Chapter 5: Biological Molecules Vocabulary Flashcards

Vocabulary flashcards covering key terms and definitions from Chapter 5 on macromolecular structure and function.

Polymer

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

Monomer

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

Macromolecule

A giant molecule formed by the joining of smaller molecules, usually by a dehydration reaction (polysaccharides, proteins, and nucleic acids).

Dehydration Reaction

A chemical reaction in which two molecules become covalently bonded to each other with the removal of a water molecule.

Hydrolysis

A chemical reaction that breaks bonds between two molecules by the addition of water; functions in the disassembly of polymers to monomers.

Enzyme

A macromolecule serving as a catalyst, a chemical agent that increases the rate of a reaction without being consumed by the reaction (most enzymes are proteins).

Monosaccharide

The simplest carbohydrate, active alone or serving as a monomer for disaccharides and polysaccharides.

Disaccharide

A double sugar, consisting of two monosaccharides joined by a glycosidic linkage formed by a dehydration reaction.

Glycosidic Linkage

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

Polysaccharide

A sugar (monosaccharide) polymer of hundreds to thousands of monosaccharides joined by glycosidic linkages.

Starch

A storage polysaccharide in plants, consisting entirely of glucose monomers joined by glycosidic linkages.

Glycogen

An extensively branched glucose storage polysaccharide found in the liver and muscle of animals; the animal equivalent of starch.

Cellulose

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

Chitin

A structural polysaccharide, consisting of amino sugar monomers, found in many fungal cell walls and in the exoskeletons of all arthropods.

Lipid

Any of a group of large biological molecules, including fats, phospholipids, and steroids, that mix poorly, if at all, with water.

Fat

A lipid consisting of three fatty acids linked to one glycerol molecule; also called a triacylglycerol or triglyceride.

Saturated Fatty Acid

A carboxylic acid with a long carbon chain where all carbons in the tail are connected by single bonds, maximizing hydrogen atoms.

Unsaturated Fatty Acid

A fatty acid that has one or more double bonds between carbons in the hydrocarbon tail, which reduces the number of hydrogen atoms attached to the carbon skeleton.

Trans Fat

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

Phospholipid

A lipid made up of glycerol joined to two fatty acids and a phosphate group, forming bilayers that function as biological membranes.

Steroid

A type of lipid characterized by a carbon skeleton consisting of four fused rings with various chemical groups attached.

Cholesterol

A steroid that forms an essential component of animal cell membranes and acts as a precursor molecule for the synthesis of other biologically important steroids.

Catalyst

A chemical agent that selectively increases the rate of a reaction without being consumed by the reaction.

Protein

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

Amino Acid

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

Polypeptide

A polymer of many amino acids linked together by peptide bonds.

Peptide Bond

The covalent bond between the carboxyl group on one amino acid and the amino group on another, formed by a dehydration reaction.

Primary Structure

The level of protein structure referring to the specific linear sequence of amino acids.

Secondary Structure

Regions of repetitive coiling or folding of the polypeptide backbone of a protein due to hydrogen bonding between constituents of the backbone (not the side chains).

Alpha Helix

A coiled region constituting one form of the secondary structure of proteins, arising from a specific pattern of hydrogen bonding between atoms of the polypeptide backbone.

Beta Pleated Sheet

One form of the secondary structure of proteins in which the polypeptide chain folds back and forth, with parallel regions held together by hydrogen bonds between atoms of the polypeptide backbone.

Tertiary Structure

The overall shape of a protein molecule due to interactions of amino acid side chains, including hydrophobic interactions, ionic bonds, hydrogen bonds, and disulfide bridges.

Hydrophobic Interaction

A type of weak chemical interaction caused when molecules that do not mix with water coalesce to exclude water.

Disulfide Bridge

A strong covalent bond formed when the sulfur of one cysteine monomer bonds to the sulfur of another cysteine monomer.

Quaternary Structure

The particular shape of a complex, aggregate protein defined by the characteristic three-dimensional arrangement of its constituent subunits.

Sickle Cell Disease

A recessively inherited human blood disorder in which a single nucleotide change in the $\beta$-globin gene causes hemoglobin to aggregate, changing red blood cell shape.

Denaturation

In proteins, a process in which a protein loses its native shape due to the disruption of weak chemical interactions; in DNA, the separation of the two strands of the double helix.

X-ray Crystallography

A technique used to study the three-dimensional structure of molecules based on the diffraction of an X-ray beam by the individual atoms of a crystallized molecule.

Gene

A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA (or RNA, in some viruses).

Nucleic Acid

A polymer (polynucleotide) consisting of many nucleotide monomers; serves as a blueprint for proteins and cellular activities (DNA and RNA).

DNA

A nucleic acid molecule, usually a double-stranded helix, consisting of nucleotide monomers with deoxyribose and nitrogenous bases (A, C, G, T) that stores hereditary information.

RNA

A type of nucleic acid consisting of nucleotide monomers with ribose sugar and nitrogenous bases (A, C, G, U); usually single-stranded; functions in protein synthesis and gene regulation.

Gene Expression

The process by which information encoded in DNA directs the synthesis of proteins or, in some cases, RNAs that are not translated into proteins and instead function as RNAs.

Polynucleotide

A polymer consisting of many nucleotide monomers in a chain (DNA or RNA).

Nucleotide

The building block of a nucleic acid, consisting of a five-carbon sugar covalently bonded to a nitrogenous base and one to three phosphate groups.

Pyrimidine

One of two types of nitrogenous bases found in nucleotides, characterized by a six-membered ring.

Purine

One of two types of nitrogenous bases found in nucleotides, characterized by a six-membered ring fused to a five-membered ring.

Deoxyribose

The sugar component of DNA nucleotides, having one fewer hydroxyl group than ribose, the sugar component of RNA nucleotides.

Ribose

The sugar component of RNA nucleotides.

Double Helix

The form of native DNA, referring to its two adjacent antiparallel polynucleotide strands wound around an imaginary axis into a spiral shape.

Antiparallel

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

Bioinformatics

The use of computers, software, and mathematical models to process and integrate biological information from large data sets.

Genomics

The systematic study of whole sets of genes and their interactions within a species, as well as genome comparisons between species.

Proteomics

The systematic study of sets of proteins and their properties, including their abundance, chemical modifications, and interactions.