Respiration Flashcards
(36 cards)
Types of respiration?
- Aerobic
- Anaerobic
What are the 4 stages of aerobic respiration?
- Glycolysis : Each glucose is broken down into 2 molecules of the compound pyruvate
- Link reaction : Pyruvate is oxidised to form acetyl CoA
- Krebs cycle : Acetyl CoA is decomposed to form CO2, NADH and H+ (reduced NAD) or FADH2 (electron carriers)
- Oxidative phosphorylation : Reduced NAD or FADH2, transfer electrons to electron transport chain (ETC). The chem energy is converted to drive chemiosmosis.
What is the overall equation for respiration?
C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP (energy)
(glucose + oxygen -> carbon dioxide + water).
What is ATP?
Adenosine triphosphate is the main source of chemical energy for cell metabolism
What is the structure of ATP?
Nucleotide consisting of adenine, a ribose sugar and 3 phosphate groups condensed tgt
When is ATP formed?
- Substrate-level phosphorylation
- Oxidative phosphorylation
- Photophosphorylation <photosynthesis></photosynthesis>
What are the significance of ATP?
(4)
- It is a universal energy carrier
- It is a mobile energy carrier
- It can be easily formed
- It is the source of energy for many energy -requiring processes
What is the equation for synthesis and hydrolysis of ATP?
Hydrolysis : ATP+H2O→ADP+Pi+ energy
Synthesis : ADP + Pi+ energy→ATP+H2O
Pi = inorganic phosphate
When does ATP form during substrate level phosphorylation?
- Glycolysis (in the cytoplasm)
- Krebs cycle (in the mitochondrial matrix)
*only a small amount of ATP is generated
Where does respiration takes place?
Mitochondrion
Outline the process of glycolysis
(3 steps)
- Phosphorylation of glucose (6C)
- 2 ATP is used
* energy level of the molecule is raised so that useful energy can be extracted later
glucose ——-> fructose 1,6 biphosphate
kinase - Splitting of fructose-1,6-biphosphate (6C) into 2 triose phosphate/ glyceraldehyde-3-phosphate (GALP) (3C)
fructose-1,6-biphosphate ————-> 2 GALP
aldolase - Oxidation of 2 GALP (3C) to 2 pyruvate (3C)
- 4 ATP formed
- NAD+ reduced to NADH + H+
2 GALP ——————————> 2 pyruvate
dehydrogenase & kinase
What are the products of glycolysis?
- Net 2 ATP
- 2 reduced NAD
- 2 pyruvate
What happens to pyruvate after glycolysis?
It depends on the presence of oxygen.
- Aerobic resp : complete oxidation of pyruvate via LR, KC and OP, releasing a lot of energy
- Anaerobic resp : incomplete oxidation of pyruvate, no energy released, regenerate NAD+ only
Outline the process of Link Reaction.
(3 main steps)
- Oxidative decarboxylation of pyruvate
- CO2 removed - Oxidation of pyruvate to form reduced NAD
- Coenzyme A added to form acetyl CoA (2C)
pyruvate dehydrogenase = enzyme that oxidize pyruvate to acetyl coA NOT coenzymeA
What are the products formed after Link Reaction?
- 2 CO2
- 2 reduced NAD
- 2 Acetyl CoA
Where does glycolysis occurs?
Cytoplasm
Where does Link Reaction occurs?
Mitochondrial matrix
Outline Krebs cycle.
(Owen’s Cat Asked Susan For Milk)
(6 steps hehe)
- Acetyl CoA (2C) combines with oxaloacetate (4C) to form citrate (6C).
- Citrate (6C) breaks down to form ketoglutarate (5C).
-Citrate (6C) undergoes oxidative decarboxylation, releasing CO2.
-H atoms released (oxidation) are picked up by e- carriers NAD+ to form reduced NAD. - Ketoglutarate (5C) breaks down to succinate (4C).
-Ketoglutarate (5C) undergoes oxidative decarboxylation, releasing CO2.
-H atoms released are picked up by e- carriers NAD+ to form reduced NAD.
-ATP is produced via substrate-level phosphorylation. - Succinate (4C) to fumarate (4C)
-H atoms released are picked up by carriers FAD to form reduced FAD - Fumarate (4C) to malate (4C)
- Malate (4C) to oxaloacetate (4C)
- H atoms released taken up by NAD+ to form reduced NAD
What are the products formed from Krebs Cycle?
- 4 CO2
- 6 reduced NAD
- 2 reduced FAD
- 2 ATP
*KC occurs twice coz of 2 Acetyl CoA needed to be oxidised
Where does Krebs cycle occur?
Mitochondrial matrix
Outline the process of oxidative phosphorylation.
(Process 1 first -> 4 steps)
2 main processes : Electron Transport Chain (ETC) and Chemiosmosis
ETC:
1. High energy electrons in reduced NAD are transferred to the first e- carrier of the ETC, reducing the first e-carrier while NAD+ is regenerated…
Similarly, high-energy e- in reduced FAD are transferred to and e-carrier in the ETC resulting in regeneration of FAD…
- The high energy e-s migrates from one e- carrier to another in a series of redox reactions until they are finally accepted by the final electron and proton acceptor, O2. Protons from the mitochondrial matrix and e-s from the ETC are taken up by O2 to form H2O.
1/2 O2 + 2H+ → H2O
- The e- carriers in the ETC are each at a progressively lower energy, when high-energy e-s are transferred down the chain, energy is released by the e-s. The e- carriers use this energy to pump H+ from the matrix into the intermembrane space.
- Inner membrane is impermeable to H+, H+ accumulates in the intermembrane space, forming a proton reservoir. *Proton gradient is set up across the inner membrane!
<3+4 helps in chemiosmosis!!>
Outline chemiosmosis in photosynthesis.
ATP synthase on the mitochondrial cristae allow H+ to pass though via facilitated diffusion.
- When H+ flow down their proton gradient back into the matrix via ATP synthase, ATP synthase uses this energy from the proton motive force to synthesize ATP.
- Each reduced NAD has sufficient energy to form 3 ATP / 2.5 ATP while each reduced FAD yields 2 ATP / 1.5 ATP per molecule.
Define chemiosmosis
It is an energy-coupling mechanism that uses energy stored in the form of a H+ gradient across a membrane to drive cellular work, such as the synthesis of ATP.
What is the products formed during OP?
ATP synthesized by chemiosmosis : 34
