Which statement is true? A. Bindin is necessary for sea urchin sperm to recogniz
ID: 97931 • Letter: W
Question
Which statement is true?
A. Bindin is necessary for sea urchin sperm to recognize eggs in a species-specific manner.
The acrosome reaction is necessary for sperm motility.
ZP3 is necessary for sea urchin sperm to recognize eggs in species-specific manner.
Resact is secreted by mammalian sperm as a chemoattractant.
After a spermatozoa penetrates an oocyte it triggers cortical granule exocytosis, the granules release _______________, and this allows for the influx of ___________ and this causes the formation of the __________. Which of the following best fills in the blanks?
H2O2, ZP3, acrosomal vesicle
Ca2+, peroxide, fertilization envelope
PIP2, Ca2+, pronucleus
Serine proteases, H20, fertilization envelope
If you have a defect that blocks the release of gonadotropin releasing hormone (GnRH) from the pituitary, which of the following statements about folliculogenesis would be true?
The lack of GnRH would block only the luteinizing hormone (LH) surge.
A lack of GnRH would inhibit folliculogenesis.
Estrogen would inhibit follicle stimulating hormone (FSH) from the hypothalamus .
Folliculogenesis would occur normally
A.A. Bindin is necessary for sea urchin sperm to recognize eggs in a species-specific manner.
B.The acrosome reaction is necessary for sperm motility.
C.ZP3 is necessary for sea urchin sperm to recognize eggs in species-specific manner.
D.Resact is secreted by mammalian sperm as a chemoattractant.
After a spermatozoa penetrates an oocyte it triggers cortical granule exocytosis, the granules release _______________, and this allows for the influx of ___________ and this causes the formation of the __________. Which of the following best fills in the blanks?
A.H2O2, ZP3, acrosomal vesicle
B.Ca2+, peroxide, fertilization envelope
C.PIP2, Ca2+, pronucleus
D.Serine proteases, H20, fertilization envelope
If you have a defect that blocks the release of gonadotropin releasing hormone (GnRH) from the pituitary, which of the following statements about folliculogenesis would be true?
A.The lack of GnRH would block only the luteinizing hormone (LH) surge.
B.A lack of GnRH would inhibit folliculogenesis.
C.Estrogen would inhibit follicle stimulating hormone (FSH) from the hypothalamus .
D.Folliculogenesis would occur normally
Explanation / Answer
1. A is correct.
a. Species-specific adhesion of sperm to the egg during sea urchin fertilization involves the interaction of the sperm adhesive protein,bindin. Biochemical studies have shown that the bindins of closely related sea urchin species are indeed different. This finding implies the existence of species-specific bindin receptors on the egg, vitelline envelope, or plasma membrane.
b. Acrosome reaction is the release of hydrolytic enzymes which softens the zona pellucida (jelly coat). When the sperm reaches an egg, the acrosome reaction allows the sperm to break through the surrounding jelly coat.
C. ZP3 is the sperm-binding protein of the mouse zona pellucida. The zona pellucida in mammals plays a role analogous to that of the vitelline envelope in invertebrates. This glycoprotein matrix, which is synthesized and secreted by the growing oocyte, plays two major roles during fertilization: it binds the sperm, and it initiates the acrosomal reaction after the sperm is bound.
D. Resact, found in sea urchins, Causes stimulation of sperm respiration and motility through intracellular alkalinization, transient elevations of cAMP, cGMP and calcium levels in sperm cells, and transient activation and subsequent inactivation of the membrane form of guanylate cyclase.
2. D is correct.
Cortical granules, specialized secretory vesicles located within the egg's cortex, are fused with the egg's plasma membrane, causing the contents of the cortical granules to be released outside the cell where they modify an existing extracellular matrix to make it impenetrable to sperm entry. The cortical granules contain proteases that clip perivitelline tether proteins, peroxidases that harden the vitelline envelope, and glycosaminoglycans that attract water into the perivitelline space, causing it to expand and form the hyaline layer.
3. B is correct.
Low levels of gonadotrophin-releasing hormone secretion, which will stop the normal production of follicle stimulating hormone and luteinising hormone, causing loss of menstrual cycles (amenorrhoea) in women, loss of sperm production in men, and loss of production of hormones from the testes and ovaries.
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