Chapter 12: Respiration Flashcards
Explain why anaerobic respiration produces less ATP than in aerobic respiration.
Only glycolysis occurs = net gain of 2 ATP from substrate-linked phosphorylation
No final hydrogen acceptor = ETC stops functioning = no chemiosmosis where most ATP would be produced
Describe the structure of mitochondria and how it relates to its function.
Outer membrane
- Presence of carriers
Intermembrane
- High concentration of protons
- Protons move from intermembrane to matrix
Inner membrane
- Folded therefore larger SA
- Has ATP synthase, ETC, carrier proteins
Matrix
- Enzymes, site of Link reaction and Krebs
Describe respiration in anaerobic conditions in mammalian liver cells and describe how this differs from yeast cells.
Only glycolysis occurs = pyruvate cannot enter mitochondrion
Pyruvate is reduced by reduced NAD forming lactate catalysed by lactate dehydrogenase
Produces 2 ATP AND allows glycolysis to continue
Yeast cells has decarboxylation producing ethanal, so 2 steps
Ethanal is reduced by reduced NAD forming ethanol catalysed by ethanol dehydrogenase
Describe the differences of chemiosmosis at mitochondria and chloroplasts.
Chemiosmosis @ mitochondria
- Oxidative phosphorylation
- Inner mitochondrial membrane
- Reduced NAD provides electrons
- H+ into intermembrane space
- Oxygen final electron acceptor
Chemiosmosis @ chloroplasts
- Photophosphorylation
- Thylakoid membrane
- Photolysis provides electrons
- H+ into thylakoid
- NADP final electron acceptor
Explain why ATP is needed in the first stage of glucose.
Activates glucose to make it more reactive
Suggest 2 reasons why actual net number of ATP produced is less than the theoretical number.
ATP used to transport pyruvate into mitochondrial matrix
Some protons leak from intermembrane space
Some energy lost as heat
Glucose not completely broken down
Outline the roles of NAD and FAD in aerobic respiration.
Transport hydrogen to the inner mitochondrial membrane = acts as coenzyme for dehydrogenation.
Reduced during glycolysis, link reaction and Krebs cycle
Explain how ATP is formed during oxidative phosphorylation.
Reduced NAD and FAD releases hydrogen at inner membrane.
Hydrogen splits into protons and electrons. Electrons pass along ETC, releasing energy used to pump protons into intermembrane space.
High concentration of protons in intermembrane space, so steep proton gradient is achieved.
Protons diffuse back into matrix through ATP synthase which triggers chemiosmosis. ATP produced from ADP and Pi.
Describe how a molecule of glucose is converted to pyruvate and then to acetyl CoA.
Glycolysis occurs first. Glucose is phosphorylated by ATP to fructose bisphosphate.
Fructose bisphoshphate splits to form 2 TP, which is oxidised so producing reduced NADH.
2 ATP is produced due to substrate-linked phosphorylation.
Pyruvate enters mitochondrial matrix, undergoes link reaction where pyruvate is decarboxylated and dehydrogenated, then combines with coenzyme A to form acetyl CoA.
Outline oxidative phosphorylation.
Reduced NAD and FAD releases hydrogen which splits into proton and electron at inner mitochondrial membrane.
Electrons pass through ETC, releasing energy that is used to actively pump protons into intermembrane space, establishing proton gradient.
Protons diffuse through ATP synthase, ATP produced from ADP and Pi from chemiosmosis.
Oxygen acts as final electron acceptor to form water.
Define the term respiratory quotient (RQ).
Volume of carbon dioxide produced/volume of oxygen consumed per unit time.
Explain how rice is adapted to grow with its roots submerged in water.
Rice plants has aerenchyma which allows gases to diffuse through aerenchyma down to roots, allowing for aerobic respiration.
Some leaves trap air underwater due to ridges on leaves.
Alcohol fermentation occurs under anaerobic conditions, and root cells can tolerate ethanol as ethanol dehydrogenase is present to break down ethanol.
Name the waste products excrete during anaerobic respiration and describe what occurs to these products to help return to normal level.
Lactate produced will be taken to liver and converted to pyruvate which is converted to glucose.
Carbon dioxide produced is detected by pH receptors, therefore increased breathing rate so carbon dioxide goes into alveoli.
Describe how ATP is made by substrate-linked reactions.
Inorganic phosphate, Pi added to ADP resulting in phosphorylated compound.
State the role of acetyl coenzyme A in respiration.
Carrier of acetyl group to the Krebs cycle.
Explain the use of extra oxygen with rapid breathing after exercising.
Oxygen debt occurs.
Extra oxygen is needed to convert lactate to pyruvate in liver cells to reoxygenate haemoglobin.
Explain what happens to reduced NAD from glycolysis and link reaction
Reduced NAD will move into mitochondrial matrix carrying hydrogen atom.
Reduced NAD will donate hydrogen atom at inner membrane.
State the specific role of oxygen in the mitochondrion.
Final electron and proton acceptor in ETC.
Explain specifically role of inner mitochondrial membrane in chemiosmosis.
Site of ETC, so energy is provided so protons are pumped into intermembrane space = creating electrochemical gradient.
Inner membrane is also impermeable to protons, so electrochemical gradient is maintained.
Protons diffuse back into matrix through ATP synthase, where chemiosmosis occurs.
ADP + Pi –> ATP, also known as oxidative phosphorylation.
Explain why lipids have higher energy value than carbohydrates.
Lipids have more C-H bonds = produces more reduced NAD = more hydrogen atoms used to create proton gradient = more oxidative phosphorylation = more ATP per unit mass.
So, RQ is lower because need more oxygen to breakdown the molecule.
Suggest why it is difficult to compare ability of 3 types of cells to respire aerobically, based only on the mean number of mitochondria per cell.
Mitochondria varying in size.
What is the role of the ETC in inner membrane?
Splits H into electrons and protons.
As electron goes along ETC, it provides energy.
Energy is used to pump protons into intermembrane space.
State how glucose and oxygen requirements of cancer cells differ from normal cells.
Cancer cells uses more glucose and less oxygen.
So, little ATP, net gain of 2 from glycolysis is already sufficient.
Describe how you would carry out an investigation to determine RQ of germinating barley seeds.
Use respirometer.
Insert seeds on gauze, and sodalime to absorb carbon dioxide in test tube.
Then, attach manometer. Movement of fluid in manometer shows oxygen uptake.
Measure oxygen uptake after certain time. Then, repeat experiment without sodalime.
Difference in manometer readings is due to CO2 given out.
