Respiration Flashcards
What are the 4 stages of aerobic respiration?
Glycolysis
Link reaction
Krebs cycle
Oxidative phosphorylation
What is glycolysis?
First stage of aerobic respiration
Takes place in cytoplasm
Converts glucose into 2 pyruvate molecules
Doesnt require oxygen
Explain the glycolysis of glucose?
Glucose is phosphorylated using 2 ATP molecules
This forms unstable molecule which breaks down into 2 triose phosphate molecules
Hydrogen is removed from each TP to convert it to 2 pyruvate molecules - releases 4 ATP molecules
Hydrogen is added to NAD to produce reduced NAD
What is the Link reaction?
Takes place in the mitochondrial matrix
converts pyruvate into acetyl coenzyme A (acetyl CoA)
Does not produce ATP
produces reduced NAD and acetyl CoA
Explain the Link reaction
Carbon atom removed from pyruvate to form CO2
Pyruvate is converted to acetate
Hydrogen removed and picked up by NAD to form reduced NAD
Acetate is combined with coenzyme A to form acetyl CoA
Each molecule of glucose produces 2x acetyl CoA, 2x CO2 and 2x reduced NAD
What is the krebs cycle?
A series of reactions which generate reduced NAD and reduced FAD which is used in oxidative phosphorylation
Explain the Krebs Cycle
Acetyl CoA reacts with 4C molecule oxaloacetate
CoA is removed and returns to link reaction
6C molecule called citrate is produced
Carbon and hydrogen removed from citrate - forms CO2 and reduced NAD
Carboxylated and Hydrogenated
Citrate converted into 5C compound
Carboxylated and Hydrogenated
5C compound converted to oxaloactetate - ATP, reduced 2x NAD and reduced FAD and CO2 produced
Cycle takes place 2x for each glucose molecule
What is oxidative phosphorylation?
Last stage of aerobic respiration
most ATP produced
Uses electrons carried by reduced NAD and FAD that have been made
takes place in inner mitochondrial membrane
Involves electron transport chain and chemiosmosis
Explain oxidative phosphorylation
Reduced NAD and FAD release H atoms which split into H+ and e-
Electrons pass onto electron carriers which travel along electron transport chain
As electrons move along chain they lose energy
Energy used to pump H+ ions from mitochondrial matrix to inner membrane
Proton gradient produced
H+ flows back through ATP synthase which adds a phosphate group to ADP to form ATP
When electons reach end of electron transport chain they are passed onto oxygen which reacts with H+ to form water
What is the total ATP production aerobic respiration?
Each molecule of reduced NAD produces 3 ATP
Each molecule of reduced FAD produces 2 ATP
Glycolysis:
2 ATP produced
2 reduced NAD = 6 ATP
Link Reaction:
2 reduced NAD = 6 ATP
Krebs cycle:
2 ATP produced
6 reduced NAD produced = 18 ATP
2 reduced FAD = 4 ATP
Total ATP = 38 ATP for each molecule of glucose
Explain anaerobic respiration
First step is the same as glycolysis
Glucose converted to pyruvate
2 ATP released, 2 reduced NAD formed
In second step, reduced NAD donated hydrogen to pyruvate to form lactate and NAD
This regenerates more oxides NAD for glycolysis
This allows anaerobic respiration to continue without oxygen
What does the body do with a build up in lactate?
Cells convert lactate back to pyruvate
Pyruvate can enter aerobic respiration at Krebs cycle
Also, liver cells can convert lactate into glucose which can be stored for aerobic respiration
How does respiratory substrate affect respiration?
cells can respire with carbs, proteins and lipids which release different amounts of energy
Lipids release most, then proteins, then carbohydrates
Majority of ATP produced using proton gradient that flows through ATP synthase
The more hydrogen atoms, the more ATP produced
What is respiratory quotient?
Respiratory quotient = CO2 produced / oxygen consumed
If RQ is greater than 1 then there is shortage of oxygen since organism respiring aerobically and anaerobically
Carbs - 1
Protein - 0.9
