8.1.1 Forms of oxidation and reduction.

 

 

Oxidation: often associated with the release of energy

 

 

 

 

 

 

Reduction: often associated with the gain of energy

 

 

 

 

 

 

 

 

 

 

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8.1.2 Glycolysis.

Location: Cytoplasm of all cells

Outline: Oxidation of Glucose (6 carbons) to two Pyruvate (3 carbons) is coupled to the reduction of ADP to ATP

In the following models the hydrogen and oxygen are not shown. The models show the number of carbons in each molecule not the structural formula.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Summary of glycolysis:

Remember in the examination you will come across the names of the molecules and stages rather than these model diagrams. So make sure you learn the terminology.

 

 

 

 

 

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8.1.3 Structure of the mitochondria.

 

 

 

 

 

 

 

 

 

 

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8.1.4 Aerobic respiration.

Stages in the Aerobic respiration:

Link Reaction: Pyruvate(3C) is transported to the matrix of the mitochondria

 

Krebs Cycle: oxidative decarboxylation of the C2 Acetyl group (CH3CO). This cycle has been broken down into 4 steps. The carbons from the original glucose molecule are shown in purple and those of mitochondria molecules in blue.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The krebs cycle is an example of the metabolic cycles mentioned in section 7.6.1 . Each step in the cycle requires enzymes to reduce the activation energy. The reactions all take place in the matrix of the mitochondria and are usually represented as a circular diagram. Try to overcome the idea that the molecules are going in a circle but more that this reaction is taking place within the confined space of the matrix where each intermediate becomes the substrate for the next step.

 

(a) Pyruvate (3C)

(b) Link reaction

(c) C4 + C2= C6

(d) Recycling of CoA

(e) Decarboxylation C6 to C5 and the reduction of NAD

(f) Decarboxylation C5 to C4 and the reduction of NAD

(g) C4 to C4 with the reduction of coenzymes FAD and NAD. ATP is made directly.

(h) C4 to C4 acceptor

 

This cycle follows one acetyl group.

Each glucose that enters glycolysis will produce 2 acetyl groups.

 

 

 

 

 

 

 

 

8.1.5 Oxidative phosphorylation in terms of chemiosmosis.

 

The following sequence of diagrams breaks down the process of oxidative phosphorylation into a number of stages. There are a number of membrane proteins involved in this process. Only a few of these proteins are shown and then only to allow specific reference to the diagrams. The overall process is shown but it is not realistic at this level to 'balance' the chemistry.

Oxidative Phosphorylation coupled to the synthesis of ATP.

 

 

 

 

 

 

 

 

 

 

 

 

A concentration gradient has been created between the high concentration of H+ between the mitochondrial membranes and the lower concentration in the matrix.

 

 

 

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8.1.6 Relationship between the structure and function of the mitochondria.

1. Cristae folds increase the surface area for electron transfer system.

2. The double membrane creates a small space into which the H+ can be concentrated.

3. Matrix creates an isolated space in which the krebs cycle can occur.

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Click4Biology: 8.1 Respiration

 

Respiration & Photosynthesis

8.1.1 Forms of oxidation and reduction.

8.1.2 Glycolysis.

8.1.3 Structure of the mitochondria.

8.1.4 Aerobic respiration.

8.1.5 Oxidative phosphorylation in terms of chemiosmosis

8.1.6 Relationship between the structure and function of the mitochondria.