasma and fertilization membrane
106
- hardens the fertilization membrane into a tough envelope that surrounds the early embryo
- kills any sperm that have penetrated the vitelline envelope
Hydrogen peroxide (H2O2)
107
animals where polyspermy is normal
- urodele
- amphibians
- birds
108
Metabolic activation of egg
1. binding of sperm to receptor site
2. minor influx of sodium ions; membrane potential change
3. liberation of Ca ions from intracellular depots; cortical reaction, release of acid; conversion of NAD to NADP; rise in oxygen consumption
4. increase intracellular pH
5. increase in protein synthesis; activation of transport systems
6. fusion of egg and sperm nuclei; initiation of DNA synthesis
7. first cell division
