Respiration Flashcards
4 stages of aerobic respiration and where they occur:
Glycolysis: Cytoplasm
Link reaction: Mitochondrial matrix
Krebs cycle: Mitochondrial matrix
Oxidative phosphorylation: Inner membrane of mitochondria, via electron transport chain
Why do Krebs cycle and link reaction take place in mitochondrial matric and not in cytoplasm?
The matrix contains all the enzymes needed for the biochemical reactions taking place, coenzymes
How are mitochondria adapted to it function?
They have a double membrane structure, inner layers with many folds to create high surface area, more space for more metabolizing proteins
Description of glycolysis:
Separates glucose into pyruvate
Outline the stages of glycolysis:
1) Glucose (6C) is phosphorylated with ATP to produce hexose bisphosphate
2) Hexose bisphosphate splits into 2 TP molecules (3C)
3) 2 molecules of TP are oxidized (H removed), H taken to NAD to form NADH
4)Dephosphorylation of TP molecules produce 2 ATP molecules in each pyruvate formed
How does pyruvate enter the mitochondria?
By active transport
Stages of link reaction:
1)Pyruvate oxidized (Hydrogen removed) to produce acetate
2)NAD is reduced using hydrogen that left pyruvate, NADH produced
3)Carbon is removed from pyruvate, in form of carbon dioxide
4)Acetate combines with coenzyme A to form acetyl coenzyme A (2C)
5)No ATP produced
Stages of Krebs cycle:
1)Acetyl (2C) is accepted by 4C compound to form 6C citrate, coenzyme A recycled
Citrate converted back to 4C oxaloacetate by:
1)Decarboxylation of citrate, CO2 released
2)Oxidation (H ions removed and added to NAD + FAD), these will be used in next stage (oxidative phosphorylation)
3)Phosphates transferred, 2 acetyl coenzymes so 2 ATPs produced
Which of the processes doesn’t release ATP?
Link reaction
What is the electron transport chain?
Series of carrier proteins in membrane of cristae of mitochondria
How does chemiosmosis occur to produce ATP?
H+ ions move down concentration gradient from the intermembrane space to the matrix via the channel protein ATP synthase
Outline of oxidative phosphorylation:
1)Hydrogen atoms donated from NADH and FADH
2)Hydrogen atoms split to H+ ions and electrons (which go to electron transport chain)
3)Release of energy, used to actively transport protons (H+ ions) from matrix to intermembrane space
4)Chemiosmosis, proton gradient allows H+ ions to diffuse to matrix through ATP synthase, generates ATP
5)Oxygen is final electron acceptor, combines with electron and H+ ions to form H20
What happens if oxygen level is low (anaerobic respiration)?
-No final acceptor of electrons, electron transport chain stops
-No more ATP produced via oxidative phosphorylation
-NADH and FADH not oxidised, no oxidised NAD and FAD means Krebs cycle and link reaction stops
-ATP only produced for glycolysis, NADH used to reduce pyruvate to lactate
Why is NAD needed for link reaction and Krebs cycle?
Link reaction:
Can accept H from pyruvate to make acetate
Krebs cycle:
To convert citrate (6C) back to 4C carbon compound, oxidation needs to occur (H adds to NAD+FAD)
What happens to lactate produced in anaerobic respiration?
Transported to the liver, oxidized to pyruvate (H is added to NAD)
Can enter link reaction in liver cells or be converted to glycogen
