Muscles and Movement Part 2 Flashcards
what are microfillamentc composed of?
Actin
Structure/growth
what is the two types actin?
Globular actin
Filamentous actin
what is the effect of ATP binding to Gactin?`
higher affinity form dimers, therefore polymerizes to form f actin
Where does hydrolyses occur adn what are its effects?
Hydrolyse ATP to ADT have less affinity cause shinkage
What end does growth occur
+ end
What is the effects of treadmilling
Growth adn shrinkage occur simultaneously
Effects of capping protiens
Increase length by stabilizing
TROPAMODULIN - cap (-) end prevent dissociation
GAPZ- Bind to (+) end prevent polymerization
Capping proteins involved in disassembly
\COFLIN - binds ADP actin
ARP - nucleate f action
Capping proteins involved in Assembly
PROFLIN- binds to g-actin promotes assembly
General arraignment of actin
+ end near the cell surface
what is the motor protein of microfilaments?
myosin
what is the monomer of actin
globular (G) actin
what is the polymer of actin
filament (F) actin
what is the critical concentration of +/- actin
the concentration of actin required for growth on either end
arranges microfilaments in criss-cross pattern
fimbrin/fascin
arranges microfilaments at 90 degree angle (tangled network)
filamen
attaches microfilaments to membrane
dystrophin
rodlike extensions of membrane
filopodia
sheet like extensions of the membrane
ex. leukocytes or macrophages
lamellapodia
which direction does myosin move (except myosin 6)
positive end
how does myosin move along actin?
forms cross bridge (chemical reaction), releases, extends and power stroke (structural change utilizing ATP)
what happens to myosin in the absence of ATP?
myosin cannot release/reattach to the actin, causes rigor mortis
what are the steps of the sliding filament model?
- ATP binds, causing myosin to dettach
- myosin head extends and attaches to adjacent actin
- release of phosphate promotes power stroke
- ADP is released
what does the distance of each cross bridge step depend on?
myosin neck length, binding sites on actin and helical shape of actin
what are the step sizes of myosin movement?
hand over hand: 74nm
inchworm: 37nm
