AP Biology Macromolecules Flashcards: Carbohydrates, Lipids, Proteins, & Nucleic Acids

Vocabulary flashcards covering core terms and definitions from Carbohydrates, Lipids, Proteins, and Nucleic Acids topics in the notes.

Monosaccharide

The basic unit (single sugar) of carbohydrates, such as glucose, fructose, or galactose.

Glycosidic bond

A covalent bond that links monosaccharides together to form polysaccharides, formed during dehydration synthesis.

Dehydration synthesis

A chemical reaction that removes water to join monomers, forming polymers.

Polysaccharide

A polymer composed of many monosaccharides linked by glycosidic bonds (e.g., starch, glycogen, cellulose, chitin).

Glucose

A monosaccharide (aldohexose) used as a primary energy source in cells; one of the C6H12O6 isomers.

Fructose

A monosaccharide (ketohexose) isomer of glucose found in fruits and honey.

Galactose

A monosaccharide (aldohexose) isomer of glucose, part of lactose.

Functional group

A specific group of atoms within a molecule responsible for its characteristic chemical reactions and properties (e.g., hydroxyl, carbonyl).

Hydroxyl group (OH)

A polar functional group present in many sugars that contributes to polarity and solubility.

Carbonyl group

A functional group (C=O) found in sugars; helps define whether a sugar is an aldose or ketose.

Isomer

Compounds with the same chemical formula but different arrangements of atoms; examples include glucose, fructose, and galactose.

Lipids

Hydrophobic, nonpolar biological molecules not formed from repeating monomer units; include fats, oils, steroids, and phospholipids.

Hydrophobic

Water-repelling; nonpolar molecules that do not dissolve well in water.

Triacylglycerol (triglyceride)

A lipid that stores energy; consists of glycerol plus three fatty acids; formed by dehydration synthesis.

Fatty acid

A hydrocarbon chain with a terminal carboxyl group; component of fats and oils.

Saturated fatty acid

Fatty acids with no carbon–carbon double bonds; max hydrogen atoms; typically straight chains.

Unsaturated fatty acid

Fatty acids containing one or more carbon–carbon double bonds; causes kinks in the chain.

Van der Waals forces

Weak intermolecular forces that contribute to tight packing of fatty acids and membrane stability.

Cholesterol

A steroid lipid important for cell membranes and as a precursor for hormone synthesis.

Phospholipid

A lipid with two hydrophobic tails and a hydrophilic head; major component of cell membranes forming a bilayer.

Amino acid

The building blocks of proteins; 20 standard amino acids form polypeptides.

Alpha carbon (α-carbon)

The central carbon in an amino acid attached to four groups: amino, carboxyl, hydrogen, and R group.

Peptide bond

A covalent bond linking amino acids; formed by dehydration synthesis between the amino group and the carboxyl group.

N-terminus

The start of a polypeptide chain bearing a free amino group.

C-terminus

The end of a polypeptide chain bearing a free carboxyl group.

Primary structure

The linear sequence of amino acids in a protein; determined by DNA.

Secondary structure

Local folding of a polypeptide into structures like α-helix and β-pleated sheet, stabilized by hydrogen bonds.

α-helix

A right-handed coil that is a common form of secondary structure in proteins.

β-pleated sheet

A secondary structure where polypeptide chains lay side by side forming a sheet-like arrangement.

Tertiary structure

The overall three-dimensional shape of a single polypeptide, determined by interactions among R groups.

Quaternary structure

Protein structure that results from assembling two or more polypeptide chains into a functional unit.

Nucleotides

The building blocks of nucleic acids; consist of a nitrogenous base, a five-carbon sugar, and a phosphate group.

Nitrogenous base

Part of a nucleotide; purines (A, G) with double rings; pyrimidines (C, T, U) with single rings.

Purines

Nitrogenous bases with a double-ring structure: adenine (A) and guanine (G).

Pyrimidines

Nitrogenous bases with a single-ring structure: cytosine (C), thymine (T), and uracil (U).

Five-carbon sugar (pentose)

Sugar part of a nucleotide; deoxyribose in DNA and ribose in RNA.

Phosphate group

Phosphate group of a nucleotide that links sugars to form the nucleic acid backbone.

Phosphodiester bond

Bond that links nucleotides to form nucleic acids; forms the backbone and provides directionality.

Directionality (5' to 3')

DNA/RNA polymerization proceeds from the 5' end to the 3' end; growth occurs at the 3' hydroxyl.

DNA double helix

Two antiparallel strands of DNA wound into a helix, stabilized by hydrogen bonds between bases.

Adenine–Thymine pairing (A–T)

Base pairing in DNA with two hydrogen bonds between A and T.

Cytosine–Guanine pairing (C–G)

Base pairing in DNA with three hydrogen bonds between C and G.

DNA vs RNA sugar

DNA uses deoxyribose (lacks 2' OH); RNA uses ribose (has 2' OH).

DNA vs RNA bases

DNA: A, T, C, G; RNA: A, U, C, G (Uracil replaces Thymine in RNA).

DNA vs RNA structure & function

DNA: typically double-stranded, stores/transmits genetic information; RNA: typically single-stranded, versatile roles including protein synthesis.