Orthogenesis - “Straight-line evolution,” held that the variation that arises is directed toward fixed goals.

So that a species evolves in a predetermined direction by some kind of internal drive, without the aid of natural selection.

TLS Online TPP Program

#Id: 8404

#XL - Q Biochemistry

The increase in Ca2+ concentration is transient because the Ca2+ is rapidly pumped back into the SR by an abundant, Ca2+ ATPase.

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.