Chapter 2 Vocabulary: Atoms to Nucleic Acids

Vocabulary flashcards covering Chapter 2 topics: atoms to nucleic acids.

Atoms

The basic unit of matter; composed of protons, neutrons, and electrons.

Elements

Pure substances that cannot be broken down into simpler substances; building blocks of matter.

CHNOPS

Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, and Sulfur.

Macromolecules

Large organic molecules built from repeating monomer units: carbohydrates, lipids, proteins, and nucleic acids.

Monosaccharide

A simple sugar; the basic unit of carbohydrates; empirical formula Cn(H2O)n (1:2:1 H:O).

1:2:1 ratio (Cn(H2O)n))

General ratio of hydrogen to oxygen in monosaccharides

Linear structure (carbohydrates)

Open-chain form of a sugar ; can convert to a ring form.

Ring structure (carbohydrates)

Cyclic form of sugars (alpha or beta anomers) common in solution.

Glycosidic bond

Covalent bond linking monosaccharides to form disaccharides and polysaccharides.

Disaccharide

Two monosaccharides joined by a glycosidic bond (e.g., sucrose, lactose, maltose).

Polysaccharide

Long chains of monosaccharides; used for energy storage (starch, glycogen) or structure (cellulose).

Oligosaccharide

Short chain o monosaccharides often attached to proteins or lipids.

Starch

Plant storage polysaccharide composed of glucose; includes amylose and amylopectin.

Glycogen

Animal storage polysaccharide; highly branched glucose polymer.

Cellulose

Structural polysaccharide in plant cell walls; beta-1,4 glycosidic bonds; indigestible by humans.

Lipids

Hydrophobic biomolecules (fats, oils, phospholipids, steroids); not true polymers.

Glycerol

Three-carbon alcohol; backbone of triglycerides and phospholipids.

Fatty acid

Hydrocarbon chain with a carboxyl group; can be saturated or unsaturated.

Saturated fatty acid

Fatty acid with no double bonds; maximum hydrogens; typically solid at room temperature.

Unsaturated fatty acid

Fatty acid with one or more double bonds; kinks; typically liquid at room temperature.

Phospholipids

Lipids with two fatty acids, a glycerol, and a phosphate head; form cell membranes; amphipathic.

Protein

Biomolecule built from amino acids; performs most cellular functions; shape determines function.

Amino acid

Monomer of proteins; contains amino group, carboxyl group, hydrogen, and a variable side chain (R) attached to the central carbon.

Primary structure

Linear sequence of amino acids held by peptide bonds.

Secondary structure

Local folding patterns such as α-helix and β-pleated sheet stabilized by hydrogen bonds.

Tertiary structure

Overall three-dimensional shape of a single polypeptide; stabilized by various interactions among side chains.

Quaternary structure

Arrangement of multiple polypeptide subunits into a functional protein.

Denaturation

Loss of a protein’s native structure and function due to heat, pH change, or chemicals.

Nucleic acids

Polymers of nucleotides that store and transmit genetic information; include DNA and RNA.

DNA

Deoxyribonucleic acid; double-stranded; sugar deoxyribose; bases A, T, C, G; phosphate-sugar backbone.

RNA

Ribonucleic acid; usually single-stranded; sugar ribose; bases A, U, C, G; various roles in protein synthesis.

Nucleotide

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

Sugar, nitrogenous bases, phosphate group

to form nucleic acids.

Nitrogenous bases (purines vs pyrimidines)

Purines: adenine and guanine; Pyrimidines: cytosine, thymine (DNA), uracil (RNA).

Base pairing rules

A pairs with T (or U in RNA); C pairs with G; base pairing forms the DNA double helix and RNA structure.

Double helix

Two antiparallel polynucleotide strands wound around each other; stabilized by hydrogen bonds between base pairs DNA.