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Describe the effect of calcium ions on tropomyosin and actin in skeletal muscle.

Within the muscle fibre tropomyosin is wrapped around actin filaments and it blocks the binding sites for the myosin-heads.

When calcium ion concentration increases, calcium ions bind to sites on the tropomyosin (troponin-c sites) and this causes a conformational change in shape.

This change in tropomyosin’s shape exposes the myosin-head binding sites on the actin filaments and allows cross-bridge binding to occur.

This then allows the actin and myosin fibres to slide over each other and shorten (contract) the muscle fibre.  This is known as Sliding Filament Theory.  

Aaron H. Mentoring -Medical School Preparation- tutor, Mentoring -Per...

1 year ago

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Degree: Graduate Entry Medicine (MB ChB) (Bachelors) - Bristol University

Subjects offered: Human Biology, -Personal Statements-+ 1 more

Human Biology
-Personal Statements-
-Medical School Preparation-

“A little about me: After graduating with a BSc degree in Physiological Science (how the body works) I applied to study medicine as a graduate and am now studying to be a doctor at the University of Bristol.  I am fascinated by how th...”

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