Muscle cells have an abundant, modified smooth ER called the sarcoplasmic reticulum.

The release and reuptake of Ca2+ by the sarcoplasmic reticulum trigger myofibril contraction and relaxation, respectively

TLS Online TPP Program

#Id: 9874

#XL - T Zoology

The innate immune system includes physical and chemical—as well as cellular responses

TLS Online TPP Program

#Id: 10057

#XL - T Zoology

Adhesion receptors mediate cell-matrix adhesions

TLS Online TPP Program

#Id: 9633

#XL - T Zoology

Binding of a GAP to Ras⋅GTP accelerates the intrinsic GTPase activity of Ras by more than a hundredfold

TLS Online TPP Program

#Id: 9089

#XL - T Zoology

ADP-ribosylation blocks the GTPase activity of Gαs and renders Gαs permanently active. 

TLS Online TPP Program

#Id: 8421

#XL - T Zoology

Human populations can exist at equilibrium densities in one of two ways:

1. High birth and high death rates

2. Low birth and low death rate