Topic 5.2 - Respiration Flashcards
What do both aerobic and anaerobic respiration start with?
Glycolysis
Where does glycolysis occur?
Happens in cytoplasm
Is glycolysis an anaerobic or aerobic process?
Anaerobic process (doesn’t need oxygen to occur)
Name the 2 stages in glycolysis
- Phosphorylation
- Oxidation
Glycolysis
Describe what happens in phosphorylation
- Glucose is phosphorylated using phosphate from a molecule of ATP
- Creates 1 molecule of glucose phosphate and 1 molecule of ADP
- ATP is then used to add another phosphate = hexose bisphosphate
- Hexose bisphosphate is splits into 2 molecules of TP
Glycolysis
Describe what happens in oxidation
- TP is oxidised (loses H) which produces 2 molecules of pyruvate
- NAD collects hydorgen ions to produce 2 reduced NAD
- 4 ATP produced, but 2 used up in stage 1 therefore there is a 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
Ethanol
(Using reduced NAD)
Anaerobic Respiration
Pyruvate is converted into ___ in animal cells and some bacteria
Lactate
(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
- Glycolysis
- Link Reaction
- Krebs Cycle
- Oxidative Phosphorylation
Describe the link reaction
- Pyruvate is decarboxylated
- (1 C is removed in form of CO₂)
- Pyruvate is oxidised to form acetate
- & NAD is reduced to form reduced NAD
- Acetate is combined with coenzyme A (CoA) to form acetyl coenzyme (acetyl CoA)
- No ATP produced
After Link Reaction
For each glucose molecule, state the quantity of each product and where they go
- 2 molecules of acetyl CoA go into the Krebs cycle
- 2 CO₂ molecules are released as waste product
- 2 molecules of reduced NAD are formed and go to oxidative phosphorylation
Krebs cycle Involves a series of ________ reactions
reduction-oxidation (redox) 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
- Acetyl CoA combines with 4C to form 6C
- CoA A goes back to link reaction to be used again
- 6C → 5C
- Decarboxylation occurs
- Dehydrogenation occurs
- H is used to NAD → reduced NAD
- 5C → 4C
- Decarboxylation and dehydrogenation occur, produced 1x reduced FAD & 2x reduced NAD
- ATP is produced by direct transfer of phosphate group from intermediate compound to ADP which is 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
- Reduced NAD → NAD & reduced FAD → FAD = releases H
- H atoms split into protons and electrons
- electrons move down electron transport chain, losing energy at each carrier
- Energy is used to pump protons from mitochondrial matrix into intermembrane space
- Conc. of protons is now higher in intermembrane space than in mitochondrial matrix
- Forms electrochemical gradient
- Protons move down electrochemical gradient into mitochondrial matrix via ATP synthase
- Movement drives synthesis of ATP from ADP and P¡
- In mitochondrial matrix, at end of transport chain, protons, electrons and O₂ (from blood) combine to form water
- O₂ = final electron acceptor
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
- May cause anaerobic respiration to increase, to try and make up some of the ATP shortage
- = lots of lactate being produced, which can cause muscle fatigue and weakness
- Some lactate will diffuse into bloodstream = high lactate concentrations in blood
Describe how proteins can be used as respiratory substrates
- Amino acids used as respiratory substances
- Those not used for protein synthesis are deaminated in liver cells
- Remainder of molecule can be converted into glycogen or fat
- 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
Fatty acids can only be broken down _______
aerobically
Why can fatty acids only be broken down aerobically?
because oxygen will be required as final electron acceptor
Why do red blood cells only respire glucose?
Have no mitochondria - only respire anaerobically
(lipids and proteins require aerobic conditions)
The production of ethanol or lactate regenerates oxidised NAD. Why is this good?
- Means glycolysis can continue when there isn’t much oxygen around
- ∴ small amount of ATP can be produced to keep some biological processes going
What is a respirometer is used for?
Used to indicate rate of aerobic respiration by measuring amount of oxygen consumed by organism in one period of time
Describe what happens to reduced NAD produced in Krebs cycle (3)
- Enters mitochondria
- NADH → oxidised to NAD
- Used to produce ATP
Describe the part played by the inner membrane of mitochondrion in producing ATP (3)
- electrons transferred down electron transport chain
- provides energy to take protons into intermembrane
- protons pass through membrane, ATP synthase
Glucose _______ cross the mitochondrial _______
Glucose cannot cross the mitochondrial membrane
Human synthesise more than their body mass of ATP each day. Explain why it is necessary for them to synthesise such a large amount of ATP. (2)
- ATP cannot be stored/is an immediate source of energy
- ATP only releases a small amount of energy at a time
What measurements should the student have taken to calculate the rate of aerobic respiration in mm3 of oxygen g-1 h-1 (3)
- Distance (drop moves) and time
- Mass of organism
- Diameter of tube
Draw Glycolysis. Include no. of carbon.
Draw the Link Reaction. Include no. of carbon.
Draw the Krebs Cycle. Include no. of carbon.
The mitochondria in muscles contain many cristae. Explain the advantage of this. (2)
- Larger surface area for oxidative phosphorylation
- Provide ATP / energy for contraction
Explain why cells gain more energy from lipid than from carbohydrate (3)
- More H in lipid
- More protons so more reduced FAD/NAD/(more protons) move across inner mitochondrial membrane
- More ATP produced
- More electrons moving down ETC
Explain why less energy is released in anaerobic respiration (1)
Glucose only partly broken down/broken down to lactate
Explain why muscles become fatigued when insufficient oxygen is available (2)
- build up / increased concentration of lactate lowers pH / increases H / increases acidity
- enzymes / named protein inhibited(not denatured)
