[LE2] Lecture 6 Flashcards
(139 cards)
1
Q
The process where the gametes fuse to begin the creation of a new organism
a) depolarization
b) fertilization
c) chemoattraction
d) polymerization
A
Fertilization
2
Q
2 Major Goals of Fertilization
A
- Combining of genes derived from two parents
- Generation of a new organisms
3
Q
Include all the processes that occur after ________ until the time _______
A
The gametes leave their respective gonads, that the nuclei fuse and the zygote is activated
4
Q
The sperm or the egg are not ______________ when they leave their respective gonads
a) phospholipase c
b) mature cells
c) four spindles
d) acrosomal
A
mature cells
5
Q
[FOUR MAJOR EVENTS OF FERTILIZATION]
_________ and _________ between sperm and egg
__________ of sperm entry into the egg
__________ of the genetic material of sperm and egg
__________ of egg metabolism to start development
A
- Contact and Recognition
- Regulation
- Fusion
- Activation
6
Q
[RECOGNITION OF SPERM AND EGG]
___________________ of the sperm to the egg by soluble molecules secreted by the egg
a) extracellular matrix
b) exocytosis
c) fertilization
d) chemoattraction
A
Chemoattraction
7
Q
[RECOGNITION OF SPERM AND EGG]
Binding of the sperm to the _____________________ of the egg
a) extracellular matrix
b) exocytosis
c) fertilization
d) chemoattraction
A
extracellular matrix
8
Q
[RECOGNITION OF SPERM AND EGG]
____________ of the sperm acrosomal vesicle and release of its enzymes
a) extracellular matrix
b) exocytosis
c) fertilization
d) chemoattraction
A
Exocytosis
9
Q
[RECOGNITION OF SPERM AND EGG]
Passage of the sperm through the extracellular matrix to the ____________________
a) extracellular matrix
b) equatorial region
c) capacitation
d) egg cell membrane
A
egg cell membrane
10
Q
[RECOGNITION OF SPERM AND EGG]
_________ of the egg and sperm cell membranes
a) fusion
b) ciliary
c) fuse
d) inside
A
Fusion
11
Q
[MAMMALIAN SPERM MODIFICATION]
- The centriole produces a ________________ at what will be the posterior end of the sperm.
a) lipid rafts
b) long flagellum
c) zona pellucida
A
long flagellum
12
Q
[MAMMALIAN SPERM MODIFICATION]
- The Golgi apparatus forms the _______________ at the future anterior end. Mitochondria collect around the flagellum near the base of the haploid nucleus and become incorporated into the _________________ of the sperm.
a) acrosomal vesicle, midpiece (“neck”)
b) sodium hydrogen, cortical granules
c) lost, recognition
A
acrosomal vesicle,
midpiece (“neck”)
13
Q
Stages of egg maturation at the time of sperm entry in different animal species. Note that in most species, sperm entry occurs before the egg nucleus has completed __________.
a) lipid rafts
b) peroxidase
c) meiosis
d) mitosis
A
meiosis
14
Q
- Completion of the second meiotic block
- Restores normal diploid number of chromosomes
- Sex of the future embryo is determined
- Variation
- Metabolic activation of the egg
A
ACCOMPLISHMENTS OF FERTILIZATIONS
15
Q
[EXTERNAL FERTILIZATION IN SEA URCHINS]
1) Sperm will be attracted to egg via _____________
2) Once attracted it would ________________, the acrosome together with actin would pass the jelly layer and digest it
3) And actin would extend and have different receptors and
4) Once bind with _____________, membrane would attach to the sperm so
5) Sperm could enter the cell ______________.
A
1) chemoattraction
2) bind
3) vitelline
4) envelope
16
Q
Some species (marine animals) release eggs and sperm into vast environment
a) depolarization
b) fertilization
c) chemoattraction
d) polymerization
A
CHEMOATTRACTION
17
Q
Two mechanisms have evolved to address chemoattraction issues:
A
- Species-specific attraction of sperm
- Species-specific sperm activation
18
Q
Sea urchins have sperm-activating peptides (resact) in the __________.
a) egg jelly
b) zona pellucida
c) mature cells
d) zinc spark
A
egg jelly
19
Q
- 14aa peptide which can diffuse in sea water
- Attracts sperm to ________
- Acts a _________________ peptide
A
egg
sperm activating
20
Q
Resact - sperm activation site, could diffuse in water so that sperm would be attracted to it - once it has reached the sperm, the sperm would be activated, motility is _______________, and mitochondria increases the number of ______
a) increased, ATP
b) zinc spark
c) anaphase
d) PLC, PLC, mammals
A
increased, ATP
21
Q
- After acrosomal vesicle fuses, an ____________ is extended
- Occurs by ________________ of globular actin molecules into actin filaments
a) acrosomal
b) DNA and protein synthesis
c) intracellular pH
d) acrosomal process, polymerization
A
acrosomal process
polymerization
22
Q
Acrosomal process is important for _____________ recognition
a) species-specific
b) sperm cell membrane
c) acrosomal process
d) polymerization
A
species-specific
23
Q
In S. purpuratus, the acrosomal process contains a protein called _________
a) positive
b) zinc spark
c) hyaline
d) bindin
A
bindin
24
Q
Bindin can bind to the surface of S. purpuratus egg but not __________________
a) A. punctulata
b) zona pellucida
c) actin-homology
d) zinc spark
A
A. punctulata
25
Biochemical studies show other species of sea urchin sperm contains bindin molecules that are closely related, but __________
different
26
_________________________ shows bindin on the tip of the acrosomal process
a) Immunohistochemistry
b) Ca2+ chelator
c) polymerization
d) four spindles
Immunohistochemistry
27
The acrosome reaction Initiated by ________________ compounds in the egg jelly
Compounds bind to receptors on ____________________
species-specific
sperm cell membrane
28
Calcium channels open → calcium flows into _____________
sperm head
29
_____________ reaction in sea urchin sperm. (A-C) The portion of the acrosomal membrane lying directly beneath the sperm cell membrane fuses with the cell membrane to release the contents of the acrosomal vesicle. (D) The actin molecules assemble to produce microfilaments, extending the acrosomal process outward.
a) acrosomal process
b) polymerization
c) meiosis
d) acrosome
Acrosome
30
Sperm-egg fusion causes ___________________ of actin in the egg to form a fertilization cone
a) acrosomal process
b) polymerization
c) meiosis
d) acrosome
polymerization
31
Acrosomal process also forms due to polymerization of _________________
a) A23187
b) Zinc spark
c) ovastacin
d) actin-homology
actin-homology
32
- Actin forms a ________________ where sperm nucleus, centriole, and tail passes
- Mediated by fusogenic proteins - bindin (2nd role)
a) electrical fast block
b) endoplasmic reticulum
c) mucopolysaccharides
d) cytoplasmic bridge
cytoplasmic bridge
33
- Once the coat is made up there will be a cytoplasmic bridge that would allow the cell to enter and make your sperm nucleus
______________________________
Mitochondria would not be entering
34
Restores the diploid chromosome number
a) monospermy (the norm)
b) sperm head
c) thermotaxis
d) centriole
Monospermy (the norm)
35
Monospermy:
Sperm __________ becomes the mitotic spindle, egg centriole degrades
a) zinc spark
b) sperm head
c) thermotaxis
d) centriole
centriole
36
Results in triploid nucleus
a) fertilization
b) exocytosis
c) thermotaxis
d) polyspermy
Polyspermy (disastrous)
37
Polyspermy:
Multiple ________________ form from the two sperms
a) acrosome
b) egg cell
c) centriole
d) mitotic spindles
mitotic spindles
38
(A) Fusion of ___________________ each containing 18 chromosomes, and the division of the two sperm centrioles to form four centrosomes (mitotic poles)
a) DNA and protein synthesis
b) intracellular pH
c) three haploid nuclei
three haploid nuclei
39
(D) At ____________ of the first division, the duplicated chromosomes are pulled to the four poles.
a) metaphase
b) anaphase
c) telophase
anaphase
39
(B,C) The 54 chromosomes randomly assort on the ______________.
a) phospholipase c
b) mature cells
c) four spindles
d) acrosomal
four spindles
40
(E) Four cells containing different numbers and types of chromosomes are formed, thereby causing
(F) the __________ of the embryo.
a) thermotaxis
b) early death
c) resact
early death
41
PREVENTION OF POLYSPERMY:
Usually done by preventing multiple sperm from entering the ____
egg
42
PREVENTION OF POLYSPERMY:
Sea urchins have 2 mechanisms:
Fast block
Slow block
43
Involves a change in egg cell ______________
(fast block)
membrane potential
44
Involves ___________ of the cortical granules in the egg
(slow block)
exocytosis
45
[FAST BLOCK TO POLYSPERMY]
- The egg has a different ____________________ from the seawater in which it exists
a) long flagellum
b) chemical gradients
c) electrical fast block
d) ionic concentration
ionic concentration
46
Egg has lower _______________ concentration higher __________ concentration
sodium ion
potassium
- This is maintained by sodium/potassium pumps in the egg cell membrane
47
The difference in charge across the egg membrane can be measured as -70mV and is called the _____________________
a) resting membrane potential
b) electrical fast block
c) ionic concentration
resting membrane potential
48
- 1 to 3 seconds after the first sperm binds, the membrane potential shifts to +20mV
- Sperm can no longer _____ to the egg
fuse
49
Experimental evidence - polyspermy can occur if:
- Eggs are supplied with an electrical current that keeps charge at ______
- Fertilization occurs in water with a ____ sodium ion concentration
-70mV
low
50
- There would be a sudden shift to the potential of the cell because of the rapid entry of your sodium, because of opening fusion membrane so sodium follows immediately
- This makes the cell more positive- becomes ______________ (makes your cell not allowing other sperm to attach)
a) hyperpolarized
b) depolarized
c) increased
depolarized
51
- Once the moment sperm contacts, there is a rapid change in potential
- And begins dying slowly so _____________ would happen
a) blocks
b) slow block
c) fast block
slow block
52
- Slower, mechanical, permanent block
- Occurs about a minute after sperm-egg fusion
SLOW BLOCK TO POLYSPERMY
53
Slow block:
Upon sperm entry __________________ fuse with the cell membrane and release several molecules
cortical granules
54
A) At 10 seconds after sperm addition, sperm _________ the egg.
(B,C) At 25 and 35 seconds after insemination, respectively, a _________________ is forming around the egg, starting at the point of sperm entry.
(D) The fertilization envelope is complete, and excess sperm has been _________.
Cortical granules are being released succeedingly and begins _________________.
surround
fertilization envelope
removed
permanent block
55
- Release vitelline membrane from its anchors to the cell membrane
- Clips of bindin molecules
Cortical granule serine protease
56
Forms a coating around the egg, protects during early embryonic development
Hyaline
57
- Cause osmotic gradient
- Water rushes into space between vitelline envelope
- Vitelline envelope expands (lifts) and becomes the fertilization envelope
Mucopolysaccharides
58
- Hardens the fertilization envelope
- A hardened jelly substance
Peroxidase
59
(A) Schematic diagram of events leading to the formation of the fertilization envelope. As cortical granules undergo exocytosis, they release _______________________, an enzyme that cleaves the proteins linking the vitelline envelope to the cell membrane.
Cortical Granule Serine Protease (CGSP)
60
Mucopolysaccharides released by the cortical granules form an osmotic gradient, causing water to enter and swell the space between the vitelline envelope and the cell membrane. The enzyme ______ in the former cortical granule membrane catalyzes the formation of hydrogen peroxide (H2O2), the substrate for soluble ovoperoxidase (OVOP). OVOP and ___________________ harden the vitelline envelope, now called the fertilization envelope.
Udx1, transglutaminases (TG)
61
(B,C) Transmission electron micrographs of the cortex of an unfertilized sea urchin egg and the same region of a recently fertilized egg. The raised fertilization envelope and the points at which the cortical granules have _______ with the egg cell membrane of the egg (arrows) are visible in (C).
fused
62
Cortical granules when there is a change in __________ are now being released in the membrane
polarity
63
Does the distribution of Ca2+ in an egg correlate with formation of the fertilization envelope?
Calcium releases across a sea urchin egg during fertilization. The egg is pre-loaded with a dye that fluoresces when it binds Ca2+. When a sperm fuses with the egg, a wave of calcium release is seen, beginning at the site of sperm entry and propagating across the egg. The wave does not simply diffuse but travels actively, taking about 30 seconds to traverse the egg.
At point of fusion of entry there is an increase number of calcium - means calcium ion is released within the cell
64
Does the distribution of Ca2+ in an egg correlate with formation of the fertilization envelope?
During fertilization, sperm typically release enzymes that help them penetrate the egg's protective layers. In response to the sperm's entry, the egg's membrane undergoes a series of changes, including a calcium ion influx. This increase in intracellular calcium triggers a series of cellular events, leading to the formation of the fertilization envelope. The fertilization envelope is usually composed of glycoproteins that cross-link to create a protective barrier.
65
Upon fertilization, intracellular concentration of ____________ in the egg increases
a) acrosomal
b) ca2+ chelator
c) calcium ion
d) ciliary
calcium ion
66
Fusion of cortical granules with the cell membrane
Fertilization/Exocytosis
67
Calcium comes not from outside the egg, but from _______ the egg itself
a) inside
b) outside
inside
68
The fusion begins near the site of ____________ and continues in a wave across the egg
A similar wave of ____________ can be observed
sperm entry
calcium ion
69
Calcium is stored in ___________________
endoplasmic reticulum
70
Placing sea urchin embryos in sea water containing A23187 results in cortical granule reaction and __________________ to rise (without presence of sperm)
a) chemoattraction
b) bind
c) vitelline envelope
d) fertilization envelope
fertilization envelope
71
calcium ionophore - transports Ca2+ across lipid membranes
a) A23187
b) zinc spark
c) ovastacin
d) actin-homology
A23187
72
- If _____________ is injected into the egg
- No cortical reaction occurs
a) Immunohistochemistry
b) Ca2+ chelator
c) polymerization
d) four spindles
Ca2+ chelator
73
- Sperm nucleus and centriole enter egg, but _____________ and ______________ disintegrate
- Mitochondrial DNA is solely from _________________
mitochondria and flagella
maternal contribution (highly contested)
74
- The sperm centriole will provide part of the _____________ (all species but mouse)
- Acts as a _____________________ which extends microtubules to form an aster
mitotic spindle
microtubule organizing center (MTOC)
75
- Microtubules extend to female pronucleus and pull the two pronuclei together
- Fusion of these pronuclei forms the ___________-nucleus
diploid zygote
76
EGG ACTIVATION AND ROLE OF IP3:
(A) Ca2+ release and egg activation by activated _______ directly from the sperm, or by a substance from the sperm that activates egg _______. This may be the mechanismin ____________.
PLC, PLC, mammals
77
(B) The bindin receptor (perhaps acting through a G protein) activates __________________ which activates PLC. This is probably the mechanism used by ______________.
tyrosine kinase (TK, an Src kinase)
sea urchins
78
Roles of ________________ in releasing calcium from the endoplasmic reticulum and the initiation of development.
Phospholipase C splits PIP2 into IP3 and DAG. IP3 releases calcium from the endoplasmic reticulum, and DAG, with assistance from the released Ca2+, activates the ___________________ exchange pump in the membrane.
a) maturity, translocated
b) inositol phosphates, sodium-hydrogen
c) invertebrates, ZP4
inositol phosphates
sodium-hydrogen
79
- Soluble factors activate phospholipase C, which then utilizes _____.
- These factors also activate your __+_, which subsequently binds to calcium receptors, increasing calcium levels within the endoplasmic reticulum (ER).
TK (tyrosine kinase)
DAI
80
- Once calcium increases it activates your ______________ exchange pump, which depolarize the cell
- Activation of the egg already happened even if fast block occurs because it allows sodium to enter and this creates the change in the cell which makes ______________ seen in the cell
sodium hydrogen
cortical granules
81
G protein involvement in Ca2+ entry into sea urchin eggs.
(A) ____ is localized to the cortex.
(B) A wave of Ca2+ appears in the control egg but not in the egg injected with an inhibitor of the ___ protein.
(C) Possible model for egg activation by the influx of Ca2+.
Gαq
82
MECHANISMS OF EGG ACTIVATION:
sperm contact and fusion
|
G protein activation
|
Src activation
|
PLCy activation (PIP2 -> IP3, DAG)
|
Ca2+ release
|
1. Cortical granule exocytosis -> slow block to polyspermy
2. Inactivation of MAP kinase -> initiation of cell cycle
83
EFFECTS OF CALCIUM RELEASE
EARLY RESPONSES:
Contact or fusion of sperm and egg activates the _______ to polyspermy
blocks
84
- ______ is responsible for the re-entry of the egg into the cell cycle and the reactivation of egg protein synthesis
- Egg cycle halted at ___________
- _________ is essential for activating a whole series of
metabolic reactions
Ca2+
metaphase II
Calcium
85
EFFECTS OF CALCIUM RELEASE
LATE RESPONSES:
Includes activation of a new burst of ______ and _______________
Increase in _______________
DNA and protein synthesis
intracellular pH
86
Cyclin B/Cdk1 cyclin creates a ____________ which is required to initiate cell division
Targets ________________ proteins
mitosis promoting factor (MPF)
translational inhibitory
87
MECHANISMS OF EGG ACTIVATION:
- Sperm binds to the ______________
- Sodium enters the cell, membrane potential
change, thereby activating the ______________
- ___________ would be stimulated
- Phospholipase c would increase inositol, allowing
increase ____________
egg cell membrane
fast block
Kinase
calcium release
88
- This calcium release degrades _______
- Activation of NAD increase from NAD to _________
- Calcium also has something to do with all of the
__________________ of the cell
- Phospholipase c would also creates activation of
__________________
MAP
NADP
late response
protein kinase
89
__________________________ is a highly specialized set of tissues that actively regulates the transport and maturity of both sperm
Female reproductive tract
90
______________ is a necessity for the fimbriae to pick up the ovary
a) endoplasmic reticulum
b) ejaculation
c) cumulus cells
d) ovastacin
Cumulus cells
91
________ beating and muscle contractions transport the egg to site of fertilization
Ciliary
92
- Female reproductive tract would allow the transport of __________ in the sperm, then sperm would be capacitated to travel faster to reach egg cell faster
- Egg cell needs to be ______________, it uses fimbriae and ciliary beating of fallopian tube down to the uterus where it could be implanted
maturity
translocated
93
TRANSLOCATION OF SPERM:
sperm ________
_________ muscle contractions
sperm __________
motility
uterine
rheotaxis
94
- Important in getting sperm through the cervical mucus and into the uterus
- Sperm train occurs in sperm of the same male
Sperm motility
95
Migrate against direction of flow of liquid
Sperm rheotaxis
96
Sperm is immature once ____________
ejaculated
97
Recognizing the cues that will guide them to the egg
Capacitation
98
- Undergoing the _________ reaction
- Fusing with the ________ membrane
acrosome
egg cell
99
The sperm cell membrane is altered by the removal of cholesterol by ______________ in the female reproductive tract
albumin proteins
100
___________ are clustered over the anterior sperm head and appear to enhance the ability to bind to the zona pellucida surrounding the egg
a) slow block
b) negative
c) protein
d) lipid rafts
Lipid rafts
101
Outer __________ membrane changes and comes into contact with sperm cell membrane
acrosomal
102
Particular proteins or carbohydrates on the sperm surface are _____ during capacitation
Possible that these compounds block the ____________ sites for the sperm proteins that bind to the zona pellucida
lost
recognition
103
Membrane potential of the sperm cell membrane becomes more __________ as potassium ions leave the sperm
____________ phosphorylation occurs
a) equatorial region
b) negative, protein
c) chemoattraction
d) metaphase II, MAP kinase
negative
Protein
104
If egg cell at the start of activation is more positive, it undergoes _________ to allow protein phosphorylation
a) positive
b) negative
c) early death
d) meiosis
positive
105
The pathway is modulated by the removal of cholesterol from the sperm cell membrane, which allows the influx of ___________ ions and ________________ ions. These ions activate adenylate kinase (SACY), thereby elevating _______ concentrations. The high cAMP levels then activate protein kinase A (PKA). Active PKA phosphorylates several tyrosine kinases, which in turn phosphorylate several sperm proteins, leading to _______________. Increased intracellular Ca2+ also activates the phosphorylation of these proteins, as well as contributing to the hyperactivation of the sperm.
bicarbonate ions (HCO3-) and calcium ions (Ca2+)
cAMP
capacitation
106
- Sperm swims at higher __________ and generate greater ________
- Appears to be mediated by the opening of the sperm-specific calcium channels (_________________)
a) haploid, fertilization
b) electrical fast block
c) velocities, force, catsper
velocity and force
CatSper proteins
107
Once sperm is _______________ -makes the tail whip faster and makes it swim continuously
hyperactivated
108
2ºC differences between the isthmus and the oviduct and the warmer ampulla
Thermal gradients
109
Sperm tends to migrate to
warmer temperature
Thermotaxis
110
Can detect and respond to picomolar amounts of progesterone secreted by the cumulus cells
Chemical gradients
111
ACROSOME REACTION:
1. The outer acrosomal membrane and the sperm plasma membrane ______ at many points
2. The two membranes break up into small ______________ (Remain connected)
3. Massive influx of _______ through the plasma membrane of the sperm head
4. ____________ are released from the acrosome (esterases, acrosin (not diffusible!), and neuraminidase)
5. Enzymes cause ________ of the zona pellucida
fuse
vesicles
Ca++
Enzymes
lysis
112
- Analogous to the vitelline membrane in invertebrates
- Zona pellucida - ZP1, ZP2, and ZP3
- Humans has _____
- Binding of sperm is relative, but not absolutely ____________
ZP4
species-specific
113
Mechanisms vary between species and are not well understood
Mammalian sperm fusion occurs on the _____ of the sperm rather than the tip
side
114
Cell adhesion molecules, such as __________ seem to be important
- Female mice with gene knockout of integrin associated CD9 molecule are _________
- Sperm can't sue with their eggs
- Can be reverse by microinjecting the sperm into the egg
integrin
infertile
115
Junction between the inner acrosomal membrane and the sperm cell membrane
a) electrical fast block
b) acrosomal membrane
c) acrosome
d) equatorial region
Equatorial region
116
Membrane fusion between sperm and egg occurs
_______ - acrosomal membrane
_______ - oocyte membrane protein
Izumo
Juno
117
[BLOCKS TO POLYSPERMY]
No __________________ is present, but slow block (cortical granule reaction) is present
a) female reproductive tract
b) thermal gradients
c) chemical gradients
d) electrical fast block
electrical fast block
118
Cortical granule releases protein digesting enzymes that modifies the _______________
a) chemical gradients
b) actin-homology
c) zona pellucida
d) ionic concentration
zona pellucida
119
Cleaves ZP2 that prevents sperm binding
Mutation in ___________ allows polyspermy in mouse
a) ovastacin
b) fertilization
c) zinc spark
ovastacin
120
Release of zinc ions induced by the 1st sperm entry
Zinc spark
121
- Inhibits acrosin and MMP2 that establishes ________________
- Forms a ___________
capacitation
zinc shield
122
Sperm DNA is bound to _____________ --> glutathione reduces the bound to allow uncoiling of sperm chromatin
protamines
123
- Docking site for sperm is removed
- Can still bind sperm in the perivitelline space
Release of juno on sperm and egg membrane fusion
124
- Sperm is already a pronucleus while the egg is still arrested in the ________________
- Calcium oscillations inactivate _________ and proteolysis of cyclin and securin
metaphase II
MAP kinase
125
- DNA synthesis occurs ___________ in the male and female pronuclei
- Centrosome from sperm produces ______ which joins the two pronuclei together
separately
asters
126
- Chromatin condenses into chromosomes that orient themselves on a common mitotic spindle --> true diploid nucleus is found in the _________ stage
- New individuals mitochondria are derived from the mother
two-cell
127
After replication, the different chromosomes would pair off - 4N, then cleavage starts so that true diploid will be the result - _____
2N
128
ACTIVATION OF THE MAMMALIAN EGG:
- ____________ rise and calcium is necessary for activation of the egg
- Release from intracellular stores
Transient
129
Triggered at fertilization through the production of
IP3 through the enzyme __________________
a) phospholipase c
b) equatorial region
c) protamines
phospholipase c
130
- Mammalian ____ may come from the sperm rather
than from the egg
- Delivered through ________ fusion
PLC
gamete
131
Determination of an individual's gender is a genetic activity specifically involves the combination of the sex chromosomes X and Y located in the nucleus of their cells during fertilization at the ________
oviduct
132
The gametes (egg and sperm) are ________ cells containing either the X and Y chromosome
The primary step in the process of mammalian sex differentiation occurs at ____________
haploid
fertilization
133
Males are 44XY females are 44XX
During _________, you have 22X because the father is the one who gives the sex
meiosis
134
Have a dissimilar or heterozygous chromosomes XY
MALE MAMMALS
135
After meiosis, _______________ may carry either X (50%) or Y (50%) chromosome
SEX DETERMINATION
- Chromatin negative = ______ chromatin mass
Spermatozoa
less
136
Have a similar or homozygous chromosomes XX
FEMALE MAMMALS
137
- After meiosis, _________ carrying and X chromosome
- Nuclei of the cells (interphase nuclei) contain chromosome called _______________
Oocyte
"Barr body" (chromatin positive)
138
- Lower and higher temperatures - they are __________
- As it reaches optimal temperatures they are ________
females
male
