Natural selection was Darwin’s brilliant hypothesis, that accounts for adaptations, features that appear “designed” to fit organisms to their environment.

TLS Online TPP Program

#Id: 7581

#Unit 5. Developmental Biology

Particular proteins or carbohydrates on the sperm surface are lost during capacitation because these compounds block the recognition sites for the sperm proteins that bind to the zona pellucida

TLS Online TPP Program

#Id: 7582

#Unit 5. Developmental Biology

The membrane potential of the sperm cell becomes more negative as potassium ions leave the sperm. 

TLS Online TPP Program

#Id: 7583

#Unit 5. Developmental Biology

Negative membrane potential may allow calcium channels to be opened and permit calcium to enter the sperm. 

TLS Online TPP Program

#Id: 7584

#Unit 5. Developmental Biology

Calcium and bicarbonate ions are critical in activating cAMP production and in facilitating the membrane fusion events of the acrosome reaction

TLS Online TPP Program

#Id: 7585

#Unit 5. Developmental Biology

The influx of bicarbonate ions (and possibly other ions) alkalinizes the sperm, raising its pH. This will be critical in the subsequent activation of calcium channels

TLS Online TPP Program

#Id: 7586

#Unit 5. Developmental Biology

During capacitation, 

cAMP formation, protein

phosphorylation occurs. 

One of these proteins is Izumo, which is critical in sperm-egg fusion