6) Unit 1 - Reversible Binding of Phosphate and Control of Conformation

Question 1

Phosphorylation is a form of _________

Answer 1

post translational modification

Question 2

what enzymes do phosphorylation and dephospholrylation

Answer 2

Kinase ( phosphorylation)

Phosphatase (dephosphorylation)

Question 3

What can kinases and phosphatase be used for in terms of enzyme acitivty

Answer 3

activation or deactivation of enzymes

Question 4

what function can ATP have other than being a source of energy for a cell

Answer 4

ATP can also be a source of phosphate in the phosphorylation of some proteins

Question 5

what is the name given to proteins which use ATP for phosphorylation

Answer 5

ATPases

Question 6

Describe the process of muscle contraction

Answer 6

CROSS BRIDGE FORMATION:
1) Muscle contraction occurs when the muscle receives an impulse from the nerve

2) The impulse causes myosin binding sites on actin to be exposed
3) The myosin is activated and forms a flexed shape and binds to the actin
4) ATP is hydrolysed to ADP and Pi, and Pi is released causing the bond between myosin and actin to become stronger.

POWER STROKE:
5) ADP is released. The conformational change will allow the head to move towards the center of the sarcomere

CROSS BRIDGE DETACHMENT:
6) A new ATP attaches and causes conformational change of the myosin, causing the myosin head to detach from the actin

REACTIVATION OF MYOSIN HEAD:
Because myosin had been detach from actin it undergoes conformational change, allowing it to hydrolyse and the process is ready to begin again.