The 5’ cap of most mRNA is monomethylated, but some small noncoding RNAs are trimethylated.

TLS Online TPP Program

#Id: 954

#Unit 5. Developmental Biology

When sulfated polysaccharide binds to its receptor on the sperm, activates 3 sperm membrane proteins: 

(1) A calcium transport channel

(2) A sodium-hydrogen exchanger

(3) A phospholipase enzyme (IP3)

TLS Online TPP Program

#Id: 955

#Unit 5. Developmental Biology

Extension of the acrosomal process by the polymerization of G-actin molecules into F-actin by RhoB

TLS Online TPP Program

#Id: 956

#Unit 5. Developmental Biology

Acrosomal process have an insoluble, 30,500-Da protein called bindin.

TLS Online TPP Program

#Id: 957

#Unit 5. Developmental Biology

Species-specific bindin receptors present on the egg vitelline envelope.

TLS Online TPP Program

#Id: 958

#Unit 5. Developmental Biology

Fast block to polyspermy 

Within 1–3 seconds after the binding of the first sperm, the membrane potential shifts from -70mV to about +20 mV

TLS Online TPP Program

#Id: 959

#Unit 5. Developmental Biology

Slow block to polyspermy (cortical granule reaction) becomes active about a minute after the first successful sperm-egg fusion