Option C2

C.2.1 & C.2.2: Enzymes and the induced-fit model

Metabolic pathways consist of chains and cycles of enzyme-catalyzed reactions.

Induced-fit model

C.2.3: How do enzymes speed up reactions?

Proteins are the most abundant organic molecules in the living cell. All proteins are made up of amino acids and it is the linear arrangement of these amino acids into chains which composes the primary (or first level) structure. The primary structure determines the three-dimensional shape of a protein, which may consist of one to several polypeptide chains either covalently linked or held together by weak bonds. Secondary (or second level) structure refers to the regular patterns of coils or folds of a polypeptide chain demonstrated in Figure 2 below. Tertiary (or third level) structure refers from the folding of the chain to produce globular or fibrous-like molecules while quaternary (or fourth level) structure results from the joining of two or more polypeptide chains.

Figure 1 - Enzymes and activation energy

activation energy link activation energy animation
Activation energy

Examine Figure 1 to describe how enzymes affect the activation energy of a reaction?

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Effect of enzymes

Explain how enzymes cause this effect?

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Activation energy explained

How can enzyme activity be controlled by substrates?

C.2.4: Competitive vs Non-competitive Inhibition


Examine Figure 2 and compare competitive to non-competitive inhibition?

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Competitive vs Non-competitive

C.2.5: How are metabolic pathways controlled within the cell?

Figure 3 - End-product inhibition of metabolic pathways

End-product Inhibition

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