#Question id: 5660
#Unit 5. Developmental Biology
Following statement regarding to acrosome reaction in sea urchin.
A. Activation of the acrosome reaction serves as a barrier to intraspecies fertilizations.
B. The acrosome reaction is initiated by sulfate-containing polysaccharides in the egg jelly that bind to specific receptors located directly above the acrosomal vesicle on the sperm cell membrane.
C. These polysaccharides are often highly species specific, but egg jelly factors from one species of sea urchin generally activate the acrosome reaction in closely related species.
D. The elevated Ca2+ level in a relatively basic cytoplasm triggers the fusion of the acrosomal membrane with the adjacent sperm cell membrane, releasing enzymes that can lyse a path through the egg jelly to the vitelline envelope.
Which of the following statements are correct?
#Question id: 5659
#Unit 5. Developmental Biology
Following are the statements related to mammalian chaemotaxis .
A. During chaemotaxis, the oocyte and its accompanying cumulus cells secrete molecules that attract only uncapacitated sperm toward the egg during the last stages of sperm migration.
B. These chaemotactic compound are hormone progesterone, which is made by the cumulus cells.
C. Progesterone has been shown to bind to a receptor that activates Ca2+ channels in the cell membrane of the sperm tail, leading to sperm hyperactivity and provides directional cue.
D. Cumulus cells also secrete a substance, CRISP1, that attracts sperm and hyperactivates them through CatSper channels similar as in sea urchins.
Which of the following statement is incorrect?
#Question id: 5658
#Unit 5. Developmental Biology
Following events occur during fertilization in mammals.
A. sperm penetrates cumulus layer
B. sperm nucleus delivered into cytoplasm
C. sperm plasma membrane fuses with egg plasma membrane
D. calcium waves
E. enzymes released from acrosome on sperm head enable sperm to penetrate zona pellucida
F. transit through the cumulus or binding to zona pellucida elicits acrosomal reaction in sperm
G. egg completes meiosis and development is initiated
which of the following sequence is correct?
#Question id: 5657
#Unit 5. Developmental Biology
Following statements regarding to the molecular processes of capacitation.
A. The sperm cell membrane is altered by the removal of cholesterol by albumin proteins in the female reproductive tract.
B. Particular proteins or carbohydrates on the sperm surface are lost during capacitation.
C. The membrane potential of the sperm cell becomes more positive as potassium ions leave the sperm. This change in membrane potential may allow calcium channels to be opened and permit calcium to enter the sperm.
D. Calcium and bicarbonate ions are critical in activating cAMP production and in facilitating the membrane fusion events of the acrosome reaction.
E. As a result of cAMP formation, protein phosphorylation occurs. Once they are phosphorylated, some proteins migrate to the surface of the sperm head. One of these proteins is juno, which is critical in sperm-egg fusion.
which one of the following combinations is correct?
#Question id: 5656
#Unit 5. Developmental Biology
What is the cortical reaction, and why is it important?
#Question id: 5655
#Unit 5. Developmental Biology
What is the "acrosomal reaction"?