ss biology unit 9 test

Energy

The ability to do work.

Potential Energy

Stored energy.

Kinetic Energy

Energy of motion.

Three Types of Cell Work

Mechanical work, transport work, and chemical work.

Mechanical Work

Movement of cell structures (example: muscle contraction, movement of cilia/flagella).

Transport Work

Moving substances across cell membranes.

Chemical Work

Building large molecules from smaller molecules.

Chemical Energy

Energy stored in the bonds between atoms of a molecule.

Entropy

A measure of disorder or randomness in a system.

First Law of Thermodynamics

Energy cannot be created or destroyed; it can only be transformed.

Second Law of Thermodynamics

Every energy transfer increases entropy and releases some energy as heat.

Third Law of Thermodynamics

As temperature approaches absolute zero, entropy approaches a minimum value.

ATP

The main energy-carrying molecule in cells.

Three Parts of ATP

Adenine, ribose sugar, and three phosphate groups.

High-Energy Phosphate Bond

The bond between the second and third phosphate groups.

ATP Energy Release

Energy is released when the third phosphate group is removed.

Endothermic Reaction

A reaction that absorbs energy from its surroundings.

Endothermic Diagram

Products have more energy than reactants.

Exothermic Reaction

A reaction that releases energy into its surroundings.

Exothermic Diagram

Reactants have more energy than products.

Spontaneous Reaction

Occurs without a continual input of energy.

Non-Spontaneous Reaction

Requires an energy input to occur.

Catabolism

Breakdown of large molecules into smaller molecules; bonds are broken and energy is released.

Hydrolysis

Breaking molecules apart using water.

Anabolism

Building large molecules from smaller molecules; requires energy.

Activation Energy

The minimum energy needed to start a chemical reaction.

Catalyst

A substance that speeds up a reaction without being consumed.

Enzyme

A biological catalyst.

Function of Enzymes

Speed up chemical reactions by lowering activation energy.

Enzyme Specificity

Enzymes only work with specific substrates.

Active Site

The region of an enzyme where the substrate binds.

Substrate

The reactant that an enzyme acts upon.

Enzyme-Substrate Complex

The temporary combination formed when an enzyme binds to its substrate.

Are Enzymes Reusable?

Yes, enzymes are not used up during reactions.

Denatured Enzyme

An enzyme that has lost its shape and can no longer function.

Cause of Denaturation

High temperatures, extreme pH, or other unfavorable conditions.

Cell Membrane

A selectively permeable barrier that controls movement into and out of the cell.

Selective Permeability

Allows some substances to pass while blocking others.

Diffusion

Movement of molecules from high concentration to low concentration.

Passive Transport

Movement across a membrane without using energy.

Facilitated Diffusion

Passive transport using protein channels.

Active Transport

Movement across a membrane using ATP, usually against the concentration gradient.

Concentration Gradient

Difference in concentration between two areas.

Which Transport Requires ATP?

Active transport.

Three Types of Passive Transport

Diffusion, osmosis, and facilitated diffusion.

Osmosis

Diffusion of water across a selectively permeable membrane.

Active Transport Example

Sodium-potassium pump.

Isotonic Solution

Equal solute concentration inside and outside the cell; no net water movement.

Hypotonic Solution

Lower solute concentration outside the cell; water enters the cell.

Hypertonic Solution

Higher solute concentration outside the cell; water leaves the cell.

Endocytosis

Cell takes materials into the cell using vesicles.

Exocytosis

Cell releases materials from the cell using vesicles.

Bulk Transport

Movement of large materials into or out of a cell using vesicles.

Why Is Bulk Transport Active?

It requires ATP energy to move materials.