Lecture 26 -- review questions Flashcards
what are the 5 phases of fertilization that you covered in class?
1) sperm capacitation
2) acrosome reaction
3) fast and slow block
4) completion of Meiosis II
5) zygote formation
what are the 2 requirements for sperm motility?
energy source (fructose from semen)
increased pH (neutralize vagina’s acidic pH)
what is the source for producing ATP (energy) for sperm motility?
fructose from semen
about how many spermatozoa are deposited in the vagina during intercourse?
~300 million
in which stage of oogenesis is the egg when it meets the sperm cell?
secondary oocyte state of oogenesis
about how many spermatozoa reach the vicinity of the ovulated secondary oocyte?
what happened to the rest?
(tip: 3 possibilities)
~200
1) immediately leak from vagina
2) destroyed by vaginal acid
3) destroyed by resident phagocytes in uterus (which recognize sperm as foreign)
Where does fertilization occur? (Site of the reproductive female tract when the sperm meet the egg)
Fallopian Tube (ampulla to be more specific) where it links an ovary to the uterus
*sperm must reach the fallopian tube
What is the sperm capacitation process?
change sperm undergo in the female reproductive tract that enables them to penetrate and fertilize an egg
occurs during sperm transport through the female genital tract
Why is sperm capacitation important?
it is needed for fertilization to occur
w/o sperm capacitation, fertilization does not occur
When does sperm capacitation occur? (i.e., before or after ejaculation, before or after fertilization…)
during sperm transport through the female genital tract
after ejaculation + before fertilization
Where does sperm capacitation occur? (tip: at a specific place or along its way through the female reproductive tract?)
during sperm transport through the female genital tract
What changes in the sperm occur during capacitation?
secretions of the female tract remove some of the sperm’s membrane proteins & cholesterol (so that the hydrolytic enzymes in the acrosomes can be released) and the tail takes on a hyperactivated pattern of swimming (increased motility so the sperm is more likely to reach the egg in the fallopian tube)
What induces capacitation? (tip: where are the chemicals changing the membrane composition of the sperm come from?)
Secretions of the female tract (uterine chemicals) induces capacitation
these secretions changes membrane composition of the sperm (removes protective proteins & cholesterol)
After ovulation, which two layers surround the oocyte that the sperm must pass through to get to the plasma membrane? What are these layers made of?
Corona Radiata
- granulosa cells
Zone Pellucida
- glycoprotein-rich extracellular matrix
Does the acrosome reaction happen before or after capacitation? Why? (tip: can they release the enzymes if the membrane surrounding the head is not weaker?)
Acrosome reaction would happen after capacitation because capacitation changes the sperm’s composition to where it is fragile which allows the hydrolytic enzymes in their acrosomes to be released
subsequently, the acrosome reaction involves exocytosis of acrosomal enzymes from the sperm’s head so the only way this would be able to occur is if the sperm went through capacitation prior
