An Introduction to Metabolism

What is metabolism?

Metabolism is the collection of chemical reac

tions that occur in an organism.

What is energy and which are the forms of energy?

Energy is capacity to cause change.

Kinetic energy = Energy of action or motion

Potential energy = stored energy or capacity to do work

Energy of activation = Energy needed to convert potential energy into kinetic energy

How can regulation of enzyme help control metabolism?

Enzymes speed up metabolic reactions by lowe

ring energy barriers.

They are biological catalysts that cause the rate of a chemical reaction to increase.

Facts:

- Every chemical reaction between molecules involves both bond breaking and bond forming.

- The quantity of energy in the universe is constant, but quality is not.

- Energy released from ATP drives anabolic reactions.

- Energy from catabolic reactions "recharges" ATP.

- Each chemical reaction in the cell requires its own enzyme.

Key words:

Metabolism = the totality of an organism’s chemical reactions

Energy = the ability to do work

Kinetic energy = energy of motion / action

Potential energy = tored energy or capacity to do work

Energy of activation = Energy needed to convert potential energy into kinetic energy

Entropy = measure of disorder

Free energy = portion of a system’s energy that can perform work when temperature and pressure are uniform throughout the system, as in a living cell

Exergonic reaction = release of free energy

Endergonic reaction = absorbs free energy

Energy coupling = a key feature in the way cells manage their energy resources to do work (chemical, transport, mechanical)

Phosphorylated = the recipient of the phosphate group

Summary:

Energy, the ability to do work can be kinetic, potential or activation energy. The laws of energy transformation say that it cannot be cr

eated or destroyed, only transfered and transformed. The second law states that spontaneous changes, those requiring no outside input of energy, increase the entropy (disorder) of the universe.

Free energy is the energy that can preform work when temperature and pressure are uniform throughout the system, as in a living cell. We can think of free energy as a measure of systems' instability - its tendency to change to a more stabile systems. The term that describes maximum stability is equilibrium.

Based on free energy changes, chemical reactions c

an be classified as either exergonic (energy released) or endergonic (energy absorbed).

ATP powers cellular work by coupling exergonic reactions to endergonic reactions.

Enzymes speed up metabolic reactions by lowering energy barriers. Their regulation helps control metabolism. An enzyme catalyzes a reaction by lowering the activation energy barrier, enabling the reactant molecules to absorb enough energy to reach the transition state even at moderate temperatures.

(diffusion, the relationship of free energy to work capacity, stability and spontaneous change)

Extra:

how ATP works (video)