Chapter 2: The Chemical Building Blocks of Life

Vocabulary flashcards covering key terms and concepts from Chapter 2: The Chemical Building Blocks of Life.

Atom

The smallest unit of an element that retains its chemical properties; composed of a nucleus of protons and neutrons and an electron cloud.

Proton

Positively charged subatomic particle located in the atomic nucleus.

Neutron

Electrically neutral subatomic particle located in the atomic nucleus.

Electron

Negatively charged subatomic particle orbiting the nucleus in an electron cloud.

Atomic number

Number of protons in an atom’s nucleus; identifies the element.

Mass number

Sum of protons and neutrons in the nucleus.

Isotope

Atoms of the same element with different numbers of neutrons, giving different mass numbers.

Ion

Atom with a net charge due to gain or loss of electrons.

Ionic bond

Bond formed by electrical attraction between oppositely charged ions; e.g., NaCl.

Covalent bond

Bond formed when atoms share electron pairs; can form molecules.

Nonpolar covalent bond

Covalent bond with equal sharing of electrons.

Polar covalent bond

Covalent bond with unequal sharing, creating partial charges.

Hydrogen bond

Weak electrostatic attraction between a partially positive hydrogen and a partially negative partner; important in water, proteins, and DNA.

Water

Universal solvent; cells are ~70% water and reactions occur in water.

CHNOPS

The six most common elements in living organisms: Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, Sulfur.

Trace elements

Elements required in small amounts (e.g., Mn, Fe, Cu, Zn) for organisms.

Dehydration synthesis

Reaction that forms bonds between monomers with the removal of a water molecule.

Hydrolysis

Reaction that breaks bonds by adding water, splitting polymers into monomers.

Carbohydrate

Organic molecule (CH2O)n that provides energy and structure; includes sugars and starches.

Monosaccharide

Simple sugar such as glucose or fructose.

Disaccharide

Carbohydrate composed of two monosaccharides (e.g., sucrose, lactose).

Polysaccharide

Complex carbohydrate made of many monosaccharides (e.g., starch, glycogen, cellulose).

Carbohydrates formula

General formula for carbohydrates: (CH2O)n.

Lipid

Hydrophobic, energy-storing molecules composed largely of hydrocarbons; includes triglycerides.

Triglyceride

Lipid with glycerol backbone and three fatty acid chains; primary form of stored energy.

Phospholipid

Lipid with a polar phosphate head and two nonpolar fatty acid tails; major component of cell membranes.

Waxes

Long-chain fatty acids forming protective coatings and barriers.

Sterol

Hydrophobic membrane-stabilizing lipid (e.g., cholesterol) that helps regulate membranes.

Nucleic acid

Polymers of nucleotides that store and transmit hereditary information.

DNA

Deoxyribonucleic acid; double-stranded genetic material that forms a double helix.

RNA

Ribonucleic acid; usually single-stranded; copies gene information for protein synthesis.

Nucleotide

Nucleic acid subunit composed of a sugar, a phosphate group, and a nitrogenous base.

Nucleobase

Nitrogen-containing base in nucleotides (A, T, C, G in DNA; variations in RNA).

ATP

Adenosine triphosphate; primary cellular energy currency formed from adenine ribonucleotide and three phosphate groups.

Amino acid

Building block of proteins; contains amino group, carboxyl group, hydrogen, and a variable R group.

Peptide bond

Covalent bond linking amino acids in a protein.

Protein

Workhorse polymers of cells performing structural, transport, and enzymatic roles.

Primary structure

Linear sequence of amino acids in a polypeptide.

Secondary structure

Local folding into alpha helices or beta pleated sheets due to hydrogen bonds.

Tertiary structure

Three-dimensional folding of a polypeptide stabilized by R-group interactions, including disulfide bridges.

Quaternary structure

Assembly of two or more polypeptides into a functional protein.

Denaturation

Loss of protein structure due to disruption of bonds, leading to loss of function.

Complementary base pairing

In DNA, A pairs with T and G pairs with C via hydrogen bonds, holding the double helix together.