DOMINANT EPISTASIS

In dominant epistasis, however, only a single copy of an allele is required to inhibit the expression of an allele at a different locus.

TLS Online TPP Program

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#Unit 2. Cellular Organization

When the Ca2+ levels drop:

Myosin LC is dephosphorylated by MLC phosphatase, causing muscle relaxation.

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#Unit 2. Cellular Organization

Sarcomere

Within each skeletal muscle cell are many myofibrils consisting of a repeating array of a specialized structure

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#Unit 2. Cellular Organization

Each sarcomere contains two major types of filaments: 

Thick filaments (myosin II)

Thin filaments (actin and associated proteins)

TLS Online TPP Program

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#Unit 2. Cellular Organization

Z disk 

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

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#Unit 2. Cellular Organization

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

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#Unit 2. Cellular Organization

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

1. CapZ 

2.Tropomodulin

3.Titin 

4.Nebulin