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19 Cards in this Set
- Front
- Back
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What is the "endpoint" of fertilization?
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When the zygote attains full capacity for development and inheritance.
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What is the perivitelline space?
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The space between the oocyte itself and the zona pellucida. Sperm is injected here.
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When is the 2nd polar body ejected?
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Upon fertilization. Meiosis II must be complete.
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Where are the polar bodies ejected into?
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The perivitelline space.
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What occurs in the epididymis?
How long are sperm in epididymis? |
Sperm maturation. Acquires proteins and motility.
80-90 days |
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What is capacitation?
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Sperm changes that occur INSIDE female repro. tract (endocervix --> tubes) that prepare egg for fertilization.
Loss of cholesterol from sperm plasma membrane. Surface charges change. Hyperactivated motility (different swimming patterns in response to different environmental conditions) |
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What sperm enzymes are involved in capacitation?
What is the pathway? |
adenylyl cyclase and PKA.
1) Adenylyl cyclase catalyzes ATP to cAMP concentration 2) cAMP activates PKA 3) Activated PKA phosphorylates sperm proteins |
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How does the sperm move in the fallopian tube?
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1) Binds to microtubules in oviduct.
2) Hyperactivated sperm can break away from microtubules. THIS IS WHY HYPERACTIVATION DURING CAPACITATION IS IMPORTANT! |
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What are the first cells that sperm must pass through to get to egg?
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Cumulous cells. Use HA to degrade cells. May be a "group effort" by sperm to break down this layer
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What happens when sperm binds to ZP?
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Acrosomal exocytosis. The first membrane will degrade, releasing new sets of digestive proteins.
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How does acrosomal exocytosis occur? Think ZP3, Ca2+, and pH.
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ZP3 binds a sperm surface receptor, which cause a transient rise in Ca2+ levels.
Increased Ca2+ levels and subsequent pH changes lead to sustained Ca2+ elevation, leading to acrosomal exocytosis. |
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What are Izumo and CD9?
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Izumo is a sperm surface component. REQUIRED for sperm-egg binding and fusion.
CD9 is egg surface component. Knock-outs show no sperm-egg fusion. |
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What is egg activation?
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A calcium-mediated event (CALCIUM-MEDIATED EGG ACTIVATION HOLDS ACROSS ALL MAMALLIAN SPECIES). PLC --> DAG + IP3 --> Ca2+
When sperm and egg combine to form a 2-cell embryo capable of full term development. Cortical granule exocytosis...extrusion of 2nd polar body. Cleavage to 2-cell stage. |
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What process prevents polyspermy?
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When sperm enters egg, cortical granules are released into perivitelline space.
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What sperm protein is involved in egg activation and drives calcium oscillations?
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PLC - gamma.
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What is the signifance of calcium oscillations?
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PLC - gamma mediated Ca2+ oscillations drive development further as noted with increasing amounts of expelled cortical granules.
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When does the zygote stop dividing and instead start growing?
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Not until it hatches from ZP (during implantation)
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How are microtubules in sperm arranged?
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in a 9+2 formation.
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true/false
Trip from ejaculation to fertilization is always long |
FALSE.
Can be as fast as 10 minutes. |
