Biology: Cell Transport, Metabolism, and Genetic Code Key Terms

diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

concentration gradient

A difference in the concentration of a substance across a distance.

solute

A substance that is dissolved in a solution.

solvent

the substance in which the solute dissolves

concentration

A measurement of how much solute exists within a certain volume of solvent

osmosis

Diffusion of water through a selectively permeable membrane

tonicity

the ability of a surrounding solution to cause a cell to gain or lose water

hypertonic

when comparing two solutions, the solution with the greater concentration of solutes

hypotonic

Having a lower concentration of solute than another solution

isotonic

when the concentration of two solutions is the same

facilitated diffusion

Movement of specific molecules across cell membranes through protein channels

active transport

Energy-requiring process that moves material across a cell membrane against a concentration difference

catabolism

Metabolic pathways that break down molecules, releasing energy.

anabolism

Metabolic pathways that construct molecules, requiring energy.

cellular metabolism

chemical activities of cells

membrane pumps

proteins that move molecules into or out of the cell

vesicle mediated transport

the movement of material in and out of the cell by placing the material into a vesicle

endocytosis

process by which a cell takes material into the cell by infolding of the cell membrane

exocytosis

Process by which a cell releases large amounts of material

phagocytosis

A type of endocytosis in which a cell engulfs large particles or whole cells

pinocytosis

A type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes.

receptor-mediated endocytosis

The movement of specific molecules into a cell by the inward budding of membranous vesicles containing proteins with receptor sites specific to the molecules being taken in; enables a cell to acquire bulk quantities of specific substances.

enzyme

protein that acts as a biological catalyst

catalyst

substance that speeds up the rate of a chemical reaction

cellular respiration

Process that releases energy by breaking down glucose and other food molecules in the presence of oxygen

glycolysis

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

ATP

(adenosine triphosphate) main energy source that cells use for most of their work

pyruvic acid

the three-carbon compound that is produced during glycolysis and needed for both the aerobic and anaerobic pathways of cellular respiration that follow glycolysis

acetyl CoA

Acetyl coenzyme A; the entry compound for the citric acid cycle in cellular respiration, formed from a fragment of pyruvate attached to a coenzyme.

base-pairing

principle that bonds in DNA can form only between adenine and thymine and between guanine and cytosine

codon

A specific sequence of three adjacent bases on a strand of DNA or RNA that provides genetic code information for a particular amino acid