Muscle Flashcards
What are the components of thin filaments?
- F-actin
- Troponin
- Tropomyosin
Actin, troponin, and tropomyosin are components of what muscle filament?
Thin filament
What constitutes thick filaments?
Myosin II
What is F-actin made up of?
Two G-actin polymers twisted to form a double stranded helix
Two G-actin polymers twisted to form a double stranded helix forms ___________
F-actin
What are the components of troponin?
- TnT
- TnC
- TnI
What is the function of TnT?
Troponin subunit that binds to tropomyosin
What is the function of TnC?
Troponin subunit that binds calcium
What is the function of TnI?
Troponin subunit that binds troponin to actin molecule; inhibits actin-myosin interaction
Where does the Tn complex bind to tropomyosin?
Grooves of actin filaments
What constitutes a tropomyosin molecule?
- Two polypeptide chains in an a-helix
- Each a-helix rests on 7 G-actin molecules, covering active site
- Head to tail of tropomyosins form tropomyosin filaments
What does trypsin do to myosin molecules?
Breaks them into heavy meromyosin and light meromyosin
What is the molecular composition of myosin?
2 heavy chains and 4 light chains
What constitutes heavy meromyosin?
- 4 light chains
- 2 globular chains
- Short twisted tail (a-helix)
What constitutes light meromyosin?
The shafts of the heavy chains wrapped around each other
What makes up a sarcomere?
Overlapping thick and thin myofilaments
Overlapping thick and thin myofilaments make up a _______________
Sarcomere
A series of sarcomeres joined end-to-end makes up a _______________
Myofibril
What makes up a myofibril?
A series of sarcomeres joined end-to-end
What makes up a muscle fiber (muscle cell)?
Many parallel myofibrils
Many parallel myofibrils make up a ______________
Muscle fiber (muscle cell)
What are the characteristics of the A band?
- Dark band - thick and thin filaments
2. Widest band
What are the characteristics of the H band?
- Thick filaments only
2. Bisects the A band
What are the characteristics of the I band?
- Thin filaments only
- Light band
- Made up of portions of adjacent sarcomeres