Biology Chapter 4 McGrawHill

energy

the ability to do work

potential energy

stored energy available to do work

kinetic energy

energy being used to do work; energy of motion

calorie

the energy required to raise temperature of 1 gram of water by 1 Celsius under standard conditions.

kilocalorie (kcal)

a measure of the energy content in food; equal to 1000 calories or 1 food calorie.

first law of thermodynamics

energy cannot be created or destroyed, just converted from one form to another.

second law of thermodynamics

energy reaction loses some energy to the surroundings as heat; entropy always increases.

entropy

randomness or disorder

metabolism

the biochemical reactions of a cell

endergonic reaction

a chemical reaction that requires a net input of energy.

exergonic reaction

an energy-releasing chemical reaction

oxidation-reduction (redox) reaction

chemical reaction in which one reactant is oxidized and another is reduced.

oxidation

the loss of one or more electrons by a participant in a chemical reaction

reduction

the gain of one or more electrons by a participant in a chemical reaction.

electron transport chain

membrane-bound molecular complex that shuttles electrons to slowly extract their energy

ATP (adenosine triphosphate)

a molecule whose high-energy phosphate bonds power many biological processes.

coupled reactions

two simultaneous chemical reactions, one of which provides the energy that drives the other.

phosphorylation

the addition of a phosphate to a molecule

enzyme

an organic molecule that catalyzes a chemical reaction without being consumed

activation energy

energy required for a chemical reaction to begin.

active site

the part of an enzyme to which substrates bind

cofactor

inorganic or organic substance required for activity of an enzyme

negative feedback

regulatory mechanism in which a change in a condition triggers action that reverses the change.

noncompetitive inhibition

change in an enzyme's shape occurring when an inhibitor binds to a site other than the active site.

competitive inhibition

change in an enzyme's activity occurring when an inhibitor binds to the active site, competing with the enzyme's normal substrate.

positive feedback

a process that reinforces an existing condition

selective permeability

the property that enables a membrane to admit some substances and exclude others.

concentration gradient

difference in solute concentration between two adjacent regions

passive transport

movement of a solute across membrane without the direct expenditure of energy

diffusion

movement of a substance from a region where it is highly concentrated to an area where it is less concentrated.

simple diffusion

form of passive transport in which a substance moves down its concentration gradient without the use of a transport protein.

osmosis

simple diffusion of water through a selectively permeable membrane.

isotonic

condition in which a solute concentration is the same on both sides of a selectively permeable membrane.

hyopotonic

describes a solution in which the solute concentration is lower than on the other side of a selectively permeable membrane

hypertonic

describes a solution in which the solute concentration is higher than on the other side of a selectively permeable membrane.

turgor pressure

the force of water pressing against the cell wall.

facilitated diffusion

form of passive transport in which a substance moves down its concentration gradient with the aid of a transport protein.

active transport

movement of a substance across a membrane against its concentration gradient, using a carrier protein and energy from ATP.

endocytosis

form of transport in which a membrane engulfs substances to bring them into a cell.

phagocytosis

form of endocytosis in which the cell engulfs a large particle.

exocytosis

form of transport in which vesicles fuse with the cell membrane to carry materials out of a cell.

Open systems

systems that can sustain themselves only by interacting with their environments, on which they depend for their survival

closed system

a system in which matter and energy exchanges do not occur across boundaries

anabolic reactions

build up large chemicals and require energy

catabolic reactions

break down large chemicals and release energy

metabolic pathway

Begins with a specific molecule, which is then altered in a series of defined steps, resulting in a certain product.

spontaneous process

A process that occurs without an overall input of energy; a process that is energetically favorable.

By what process will that bond break ?

hydrolysis

sodium-potassium pump

a carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell

redox reaction

an oxidation reaction paired with a reduction reaction

membrane potential

the voltage difference of electron charges across a membrane

Catabolism

Metabolic pathways that break down molecules, releasing energy.

Anabolism

Metabolic pathways that construct molecules, requiring energy.

Glycoproteins

serve as cell recognition molecules on cell surfaces

Glycolysis

the breakdown of glucose by enzymes, releasing energy and pyruvic acid.

saturated

describes a fatty acid with all single bonds

aquaporin

Channel protein that transports water across cell membranes

phosphate group

functional group gives a phospholipid hydrophilic properties

required to power the sodium-potassium pump

ATP

Denaturation

describing a change in the proper folding of proteins

surface area:volume ratio

Feature of cells that determines the maximum size for successful function