Respiration

OCR Central ConceptsA2 Revision

Energy and respiration

Metabolism– Total of all biochemical reactions needed for an

organism to stay alive– Anabolism + catabolism

Energy needed to do work– Synthesis– Active transport– Movement– Maintenance of body temperature

Photosynthesis and Respiration

Energy transfer processes

Photosynthesis6CO2 + 6H2O in the presence of light energy C6H12O6 + 6O2

RespirationC6H12O6 + 6O2 energy is released 6CO2 + 6H2O

Most energy transferred to ATP originally derived from light energy

Energy and Living Organisms

Transfer of materials and energy in an ecosystem

Adenosine Triphosphate

Small water soluble moleculePhosphorylated nucleotideATPADP = 30.5KJmol-1 energyATPaseATPsynthase

Synthesis of ATP

ATP is formed during respiration (and in photosynthesis

Synthesis of ATP

Mitochondria

Respiration as a REDOX reaction

Oxidation involves

•Addition of oxygen

•Removal of hydrogen

•Loss of electrons

•Release of energy

Reduction involves

•Removal of oxygen

•Addition of hydrogen

•Gain of electrons

•Uptake of energy

Aerobic Respiration

The transfer of chemical potential energy from organic molecules to ATP in living cells.GlycolysisLink reactionKrebs cycleOxidative phosphorylation

Glycolysis

One molecule of glucose is oxidised to two molecules of pyruvate.– Phosphorylation– Lysis– Oxidation

Glucose

Hexose phosphate

Hexose biphosphate

2 X triose phosphate (3C)

2 X pyruvate (3C)

Link Reaction

Pyruvate is– Decarboxylated– Dehydrogenated– Combined with coenzyme A (adenine, ribose,

pantothenic acid)

Pyruvate (3C) + coenzyme A------------------acetyl (2C) coenzyme A

Carbon dioxide

NAD NADred

Krebs Cycle

Each cycle releases– 2CO2

– 1 FADred

– 3NADred

– 1 ATP

Electron Transport Chain

When reduced FAD is oxidised, only two molecules of ATP are formed

Summary of aerobic respiration

* Oxidative phosphorylation

*

Anaerobic Respiration

The Ethanol Pathway

Anaerobic Respiration

Lactate Pathway

The Cori Cycle

Rescues lactate and prevents waste of its chemical bond energyPrevents fall in plasma pH

Respiratory Substrates

Substrate energy density (KJg-1)Carbohydrate 16Lipid 39Protein 17

Bomb calorimeter

Respiratory Quotient

RQ = Volume of carbon dioxide given off Volume of oxygen

taken in

Glucose = 1Lipids = 0.7Protein = 0.9

Investigating Respiration

Respirometer

Effect of temperature on respirationQ10 = rate of reaction at temperature t + 10oC

rate of reaction at a temperature t