Chapter 5: The Structure and Function of Large Biological Molecules

Vocabulary flashcards generated from Chapter 5 lecture notes on large biological molecules, including detailed definitions and key structural terms.

Polymer

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

Monomer

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

Enzyme

A specialized macromolecule that acts as a biological catalyst to speed up chemical reactions, such as those that synthesize or break down polymers.

Dehydration reaction

A chemical reaction in which two monomers become covalently bonded to each other through the loss of a water molecule ($\text{H}_2\text{O}$).

Hydrolysis

A chemical reaction that breaks covalent bonds between monomers within a polymer through the addition of a water molecule ($\text{H}_2\text{O}$).

Monosaccharide

The simplest carbohydrate or simple sugar, possessing a molecular formula that is generally a multiple of $\text{CH}_2\text{O}$.

Glucose

The most common monosaccharide, having the chemical formula $\text{C}_6\text{H}_{12}\text{O}_6$, which serves as a major cellular fuel.

Disaccharide

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

Glycosidic linkage

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

Polysaccharide

A polymer composed of many monosaccharide sugar monomers joined by glycosidic linkages, fulfilling storage or structural roles.

Starch

A plant storage polysaccharide consisting entirely of glucose monomers joined by $\alpha$ 1–4 glycosidic linkages.

Amylose

The simplest, unbranched form of plant starch.

Glycogen

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

Cellulose

A structural polysaccharide that forms tough plant cell walls, consisting of unbranched glucose polymers joined by $\beta$ 1–4 glycosidic linkages.

Chitin

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

Lipids

A diverse class of biological molecules that are hydrophobic, mixing poorly or not at all with water, and do not form true polymers.

Fat (Triacylglycerol)

A lipid molecule composed of one glycerol bonded to three fatty acids via ester linkages.

Fatty acid

A molecule consisting of a carboxyl group attached to a long hydrocarbon chain.

Saturated fatty acid

A fatty acid in which all carbons in the hydrocarbon chain are connected by single bonds, maximizing attached hydrogen atoms.

Unsaturated fatty acid

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

Hydrogenation

The process of converting unsaturated fats to saturated fats by adding hydrogen atoms.

Trans fats

Unsaturated fats containing trans double bonds, created during the hydrogenation of vegetable oils, which contribute to cardiovascular disease.

Phospholipid

A lipid composed of glycerol attached to two hydrophobic fatty acid tails and a hydrophilic phosphate head group.

Steroids

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

Cholesterol

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

Polypeptide

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

Protein

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

Amino acid

An organic monomer containing an amino group, a carboxyl group, an $\alpha$ carbon, a hydrogen, and a variable side chain (R group).

Peptide bond

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

Primary structure

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

Secondary structure

Coils ($\alpha$ helix) and folds ($\beta$ pleated sheet) in a polypeptide backbone resulting from hydrogen bonding.

Tertiary structure

The overall three-dimensional shape of a single polypeptide chain resulting from interactions among amino acid side chains (R groups).

Quaternary structure

The structural level that arises when two or more polypeptide subunits aggregate into one functional macromolecule.

Disulfide bridges

Strong covalent bonds formed between sulfhydryl groups of cysteine residues that reinforce tertiary protein structure.

Sickle-cell disease

An inherited blood disorder resulting from a single amino acid substitution in the $\beta$ subunit of hemoglobin.

Denaturation

The process by which a protein unravels and loses its native shape and biological activity due to altered environmental factors like pH or temperature.

X-ray crystallography

An experimental method used by scientists to determine the three-dimensional atomic structure of a protein crystal.

Gene

A discrete unit of inheritance composed of DNA that programs the primary sequence of a polypeptide.

Nucleic acids

Polymers (polynucleotides) made of nucleotide monomers that store, transmit, and express hereditary information.

Deoxyribonucleic acid (DNA)

A double-stranded nucleic acid molecule containing deoxyribose sugar that provides directions for its own replication and mRNA synthesis.

Ribonucleic acid (RNA)

A usually single-stranded nucleic acid containing ribose sugar and uracil that functions in gene expression and protein synthesis.

Gene expression

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

Polynucleotide

A polymer consisting of many nucleotide monomers linked covalently by phosphodiester linkages.

Nucleotide

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

Nucleoside

The portion of a nucleotide consisting of a nitrogenous base attached to a pentose sugar, lacking phosphate groups.

Pyrimidines

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

Purines

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

Antiparallel

The structural arrangement of the two sugar-phosphate backbones in a DNA double helix running in opposite $5' \rightarrow 3'$ directions.

Genomics

An approach analyzing large sets of genes or comparing whole genomes across species using computational tools.

Proteomics

The systematic study and analysis of full sets of proteins and their properties in organisms.

Bioinformatics

The use of computer software and computational tools to manage and analyze large biological datasets.