Dicot stem

Epidermis ; 

Cutinized, bears multicellular hairs.

Cortex ;

It is differentiated into hypodermis, general cortex and endodermis.

Hypodermis is Collenchymatous

Pericycle ;

Above vascular bundle it is Sclerenchymatous

Vascular bundles ;

Conjoint, Collateral, Endarch and Open

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

TLS Online TPP Program

#Id: 8396

#XL - Q Biochemistry

Each sarcomere contains two major types of filaments: 

Thick filaments (myosin II)

Thin filaments (actin and associated proteins)

TLS Online TPP Program

#Id: 8395

#XL - Q Biochemistry

Sarcomere

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

TLS Online TPP Program

#Id: 8394

#XL - Q Biochemistry

When the Ca2+ levels drop:

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

TLS Online TPP Program

#Id: 8393

#XL - Q Biochemistry

Phosphorylation of MLC 

unfolds the myosin II, active and can assemble into bipolar filaments for contraction