Respiration Flashcards
Stages of Aerobic respiration
- Glycolysis
- Link reaction
- Krebs cycle
- Oxidative phosphorylation
Rate equation
oxygen + glucose → carbon dioxide + water
Where does glycolysis take place?
In the cytoplasm of a cell
Steps of glycolysis
- Glucose is phosphorylated twice using 2 ATP to produce hexose bisphosphate
- This is split to form 2 TP and oxidised to form 2 pyruvate using 2 NAD’s to form reduced NAD and 4 ATP are produced
- 2 molecules of reduced NAD go to oxidative phosphorylation
- 2 pyruvate are actively transported into the matrix of the mitochondria for the link reaction
What is the net gain of ATP after glycolysis?
2
What happens in anaerobic respiration in plants + yeast?
- Pyruvate in converted to ethanal producing CO₂
- Ethanal is reduced to ethanol using NADH
- the regeneration of NAD means that glycolysis can continue
What happens in anaerobic respiration in animals?
- Pyruvate is converted to lactate/ lactic acid using NADH
- NAD is regenerated so can be used in glycolysis again to make more ATP
Steps of link reaction
- Pyruvate is decarboxylated and oxidised to produce acetate
- NAD is reduced to form reduced NAD, CO₂ formed as well
- Acetate combines with coenzyme A to form acetyl coenzyme A
Where does the link reaction take place?
Matrix of the mitochondria
Steps of the Krebs cycle
- Acetyl coenzyme A combines with 4C molecule, to produce a 6C molecule. Coenzyme A goes back to the link reaction
- 6C molecule is converted to a 5C molecule, CO2 is removed. NAD is used and produces reduced NAD
- 5C molecule is then converted to a 4C molecule. ATP is reformed, a carbon dioxide molecule is removed, 2 reduced NAD molecules and reduced FAD are produced for oxidative phosphorylation
Where does the Krebs cycle take place?
Matrix of the mitochondria
Steps of oxidative phosphorylation
- H⁺ atoms are released from reduced NAD and reduced FAD during their oxidation. H+ split into electrons + protons
- The electrons travel along the ETC. The energy released is used by the electron carriers to pump protons from the matrix to intermembrane space
- The conc. of protons is higher in the intermembrane space than in the matrix forming an electrochemical gradient
- Protons move down the gradient into the matrix via ATP synthase, resynthesising ATP (chemiosmosis)
- In the matrix the protons, electrons + oxygen combine to form water. Oxygen is the final electron acceptor
Where does oxidative phosphorylation take place?
Inner membrane of the mitochondria
How many ATP molecules are produced?
32 ATP
How does mitochondrial disease affect ATP production
- It affects the functioning of the mitochondria, it affects the proteins involved in the Krebs cycle and oxidative phosphorylation reducing ATP production
- Causing anaerobic respiration to increase to make up for shortage
- So lots of lactate is produced causing muscle fatigue and some lactate can also diffuse into the bloodstream leading to a high concentration in the blood
Name 2 types of anaerobic respiration
- Ethanol fermentation - plants + yeast
- Lactate fermentation - animals
What other respiratory substrates can be used?
- Fatty acids
- Amino acids
Method for RP9
- Use a beaker as a water bath at 35℃
- Shake glucose and yeast together
- Add 2cm³ into each test tube
- Place all 5 tubes into the water bath until 35℃
- Add 2cm³ of methylene blue into test tube 1 and shake
- Record how long it takes for the mixture to go from blue to colourless
- Repeat at different temps
How can respiration be measured?
- Measuring the volume of carbon dioxide produced
- Measuring the volume of oxygen used up
What equipment is used to measure respiration?
Respirometer
What is the purpose of the potassium hydroxide?
To absorb the CO₂ gas
Why must the respirometer be placed in a water bath?
So that temp is maintained so that the enzymes that control respiration can work at their optimum temp
Why must the equipment be left for 10-15 mins before the experiment?
- So that respiration rate remains constant
- Pressure to be constant/ equilibrium
Why does the coloured liquid move?
- Respiration starts
- CO₂ is absorbed by KOH
- The organism respires aerobically + use up O₂
- So volume + pressure in tube decreases
- Causing the coloured liquid to move towards respiring organism
