5.2.2 Respiration

• Structure of mitochondria 


  • surrounded by a double membrane
  • folded inner membrane - cristae - site of ETC
  • Fluid matrix - contains mitochondrial DNA, respiratory enzymes, lipids, proteins
• 4 main stages of aerobic respiration and where they occur

  • glycolysis - cyctoplasm
  • Link reaction - mitochondrial matrix
  • Krebs cycle - mitochondrial matrix
  • Oxidative phosphorylation - ETC in the membrane of the cristae
• Glycolysis;


  • glucose phosphporyalted --> hexose bisphosphate (uses 2x ATP)
  • Hexose bisphosphate --> 2x TP (triose phosphate)
  • Oxidised --> 2x pyruvate

  net gain of 2x NADH and 2x ATP (per glucose molecule)
• Label diagram:

  answers

  A) Hexose Bisphosphate

  B) 2x Triose Phosphate

  C) 2x pyruvate

  D) ATP

  E) Reduced NAD

  
• How does the pyruvate enter the mitochondria

  active transport
• Link reaction; equation 


  pyruvate + NAD + CoA (coenzyme A) --> Acetyl CoA + NADH +$CO_2$
• What happens in the link reaction

  1. pyruvate oxidised into acetate -->net gain of one $CO_2$(decarboxylation), 2 Hydrogen (reduced NAD)
  2. Acetate combines with coenzyme A to from Acetyl CoA
• What is an electron transport chain?

  • carrier proteins embedded in the membrane of the cristae of the mitochondria
  • Produces ATP through oxidative phosphorylation via chemiosmosis in aerobic respiration
• What happens in the ETC?

  Electrons released from NADH and FADH - undergo successive redox reactions. then energy is released and maintains proton gradient or released as heat. oxygen acts as the final electron acceptor
• How does chemiosmosis produce ATP during aerobic respiration

  fill in gaps:

  A) H+

  B) Mitochondrial matrix

  C) inter membrane space

  D) down concentration gradient

  E) matrix

  F) ATP synthase

  G) ADP + Pi --> ATP

  
• What is role of oxygen in aerobic respiration


  final electron acceptor in ETC (produces water as byproduct)
• Which two stages produce ATP via substrate-level phosphorylation

  1. glycolysis (anaerobic)
  2. Krebs cycle (aerobic)
• What happens during anaerobic respiration in animals

  fill in gaps

  A) pyruvate

  B) hydrogen acceptor

  C) oxidised NAD

  D) lactate

  
• What happens in anaerobic respiration in microorganisms?

  • only glycolysis - much less ATP than aerobic respiration
  • pyruvate is decarboxylated to form ethanal
  • ethanal --> ethanol using reduced NAD
  • produces oxidised NAD - further glycolysis
• How is ethanol produced during anaerobic respiration

  fill in gaps

  A) decarboxylated

  B) CO2

  C) ethanal

  D) Oxidised NAD

  E) reduction

  F) ethanol

  
• 2 other molecules used as respiratory substrates

  • amino acids/ proteins
  • lipids/ fatty acids or glycerol
• What is the respiratory quotient

  $\frac{CO_2\ produced}{O_2\ consumed}$
• What is the RQ of carbohydrates

  1
• what is the RQ of lipids

  0.8
• What is the RQ of proteins

  0.9
• How does anaerobic respiration affect RQ


  Values will be larger
• Why do different respiratory substrates have different relative energy values

  depends of the number of hydrogens in the structure that are oxidised into water
• Krebs cycle

  .

  A) acetyl CoA

  B) Citrate

  C) Reduced NAD

  D) Reduced NAD

  E) ATP

  F) Reduced FAD

  G) Reduced NAD

  H) CO2

  I) CO2

  
• Importance of Coenzymes in Cellular Respiration

  1. NAD - accepts hydrogen and transfers H+ and e- to ETC used in glycolysis, link reaction and Krebs cycle
  2. FAD - accepts hydrogen and transfers H+ and e- to ETC used in Krebs cycle
  3. CoA - transfers acetate group to form acetyl CoA in link reaction.
  4. NADP - accepts hydrogen and transfers H+ and e- to ETC but in photosynthesis