Macromolecules, Water Properties, and Nucleic Acids

Vocabulary flashcards covering key terms from the notes on water properties, macromolecules, carbohydrates, lipids, and nucleic acids.

Polar

A condition where a pair of electrons is shared unequally between two atoms, creating partial charges on atoms.

Hydrogen bonds

Weak intermolecular forces, especially between O–H groups, contributing to water’s properties and high surface tension.

Water (H2O)

A polar molecule that forms hydrogen bonds, is a good solvent, and has high surface tension; ice is less dense than liquid water and floats.

Hydrophilic

Substances that are attracted to water and are usually polar.

Hydrophobic

Substances that repel water and are typically non-polar.

Macromolecule

A very large molecule, such as a protein, nucleic acid, or polymer, built from smaller subunits.

Common elements in macro molecules

Carbon, Hydrogen, Oxygen, and Nitrogen.

king of all macromolecules

Carbon. forms four bonds (including with itself) and is the building block for diverse macromolecules.

Isomers

Molecules with the same molecular formula but different structures and properties.

Functional groups

Groups attached to carbon that affect a molecule’s reactivity and solubility (e.g., OH, COOH, NH2, SH, CH3, PO4).

Hydroxyl (OH)

A functional group that is polar and increases solubility when present.

Carbohydrates

Biomolecules composed of carbon, hydrogen, and oxygen; store energy and provide structure; monomers are sugars.

Monomer

A basic building block that links to form polymers.

Polymer

A large molecule made by linking many repeating monomers.

Monosaccharides

Simple sugars (e.g., glucose); the monomer units of carbohydrates; often form rings in solution for ≥5 carbons.

Disaccharides

Two monosaccharides joined together (e.g., sucrose).

Polysaccharides

Large carbohydrates formed by many monosaccharide units; examples include starch, glycogen, and cellulose.

Cellulose

A linear polysaccharide that provides tough structural support in plant cell walls.

Starch

A branched polysaccharide used by plants for energy storage.

Glycogen

A highly branched polysaccharide used by animals for rapid energy storage.

Dehydration synthesis (condensation reaction)

Joining two monomers by removing a water molecule to form a bond.

Hydrolysis

Breaking polymers into monomers by adding water.

Lipids

A diverse group of nonpolar, non-polymeric biomolecules consisting mainly of carbon, hydrogen, and oxygen; include fats, phospholipids, and steroids.

Glycerol

A three-carbon alcohol that forms the backbone of triglycerides.

Fatty acids

Long hydrocarbon chains with a carboxyl group that attach to glycerol in fats.

Triglyceride

A lipid formed by three fatty acids linked to glycerol via ester bonds.

Saturated fats

Fats where every carbon bond is bonded to the maximum number of hydrogens (no C=C); typically solid at room temperature.

Unsaturated fats

Fats with one or more C=C double bonds causing kinks; typically liquid at room temperature.

Phospholipids

Lipids with two fatty acids and a phosphate group; amphiphilic and form bilayers in cell membranes.

Amphiphilic

Molecule having both hydrophobic and hydrophilic regions.

Cholesterol

A steroid essential for animal cell membranes and a precursor to steroid hormones.

Nucleic acids

DNA and RNA; store, transmit, and translate genetic information.

DNA

Deoxyribonucleic acid; double-stranded (in most organisms) and maintains/transmits genetic information; bases pair A–T and C–G.

RNA

Ribonucleic acid; usually single-stranded and plays roles in protein synthesis; base U replaces T.

Nucleotide

The monomer of nucleic acids; composed of a nitrogenous base, a pentose sugar, and a phosphate group.

Nitrogenous bases (Purines)

Purines (Adenine and Guanine) have a double-ring structure.

Nitrogenous bases (Pyrimidines)

Pyrimidines (Cytosine, Thymine, and Uracil) have a single-ring structure.

Adenine–Thymine and Cytosine–Guanine

Base pairing rules in DNA: A pairs with T; C pairs with G.

DNA structure (antiparallel)

Two complementary strands run in opposite (antiparallel) directions.

DNA function

To maintain and transmit genetic information across generations.