AP Biology Marcromolecule Flashcards

Macromolecule

A large molecule formed by the joining of smaller molecules, usually by dehydration synthesis.

Monomer

The subunit that serves as the building block of a polymer.

Polymer

A long molecule consisting of many similar or identical monomers linked together.

Dehydration Synthesis

A chemical reaction where two molecules bond by removing a water molecule.

Hydrolysis

A chemical reaction that breaks bonds between molecules by adding water.

Monomer of a carbohydrate

Monosaccharide (ex. glucose)

Bond linking monosaccharides

Glycosidic linkage

Starch

An energy storage polysaccharide in plants.

Glycogen

An energy storage polysaccharide in animals, stored in the liver and muscles.

cellulose

A structural polysaccharide of plant cell walls

Chitin

A structural polysaccharide in arthropod exoskeletons and fungal cell walls.

Defining characteristic of lipids

They are hydrophobic (do not mix with water).

components of a triglyceride

One glycerol molecule and three fatty acid molecules 

saturated fatty acid

A fatty acid where all carbons in the hydrocarbon tail are connected by single bonds.

Unsaturated fatty acid

A fatty acid with one or more double bonds between carbons in its tail.

Structure of a phospholipid

A glycerol, two fatty acids, and a phosphate group creating a hydrophilic head and hydrophobic tail 

Basic structure of a steroid

A lipid with a carbon skeleton of four fused rings.

Monomer of a protein

Amino acid.

Components of an amino acid

A central carbon atom, an amino group, a carboxyl group, and a variable R group (side chain).

Bond linking amino acids

Peptide bond.

How many R groups (side chains) are there?

There are 20 of them

Primary (1°) structure

The specific linear sequence of amino acids in a polypeptide chain.

Secondary (2°) structure

Coils (α-helix) and folds (β-pleated sheet) formed by hydrogen bonds in the polypeptide backbone.

Tertiary (3°) structure

The overall 3D shape of a polypeptide, resulting from interactions between R groups.

Quaternary (4°) structure

The overall protein structure that results from the aggregation of two or more polypeptide subunits. (e.g., hemoglobin).

Monomer of a nucleic acid

Nucleotide.

Components of a nucleotide

A five-carbon sugar, a phosphate group, and a nitrogenous base.

Functions of proteins

Enzyme, defense, transport, receptor, structure, motor/movement, hormones, storage

Hydroxyl Group

Structure: —OH 

Found in: Alcohols, carbohydrates Properties / Function: Polar; forms hydrogen bonds; helps dissolve sugars

Carbonyl Group

Structure: C=O (Aldehyde/Ketone) 

Found in: Sugars (glucose, fructose) Properties / Function: Polar; contributes to sugar reactivity

Carboxyl Group

Structure: -COOH

Found in: Amino acids, fatty acids 

Properties / Function: Acts as acid (donates H+); very polar

Amino 

Structure: -NH₂ 

Found in: Amino acids, proteins 

Properties / Function: Acts as base; picks up H+; forms hydrogen bonds

Sulfhydryl

Structure: -SH

Found in: Cysteine (amino acid)

Properties / Function: Forms disulfide bridges; stabilizes protein shape

Phosphate

Structure: -PO₃²

 Found in: ATP, DNA, RNA, phospholipids Properties / Function: Contributes negative charge; stores energy

Methyl

Structure: -CH3

Found in: DNA (methylation), lipids Properties / Function: Nonpolar; affects gene expression & molecule shape

Adenine (A) 

Always pairs with Thymine (DNA)

Always pairs with Uracil (RNA)

Guanine (G)

Always pairs with cytosine

Phosphodiester bond

It forms between the phosphate group of one nucleotide and the sugar (the 3’ hydroxyl group) of the next nucleotide.

This creates the sugar-phosphate backbone of DNA/RNA, which is strong and stable, holding the sequence of nitrogenous bases in place.

The bond specifically connects the 5’ carbon of one sugar (via the phosphate) to the 3’ carbon of the next sugar — which is why we call DNA/RNA strands “5’ to 3’.”

In short: a phosphodiester bond = the "glue" that links nucleotides into a continuous chain. ntinuous chain.

Disulfide bridge

• A disulfide bridge is a covalent bond between the sulfur atoms of two cysteine amino acids (–SH side chains).

• The bond forms when the sulfhydryl groups are oxidized, creating a covalent –S–S– linkage.

• This type of bond is sometimes called a cystine bond (because two cysteine residues linked by a disulfide form "cystine").

• Role: Stabilizes tertiary and quaternary structure.

Environment: More common in extracellular proteins (inside the cell is a reducing environment, which prevents disulfide bond formation).

Hydrophobic side chain =

nonpolar

Hydrophilic side chains = 

polar