Cellular Energetics and Enzyme Regulation in Biology

What is the definition of energy in biological systems?

The ability to do work, which may change the state of motion to matter.

What must energy input be in relation to energy output for life to be sustained?

Energy input should be higher than energy output.

What is metabolism?

All the chemical reactions in an organism.

What is a metabolic pathway?

A series of complex molecules that either build or break down molecules.

What are catabolic pathways?

Pathways that break down complex molecules, releasing energy.

What are anabolic pathways?

Pathways that build complex molecules from simpler compounds and require energy.

What does the first law of thermodynamics state?

Energy cannot be created or destroyed, only transferred and transformed.

What does the second law of thermodynamics state?

Energy transformation increases entropy; some energy is lost as heat.

What is free energy?

A measure of how much energy is available to do work in a reaction.

What are exergonic reactions?

Reactions that release energy.

What are endergonic reactions?

Reactions that absorb energy.

What is ATP?

Adenosine triphosphate, a molecule that provides energy for cellular work.

How is ATP regenerated from ADP?

ADP can be regenerated to ATP via the ATP cycle.

What is phosphorylation?

The process where a phosphate group is transferred to another molecule, making it more reactive.

What role do enzymes play in metabolic reactions?

Enzymes catalyze reactions by lowering the activation energy required.

What is the active site of an enzyme?

The area where substrates bind to the enzyme.

What is induced fit in enzyme activity?

When a substrate binds to the active site, the enzyme changes shape slightly to better fit the substrate.

What is denaturation in enzymes?

The loss of shape, structure, and function of an enzyme due to environmental changes.

What factors can cause denaturation of enzymes?

Temperature, pH, and chemical environment.

What are enzyme cofactors?

Nonprotein molecules that bind to enzymes and assist in catalysis.

What are competitive inhibitors?

Molecules that reduce enzyme activity by preventing substrates from binding to the active site.

What are noncompetitive inhibitors?

Molecules that bind to an allosteric site, changing the shape of the active site and preventing substrate binding.

What is allosteric regulation?

Regulation of enzyme activity through binding at sites other than the active site.

What is cooperativity in enzyme action?

When the binding of a substrate to one active site increases the activity at other active sites.

What is feedback inhibition?

A regulatory mechanism where the end product of a metabolic pathway inhibits an earlier step in the pathway.