Respiration Flashcards
(17 cards)
What are the stages of aerobic respiration?
- Glycolysis → phosphorylation and splitting of glucose (Cell Cytoplasm)
- Link Reaction → decarboxylation and dehydrogenation of pyruvate (Matrix of Mitochondria)
- Krebs cycle → cyclical pathway with enzyme-controlled reactions (Matrix of Mitochondria)
- Oxidative Phosphorylation → production of ATP through oxidation of hydrogen atoms (Inner Membrane of Mitochondria)
What is the site of aerobic respiration in eukaryotes
Mitochondria
Describe the process of glycolysis.
- Phosphorylation → glucose (6C) is phosphorylated by 2 ATP to form glucose phosphate (6C)
- glucose phosphate (6C) splits into two molecules of triose phosphate (3C)
-
Oxidation of triosephosphate to produce pyruvate
- H is removed from each molecule of triose phosphate and transferred to coenzyme NAD to form 2 NADH
- 4 ATP are produced through dephosphorylation - Phosphorylation of glucose using 2 ATP
- Oxidation of triose phosphate to pyruvate
- Net gain of 4 ATP
- NAD reduced
What are the products of glycolysis?
- 2 pyruvate
- net gain of 2 ATP
- 2 NADH/ reduced NAD
Describe the link reaction.
- Pyruvate and NADH are actively transported from the cytoplasm to the mitochondrial matrix
- Pyruvate is oxidised by enzymes to produce acetate and carbon dioxide, requiring the reduction of NAD to NADH
- Acetate combines with coenzyme A to form acetyl coenzyme A (acetyl CoA)
- link rection occurs 2x for every glucose molucule
Products of the link cycle for one glucose molecule
- 2 acetyl coenzyme A
- 2 CO2 released
- 2 NADH
Describe the Krebs cycle.
- Acetyl CoA (2C) enters the circular pathway from the link reaction in glucose metabolism
- Acetyl coenzyme A reacts w/ 4C molecule, releasing coenzyme A and producing a 6C molecule that enters the Krebs cycle
- series of redox reactions;
- 2 CO2 is lost
- produces 1 ATP
- Reduction of FAD into reduced FAD
- Reduction of NAD into reduced NAD
Products of the Krebs cycle (includes link reaction)
- 3 reduced NAD
- 1 reduced FAD
- 1 ATP
- 2 CO2
(per glucose) (doubled)
- 6 reduced NAD
- 2 reduced FAD
- 2 ATP
- 4 CO2
Describe the process of oxidative phosphorylation.
- Hydrogen atoms are donated by reduced NAD and reduced FAD from the Krebs Cycle.
- Hydrogen atoms split into H+ and electrons
- The high energy electrons enter the electron transport chain and release energy as they move through the ETC
- this energy is used to actively transport the H+ from mitochondrial matrix to intermembrane space
- this creates an electrochemical gradient so the protons return to the matrix via facilitated diffusion through the channel protein ATP synthase
- ATP synthase phosphorylate ADP to create ATP
- Oxygen acts as the final electron acceptor and combines with protons and electrons at the end of the electron transport chain to form water
what is the importance of oxygen in aerobic respiration
- O2 is final electro acceptor in electron transport chain
- if it didn’t accept the electrons= no electrons to move down ETC= protons wouldn’t be transported= no electrochemical gradient= no ATP made
How many reduced NAD made in aerobic respiration of a single glucose molecule?
- 2 x 1 = 2 from Glycolysis
- 2 x 1 = 2 from the Link Reaction
- 2 x 3 = 6 from the Krebs cycle
Total (10)
How many reduced FAD made in aerobic respiration of a single glucose molecule?
- 2 x 1 = 2 from the Krebs cycle
Total (2)
Describe the process of anaerobic respiration in animals
- pyruvate produced in glycolysis remains in the cytoplasm
- Pyruvate is reduced to form lactate in animals by oxidation of NADH to NAD
(NAD can be reused in glycolysis to ensure more ATP is continuing to be produced) - Net gain of 2 ATP
Why can anaerobic respiration only occur for a short period of time?
Animals:
- Lactate is an acid and will eventually denature enzymes
Plants:
- ethanol will denature enzymes involved in glycolysis and all resp will stop
- but is useful for the absence of O2 for short periods of time as ATP is still being produced
Describe the process of anaerobic respiration in plants
- pyruvate produced in glycolysis remains in the cytoplasm
- Pyruvate is reduced to form ethanol and CO2 by the oxidation of NADH to NAD (NAD can be reused in glycolysis to ensure more ATP is continuing to be produced)
- Net production of 2 ATP
Metabolisation of lactate.
- It can be oxidised back to pyruvate which is then channelled into the Krebs cycle for ATP production
- It can be converted into glycogen for storage in the liver
What are possible respiratory substrates?
- lipids
- amino acids
- carbohydrates
