muscles and movement peq Flashcards
joins bone to bone
ligament
describe changes caused when calcium ions bind to the molecules in a myofibril
tropomyosin is moved by troponin
myosin binding sites on actin are exposed
explain how changes [when calcium binds to molecules in a myofibril] cause muscles to contract
myosin heads can bind to binding sites
bound myosin changes shape
actin filaments slide/ are pulled over the myosin
therefore muscle fibres/ myofibril/ sarcomeres shorten
ATP is hydrolysed/ ADP and inorganic phosphate (Pi) released
describe the interaction between troponin and tropomyosin that allows muscle contraction
troponin changes shape
causing the tropomyosin to move away from the myosin binding sites on actin
explain the importance of primary structure for the functioning of an enzyme
primary structure determines interaction between amino acids/ R groups
primary structure determines folding/ tertiary structure
therefore affecting the shape of the active site
active site is complementary to substrate molecule
describe how concentration of calcium ions around the myofibrils is controlled
calcium ions released from sarcoplasmic reticulum
in response to nerve impulse/ depolarisation at neuromuscular junction
calcium ion channels open to allow calcium ions to cross the membrane and enter the sarcoplasm
calcium ions taken back up into the sarcoplasmic reticulum by AT
describe the role of calcium ions in the contraction of muscle fibres
calcium ions bind to the troponin
causing tropomyosin to be displaced/ altered in shape
exposing myosin binding sites on actin
explain how the extensor and flexor muscles bring about movement in the lower leg
tendons attach muscles to bonds
flexor and extensor muscles act as an antagonistic pair
when the extensor muscle contracts, it pulls on the tibia to extend the leg
the flexor muscle contracts and pulls on the fibula to flex the leg
where is myosin binding site found
actin
describe two structural differences between fast and slow twitch muscle fibres
fast twitch fibres have no/ few mitochondria present
slow twitch fibres have many mitochondria
fast twitch fibres have no/ few capillaries
slow twitch fibres have many capillaries present
explain how the structure of a muscle fibre is related to its specialised function
cell surface membrane contains voltage gated channels to allow depolarisation of muscle fibre
many mitochondria for aerobic respiration to supply ATP
presence of myofibrils/ actin and myosin
myofibrils allow contraction of muscle
describe how the tertiary structure of myosin is related to its function
folded into a specific shape with a globular head that can bind to actin
myosin has a site that can bind with ATP
part straight to form a bundle with other myosin molecules
explain the effect of increasing calcium ion concentration on the mean force produced by the muscle fibres
as calcium ion concentration increases, force produced increases
because more actin and myosin interact/ myosin binding sites are exposed
plateaus when all myosin binding sites are occupied/ when all actin and myosin are interacting
