OCR Respiration

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  • Created by: Yetunde
  • Created on: 28-10-11 15:37

Respiration - Process whereby energy stored in complex organic molecules (carbs,fats,lipids) is released and used to make ATP in living cells.

Energy - cannot be created or destroyed, only transferred to other forms

             - measured in J or KJ

             - has many forms (sound, heat, light etc)

Outline why plants, animals and micro-organisms  need to respire with reference to active transport and metabolic reactions

Energy is required in living organisms to drive metabolic processes. There are two types of metabolic reactions:

  Anabolic : Building up large molecules 

Catabolic : Breaking down molecules some catabolic processes release energy in the form of heat.

Metabolic reactions are controlled by enzymes and this release of heat is useful in maintaining suitable temperature at which the enzyme works best. Metabolic reactions that require energy:

  • Active Transport (moving ions across it's own concentration gradient
  • Secretion (Exocytosis)
  • Movement (Flagellum and Cillia) 

Living organisms require the energy ( ATP) in order to carry out metabolic processes. The ATP is provided by respiration.

Describe, with the aid of diagrams, the structure of ATP + state that ATP provides immediate source of energy for biological processes. 

ATP (adenosine triphosphate) is a phosphorylated nucleotide


ATP is made up of Adenosine (Adenine + Ribose Sugar) and 3 phosphoryl groups.

ATP can be hydrolysed (split with water) to produce ADP ( Adenosine diphosphate) and Pi (Inorganic Phosphate)

When hydrolysed, 30.6kj is released. ATP provides cells with manageable amounts of energy that will not cause damage or be wasted.

Explain the importance of coenzymes in respiration with  reference to NAD and CoEnzyme A

During glycolysis, the link reaction and the Krebs Cycle, H atoms are removed in oxidation reactions. The reactions are catalysed by dehydrogenase enzymes however these enzymes do not catalyse oxidation or reduction reactions very well.

Co enzymes are needed to carry out the oxidation reactions and transport the H atoms.

The two coenzymes you need to know about :

NAD - Organic, non protein molecules. when a molecules of NAD accepts 2 hydrogen atoms it becomes reduced. NAD is used in gylcolysis, the link reaction and the krebs cycle. 

Coenzyme A - Carries ethanoate groups ( such as acetate) make from pyruvate during the link reaction into the krebs cycle

State that gylcolysis takes part in the cytoplasm of the mitochondria

Outline the processes of Glycolysis



Glucose 6 Phosphate

Fructose 1Phosphate


Hexose 1,6 Biphosphate

2 xTriose Phosphate

                                                                  2 ATP + 2NADH

2 x Intermediate Compounds 



Kelly Davies


This is very useful thank you.

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