When Pr molecules are exposed to red light, most of them absorb it and are converted to Pfr, but some of the Pfr also absorbs the red light and is converted back to Pr because both Pr and Pfr absorb red light. 

TLS Online TPP Program

#Id: 7025

#Unit 5. Developmental Biology

Unpaired protein activates the JAK-STAT pathway in the adjacent germ stem cells to specify their self-renewal

TLS Online TPP Program

#Id: 941

#Unit 5. Developmental Biology

 The mode of fertilization in sea urchin being external, the egg and spermatozoa are released into the sea water.

TLS Online TPP Program

#Id: 942

#Unit 5. Developmental Biology

Two major mechanisms during fertilization in sea urchin:

Species-specific sperm attraction 

Species-specific sperm activation

TLS Online TPP Program

#Id: 943

#Unit 5. Developmental Biology

Chemotaxis 

sperms are attracted toward eggs of their species by following a gradient of a chemical secreted by the egg.

TLS Online TPP Program

#Id: 944

#Unit 5. Developmental Biology

In Sea urchin,

Sperm-activating peptides provide direction to sperm during chemotaxis.

TLS Online TPP Program

#Id: 945

#Unit 5. Developmental Biology

SAP in the egg jelly of the sea urchin Arbacia punctulata 

Resact (14-amino acid chemotactic peptide)