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

TLS Online TPP Program

#Id: 8403

#XL - Q Biochemistry

AP activates a  voltage gated Ca2+ channel in the T-tubule membrane, it triggers the opening of a Ca2+ -release channel in the closely associated SR membrane

TLS Online TPP Program

#Id: 8402

#XL - Q Biochemistry

The arrival of a nerve impulse at a neuromuscular junction triggers an action potential in sarcolemma.

TLS Online TPP Program

#Id: 8400

#XL - Q Biochemistry

In skeletal muscle cells, 

a low cytosolic Ca+2 level is maintained by a unique Ca+2 ATPase that continually pumps Ca+2 ions from

the cytosol containing the myofibrils into the SR, establishes a reservoir of Ca+2 in the SR.

TLS Online TPP Program

#Id: 8399

#XL - Q Biochemistry

The structure of the sarcomere is maintained by a number of accessory proteins: 

1. CapZ 

2.Tropomodulin

3.Titin 

4.Nebulin

TLS Online TPP Program

#Id: 8398

#XL - Q Biochemistry

In the presence of ATP and Ca+2 , the myosin heads extending from the thick

filaments walk toward the (+) ends of the thin filaments.

TLS Online TPP Program

#Id: 8397

#XL - Q Biochemistry

Z disk 

Thin actin filaments are assembled with their (+) ends embedded in a densely staining structure