Cytoplasmic Inheritance

a. Present in males and females.

b. Usually inherited from one parent, typically the maternal parent.

c. Reciprocal crosses give different results.

d. Exhibit extensive phenotypic variation, even within a single family.

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

TLS Online TPP Program

#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

TLS Online TPP Program

#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