Biology Recall

Question 1

What structures attach muscle to bone?

Answer 1

Tendons

Question 2

What does multinucleate mean and why are muscles often multinucleate?

Answer 2

Has several nuclei.

A single nucleus could not effectively control the metabolism of a long cell

Question 3

Describe the events that occur after a nerve impulse arrives at the neuromuscular junction

Answer 3

· Calcium ions are released from the sarcoplasmic reticulum and diffuse through the sarcoplasm.

· Calcium ions attach to the troponin, causing it to move.

· This causes the tropomyosin to shift exposing the myosin binding site on the actin filament.

· Myosin head binds with the binding site on the actin filament.

· ADP and inorganic phosphate on the myosin head are released. The myosin changes shape and the head nods forward moving the actin over the myosin.

· ATP binds to the myosin head causing it to detach from the actin.

· ATPase on the myosin head hydrolyses the ATP to ADP and Pi

· Myosin head returns to upright position

Question 4

Describe Glycolysis

Answer 4

· Phosphate groups from two ATP molecules are added to Glucose to increase its reactivity.

· Glucose then splits into 2 molecules of phosphorylated 3 carbon intermediate compounds.

· Each 3C compound is oxidised to produce a molecule of pyruvate.

· Two hydrogen atoms are removed from each compound and taken up by NAD to form rNAD.

· Substrate level phosphorylation takes place to produce 4 molecules of ATP (Net gain of 2ATP)

Question 5

Describe the events following rNAD/rFAD arriving at the electron transport chain (chemiosis)

Answer 5

· Hydrogen atoms, electrons and protons separate and the electrons enter the electron transport chain.

· Electrons pass along the electron transport chain in a series of redox reactions, releasing energy.

· Protons move across the inner mitochondrial membrane creating high H+ concentration in the intermembrane space.

· H+ diffuse back down electrochemical gradient into the mitochondrial matrix through the channel in ATP Synthase.

· This causes a change in shape of the enzymes active site, enabling ATP to be synthesised.

· Electrons and protons recombine to form Hydrogen atoms which combine with oxygen to create water.

Question 6

Describe and explain 3 adaptations of a slow twitch muscle fibre

Answer 6

· Many mitochondria for aerobic respiration

· Numerous capillaries – good blood supply for the delivery of oxygen and glucose

· Low glycogen content – glucose can be supplied easily due to numerous capillaries

· Lots of myoglobin – high affinity for oxygen used in aerobic respiration

Question 7

Describe what is meant by the term substrate level phosphorylation

Answer 7

Energy for the formation of ATP comes from substrates

Question 8

Name the end product of anaerobic respiration

Answer 8

Lactate