muscle
No description yet. This curated deck is ready for daily study.
Card preview (24)
what are thin filaments made of
troponin T,C, I tropomyosin ACTIN (g actin and f actin)
what are thick filaments made up of?
myosin II
G actin
a monomer of actin that is assembled together to form a twisted double stranded helix called F actin
f actin
made up of 2 G actin monomers twisted in a helix and called filamentous actin
Troponin
a complex of three subunits: Tnt- attaches to tropomyosin TnC- attaches to Ca during muscle contraction TNI- binds troponin complex to actin molecules and inhibits actin/myosin interaction
Tropomyosin
• two polypeptide chains which form an alpha helix • each tropomyosin alpha helix rest on 7 G actin molecules and covers their active sites (for myosin) to prevent myosin/actin interaction • tropomyosin alpha helixes line up in a head to tail arrangement to form long tropomyosin filaments
what three things assemble to form the thin filaments of muscle
troponin, tropomyosin, F actin
thick filaments consist of-
mysosin 2 two heavy chains (golf club) four light chains (flattened golf balls)
when trypsin is used to break down a thick filament to get MYOSIN MOLECULE, what do we get?
• heavy meromyosin- 4 light chains, 2 globular heads, a short twisted tail in helical configuration • light meromyosin - long twisted tail- 2 chains wrapped around each other in an alpha helix • can break up heavy meromysosin and get: 2 S1, 1 S2
sarcomeres
• contractile unit - combo of actin and myosin overlapping
what is a muscle fiber made up of (build it)
• thin and thick filaments make a sarcomere • long, cylindrical series of end-to-end sarcomeres makes a myofibril • many parallel myofibrils are enclosed within a muscle fiber (muscle cell)
what’s the A band?
dark band of thick and thin filaments widest band bisected by H band
what’s the H band
middle of the sarcomere just thick filaments
I band
light band of THICK FILAMENTS ONLY it made up of portions of adjacent sarcomeres bisected by Z disk
z line (disk)
ends of sarcomere attachment for thin filaments contains alpha actinin that anchors actin filaments to z disk
M line
consists of protein structures lying between thick and thin filaments holding them in register major protein = creatine kinase bisects the M line
alpha actinin
binds thin filaments to z disk
creatine kinase
major protein of M line
nebulin
non elastic protein that holds thin filaments to z disk and wraps around the thin filament (2)
titin
elastic protein that anchors thick filaments (4)
myomesin and c protein
hold thick filaments (in middle) in register at M line
dystrophin
cytoplasmic protein that bind actin filaments to laminin (surrounding lamina of muscle fiber)
sarcolemma vs sarcoplasm vs sarcosomes
sarcolemma- cell membrane, external lamina, reticular lamina sarcoplasm- muscle cell cytoplasm sarcosomes- mitochondria
sarcoplasmic reticulum
like the muscle cell’s soft ER