Muscle Contraction

Question 1

what proteins interact to cause muscles to contract?

Answer 1

actin & myosin using ATP as source

Question 2

whats phase 1 of muscular contraction?

Answer 2

for contraction to occur, part of the myosin molecule (head group) attaches to a binding site on the actin filament - cross bridge = formed.

Question 3

whats phase 2 of muscular contraction?

Answer 3

the head group bends, pulling the actin filament along & ADP and P are released - power stroke.

Question 4

whats phase 3 of muscle contraction?

Answer 4

the attachment of a new ATP molecule to the myosin head breaks the cross bridge

Question 5

whats phase 4 of muscular contraction?

Answer 5

the head group moves back to its original confirmation as ATP is hydrolysed to ADP & P so another cross bridge can be formed.

Question 6

what is myosin?

Answer 6

thick protein filament, each molecule consisting of a tail & two head regions.

Question 7

what is actin?

Answer 7

thin filament of globular subunits, twisted like a double strand of beads.

Question 8

how do muscle cells produce a force on contraction?

Answer 8

they contain filaments made of actin & myosin,

Question 9

whats ATP role in muscle contraction?

Answer 9

ATP = unstable but only small amounts of it exist in cells at any one time. contraction uses a lot of ATP which is completely used up after 2 secs.