Metabolism: Energy and Enzymes

Vocabulary flashcards covering key concepts from the lecture on Metabolism, Energy, Enzymes, and Cellular Respiration.

Metabolism

The sum of all chemical reactions within a living organism.

Eukaryotic cells

Cells that contain membrane-bound organelles, such as Plant and Animal cells.

Prokaryotic cells

Cells that do not contain membrane-bound organelles, such as Bacteria.

Anabolic pathway

Metabolic pathway where small molecules are built into large ones, requiring energy.

Catabolic pathway

Metabolic pathway where large molecules are broken down into small ones, releasing energy.

Energy

The ability to do work.

Kinetic Energy

Energy of motion.

Potential Energy

Stored energy.

First Law of Thermodynamics

States that energy cannot be created or destroyed (law of conservation of energy).

Second Law of Thermodynamics

States that energy cannot be changed without a loss of usable energy (heat).

Endergonic reaction

An energy-absorbing ('uphill') reaction that requires activation energy and absorbs energy.

Exergonic reaction

An energy-releasing ('downhill') reaction that is spontaneous and releases energy.

Activation energy

The energy required to cause a reaction to occur.

Enzyme

A protein molecule that functions as an organic catalyst to speed reactions.

Substrate

The reactants in an enzymatic reaction, which is what an enzyme attaches to.

Induced Fit Model

A model describing how enzymes and substrates fit together, also called the 'lock and key model'.

Degradation

The process of breaking down molecules.

Synthesis

The process of building up molecules.

Denaturation

When an enzyme changes its shape so much (e.g., due to high temperature or pH) that it is no longer effective.

Competitive Inhibition

Enzymatic regulation where an inhibitor binds to the active site of an enzyme and blocks it.

Allosteric Inhibition

Enzymatic regulation where an inhibitor binds to another site on the enzyme (allosteric site) and changes its shape.

Allosteric Activator

A molecule that changes the shape of an enzyme so that it can bind to the substrate more efficiently.

Active Site

The specific region of an enzyme where the substrate binds.

Allosteric Site

A site on an enzyme other than the active site where activators or inhibitors can bind.

Feedback Inhibition

Enzymatic regulation where the product of a reaction becomes an inhibitor, slowing down or stopping the creation of more product.

Catabolic reactions

Reactions that break down larger, more complex molecules into smaller molecules and release energy; also called degradation or exergonic.

Anabolic reactions

Reactions that use energy to build more complex molecules from simple raw materials; also called synthesis or endergonic.

Cellular Respiration

The set of metabolic reactions and processes that convert energy from nutrients into adenosine triphosphate (ATP) and release waste products.

ATP

Adenosine Triphosphate, the main energy currency of the cell, created from nutrients during cellular respiration.

Glycolysis

The first stage of cellular respiration, occurring in the cytoplasm, which breaks down glucose into pyruvate and releases 2 ATP.

Kreb's Cycle (Citric Acid Cycle)

The second stage of cellular respiration, occurring in the mitochondrial matrix, where Acetyl CoA is reshuffled, producing NADH, FADH2, ATP, and CO2.

Electron Transport Chain

The third stage of cellular respiration, occurring on the inner mitochondrial membrane, where electrons from NADH and FADH2 drive ATP synthesis through chemiosmosis, yielding 36-38 ATP.

Aerobic Respiration

Cellular respiration that occurs in the presence of oxygen.

Fermentation (Anaerobic Respiration)

A metabolic pathway that occurs without oxygen when the Krebs cycle cannot, with byproducts including lactic acid and alcohol.

Lactic Acid

A byproduct of fermentation in muscle cells that can cause muscle cramps due to lack of oxygen.

Alcohol

A byproduct of fermentation, alongside lactic acid.