Metabolism and Energy Dynamics

Bioenergetics

Study of energy flow through a living system

Metabolism

All chemical reactions in a cell or organism.

Metabolic Pathways

Series of interconnected biochemical reactions that convert substrate molecules thru series of metabolic intermediates, eventually yielding final products (2 reactions required for cell energy balance= anabolic and catabolic)

Anabolic Pathway

Builds larger molecules, requires energy input.

Catabolic Pathway

Breaks down molecules, releases energy.

Photosynthesis

Process converting sunlight into chemical energy.

Cellular Respiration

Process converting glucose into ATP.

Kinetic Energy

Energy of objects in motion.

Potential Energy

Stored in objects due to its position, properties, and forces acting on it and can be transformed into kinetic energy.

Chemical Energy

Energy stored in chemical bonds.

Gibb's Free Energy (G)

Usable energy available to do work.

Exergonic Reaction

Releases energy, spontaneous, ΔG<0.

Endergonic Reaction

Requires energy input, non-spontaneous, ΔG>0.

Activation Energy

Energy needed for a reaction to proceed (always positive).

Thermodynamics

Study of energy and energy transfer.

First Law of Thermodynamics

Energy cannot be created or destroyed.

Second Law of Thermodynamics

Energy transfer is inefficient, increases entropy.

ATP (Adenosine Triphosphate)

Energy currency of the cell.

ATP Hydrolysis

Breakdown of ATP to release energy.

Energy Coupling

Using exergonic reactions to drive endergonic reactions.

Sodium-Potassium Pump

Uses ATP to transport ions across membranes.

Enzymes

Protein catalysts that speed up reactions.

Active Site

Region where substrates bind on an enzyme.

Induced Fit

Enzyme shape change optimizing substrate interaction.

Enzyme Regulation

Control of enzyme activity based on conditions.

Competitive Inhibitors

Compete with substrate for active site; have similar shape to the substrate

Noncompetitive Inhibitors

Bind elsewhere, reducing reaction rate and maximal rate.

Allosteric Inhibitors

Change enzyme shape/modify the active site of the enzyme, reducing substrate binding.

Cofactors

Inorganic ions needed for enzyme function.

Coenzymes

Organic molecules aiding enzyme activity.

Feedback Inhibition

End product inhibits upstream enzyme activity.

Bioenergetics

The study of energy flow through living systems.

Metabolism

Refers to all chemical reactions occurring within a cell or organism (includes reactions that use and release energy)

Anabolic reactions

Metabolic pathways that build larger molecules, requiring energy input.

Catabolic reactions

Metabolic pathways that break down larger molecules, releasing energy.

Activation energy

The energy required to initiate a chemical reaction.

Exergonic reactions

Reactions that release energy; characterized by a negative change in Gibbs Free Energy (ΔG < 0).

Endergonic reactions

Reactions that require an input of energy; characterized by a positive change in Gibbs Free Energy (ΔG > 0).

Second law of thermodynamics

States that energy transfer is not 100% efficient, increasing entropy with each reaction.

ATP (Adenosine Triphosphate)

The primary energy carrier in cells, composed of adenosine and three phosphate groups.

Enzymes

Biological catalysts that speed up reactions by lowering activation energy.

Induced fit model

The model describing how enzymes change shape slightly to optimize the interaction with the substrate.

Cofactors

Inorganic ions required for enzyme function, e.g., Fe++, Mg++, Zn++.

Coenzymes

Organic molecules that aid enzyme function, e.g., ATP, NADH+, and vitamins.

Feedback inhibition

A regulatory mechanism in metabolic pathways where the end product inhibits an upstream process.