Sliding filament theory

Question 1

Step 1

Answer 1

Calcium ion binds with troponin moving tropomyosin out of the way, exposing myosin binding sites on actin

Question 2

Step 2

Answer 2

Myosin globular heads attach to actin (crossbridge)

Question 3

Step 3

Answer 3

Each cross bridge pivots causing myosin to pull on the thin filaments (power stroke), sliding them toward the center of the sarcomere = contraction
a. contraction occurs, and cell shortens
b. During a contraction, a cross bridge attaches and detaches several times

Question 4

Step 4

Answer 4

ATP provides the energy to break the cross bridge

Question 5

Step 5

Answer 5

ATP hydrolysis (ATP broke apart) occurs and myosin globular heads reposition

Question 6

Step 6

Answer 6

Calcium ions return to SR