Lecture 3 Energy and Enzymes

Vocabulary flashcards covering the basics of energy classes, chemical reactions, and the structure and function of enzymes based on lecture materials.

Energy

The capacity to do work; it is invisible but can be observed by its effect on matter.

Potential Energy

Stored energy that has the ability or potential to do work, such as water behind a dam wall.

Kinetic Energy

Energy in motion, such as water moving down pipes to spin a turbine.

Chemical energy

The most important form of potential energy in the human body, stored in a molecules’ chemical bonds and released when bonds are broken.

Triglycerides

Molecules involved in long-term energy storage within the human body.

Glucose

A form of energy stored in the liver and skeletal muscles as glycogen.

ATP

Stored in all cells in limited amounts, typically produced at a continuous rate and used immediately.

Electrical energy

The movement of charged particles/ions, such as $Na^+$ and $K^+$ moving down concentration gradients.

Mechanical energy

An object in motion due to an applied force (pressure), such as the heart pumping to move blood.

Sound energy

Compression of a semi-solid, liquid, or gas caused by a vibrating object, which initiates hearing by vibrating the ear drum.

Radiant Energy

Energy from electromagnetic waves, ranging from low frequency waves used for vision to high frequency UV light.

Thermodynamics

The study of energy transformations.

First law of thermodynamics

States that energy can neither be created nor destroyed, only transformed or converted from one form to another.

Second law of thermodynamics

States that every time energy is transformed, some of that energy is converted to heat.

Heat

The kinetic energy produced by the random motion of atoms; considered a 'waste product' because it cannot be used for work.

Concentration Gradient

The unequal distribution of solutes (such as $Na^+$ or glucose) across a semi-permeable membrane; it can act as both potential and kinetic energy.

Diffusion

The random movement of atoms/ions from areas of higher concentration to areas of lower concentration.

Equilibrium

A state where there is an equal concentration of a molecule on both sides of a membrane, resulting in no gradient.

Metabolism

The collective term for all biochemical reactions in living organisms.

Reactants (substrates)

Substances entering a chemical reaction.

Products

Substances resulting from a chemical reaction.

Decomposition Reactions

Reactions that break molecules into smaller fragments, such as breaking proteins into amino acids.

Hydrolysis

A type of decomposition reaction involving the addition of water: $AB + H_2O \rightarrow A-H + HO-B$.

Catabolism

The collective term for all decomposition reactions within the body.

Synthesis Reactions

Reactions that assemble larger molecules from smaller components, such as forming proteins from amino acids.

Dehydration synthesis

The formation of a larger molecule by the removal of water: $A-H + HO-B \rightarrow AB + H_2O$.

Anabolism

The collective term for all synthesis reactions within the body.

Exergonic reactions

Chemical reactions where energy is released, typically seen in catabolic (decomposition) reactions.

Endergonic reactions

Chemical reactions where energy is required/supplied, typically seen in anabolic (synthesis) reactions.

Reaction Rate

Measurement of how quickly a chemical reaction happens, dependent on the activation energy required.

Activation energy

The small amount of energy required to get any chemical reaction started, whether endergonic or exergonic.

Enzymes

Biologically active protein catalysts that accelerate physiologic activities by decreasing necessary activation energy.

Carbonic anhydrase

An enzyme that increases the production of $H_2CO_3$ from 100 molecules per hour naturally to 2.16 billion molecules per hour.

Active site

A specific region on a globular protein enzyme where the substrate temporarily binds.

Enzyme-substrate complex

The temporary structure formed when a substrate binds to the active site of an enzyme.

Denaturation

A shape change in a protein (enzyme) caused by severe temperature increases or pH changes, rendering the enzyme nonfunctional.

Inorganic cofactors

Non-protein structures like Zinc or Magnesium that attach to an enzyme and are required for its normal function.

Organic cofactors (coenzymes)

Organic molecules like $NAD^+$ that are not attached to enzymes but assist their function, such as during cellular respiration.

Inhibitors

Substances that bind reversibly to enzymes to turn them off and regulate product production.

Competitive inhibitors

Structural analogs of substrates that bind to the active site of an enzyme, blocking the actual substrate.

Noncompetitive (allosteric) inhibitors

Substances that bind to an allosteric site (not the active site), changing the enzyme's shape so the substrate can no longer bind.

Protein kinases

Enzymes that add a phosphate group (phosphorylation) to another enzyme to activate or deactivate it.

Phosphatases

Enzymes that remove a phosphate group (de-phosphorylation) from other enzymes to activate or deactivate them.