Metabolism, Energy, and Enzymes: Key Concepts for Biology

What is metabolism?

The sum of an organism's chemical reactions.

What is a metabolic pathway?

A series of chemical reactions where a specific molecule is transformed into a product, with each step catalyzed by a specific enzyme.

What are the two types of metabolic pathways?

Catabolic pathways (catabolism) that release energy by breaking down complex molecules, and anabolic pathways (anabolism) that consume energy to build complex molecules.

Give an example of a catabolic pathway.

Digestive enzymes breaking down food or cellular respiration.

Give an example of an anabolic pathway.

Linking amino acids to form proteins or photosynthesis.

What is free energy?

Energy that is available to do work in a cell.

What is the difference between exergonic and endergonic reactions?

Exergonic reactions release free energy and are spontaneous, while endergonic reactions absorb free energy from their surroundings and are non-spontaneous.

What is dehydration synthesis?

An anabolic reaction that forms covalent bonds between monomers to build polymers, producing water as a byproduct.

What is hydrolysis?

A catabolic reaction that breaks covalent bonds between monomers to break down polymers, using water as a reactant.

What is the role of enzymes in metabolic reactions?

Enzymes catalyze each step in a metabolic pathway, facilitating chemical reactions.

What is the Krebs Cycle?

A series of reactions that connect catabolic and anabolic pathways in metabolism.

What are the two main categories of energy?

Kinetic energy, associated with motion, and potential energy, associated with the position or structure of matter.

What does the first law of thermodynamics state?

Energy can be transferred and transformed, but cannot be created or destroyed.

What does the second law of thermodynamics state?

Every energy transfer or transformation increases the entropy of the universe.

What is entropy?

A measure of disorder or randomness in a system.

How do organisms affect entropy?

Organisms create organized structures from less organized materials, decreasing internal entropy while increasing the entropy of their surroundings.

What is free energy change (ΔG)?

A measure that indicates whether a reaction will occur spontaneously; only processes with a negative ΔG are spontaneous.

What is ATP and its role in metabolism?

ATP (adenosine triphosphate) is the cell's renewable energy shuttle, providing energy for cellular functions.

What is the significance of ATP hydrolysis?

The energy released from ATP hydrolysis can drive endergonic reactions, coupling exergonic and endergonic processes.

What are the components of ATP?

Adenine, ribose, and three phosphate groups.

What happens during ATP cycling?

Energy released from ATP drives anabolic reactions, and energy from catabolic reactions recharges ATP.

How does ATP compare to food in terms of energy storage?

ATP is a renewable energy resource with unstable bonds, while food serves as long-term energy storage with stable bonds.

What is activation energy?

The energy needed to convert potential energy into kinetic energy.

What is a spontaneous process in thermodynamics?

A process that occurs without energy input and must increase the entropy of the universe.

What is the role of ATP in cellular work?

ATP powers mechanical work (muscle contraction), transport work (pumping across membranes), and chemical work (making polymers).