Respiration - me

• What are the 4 stages of aerobic respiration?


  1. Glycolysis

  2. Link reaction

  3. Krebs cycle

  4. Oxidative phosphorylation
• What part of aerobic respiration takes place in the cytoplasm?


  Glycolysis
• What parts of aerobic respiration takes place in the mitochondria?


  Link reaction, krebs cycle and oxidative phosphorylation
• What are the products of glycolysis?


  2 ATP, 2 NADH, 2 pyruvate (3C) per one molecule of glucose
• Why is glycolysis an anaerobic process?


  it does not require oxygen and its the first stage of both aerobic and anaerobic respiration
• What happens in stage 1 of glycolysis?


  Phosphorylation:

  1. glucose is phosphorylated by adding 2 phosphates from 2 molecules of ATP

  2. From this, 1 molecule of fructose biphosphate and 2 molecules of ADP is created

  3. Then, fructose biphosphate is split into 2 molecules of triose phosphate
• What happens in stage 2 of glycolysis?


  1. Triose phosphate is oxidised (loses hydrogen), forms 2 molecules of pyruvate

  2. NAD collects the hydrogen ions, forms 2 NADH

  3. 4 ATP molecules are produced but the net GAIN is only 2 ATP
• What happens to the molecules of pyruvate after glycolysis?


  Transported to the matrix of the mitochondria for the link reaction
• What happens to the molecules of NADH after glycolysis?


  They go to oxidative phosphorylation
• What is the product of the link reaction?


  Acetyl CoA = co-enzyme A and 2 carbons ( 2x produced per 1 molecules of glucose)
• What happens during the Link reaction


  1. Pyruvate is decarboxylated (1 carbon removed in the form of CO2)

  2. NAD is reduced to NADH - collects hydrogen from pyruvate, forming acetate

  3. Acetate + CoA = acetyl CoA

  
  

  NO ATP PRODUCED
• Is Co-enzyme A an enzyme?


  No because co-enzymes are not made out of proteins
• What are the products of the Krebs cycle?


  2 molecules of CO2, ATP, 3 molecules of NADH, FADH2
• Where in the mitochondria does the Krebs cycle occur?


  matrix
• How many times does the Krebs cycle occur for each molecule of glucose?


  twice
• What is the 1st stage of Krebs cycle?


  Acetyl (from acetyl CoA) combines with oxaloacetate to form citrate (catalysed by citrate synthase)

  CoA goes back to the link reaction to be used again
• What is the 2nd stage of Krebs cycle?


  The 6C citrate is converted to a 5C molecule

  Decarboxylation occurs where CO2 is removed

  Dehydrogenation occurs where hydrogen is removed

  The hydrogen is used to produce NADH from NAD
• What is the 3rd stage of Krebs cycle?


  The 5C molecule is converted to a 4C molecule

  Decarboxylation and dehydrogenation occur, producing 1 FADH2 and 2 NADH

  
  

  ATP is produced by the direct transfer of a phosphate group from an intermediate compound to ADP.

  When a phosphate group is directly transferred from 1 molecule to another its called substrate-level phosphorylation

  
  

  Citrate has now been converted into oxaloacetate
• What happens to the products from Krebs?


  CoA = reused in link reaction

  Oxaloacetate = regenerated for use in the next Krebs cycle

  2 CO2 = released as waste product

  ATP = used for energy

  3 NADH = to oxidative phosphorylation

  FADH2 = to oxidative phosphorylation
• Where in the mitochondria does the electron transport chain (oxidative phosphorylation) occur?


  inner membrane of mitochondria. This membrane is folded into cristae, which increases the membrane's surface area to maximise respiration.See an expert-written answer!We have an expert-written solution to this problem!
• What is oxidative phosphorylation?


  The process where the energy carried by electrons from reduced coenzymes (NADH and FADH) is used to make ATP
• Where are the regenerated coenzymes used after oxidative phosphorylation?


  They are reused in the Krebs cycle
• What happens during oxidative phosphorylation?


  1. H atoms are released from NADH and FADH as they're oxidised to NAD and FAD - the H atoms split into H+ and e-

  2. The e- move along the ETC which lose energy at each carrier

  3. This energy is used by the electron carriers to pump H+ from the mitochondrial matrix into the inter membrane space

  4. The concentration of H+ is now higher in the inter membrane space than in the mitochondrial matrix - this forms an electrochemical gradient, back into the mitochondrial matrix via ATP synthase. This movement drives the synthesis of ADP to ATP and inorganic phosphate

  6. This process of ATP production is driven by the movement of H+ across a membrane (due to electrons moving down an electron transport chain) is called chemiosmosis

  7. In the mitochondrial matrix, at the end of the transport chain, the H+, e- and O2 (from the blood) combine to form water

  
  

  Oxygen is said to be the final electron acceptor
• What is the inter membrane space of the mitochondria?


  space between inner and outer membrane
• How many carriers is the ETC made up of?


  3 carriers
• What is the ETC?


  electron transport chain
• What is chemiosmosis?


  the movement of ions across a semipermeable membrane, down their electrochemical gradient
• What is the chemiosmotic theory?


  The process of electrons flowing down the electron transport chain and creating a proton gradient across a membrane to drive ATP synthesis.
• What does ATP synthesis do?


  it is located at the end of the electron transport chain and it takes ADP and inorganic phosphate and makes it into ATP
• How many molecules of ATP can be made from 1 molecule of glucose?


  32
• What are the 2 types of anaerobic respiration?


  alcoholic fermentation and lactic acid fermentation
• Does anaerobic respiration use oxygen?


  nope
• Does anaerobic respiration involve the link reaction, Krebs cycle or oxidative phosphorylation?


  Nope
• Where does lactic acid fermentation occur?


  muscle cells/ cytoplasm
• What is the process of lactic acid fermentation?

  pyruvate + NADH --> lactic acid + NAD+ (NAD can then be reused in glycolysis)
• What is NAD used for after lactic acid fermentation?


  The production of lactic acid regenerates NAD. Glycolysis needs NAD in order to take place. This means glycolysis can continue even when there isn't not much oxygen around, so a small amount of ATP can be produced to keep some biological processes going
• What happens to the lactate acid after anaerobic respiration?


  Our cells can tolerate a high level of lactate for short periods of time, e.g. short periods of hard exercise, when they can't get enough ATP from aerobic respiration

  
  

  Too much lactate is toxic and is removed from the cells into the bloodstream. The liver takes up lactate from the bloodstream and converts it back into glucose
• What is glucogenesis?


  The reverse of glycolysis to produce glucose. (E.g. lactate to glucose)
• Does anaerobic respiration release less energy than aerobic respiration?


  The ATP yield from anaerobic respiration is always lower than from aerobic re aspiration
• Why does anaerobic respiration release less energy than aerobic respiration?


  The oxidation of glucose is incomplete in anaerobic respiration

  
  

  Anaerobic respiration only includes one energy releasing stage, which produces 2 ATP per glucose molecule - krebs and oxidative phosphorylation cant occur due to the lack of oxygen