Respiration Flashcards
(11 cards)
Why is respiration important?
Respiration produces ATP which is hydrolysed to release energy. This energy is used for important processes like protein synthesis and active transport
What are the stages of aerobic and anaerobic respiration and where do they occur?
- Aerobic Respiration
1. Glycolysis - cytoplasm (anaerobic)
2. Link reaction - mitochondrial matrix
3. Krebs cycle - mitochondrial matrix
4. Oxidative phosphorylation - inner
mitochondrial membrane - Anaerobic Respiration
1. Glycolysis - cytoplasm
2. NAD regeneration - cytoplasm
Give 2 similarities and 2 differences between Chloroplasts and Mitochondria.
Similarities
* Both organelles are double membrane bound
* Both organelles contains their own DNA and ribosomes
Differences
* The fluid inside the organelles is called the matrix in mitochondria and is called the stroma in chloroplasts
* Chloroplasts contain thylakoid membrane and grana, whereas mitochondria contain cristae
Describe the process of glycolysis
Glucose is phosphorylated to glucose phosphate using inorganic phosphates from 2 ATP molecules. This glucose phosphate is hydrolysed to 2 x 3C Triose Phosphate molecules, which are then oxidised to 2 x 3C Pyruvate, and the hydrogen removed is transferred to the co-enzyme NAD to form 2 x reduced NAD. 4 molecules of ADP are phosphorylated, forming ATP. Therefore, overall net gain is 2 x ATP, 2 x reduced NAD and 2 x 3C Pyruvate
Explain what happens after glycolysis if respiration is anaerobic
Fermentation:
1. Pyruvate is converted to lactate (animals & some bacteria) or ethanol (plants & yeast)
2. This oxidises reduced NAD, so NAD is regenerated
3. So glycolysis can continue (which requires
NAD) allowing continued production of ATP
Suggest why anaerobic respiration produces less ATP per molecule of
glucose than aerobic respiration
Only glycolysis is involved which produces a small amount of ATP. There is no oxidative phosphorylation which forms majority of ATP.
What happens after glycolysis if respiration is aerobic?
Pyruvate is actively transported into the mitochondrial matrix
Describe the link reaction
Pyruvate is oxidised and decarboxylated to 2C Acetate. CO2 is produced and NAD is reduced. Acetate combines with coenzyme A, forming Acetyl Coenzyme A. This reaction happens twice per glucose molecule and the products per glucose molecule are 2 x Acetyl Coenzyme A, 2 X CO2 and 2 X reduced NAD
Describe the Krebs cycle
Acetyl Coenzyme A combines with a 4C molecule, releasing Coenzyme A and producing a 6C molecule. The 6C molecule is decarboxylated and dehydrogenated to a 5C molecule, so Carbon Dioxide and reduced NAD is released. The 5C molecule is decarboxylated and dehydrogenated into the 4C molecule from the start. This process creates ATP, 3 molecules of reduced NAD, a molecule of reduced FAD and 2 molecules of carbon dioxide. This process occurs twice per glucose molecule.
Describe the process of oxidative phosphorylation
- Reduced NAD/FAD is oxidised to release H atoms, which then split into protons (H+) and electrons (e-)
- Electrons are transferred down electron transfer chain by redox reactions, as they move down, energy is released.
- Energy released by electrons is used to actively pump protons from matrix to the inner membrane, so proton accumulate in the intermembrane space, creating a proton gradient.
- Protons diffuse into matrix down the electrochemical gradient, via ATP synthase
- In the matrix at the end of the ETC, oxygen is the final electron acceptor. The oxygen combines with the hydrogen ions to form water
How do metabolic poisons affect respiration?
Poisons such as Cyanide disrupts respiration by binding to the electron carriers and inhibiting the movement of electrons down the ETC. This reduces chemiosmosis as the proton gradient can not be established and inhibits the Krebs Cycle as reduced FAD/NAD can not release the electrons to the ETC so they can not return to the Krebs cycle. This results in ATP production stopping.
