Macromolecules: Carbohydrates, Lipids, Proteins, and Nucleic Acids

Vocabulary practice flashcards covering the structure, classes, and biological roles of macromolecules: carbohydrates, lipids, proteins, and nucleic acids.

Macromolecules

The four major classes of large biological molecules: carbohydrates, lipids, proteins, and nucleic acids.

Carbohydrates

Polar, hydrophilic biological molecules composed of carbon, hydrogen, and oxygen, functioning primarily in energy storage and structural support.

Monosaccharide

A carbohydrate composed of a single sugar unit with a carbon, hydrogen, and oxygen ratio of $1:2:1$ ($CH_2O$), such as trioses ($C_3H_6O_3$), pentoses ($C_5H_{10}O_5$), or hexoses like glucose and fructose ($C_6H_{12}O_6$).

Hydroxyl Group

A functional group consisting of $-OH$; molecules containing this group are classified as alcohols.

Carbonyl Group

A functional group consisting of a carbon double-bonded to an oxygen ($>C=O$), found in ketones and aldehydes.

Aldose

A sugar containing a carbonyl group located at the end of the carbon skeleton (an aldehyde).

Ketose

A sugar containing a carbonyl group located in the middle of the carbon skeleton (a ketone).

Dehydration Synthesis

A chemical reaction that joins monomers together to form polymers through the removal of a water molecule ($H_2O$).

Disaccharide

A carbohydrate formed by combining two monosaccharide units via dehydration synthesis.

Sucrose

A disaccharide formed by joining one glucose molecule and one fructose molecule.

Lactose

A disaccharide formed by joining one glucose molecule and one galactose molecule.

Polysaccharide

A polymer made of many monosaccharide units joined together.

Glycogen

A branched polymer of glucose used to store energy in animals, stored primarily in the liver and muscle.

Starch

A polymer of $\alpha$-glucose used to store energy in plants.

Cellulose

A plant structural polysaccharide (fiber) composed of $\beta$-glucose monomers with alternating bonds that make up plant cell walls.

Lipids

A class of nonpolar, hydrophobic macromolecules that includes fats, phospholipids, steroids, and waxes.

Carboxyl Group

A functional group consisting of $-COOH$; molecules containing it are carboxylic acids.

Glycerol

A three-carbon molecule with three hydroxyl groups that forms the backbone of fats and phospholipids.

Fat Molecule

A lipid molecule composed of one glycerol molecule bonded to three fatty acids, used for long-term energy storage.

Saturated Fatty Acid

A fatty acid that is full of hydrogen with only single bonds in its carbon chain; fats containing all saturated fatty acids are solid at room temperature.

Unsaturated Fatty Acid

A fatty acid containing one or more double bonds in its carbon chain that cause it to bend; fats with at least one unsaturated fatty acid are liquid at room temperature.

Phospholipid

A lipid composed of a glycerol molecule attached to two fatty acids and a phosphate group, possessing a hydrophilic polar head and hydrophobic nonpolar tails.

Phospholipid Bilayer

A double-layered arrangement of phospholipids that forms the structural foundation of cell membranes.

Steroids

Lipids characterized by a carbon skeleton consisting of four fused rings, differing in the placement of attached functional groups.

Hormone

A signaling molecule used for communication between organs.

Cholesterol

A steroid used as a precursor to synthesize other steroids, including sex hormones.

Proteins

Polymers composed of carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur ($\text{CHON(S)}$) that perform diverse cellular functions, whose specific function depends on their shape.

Amino Acid

The monomer of proteins, containing a central carbon bonded to an amino group ($-NH_2$), a carboxyl group ($-COOH$), a hydrogen atom, and one of $20$ variable R groups.

Peptide Bond

The covalent bond formed between the carboxyl group of one amino acid and the amino group of another via dehydration synthesis.

Polypeptide

A chain of hundreds to thousands of amino acids joined together by peptide bonds.

Primary Structure

The unique sequence and order of amino acids in a polypeptide, held together by peptide bonds and coded by a gene in DNA.

Secondary Structure

The localized folding of a polypeptide chain into an alpha ($\alpha$) helix or beta ($\beta$) pleated sheet, stabilized by hydrogen bonds.

Tertiary Structure

The overall three-dimensional shape of a polypeptide produced by interactions among R groups, including hydrogen bonds, ionic bonds, hydrophobic interactions, and disulfide bridges.

Disulfide Bridge

A covalent bond formed between the sulfhydryl groups ($-SH$) of two cysteine amino acids in a polypeptide's tertiary structure.

Quaternary Structure

The structure resulting from two or more polypeptide subunits bonding together to form a functional protein.

Kinesin

A motor protein that carries cargo across the cell.

Hemoglobin

A transport protein in the blood that carries oxygen.

Aquaporin

A transport protein that allows water ($H_2O$) to move in and out of the cell.

Keratin

A structural protein found in hair and nails that supports cell shape.

Albumin

A storage protein found in egg whites and blood that stores amino acids for use in building other proteins.

Amylase

An enzyme that speeds up the breakdown (hydrolysis) of starch.

Enzyme

A protein that catalyzes (speeds up) a chemical reaction.

Mutation

Damage to a gene that leads to an altered primary structure, damaging subsequent structural levels and resulting in a loss of protein function (such as in sickle cell anemia).

Denaturation

The loss of secondary, tertiary, and quaternary protein structure caused by environmental changes such as high heat, extreme pH, or chemicals, leaving peptide bonds intact.

DNA (Deoxyribonucleic Acid)

A double-stranded, double-helical nucleic acid polymer that stores genetic information.

RNA (Ribonucleic Acid)

A single-stranded nucleic acid polymer.

Gene

A segment of DNA that carries instructions for synthesizing a specific protein.