Sliding filament theory

Question 1

What is it

Answer 1

Muscles use ATP as an energy source to contract

Question 2

Myosin

Answer 2

Thick protein filament having a tail and 2 head regions

Question 3

Actin

Answer 3

Thin protein filament of globular subunits, twisted like a double strand of beads

Question 4

Sarcomeres

Answer 4

-unit for striated muscle
-during contraction, sarcomeres shorten and actin and myosin fibres slide past each other

Question 5

During contraction the…

Answer 5

I-band - narrows
Z-lines/disks-closer together
A-band- stays the same
H-zone-narrows

Question 6

Stage 1 - myosin grabs actin

Answer 6

-myosin head attaches to a binding site on the actin filament
-forms a cross bridge
-requires ADP to reach towards the actin

Question 7

Stage 2 - pull

Answer 7

• myosin heads bends pulling the actin filament along
  -ADP and phosphate (Pi) are released
  -binding sites are revealed
  -the ‘power stroke’ can proceed

Question 8

Stage 3 - let go

Answer 8

-the ATP molecules attaches to the myosin head
-this breaks the cross bridge

Question 9

Stage 4- the ATP molecule attaches to the myosin head

Answer 9

-this breaks the cross bridge