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level: Muscles and Respiration

Questions and Answers List

level questions: Muscles and Respiration

QuestionAnswer
steps for respirationGlycolysis, link reaction, Krebs's cycle and oxidative phosphorylation
define tendonmade connective tissue they connect skeletal muscles to bones
what are muscles?tissues composed of cells with the ability to contract in order to produce movement made up of long, slender cells called muscle fibres there are three types of muscle cell: skeletal, cardiac and smooth
structure of muscle cellsmyofibrils actin and myosin filaments sarcomere sarcolemma sarcoplasm sarcoplasmic reticulum
what is the sarcomere?section of myofibrils between two Z lines
what is the sarcolemma?muscle fibre membrane
what is the sarcoplasmic reticulum?the ER of a muscle fibre releases Ca2+ ions during contraction
sliding filament theorya nerve impulse is received at the neuromuscular junction this causes Ca2+ ions to be released from the sarcoplasmic reticulum the Ca2+ ions diffuse through the sarcoplasm bind to troponin changing its shape and position which displaces tropomyosin exposing the actin binding sites myosin heads and actin filaments can now form a cross bridge the hydrolysis of ATP provides energy for the myosin heads to pull on the actin filaments and the sarcomere shortens ATP then binds to the myosin head to break the cross bridge and cock the myosin head back for another power stroke this happens along the whole actin filament when the nerve impulse stops ATP is used to actively transport Ca2+ back into the sarcoplasmic reticulum
the role of ATPase in contractionthe enzyme that catalyses the hydrolysis of ATP into ADP and Pi to release energy so the myosin heads can pull the actin filaments and shorten the sarcomere
the role of ATP in contractionit is used to detach the myosin head from the actin filament to break the cross bridge also provides energy for the active transport of Ca2+ back into the sarcoplasmic reticulum when the nerve impulse stops
the role of calcium ions in contractionattaches to troponin to change its shape to that tropomyosin can expose the actin binding sites
define flexorsmuscles that bend the limbs/joints
define extensorsmuscles that straighten the limbs/joints
define antagonistic muscle pairsa pair of muscles that pull in opposite directions as one muscle contracts the other relaxes
what is the skeleton?gives the body its structure the skeletal muscles are attached to the skeleton to provide movement
define ligamentmade of connective tissue they connect bones together and stabilise the joint in between
where does respiration happen?in the mitochondrial matrix
process of glycolysisfirst glucose is phosphorylated using ATP to create 2 molecules of triose phosphate-TP (3C) and 2 ADP TP is then oxidised forming pyruvate (3C) NAD collects the lost hydrogens to form 2NADH then 4 ATP molecules are made
where does glycolysis occur?in the cytoplasm
process of the link reactionpyruvate is decarboxylated and oxidised by NAD making NADH and acetate(2C) acetate combines with co-enzyme A to form acetyl CoA this reaction happens twice per glucose molecule
where does the link reaction take place?the mitochondrial matrix
Krebs's cycleAcetyl CoA (2C) combines with oxaloacetate(4C) to form citrate (6C) CoA returns back to the link reaction to be used again and citrate is decarboxylated into a 5C compound dehydrogenation of citrate also occurs and NADH is made ATP is also produced the 5C compound is then converted back into oxaloacetate by decarboxylation dehydrogenation occurs again to form FADH2 and 2NADH molecules this reaction also happens twice per glucose molecule
where does the Kreb's cycle happen?in the mitochondrial matrix
ETCelectron transport chain made up of proteins in the membrane that transport electrons via a series of redox reactions
oxidative phosphorylationNADH and FADH2 are oxidised the released hydrogen atoms split into H+ ions and electrons the electrons move down the ETC via electron carriers releasing energy along the chain this released energy is used to actively pump H+ from the matrix into the intermembrane space an electrochemical gradient is formed because the H+ concentration is higher in the intermembrane space than the matrix the H+ ions move down the electrochemical gradient back into the matrix via ATP synthase the movement of the ions provides the energy needed to form ATP from ADP and Pi; this is known as chemiosmosis at the end of the ETC the H+, electrons and O2 from blood combine to form water and oxygen acts as the final electron acceptor
where does oxidative phosphorylation occur?inner membrane/ intermembrane space
what is aerobic respiration?the splitting of the respiratory substrate glucose to reunite hydrogen with atmospheric oxygen making water and CO2 also releasing a large amount of energy C6H12O6 + 6O2 ==> 6CO2 + 6H2O
what is anaerobic respiration?respiration without oxygen pyruvate is converted into lactate NAD is regenerated causes muscle fatigue
the effect of lactate build upblood lactate increases pH falls as H+ is released the H+ combine with the negatively charged areas on the enzyme the active site changes shape the substrate is unable to fit with the enzyme
what happens to lactate after a period of aerobic respiration?most of the lactate is converted back into pyruvate it is oxidised directly to CO2 and H2O via the Krebs cycle this releases energy to synthesise ATP increasing oxygen uptake some lactate may also be converted into glycogen
define oxygen debtexcess oxygen needed to oxidise lactate into pyruvate
investigate the rate of respirationtwo test tubes attached to a respirometer one should contain a woodlouse with a known mass on a gauze over some soda lime the other test tube will only have water mark the starting position of the coloured liquid close the tap and start the stop watch take a reading every min for 5 min carry out repeats to get the mean calculate the volume of oxygen uptake by doing v = πrh
how is lactate removed from the body?transported to the liver via the blood to be broken down oxidised into CO2 and water or converted into glucose then glycogen