Energy, Thermodynamics, and Cell Transport Vocabulary

Vocabulary flashcards defining fundamental bioenergetic terms, thermodynamic principles, diffusion principles, tonicity types, and membrane transport systems.

Energy

A property of objects that makes work possible, existing in forms such as light, heat, potential, kinetic, and chemical bond energy.

First law of thermodynamics

The law stating that the total amount of energy in the universe is constant; energy can be transformed from one kind to another, but it cannot be created or destroyed.

Second law of thermodynamics

The law stating that no energy transformation in the universe is completely efficient, meaning some amount of energy is always lost in an unusable form (usually heat).

Heat energy

The energy transferred from one system to another that is not doing work, defined as the random thermal movement of atoms and molecules.

Entropy

The measure of randomness or disorder within a system, where high entropy indicates high disorder and low energy.

Metabolism

The collective set of all chemical reactions that occur within an organism.

Exergonic reactions

Reversible chemical reactions that proceed in a direction that releases energy into their environment.

Endergonic reactions

Reversible chemical reactions that proceed in a direction that absorbs energy from their environment.

Adenosine triphosphate (ATP)

The primary temporary energy storage nucleotide in cells, often called the 'energy currency' of the cell, composed of AMP and three phosphate groups.

Adenosine monophosphate (AMP)

A nucleotide composed of an adenine base covalently attached to a ribose molecule and a single phosphate group, forming the core structure of ATP.

Adenosine diphosphate (ADP)

A molecule formed by the endergonic addition of a second phosphate group to adenosine monophosphate (AMP).

Diffusion

A passive process involving the tendency of a substance to move down its concentration gradient from an area of high concentration to an area of low concentration until equal distribution is reached.

Absolute zero

The temperature at $-273^{\circ}\text{C}$ above which molecules move constantly in a random manner.

Solvent density

The density of the substance in which a diffusing molecule resides; as solvent density increases, the rate of diffusion decreases.

Osmosis

A special case of diffusion involving the movement of water across a semi-permeable membrane from an area of higher water concentration to an area of lower water concentration.

Tonicity

A measure of the relative concentration of water and solutes on opposite sides of a semi-permeable membrane.

Hypotonic solution

A solution that has a lower concentration of solutes and a higher concentration of water compared to another solution on the opposite side of a semi-permeable membrane.

Hypertonic solution

A solution that has a higher concentration of solutes and a lower concentration of water compared to another solution on the opposite side of a semi-permeable membrane.

Isotonic solution

A solution that has the exact same concentration of solutes as another solution, resulting in balanced water movement across a membrane.

Facilitated diffusion

Also called passive transport; a process where materials diffuse across the plasma membrane down their concentration gradient with the assistance of membrane transport proteins, using no cellular energy.

Channel proteins

Transport proteins that create a continuous pore through the membrane that can be opened or closed, allowing up to ten million ions or molecules to pass per second.

Carrier proteins

Transport proteins that move materials by binding to a specific substance on one side of the membrane and changing shape to carry one ion or molecule at a time to the other side.

Active transport

A cellular transport process that uses an energy source to move materials in a specific direction across a membrane, including against their concentration gradient.

Sodium-potassium pump

An active transport pump in animal cells that expends energy from ATP hydrolysis to simultaneously move potassium ions into the cell and sodium ions out of the cell.