Respiration Flashcards
What is respiration
The process whereby energy stored in complex molecules is used to make ATP
What is ATP used for
Metabolic processes
Active transport
Movement
Nerve transmission
Synthesis of materials
Secretion
What are the advantages of using ATP
Only one enzyme needed to release energy from ATP
Energy released in small amounts when and where needed
International energy currency
What is the structure of the mitochondria
Double membrane to increase surface area
Mitochondrial DNA and ribosomes
Inner membrane = cristae
Many enzymes
What is the endosymbiont theory
Some of the organelles in todays eukaryotic cells were once prokaryotic microbes
What coenzymes are used in respiration and why are they used
NAD
CoA
FAD
Used in oxidative phosphorylation at the end to produce lots of ATP
What are the four main stages of aerobic respiration
Glycolysis
Link reaction
Krebs Cycle
Oxidative Phosphorylation
Where does glycolysis occur
cytoplasm
What are the products of glycolysis
2 pyruvate molecules, 2 NADH and 2 ATP
What happens in glycolysis
- ATP is hydrolysed - glucose undergoes phosphorylation into Glucose-6-P
- Molecule is unstable so undergoes isomerisation into Fructose-6-P
- ATP hydrolysed so Fructose-6-P undergoes phosphorylation into Hexose 1,6-biphosphate
- Hexose splits into 2x triose phosphate
- Substrate level phosphorylation causes condensation of ATP and reduction of NAD by dehydrogenation of TP
- Substrate level phosphorylation of intermediate to produce 2x pyruvate and ATP
Where does the Link reaction occur
matrix of mitochondria
What happens in the Link reaction
Repeated twice as there are 2 pyruvates
- Pyruvate dehydrogenase removes 2 hydrogens from pyruvate
- NADH, CO2 and acetate(2C) formed
- CoA accepts acetate to form acetyl CoA
- Acetyl CoA moves into Krebs cycle
Products of Link reaction
2NADH
2CO2
2 Acetyl CoA
What happens in the Krebs cycle
- Acetate leaves CoA and joins oxaloacetate (4C) to form citrate (6C)
- Citrate oxidised and decarboxylated to form 5C by dehydrogenase and decarboxylase, forms NADH and CO2
- 5C oxidised + decarboxylated to 4C, forms NADH and CO2
- 4C undergoes substrate level phosphorylation into another 4C - ATP released
- 2nd 4C converted into 3rd 4C through dehydrogenation - FADH formed
-3rd 4C converted into oxaloacetate(4C) through dehydrogenation forming NADH
HAPPENS TWICE AS THERE ARE TWO ACETATES ENTERING CYCLE
What are the products of the Krebs Cycleq
4CO2
6NADH
2FADH
2ATP
What occurs in oxidative phosphorylation
- NADH is oxidised and donates 2H
- 2H is split into 2e- and 2 protons
- Complex 1 receives electrons - these are passed along electron transfer chain
- Protein carries go from Fe3+ to Fe2+ until it is passed to next protein
- Energy from ETC used for the active transport of protons from matrix to intermembrane space
- FADH is oxidised into 2e- and 2 protons
- electrons received by complex 2, protons pumped to intermembrane space
- H+ conc in intermembrane > than in matrix, electrochemical gradient made and protons move out by chemiosmosis
- Protons travel out through protein channel in ATP synthase - causes synthesis of ATP
- protons join electron that are released from ETC, then reacts with O2 to form water
Why is oxygen important in respiration
Driving force of oxidative phosphorylation
without it, the electrochemical gradient between intermembrane space and matrix wouldn’t be as steep as protons wouldnt get removed from matric
What is a respiratory substrate
An organic substance that can be used in respiration to release ATP
Why is there a difference in energy released
Molecules with more carbon-hydrogen bonds produced more NADH and FADH - meaning more ATP is made
Features of lipids as respiratory substrates
Only respired aerobically
Hydrolysed into glycerol and fatty acids
Glycerol -> pyruvate
Fatty acids -> acetyl groups
Features of proteins as respiratory substrates
Respired aerobically
Only used during starvation
Hydrolysed into amino acids
amino acids -> pyruvate or acetate or enter Krebs cycle directly
What is the respiratory quotient
Ratio of the volume of CO2 given out to that of oxygen used
Respiratory quotient for carbohydrates
1
Respiratory quotient for lipid
0.7
