Chapter 1 - The Chemistry of Life: Vocabulary Flashcards

Vocabulary flashcards covering key terms and definitions from Chapter 1: The Chemistry of Life (Biology).

Atom

The basic unit of an element that retains its chemical properties.

Molecule

Two or more atoms bonded together; the smallest unit of a compound that retains its properties.

Element

A substance that cannot be broken down into simpler substances by chemical means; defined by its number of protons.

Compound

A substance formed when two or more elements are chemically bonded in a fixed proportion.

Proton

Positively charged subatomic particle located in the nucleus.

Neutron

Electrically neutral subatomic particle located in the nucleus.

Electron

Negatively charged subatomic particle orbiting the nucleus in electron shells.

Nucleus

Center of an atom that contains protons and neutrons.

Electron shell

Energy level around the nucleus where electrons are found.

Isotope

Atoms of the same element with different numbers of neutrons.

Radioisotope

Unstable isotope that decays, releasing radiation.

Ion

An atom or molecule with a net positive or negative charge due to gain or loss of electrons.

Ionic bond

Attraction between oppositely charged ions formed by transfer of electrons.

Covalent bond

Bond formed by sharing one or more pairs of electrons.

Polar covalent bond

Covalent bond with unequal sharing of electrons, creating partial charges.

Nonpolar covalent bond

Covalent bond with equal sharing of electrons.

Hydrogen bond

Weak attraction between a slightly positive hydrogen and a nearby electronegative atom; many together can be strong.

pH

A scale (0-14) measuring hydrogen ion concentration; 7 is neutral.

Acid

Substance that increases H+ concentration, lowering pH.

Base (alkaline)

Substance that decreases H+ concentration or increases OH-, raising pH.

Ionization

Process of forming ions from a neutral compound.

Organic compound

Compound containing carbon-hydrogen bonds; building blocks of life.

Carbon skeleton

The carbon framework of a molecule to which other atoms attach.

Carbohydrate

Macromolecule class composed of C, H, and O; main energy source and structural roles.

Monosaccharide

Simple sugar, e.g., glucose; typically 3–7 carbon atoms.

Disaccharide

Two monosaccharides bonded together, e.g., sucrose.

Polysaccharide

Complex carbohydrate formed by many monosaccharides (e.g., starch, cellulose).

Sugar-phosphate group

Phosphate group attached to a sugar; common in sugar-phosphates.

Lipid

Nonpolar macromolecule for long-term energy storage and membranes; includes fats, oils, and cholesterol.

Fat

A lipid; glycerol bonded to three fatty acids; major energy storage form.

Fatty acid

Hydrocarbon chain with a carboxyl group; determines saturation.

Glycerol

Three-carbon molecule that forms triglycerides with fatty acids.

Phospholipid

Lipid with glycerol, two fatty acids, and a phosphate group; forms cellular membranes.

Cholesterol

Sterol lipid important in membranes and as hormone precursor.

Protein

Macromolecule made of amino acids; functions include enzymes, structure, signaling.

Amino acid

Building block of proteins; contains amino group, carboxyl group, and unique R-group.

Peptide bond

Covalent bond linking amino acids in a chain.

Polypeptide

Long chain of amino acids forming a protein.

Hydrophobicity

Tendency of nonpolar amino acids to avoid water; influences protein folding.

Nucleic acid

Macromolecule that stores genetic information.

Nucleotide

Monomer of nucleic acids; consists of a sugar, a nitrogenous base, and a phosphate.

Ribose

Five-carbon sugar used in RNA.

Deoxyribose

Five-carbon sugar used in DNA; lacks one oxygen compared to ribose.

RNA

Ribonucleic acid; sugar ribose; usually single-stranded; bases A, U, C, G.

DNA

Deoxyribonucleic acid; double-stranded helix; stores genetic information.

Adenine

Purine base that pairs with thymine in DNA (and with uracil in RNA).

Thymine

Pyrimidine base that pairs with adenine in DNA.

Cytosine

Pyrimidine base that pairs with guanine.

Guanine

Purine base that pairs with cytosine.

Uracil

Pyrimidine base in RNA that pairs with adenine (replaces thymine).

Triplet codon

Three-nucleotide unit in DNA that codes for an amino acid.

Codon

Three-nucleotide sequence in mRNA that codes for an amino acid.

Primary structure

Linear sequence of amino acids in a protein.

Secondary structure

Local folded structures like alpha helices and beta sheets.

Tertiary structure

Three-dimensional folding of a single polypeptide.

Quaternary structure

Arrangement of multiple polypeptide chains in a protein.

Double helix

Two long nucleotide chains wound around each other in DNA.

Base pairing

Hydrogen-bonded pairing rules between bases (A with T/U, C with G).

Chromosome

Structure carrying genes; made of DNA.

Activation energy

Energy required to start a chemical reaction.

Conservation of matter

Matter cannot be created or destroyed in a chemical reaction; only rearranged.