Page 27 - E-Biology Sec.2 2024-2025 U1_Handy

L3: Heterotrophic Nutrition
(Human Digestive System)

1- It breaks down and digests the complex food to simpler form.
(Digestion process)

2- It extracts (absorbs) the nutrients by diffusion / active transport, so the body can
use it as a source of energy / build new tissues.
(Absorption process)

1. Digestion process:

Changing (Breaking down) food from complex (polymers)
into simpler substances (monomers) by hydrolysis using enzymes.

Enzymes

Biological catalysts are made of protein, they activate particular chemical reactions and
decrease the consumption of energy without being affected.

Mechanism of the enzyme action:

The enzyme has a (specific activation) activates a particular reaction depending on:
1- The structure of the substrate (reactant).
2- The nature (shape) of enzyme.

Unstable intermediate

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First Term