Biochemistry of muscle

Question 1

How is the myosin heavy chain formed?

Answer 1

Myosin heavy chains contain a large head group and a long α-helical tail. The tails of two heavy chains intertwine to form a coiled coil of a-helices which holds a homodimer together. In turn, the tails of many such homodimers wrap together to form the thick filament

Myosin light chains wrap around the neck of the heavy chain head group.

Question 2

Each myosin bundle is surrounded by how many actin? How many myosin surround actin?

Answer 2

Each myosin bundle is surrounded by 6 f-actin (fibrous)

Each f-actin is surrounded by 3 myosin bundles.

Question 3

What is a fascicle?

Answer 3

Bundle of muscle fibers/cells

Question 4

How is tropomyosin structured? What is the purpose of G-actin?

Answer 4

Tropomyosin wraps around f-actin and like myosin is a coiled coil of alpha helices.

G-actin (globular) links head to tail into helices. monomeric and polymerizes to form f-actin.

Question 5

What does connectin do?

Answer 5

Binds titin to actin

Question 6

Aerobic metabolism has what fuel sources?

Answer 6

This is the kreb cycle and ETC and can be fueled by
        glycolysis
	lactate - pyruvate
	fatty acid oxidation
	ketone body oxidation
	amino acid degradation

Question 7

Compare and contrast slow and fast twitch muscle fibers biochemically

Answer 7

Type I muscle fiber- mostly aerobic metabolism
efficient but slow/twitch (high endurance)

Slow oxidative (SO). Red

Type IIA: Red/White

Type IIB muscle fiber- change from aerobic to anaerobic during heavy use. inefficient but fast/twitch (low endurance)

Fast glycolytic (FG) White