3.3.3 Respiration Flashcards Preview

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What do both aerobic and anaerobic respiration start with?



Where does glycolysis occur?

Happens in cytoplasm 


Is glycolysis are anaerobic or aerobic process?

Anaerobic process 


Name the 2 stages in glycolysis

  1. Phosphorylation
  2. Oxidation



Describe what happens in phosphorylation

  1. Glucose is phosphorylated using phosphate from a molecule of ATP
    • Creates 1 molecule of glucose phosphate and 1 molecule of ADP
  2. ATP is then used to add another phosphate = hexose bisphosphate
  3. Hexose bisphosphate is splits into 2 molecules of TP



Describe what happens in oxidation

  1. TP is oxidised (loses H) = 2 molecules of pyruvate
  2. NAD collects H+ ions = 2 reduced NAD
  3. 4 ATP produced, but 2 used up in stage 1 ∴ net gain of 2 ATP


What happens to the products of glycolysis in aerobic respiration?

  • 2 molecules of reduced NAD go to oxidative phosphorylation
  • 2 pyruvate molecules are actively transported into matrix of mitochondria for link reaction


Anaerobic Respiration 

Pyruvate is converted into ___ in plants and yeast


(Using reduced NAD)


Anaerobic Respiration 

Pyruvate is converted into ___ in animal cells and some bacteria


(Using reduced NAD)


Illustrate Alcoholic Fermentation 

(i.e. write equation)

Reduced NAD reduces/donate H ions to pyruvate to ethanol


Illustrate Lactate Fermentation


Name the 4 main stages in aerobic respiration

  1. Glycolysis 
  2. Link Reaction 
  3. Krebs Cycle 
  4. Oxidative Phosphorylation


Describe the link reaction

  1. Pyruvate is decarboxylated
    • (1 C is removed in form of CO₂)
  2. Pyruvate is oxidised to form acetate
    • & NAD is reduced to form reduced NAD
  3. Acetate is combined with coenzyme A (CoA) to form acetyl coenzyme (acetyl CoA)
  4. No ATP produced 


2 pyruvate molecules are made for every glucose molecule that enters glycolysis. This means that the ____ _____ and _____ _____ happens _____ for every glucose molecule.

2 pyruvate molecules are made for every glucose molecule that enters glycolysis. This means that the link reaction and Krebs cycle happens twice for every glucose molecule.


After Link Reaction

For each glucose molecule, state the quantity of each product and where they go

  1. 2 molecules of acetyl CoA go into the Krebs cycle
  2. 2 CO₂ molecules are released as waste product
  3. 2 molecules of reduced NAD are formed and go to oxidative phosphorylation


Krebs cycle Involves a series of ________ reactions



Where does the Krebs cycle takes place?

In matrix of mitochondria


Krebs cycle happens once for every ______ molecule & goes round 2x for every ______ molecule

Krebs cycle happens once for every pyruvate molecule & goes round 2x for every glucose molecule


Describe the Krebs cycle 

  1. Acetyl CoA combines with 4C to form 6C 
    1. CoA A goes back to link reaction to be used again
  2. 6C → 5C
    1. Decarboxylation occurs
    2. Dehydrogenation occurs
    3. H is used to NAD → reduced NAD
  3. 5C → 4C
    1. Decarboxylation and dehydrogenation occur, produced 1x reduced FAD & 2x reduced NAD
    2. ATP is produced by direct transfer of phosphate group from intermediate compound to ADP
      1.  Called substrate-level phosphorylation



Define oxidative phosphorylation

  • Process where energy carried by electrons, from reduced coenzymes (reduced NAD and reduced FAD), is used to make ATP
  • Involves electron transport chain and chemiosmosis


Describe Oxidative Phosphorylation

  1. Reduced NAD → NAD & reduced FAD → FAD = releases H 
    • H atoms split into protons and e 
  2. e move down electron transport chain, losing energy at each carrier
  3. Energy is used to pump protons from mitochondrial matrix into intermembrane space
  4. Conc. of protons is now higher in intermembrane space than in mitochondrial matrix
    • Forms electrochemical gradient
  5. Protons move down electrochemical gradient into mitochondrial matrix via ATP synthase
    • Movement drives synthesis of ATP from ADP and P¡
  6. In mitochondrial matrix, at end of transport chain, protons, electrons and O₂ (from blood) combine to form water
    • O₂ = final electron acceptor 


____ ATP are made from each reduced NAD and ___ ATP are made from each reduced FAD

2.5 ATP are made from each reduced NAD and 1.5 ATP are made from each reduced FAD



What do mitochondrial diseases affect?

  • Affect functioning of mitochondria
    • Affect how proteins involved in oxidative phosphorylation or Krebs cycle function = reducing ATP production


Describe the effect of mitochondrial diseases

  1. May cause anaerobic respiration to increase, to try and make up some of the ATP shortage
  2. = lots of lactate being produced, which can cause muscle fatigue and weakness
  3. Some lactate will diffuse into bloodstream = high lactate concentrations in blood


Describe how proteins can be used as respiratory substrates

  1. Amino acids used as respiratory substances
  2. Those not used for protein synthesis are deaminated in liver cells
  3. Remainder of molecule can be converted into glycogen or fat
  4. If there's not enough carbohydrates, muscle proteins can be hydrolysed to amino acids


Describe how glycerol can be used as a respiratory substrate

Glycerol oxidised and phosphorylated into TP and then enters end of glycolysis


Describe how fatty acids can be used as a respiratory substrate

Fatty acids are broken down by process known as beta oxidation to produce acetyl CoA when then enters the Krebs cycle


What is produced a lot in beta oxidation?

Large amounts of FADH2 and NADH

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