BIology Review

Atom

Basic unit of a chemical element.

Element

Substance that cannot be broken down by chemical means.

Molecule

Two or more atoms held together by chemical bonds.

Compound

Substance formed by two or more chemically bonded elements.

Chemical bond

Attraction between atoms that allows formation of chemical substances.

Covalent bond

Chemical bond involving the sharing of electron pairs between atoms.

Ionic bond

Bond formed by electrostatic attraction between oppositely charged ions.

Hydrogen bond

Weak bond between molecules due to electrostatic attraction.

Inorganic compound

A substance that lacks carbon-hydrogen bonds.

Organic compound

A carbon-containing chemical compound found in living things.

Monomer

A molecule that can react to form polymers.

Polymer

A large molecule made of repeating monomer subunits.

Amino acid

Organic molecule that serves as the building block of proteins.

Nucleotide

Building block of nucleic acids, containing sugar, phosphate, and base.

Catalyst

Substance that increases chemical reaction rate without being consumed.

Cell

The basic structural and functional unit of all living organisms.

Nucleus

Membrane-bound organelle containing a cell's genetic material.

Cytoplasm

Jelly-like fluid filling the cell interior outside the nucleus.

Chromatin

Complex of DNA and proteins that forms chromosomes within the nucleus.

Hydrophobic

Tending to repel or fail to mix with water.

Hydrophilic

Having a tendency to mix with or dissolve in water.

Organelle

Specialized structure within a cell performing specific functions.

Vesicle

Small fluid-filled sac enclosed by a lipid bilayer membrane.

Cytoskeleton

Network of protein filaments providing structural support to a cell.

Solution

A homogeneous mixture of a solute dissolved in a solvent.

Solvent

A liquid substance capable of dissolving other substances.

Solute

The substance that is dissolved in a solvent.

Intracellular fluid

Fluid located entirely within the cell membrane.

Extracellular fluid

Fluid found outside of cells in an organism.

Selective permeability

Membrane property allowing certain molecules to pass while blocking others.

Concentration gradient

Gradual change in chemical concentration across a given area.

Pressure gradient

Physical difference in pressure between two connected regions.

Interphase

Phase of the cell cycle where the cell prepares for division.

Mitosis

Cell division resulting in two genetically identical daughter cells.

Gene

Basic physical and functional unit of heredity made of DNA.