Sequences that presumably diverged as a result of gene duplication are paralogous.

TLS Online TPP Program

#Id: 7606

#Unit 5. Developmental Biology

Gamete fusion involve proteins: Izumo, originally in the acrosomal membrane Juno, an oocyte membrane protein

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#Id: 7607

#Unit 5. Developmental Biology

TLS Online TPP Program

#Id: 7608

#Unit 5. Developmental Biology

Mutations in either Juno or Izumo block fertilization

TLS Online TPP Program

#Id: 7609

#Unit 5. Developmental Biology

Slow Block to polyspermy

When the cortical granules fuse with the egg cell membrane, they release protein-digesting enzymes that modify the zona pellucida proteins such that they can no longer bind sperm

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#Id: 7610

#Unit 5. Developmental Biology

Cortical granule proteases is ovastacin When ZP2 is cleaved by ovastacin, it loses its ability to bind sperm

TLS Online TPP Program

#Id: 7611

#Unit 5. Developmental Biology

Polyspermy occurs more frequently in mouse eggs bearing mutant ZP2 that cannot be cleaved by ovastacin