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2.4 Mammalian Fertilization — Test 1
Q1. During mammalian fertilization, sperm–egg recognition is mediated by the interaction of:✓ Izumo (sperm) with Juno (egg)
Q2. The principal zona pellucida protein whose modification is important for sperm binding in mammals is:✓ ZP3
Q3. In a competitive assay, which modification of ZP3 would NOT inhibit sperm–egg interaction (i.e. fails to compete)?✓ Deglycosylated ZP3
Q4. Ovastacin, released from the egg's cortical granules, blocks polyspermy by cleaving:✓ ZP2 of the zona pellucida
Q5. The egg-membrane protein CD9 is required in mammals for:✓ Fusion of the sperm and egg membranes
Q6. A good in vitro test to show a DIRECT physical interaction between Izumo and Juno is:✓ FRET between CFP-Izumo and YFP-Juno when mixed
Q7. Which statement about mammalian egg activation is INCORRECT?✓ The sperm activates the egg without involving Ca2+
Q8. Sperm PLC-zeta introduced into the mammalian egg at fertilization causes:✓ Repeated Ca2+ oscillations that activate the egg
Q9. In mammals, the acrosome reaction is largely triggered when the sperm contacts the:✓ Zona pellucida
Q10. The cortical (zona) reaction in mammals modifies the zona pellucida so that:✓ No further sperm can bind or penetrate (block to polyspermy)
Q11. Juno, the egg receptor for Izumo, is shed from the egg surface soon after fertilization, which helps to:✓ Prevent additional sperm from fusing (block to polyspermy)