Metabolism Totality of an organism’s chemical processes

Catabolic pathways (release energy) Breakdown

Respiration Anabolic pathway

Build up Photosynthesis

Metabolism, Energy, & Life

Energy Capacity to do work or cause change Kinetic energy (energy of motion) Potential energy

capacity of matter to cause change as a consequence of its location or arrangement.

Chemical energy A form of potential energy that is available for

release in chemical reactions.

Metabolism, Energy, & Life

Free energy (G) The portion of a system’s energy that can perform

work when temperature is uniform throughout the system.

Energy available for work. Exergonic reactions

Negative G Endergonic reactions

Positive G

Metabolism, Energy, & Life

ATP Adenosine triphosphate Powers cellular work by coupling exergonic

reactions to endergonic reactions. ATP Cycle

Metabolism, Energy, & Life

ATP

ADP + Pi

Energy fromcatabolism

Energy forCellular work

Speed up the rate of a reaction. Unchanged by the reaction. Lower the Activation Energy required for

the reaction to go forward. Do not change the ∆G for reaction. Substrate specific

Active site compatible to substrate Forms enzyme-substrate complex Induced fit model

EnzymesBiological Catalysts

Temperature and pH Speed of an enzyme-catalyzed reaction may increase

with rising temperature or pH up to the point at which increase thermal agitation or acidic/basic conditions begins to disrupt the weak bonds and interactions that stabilize protein shape.

Cofactors Small molecules that bind either permanently or

reversibly with enzymes and are necessary for enzyme function Inorganic metal ions or organic coenzymes

Most vitamins are coenzymes or precursors of coenzymes. Each enzyme has optimal conditions.

Effects of Local Conditions on Enzyme Activity

Competitive inhibitors Compete for the active site. Reversible

Increasing the concentration of substrate Noncompetitive inhibitors

Do not directly compete with the substrate at the active site. Bind to another part of the enzyme

Change in shape, altering the active site. nonnreversible

Pesticide DDT; Many antibiotics

Enzymes Inhibitors

Allosteric Regulation Regulatory molecules that change an

enzyme’s shape and function by binding to an allosteric site.

Allosteric site A specific receptor site on some part of the

enzyme molecule, separate from the active site. Effect:

Inhibition or stimulation of enzyme active

Control of Metabolism

Allosteric Regulation Allosteric activator Allosteric inhibitor

Feedback Inhibition

Control of Metabolism