Unit 1: Chemistry of Life (anjeline's version)

Element

A pure substance made of one type of atom.

Atom

The basic unit of an element.

Trace element

An element needed in very small amounts.

Proton

A positively charged particle in the nucleus.

Neutron

An uncharged particle in the nucleus.

Electron

A negatively charged particle around the nucleus.

Isotope

Atoms of the same element with different neutrons.

Valence electrons

Electrons in the outer shell involved in bonding.

Electronegativity

The ability of an atom to attract electrons.

Covalent bond

A bond formed by sharing electrons.

Polar covalent bond

A bond with unequal sharing of electrons.

Ionic bond

A bond formed by the attraction between charged ions.

Cation

A positively charged ion.

Anion

A negatively charged ion.

Hydrogen bond

A weak attraction involving hydrogen and an electronegative atom.

Chemical reaction

A process that rearranges atoms by breaking/forming bonds.

Water polarity

Water has a partial negative charge on oxygen.

Cohesion

Molecules of the same kind stick together.

Hydrophobic effect

Nonpolar molecules aggregate in water.

Acid

A substance that increases H⁺ concentration.

Base

A substance that decreases H⁺ concentration.

pH

A measure of hydrogen ion concentration.

Buffer

A solution that resists changes in pH.

Organic molecule (biology)

A molecule containing carbon.

Carbon (tetravalent)

Carbon can form four covalent bonds.

Hydroxyl group (–OH)

A polar group that forms hydrogen bonds.

Carboxyl group (–COOH)

An acidic group that can donate H⁺.

Amino group (–NH₂)

A basic group that can accept H⁺.

Phosphate group (–PO₄²⁻)

A group important for energy transfer.

Monomer

A small molecular subunit.

Polymer

A large molecule made of repeating units.

Dehydration synthesis (condensation)

A reaction that builds polymers by removing water.

Hydrolysis

A reaction that breaks polymers by adding water.

Monosaccharide

A single sugar molecule.

Glycosidic linkage

The bond joining two sugars.

Starch

A plant energy-storage polysaccharide.

Glycogen

An animal energy-storage polysaccharide.

Cellulose

A plant structural polysaccharide.

Triglyceride (triacylglycerol)

A fat molecule for long-term energy storage.

Phospholipid

A molecule that makes up cell membranes.

Lipid saturation

Describes the presence of double bonds in fatty acids.

Cholesterol

A steroid in cell membranes that regulates fluidity.

Amino acid

The building block of proteins.

Peptide bond

The bond linking amino acids.

Denaturation

Loss of protein shape affecting function.

Nucleotide

The building block of nucleic acids.

DNA (deoxyribonucleic acid)

The molecule for long-term genetic information.

RNA (ribonucleic acid)

The molecule essential for protein synthesis.

Complementary base pairing

Specific pairing of bases in DNA.

ATP (adenosine triphosphate)

The energy currency of the cell.