Campbell Biology Chapter 5: The Structure and Function of Large Biological Molecules

Comprehensive vocabulary flashcards covering the structure, synthesis, types, and biological functions of large biological molecules (carbohydrates, lipids, proteins, and nucleic acids) based on Campbell Biology Chapter 5.

Polymer

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

Monomer

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

Enzyme

A specialized macromolecule that acts as a catalyst to speed up chemical reactions without being consumed.

Dehydration Reaction

A chemical reaction in which two monomers become covalently bonded to each other through the loss of a water molecule ($H_2O$).

Hydrolysis

A chemical process that disassembles polymers into monomers by breaking bonds through the addition of a water molecule ($H_2O$); the reverse of a dehydration reaction.

Monosaccharide

The simplest carbohydrate, also called a simple sugar, which has a molecular formula that is generally a multiple of $CH_2O$ and serves as a major cellular fuel and building block.

Aldose (Aldehyde Sugar)

A monosaccharide classified by having its carbonyl group located at the end of the carbon skeleton (e.g., glyceraldehyde, ribose, glucose, galactose).

Ketose (Ketone Sugar)

A monosaccharide classified by having its carbonyl group located within the carbon skeleton (e.g., dihydroxyacetone, ribulose, fructose).

Glycosidic Linkage

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

Disaccharide

A double sugar consisting of two monosaccharides joined by a glycosidic linkage, such as maltose or sucrose.

Polysaccharide

A polymer of many monosaccharides formed by glycosidic linkages, serving energy storage or structural functions.

Starch

A plant storage polysaccharide consisting entirely of glucose monomers connected largely by $\alpha$ 1–4 glycosidic linkages, stored as granules in chloroplasts and other plastids.

Amylose

The simplest, unbranched form of starch composed of glucose monomers in an $\alpha$ configuration.

Glycogen

An extensively branched storage polysaccharide of glucose found in animals, primarily stored in liver and muscle cells.

Cellulose

A major structural polysaccharide of plant cell walls, consisting of unbranched glucose monomers joined by $\beta$ 1–4 glycosidic linkages that form parallel hydrogen-bonded microfibrils.

Chitin

A structural polysaccharide found in the exoskeletons of arthropods and the cell walls of fungi, also utilized to make surgical thread that biodegrades.

Lipids

A diverse class of large biological molecules that do not consist of true polymers and mix poorly, if at all, with water due to their hydrocarbon structure.

Fatty Acid

A lipid component consisting of a carboxylic acid with a long carbon skeleton, which binds to glycerol via an ester linkage.

Triacylglycerol (Triglyceride)

A lipid molecule composed of three fatty acids linked to one glycerol molecule through ester linkages, functioning as an energy storage molecule.

Saturated Fatty Acid

A fatty acid in which all carbons in the hydrocarbon chain are connected by single bonds, maximizing hydrogen atoms; saturated fats are typically solid at room temperature.

Unsaturated Fatty Acid

A fatty acid possessing one or more double bonds in the hydrocarbon chain (typically cis), causing bends in the chain and causing the fat to remain liquid at room temperature.

Hydrogenation

The process of converting unsaturated fats to saturated fats by synthetically adding hydrogen, which can generate trans double bonds.

Trans Fats

Unsaturated fats with trans double bonds produced during hydrogenation that significantly increase the risk of cardiovascular disease.

Phospholipid

A lipid molecule composed of a glycerol molecule joined to two fatty acid tails and a phosphate group, creating an amphipathic structure with a hydrophilic head and hydrophobic tails.

Phospholipid Bilayer

A double-layered sheet self-assembled by phospholipids in aqueous solutions, where hydrophobic tails point inward and hydrophilic heads face outward, forming biological membranes.

Steroids

Lipids characterized by a carbon skeleton consisting of four fused rings with attached chemical groups.

Cholesterol

A crucial steroid that acts as a structural component of animal cell membranes and serves as the precursor from which other steroids, including sex hormones, are synthesized.

Polypeptide

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

Protein

A biologically functional molecule that consists of one or more polypeptides folded and coiled into a specific three-dimensional conformation.

Amino Acid

An organic molecule possessing an $\alpha$-carbon bonded to an amino group ($-NH_2$), a carboxyl group ($-COOH$), a hydrogen atom, and a variable side chain ($R$ group).

Peptide Bond

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

Primary Structure

The unique, linear sequence of amino acids in a polypeptide chain, determined directly by inherited genetic information.

Secondary Structure

The repetitive coiling or folding of the polypeptide backbone, stabilized by hydrogen bonds between repeating constituents of the polypeptide backbone.

$\alpha$ Helix

A spiral secondary protein structure held together by hydrogen bonds between every fourth amino acid of the polypeptide backbone.

$\beta$ Pleated Sheet

A secondary protein structure composed of parallel or antiparallel polypeptide segments ($\beta$ strands) connected by hydrogen bonds between the backbones.

Tertiary Structure

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

Disulfide Bridge

A strong covalent bond formed when sulfur atoms of two cysteine monomers oxidize and link, reinforcing tertiary or quaternary protein structure.

Quaternary Structure

The overall protein conformation that results when two or more individual polypeptide chains aggregate to form a functional macromolecule (e.g., collagen, hemoglobin).

Sickle-Cell Disease

An inherited blood disorder caused by a single amino acid substitution (valine replacing glutamic acid) in the primary structure of hemoglobin, deforming red blood cells into a sickle shape.

Denaturation

A process in which a protein unravels and loses its native three-dimensional conformation due to alterations in pH, salt concentration, temperature, or other environmental factors, rendering it biologically inactive.

X-ray Crystallography

A technique used to study the three-dimensional atomic structure of crystallized molecules by measuring the diffraction patterns of X-rays passed through them.

Gene

A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA that programs the amino acid sequence of a polypeptide.

Deoxyribonucleic Acid (DNA)

A double-stranded, helical nucleic acid molecule containing deoxyribose sugar and the nitrogenous bases adenine ($A$), cytosine ($C$), guanine ($G$), and thymine ($T$), capable of replicating and determining inherited structure.

Ribonucleic Acid (RNA)

A typically single-stranded nucleic acid molecule containing ribose sugar and the nitrogenous bases adenine ($A$), cytosine ($C$), guanine ($G$), and uracil ($U$), functioning in protein synthesis and gene regulation.

Gene Expression

The cellular process by which DNA directs the synthesis of messenger RNA (mRNA) and, through mRNA, controls protein synthesis ($\text{DNA} \rightarrow \text{RNA} \rightarrow \text{protein}$).

Polynucleotide

A polymer consisting of many nucleotide monomers in a chain; nucleic acids are polynucleotides.

Nucleotide

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

Nucleoside

The portion of a nucleotide consisting of only a nitrogenous base covalently linked to a pentose sugar, lacking the phosphate group.

Pyrimidine

A family of nitrogenous bases characterized by a single six-membered ring of carbon and nitrogen atoms; includes cytosine ($C$), thymine ($T$), and uracil ($U$).

Purine

A family of nitrogenous bases characterized by a six-membered ring fused to a five-membered ring; includes adenine ($A$) and guanine ($G$).

Phosphodiester Linkage

A covalent bond consisting of a phosphate group linking the sugars of two adjacent nucleotides together to form the sugar-phosphate backbone of a nucleic acid.

Antiparallel

The arrangement of the two sugar-phosphate backbones in a DNA double helix, running parallel to each other but oriented in opposite directions ($5^\prime \rightarrow 3^\prime$ versus $3^\prime \rightarrow 5^\prime$).

Complementary Base Pairing

The predictable pairing of specific nitrogenous bases via hydrogen bonding, where adenine ($A$) pairs with thymine ($T$) (or uracil in RNA) and guanine ($G$) pairs with cytosine ($C$).

Genomics

The systematic study and comparison of whole sets of genes and their interactions within or between entire genomes of different species.

Proteomics

The systematic study of full sets of proteins and their properties, including sequences, abundances, and cellular interactions.

Bioinformatics

The application of computer software, mathematics, and computational tools to store, manage, and analyze large biological datasets, such as genomic and protein sequences.