Muscle Biochemistry

Question 1

Arrangement of thick filaments

Answer 1

• myosin: each is surrounded by 6 thin filaments

- each is also surrounded by 6 thick filaments

Question 2

Arrangements of thin filaments

Answer 2

• actin: each thin filament is surrounded by 3 thick filaments
• twice as many thin as thick filaments

Question 3

Cross bridge cycle of actin and myosin

Answer 3

• ATP binding site also serves as an enzyme

- ATPase that hydrolyzes the bound ATP for contraction

Question 4

9 muscular dystrophies, what are the 3 most common?

Answer 4

• Duchenne muscular dystrophy (DMD)
• Becker muscular dystrophy (BMD)
• Myotonic dystrophy (DM, dystophia myotonica)

Question 5

Duchenne muscular dystrophy

Answer 5

• X linked recessive disorder
• primarily expressed in males
• average life span is ~25years

Question 6

Myotonic dystrophy

Answer 6

• CTG trinucleotide repeat on chromosome #19
• anticipation:alleles which are longer than their parents and are more likely to be affected
• Repeat of the CCTG, ranging from 75 to over 11,000 repeats

Question 7

Last slide of the lecture

Answer 7

1. DMD is a x-linked recessive disorder
2. Ca++ released into a myofibril by the action of a nerve impulse must bind to troponin
3. For cross-bridge movement myosin acts as an enzyme for hydrolysis of ATP