Chapter 5: Biological Macromolecules and Lipids

A complete set of vocabulary flashcards covering macromolecules, carbohydrates, lipids, proteins, and nucleic acids from Chapter 5.

Polymer

A long molecule consisting of many similar or identical building blocks linked by covalent bonds.

Monomer

A repeating subunit that serves as the building block of a polymer.

Enzyme

A specialized macromolecule that speeds up chemical reactions without being consumed in the process.

Dehydration Reaction

A chemical reaction in which two monomers bond together through the loss of a water molecule.

Hydrolysis

A chemical reaction that breaks bonds between monomers in a polymer by adding a water molecule.

Monosaccharide

The simplest carbohydrate, or simple sugar, with molecular formulas that are usually multiples of $CH_2O$.

Disaccharide

A double sugar formed when a dehydration reaction joins two monosaccharides together.

Glycosidic Linkage

A covalent bond formed between two monosaccharides by a dehydration reaction.

Polysaccharide

A polymer composed of many sugar building blocks joined by glycosidic linkages, serving storage or structural roles.

Starch

A storage polysaccharide in plants consisting entirely of glucose monomers, stored as granules within plastids.

Glycogen

An extensively branched glucose storage polysaccharide found mainly in the liver and muscle cells of animals.

Cellulose

A structural polysaccharide of plant cell walls consisting of glucose monomers joined by $\beta$ glycosidic linkages.

Chitin

A structural polysaccharide found in the exoskeleton of arthropods and the cell walls of many fungi.

Lipid

A class of large biological molecules, including fats, phospholipids, and steroids, that mix poorly, if at all, with water.

Triacylglycerol

A fat molecule constructed from three fatty acids joined to a glycerol molecule by ester linkages; also called a triglyceride.

Saturated Fatty Acid

A fatty acid having no double bonds between carbon atoms in the hydrocarbon tail, resulting in the maximum number of attached hydrogen atoms.

Unsaturated Fatty Acid

A fatty acid possessing one or more double bonds in the hydrocarbon chain, creating a bend or kink in the molecule.

Trans Fat

An unsaturated fat containing one or more trans double bonds, formed during the hydrogenation of vegetable oils.

Phospholipid

A lipid composed of glycerol joined to two fatty acids and a phosphate group, forming a molecule with hydrophobic tails and a hydrophilic head.

Steroid

A type of lipid characterized by a carbon skeleton consisting of four fused rings.

Cholesterol

A steroid that forms an essential component of animal cell membranes and acts as a precursor for synthesizing other steroids.

Protein

A biologically functional molecule consisting of one or more polypeptides folded and coiled into a unique three-dimensional structure.

Polypeptide

An unbranched polymer of amino acids linked together by peptide bonds.

Amino Acid

An organic molecule possessing both a carboxyl group and an amino group, serving as the monomer of polypeptides.

Peptide Bond

The covalent bond linking amino acids together in a polypeptide chain, formed by a dehydration reaction.

Primary Structure

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

Secondary Structure

Repetitive coiling or folding of the polypeptide backbone in a protein due to hydrogen bonding between backbone constituents.

Tertiary Structure

The overall three-dimensional shape of a polypeptide resulting from interactions between the side chains (R groups) of various amino acids.

Quaternary Structure

The overall protein structure that results from the aggregation of two or more polypeptide subunits.

Denaturation

A process in which a protein unravels and loses its native shape due to environmental alterations, rendering it biologically inactive.

Gene Expression

The process by which DNA directs its own replication and mRNA synthesis, which in turn controls protein synthesis (DNA $\rightarrow$ RNA $\rightarrow$ protein).

Polynucleotide

A polymer consisting of many nucleotide monomers in a chain, such as DNA or RNA.

Nucleotide

The monomer of a nucleic acid, consisting of a five-carbon sugar, a nitrogenous base, and one or more phosphate groups.

Nucleoside

The portion of a nucleotide consisting of a nitrogenous base covalently bound to a pentose sugar, without any phosphate groups.

Pyrimidine

A family of nitrogenous bases characterized by a single six-membered ring, including cytosine, thymine, and uracil.

Purine

A family of nitrogenous bases characterized by a six-membered ring fused to a five-membered ring, including adenine and guanine.

Phosphodiester Linkage

A covalent bond joining adjacent nucleotides in a polynucleotide, consisting of a phosphate group linking the sugars of two nucleotides.

Antiparallel

Referring to the arrangement of sugar-phosphate backbones in a DNA double helix, which run in opposite $5' \rightarrow 3'$ directions.