Cellular metabolism

1. ‫أ‬. ‫عبدالناصر‬
‫العبيدي‬

2. Metabolism is the sum total or a set of all
chemical reactions that occur in the cell, in
order to maintain life
The chemical reactions of metabolism are
arranged in metabolic pathways that never
reach to equilibrium; products of one reaction
are used in the next reaction.

3. Metabolism is: Catabolism and Anabolism reactions.

4. Catabolism: is breaking down and oxidize of
macromolecules (Hydrolysis), releasing (or
transferring) energy, that was stored in the molecule
to supporting other cellular functions that require
energy.
Anabolism: is synthesis of
macromolecules(condensation), such as proteins and
nucleic acid, that requiring energy released through
catabolism.

5. Cells cannot creates or generate the energy;but
transforms energy from one form to another.
 Energy is the ability (capacity) to do work.
 There are two types of energy:-
1. kinetic energy is energy of motion e.g. Heat
(thermal energy)
2. potential energy that resulting from position of
structure, e.g. chemical energy and the stored
energy in covalent links in molecules

6. according laws of thermodynamics, The most important laws,
the Energy cannot be created or destroyed But can change in
forms
The reactions can be either Endergonic"endothermic" where
absorb energy, or Exergonic "Exothermic" where release the
energy.

7. Energy is released to do work .What kind of work?
1- Mechanical work such as the movement of
organelles and movement of the cell.
2- Transport such as pumping molecules across
membrane.
3- Chemical work to pushing endergonic reaction to
completion.
What is the most available, most intermediate source
of energy for cellular work? It is the ATP

8. Cellular respiration takes place into 2 stages:
1- Cellular respiration begins with glycolysis that
takes place in the cytosol, yields a relatively small
amount of ATP, and does not require Oxygen.
2- Oxidative respiration follows glycolysis takes place
in the mitochondria in the eukaryotic cells and in the
cytosol of prokaryotic cells. Is far more effective than
glycolysis in recovering the energy from food.

9. There are two types of cellular respiration
1-Aerobic (presence of O2) the effectively up to 20 times.
2-Anaerobic (in the absence of O2).