topic 7

• Ligament


  attach bones to other bones, holding them together. control and restrict the amount of movement in the joint
• Cartilage


  protects bones within joints by absorbing shock
• Synovial fluid


  fluid that acts as a lubricant as it enables bones to move freely
• Tendon


  attach muscles to bone, enables muscles to power joint movement
• Flexor


  a muscle that bends a joint when it contracts
• Extensor


  a muscle that extends a joint when it contracts
• Antagonistic pairs


  Muscles that work together to move a bone by creating opposite forces
• Skeletal muscle


  type of muscle you use to move
• Why do muscles work in pairs


  because they can only pull when they contract
• What is skeletal muscle made up of

  large bundles of long cells called muscle fibres
• why are muscle cells multinucleate

  a single nucleus could not effectively control the metabolism of such a long cell, maximises protein synthesis
• transverse (T) tubules


  formed by bits of the sarcolemma fold inwards into the sarcoplasm. they help to spread electrical impulses throughout the sarcoplasm so they reach all parts of the muscle fibre
• sarcolemma


  cell membrane of muscle fibre cells
• Sarcoplasmic reticulum


  network of internal membranes that run through the sarcoplasm. it stores and releases calcium ions
• Myosin


  thick myofilament
• Actin


  thin myofilament
• Myofibrils


  long, cylindrical organelles inside muscle fibres.
• Three types of muscle

  Skeletal, smooth, cardiac
• Ion required for muscle contraction


  Calcium ion
• What myofibrils are made up of

  Myosin and actin
• One contractile unit in a muscle cell

  Sacromere
• Sliding filament theory


  myosin and actin filaments slide over eachother making the sarcomeres contract. the simultaneous contraction of lots of sarcomeres means the myofibrils and mucle fibres contract
• What are the binding sites on myosin heads for?

  Actin and ATP
• Why are the myosin globular heads hinged

  so they can move back and forth
• Names of the proteins found between actin filaments

  Troponin and tropomyosin
• What happens to the actin-myosin binding site during muscle relaxation?

  Blocked by tropomyosin which is held in place by troponin
• What happens to troponin during muscle contraction and what is the effect of this?

  Calcium ion binds to the troponin, changing it's shape so the tropomyosin is moved and the actin-myosin binding sites are exposed
• What is the effect of the actin-myosin binding sites being blocked?


  Filaments cannot slide past eachother
• What is formed when the actin-myosin binding site is exposed?

  Actin-myosin cross bridge is formed
• Why is ATP required for muscle contraction?

  Provides energy to move the myosin head and break the cross bridge to allow binding to the next binding site
• What happens when a muscle stops being stimulated

  Calcium ions leave their binding sites on the troponin and are active transported back into the sarcoplasmic reticulum. troponin return to original shape pulling tropomyosin causing it to block the actin myosin binding site again
• What are the folds in the inner membrane of mitochondria called?

  Cristae
• Why do mitochondria increase the efficiency of respiration?

  Everything needed is in one place
• How is ATP broken down?

  Hydrolysis
• What is ATP made up of?

  Adenine, ribose and three phosphates
• What are the coenzymes involved in respiration?

  NAD+ , FAD and CoA
• What is a coenzyme?

  A molecule that aids an enzyme in it's action
• Why does the Link reaction occur in the mitochondrial matrix

  the enzymes and coenzymes needed are locate here. NADH made is in the right place to be used by oxidative phosphorylation
• How is acetate made from pyruvate

  Pyruvate is carboxylated and then NAD is reduced by collecting hydrogen from pyruvate to form acetate
• What happens to pyruvate during the Link reaction

  it is carboxylated as one carbon atom is removed to form CO2