471369
Descrição
Mapa Mental por kirareynolds, atualizado more than 1 year ago
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Criado por kirareynolds
mais de 10 anos atrás
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The Sliding Filament Model
- The Sacromere
- Striped appearance of voluntary muscle under the microscope
is different when muscles are relaxed and when they are
contracted.
- The span of one Z line to the next.
- In a relaxed state, 2.5µm in length
- Z lines closer together during contraction
- Striped appearance of voluntary muscle under the microscope
is different when muscles are relaxed and when they are
contracted.
- Two Types of Protein Filament in Contraction
- Actin
- Thin filaments are two strands made mostly of actin (F Actin),
coiled around each other (twisted)
- Each strand composed of G Actin subunits
- Tropomyosin molecules coil
around the F Actin to reinforce it.
- A troponin complex is attached to each Tropomyosin molecule.
- Each troponin complex consists of
three polypeptides
- One binds to actin, one to
Tropomyosin and one to calcium ions
- One binds to actin, one to
Tropomyosin and one to calcium ions
- Thin filaments are two strands made mostly of actin (F Actin),
coiled around each other (twisted)
- Myosin
- Thick filaments are bundles of the protein myosin
- Each myosin molecule consists of a tail
and two protruding heads
- Each thick filament consists of many
myosin molecules whose heads stick out
from opposite ends of the filament
- Thick filaments are bundles of the protein myosin
- Actin
- The Power Stroke (Muscle
Contraction)
- 1) Myosin head groups attach to
the surrounding actin filaments
forming a cross-bridge.
- 2) The head group then
bends, causing the thin
filament to be pulled
along and overlap more
with the thick filament
(Power Stroke). ADP
and Pi are released.
- 3) The cross bridge is then
broken as new ATP attaches
to the myosin head.
- 4) The head group
moves backwards
as the ATP is
hydrolysed to ADP
and Pi. It can then
form a cross bridge
with the thin
filament further
along and bend
again.
- 4) The head group
moves backwards
as the ATP is
hydrolysed to ADP
and Pi. It can then
form a cross bridge
with the thin
filament further
along and bend
again.
- 3) The cross bridge is then
broken as new ATP attaches
to the myosin head.
- 2) The head group then
bends, causing the thin
filament to be pulled
along and overlap more
with the thick filament
(Power Stroke). ADP
and Pi are released.
- 1) Myosin head groups attach to
the surrounding actin filaments
forming a cross-bridge.
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