Sarcomeres Flashcards
What is the order surrounding the muscle fibre
- Endomesium separates muscle fibres
- perimysium lies between fasiculi
- epimysium is the dense sheath on the surface
what is a sarcomere
the portion of a myofibril that lies between two successive Z discs
how long is myosin
1.6 um long
features of myosin (make up thick filament)
tail consists of two intertwined heavy chains
two globular heads extend out, forming cross bridges
globular heads contain heavy and light chains
globular heads also contain binding sites for actin (thin filaments) and ATP (myosin-ATPase)
How long is Actin (thin filaments)
1um
features of actin
contractile protein
each G actin has a binding site for myosin
tropomyosin
regulatory protein
overlaps binding sites om actin for myosin and inhibits interaction when in relaxed state
what is the role of troponin
regulatory protein
forms a complex with actin and tropomyosin, it binds ca2+ reversibly and this changes the conformation to pull tropomyosin away from the myosin interaction sites therefore regulating skeletal muscle contraction
role of nebulin
helps align actin
role of titin
provides elasticity and stabilises myosin
What are the contractile proteins
actin
myosin
tropomyosin
troponin complex
what are the structural proteins
titin
z-line protein (alpha-actin)
m-line proteins (myosin, m-protein)
nebulin
Iband contains what
thin filaments only (actin bisected by z line)
h zone contains what
thick filaments only(myosin) (region of a band)
m-line contains what
thick filaments linked with accessory proteins
