AP Biology - Biological Molecules (Carbohydrates, Lipids, Proteins, Nucleic Acids)

Vocabulary flashcards covering key terms and definitions from carbohydrates, lipids, proteins, and nucleic acids as described in the lecture notes.

Glucose

A monosaccharide with the formula C6H12O6; a primary quick-energy source used in cellular respiration.

Carbohydrates (general)

Biomolecules composed of C, H, and O in a 1:2:1 ratio; include monosaccharides, disaccharides, and polysaccharides.

Monosaccharide

A single sugar unit (e.g., glucose) that is the building block of more complex carbohydrates.

Disaccharide

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

Polysaccharide

Long chains of monosaccharides; used for energy storage or structural roles.

Glycosidic linkage

Bond formed between monosaccharides during carbohydrate polymerization.

Hydrolysis

Chemical reaction that uses water to break bonds, breaking polysaccharides into monosaccharides.

Dehydration synthesis

Chemical reaction that removes a water molecule to join monomers into polymers.

Starch

Storage polysaccharide in plants.

Glycogen

Storage polysaccharide in animals.

Cellulose

Structural polysaccharide in plants; provides rigidity (cell walls) and is not digestible by humans.

Chitin

Structural polysaccharide in fungi and arthropods (insects, crustaceans).

Energy storage polysaccharides

Polysaccharides like starch and glycogen used to store energy for later use.

Structural polysaccharides

Polysaccharides like cellulose and chitin that provide support and protection to organisms.

Glycerol

A three-carbon alcohol backbone that forms the triglyceride or phospholipid backbone.

Fatty acid

Long hydrocarbon chain with a terminal carboxyl group; can be saturated or unsaturated.

Triglyceride

A lipid made of glycerol bound to three fatty acids; primary form of energy storage in animals.

Phospholipid

A lipid with two fatty acids and a phosphate group attached to glycerol; major component of cell membranes.

Saturated fatty acid

Fatty acid with no double bonds between carbon atoms; typically straight and pack tightly.

Unsaturated fatty acid

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

Hydrophobic region

Nonpolar region of a molecule that repels water.

Hydrophilic region

Polar region of a molecule that interacts with water.

Disulfide bridge

Functional covalent bond between cysteine side chains that can stabilize protein structure.

Hydrogen bond (in proteins)

Attractive interaction between polar groups, important in stabilizing secondary structure.

Ionic bond (in proteins)

Electrostatic attraction between charged side chains that can stabilize tertiary/quaternary structure.

Hydrophobic interaction

Nonpolar R groups cluster away from water, contributing to protein folding and stability.

Amino acid

A molecule with an amino group, a carboxyl group, a central (alpha) carbon, and an R group; the building blocks of proteins.

R group (side chain)

Variable chemical group attached to the central carbon of an amino acid that determines its properties (polar, nonpolar, charged).

Dehydration synthesis (peptide bond formation)

Removal of water to link amino acids into a dipeptide or polypeptide via a peptide bond.

Dipeptide

Two amino acids joined by a single peptide bond.

Peptide bond

Covalent bond between the carboxyl carbon of one amino acid and the amino nitrogen of the next amino acid.

Primary structure

Linear sequence of amino acids in a polypeptide.

Secondary structure

Folding patterns stabilized by hydrogen bonds between backbone atoms, including alpha helices and beta-pleated sheets.

Alpha-helix (α-helix)

A helical secondary structure stabilized by hydrogen bonds between the backbone.

Beta-pleated sheet (β-sheet)

A folded secondary structure with strands lying side by side, stabilized by hydrogen bonds.

Tertiary structure

3D folding of a polypeptide driven by interactions among R groups, including hydrophobic, ionic, hydrogen bonds, and disulfide bridges.

Quaternary structure

Overall structure formed by the association of multiple polypeptide chains.

Polypeptide

A polymer consists of many amino acids linked by peptide bonds; the functional unit of a protein before folding.

Cysteine

A amino acid that can form disulfide bonds, contributing to protein stability.

Nucleotide

Monomer of nucleic acids consisting of a phosphate, a pentose sugar, and a nitrogenous base.

Phosphate group (in nucleotides)

Phosphate functional group essential for nucleic acid backbone; connects to the sugar.

Pentose sugar

Five-carbon sugar in nucleotides; ribose in RNA and deoxyribose in DNA.

Nitrogenous base

Purine or pyrimidine base hanging off the sugar; participates in base pairing.

Deoxyribose

Five-carbon sugar lacking a hydroxyl group at the 2' position (DNA sugar).

Ribose

Five-carbon sugar with a hydroxyl group at the 2' position (RNA sugar).

Purines

Class of nitrogenous bases with two fused rings; includes adenine and guanine.

Pyrimidines

Class of nitrogenous bases with a single ring; includes cytosine and thymine (DNA) or uracil (RNA).

Adenine–Thymine pairing

Base pairing in DNA where adenine pairs with thymine via two hydrogen bonds.

Guanine–Cytosine pairing

Base pairing in DNA/RNA where guanine pairs with cytosine via three hydrogen bonds.

Uracil

Nitrogenous base in RNA that replaces thymine; pairs with adenine.

DNA

Nucleic acid that stores genetic information; typically double-stranded and uses deoxyribose and thymine.

RNA

Nucleic acid that transmits genetic information and assists in protein synthesis; typically single-stranded and uses ribose and uracil.

5' to 3' orientation

Directionality of nucleotide polymers in which growth occurs from the 5' end to the 3' end.

Base pairing rules (general)

A pairs with T (or U in RNA) via two or three hydrogen bonds with G pairing to C.