Chapter 5: The Structure and Function of Large Biological Molecules - Key Terms

A complete set of vocabulary flashcards covering the key terms from Chapter 5: The Structure and Function of Large Biological Molecules.

Amino acid

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

Antiparallel

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

Carbohydrates

A sugar (monosaccharide) or one of its polymers, such as disaccharides or polysaccharides.

Catalyst

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

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.

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.

Dehydration reaction

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

Denaturation

A process in which a protein loses its native shape due to the disruption of weak chemical bonds and interactions, becoming biologically inactive.

Deoxyribonucleic acid (DNA)

A nucleic acid molecule, usually a double-stranded helix, in which each polynucleotide strand consists of nucleotide monomers with a deoxyribose sugar and nitrogenous bases.

Deoxyribose

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

Disaccharide

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

Double helix

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

Enzyme

A macromolecule serving as a catalyst, which increases the rate of a chemical reaction without being consumed by it.

Fat

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

Fatty acid

A carboxylic acid with a long carbon chain that varies in length and in the number and location of double bonds.

Genes

Discrete units of hereditary information consisting of specific nucleotide sequences in DNA or RNA.

Glycogen

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

Glycosidic linkage

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

α helix

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

Hydrolysis

A chemical reaction that breaks bonds between two molecules by the addition of water, disassembling polymers into monomers.

Lipids

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

Macromolecules

Giant molecules formed by the joining of smaller molecules, usually by a dehydration reaction.

Monomers

The subunit building blocks that serve as the repeating units of polymers.

Monosaccharides

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

Nucleic acids

Polymers consisting of many nucleotide monomers, serving as a blueprint for proteins and all cellular activities.

Nucleotides

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

Peptide bond

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

Phosphodiester linkage

The covalent bond connecting nucleotides in a polynucleotide strand, consisting of a phosphate group linking the sugars of two nucleotides.

Phospholipid

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

β pleated sheet

A form of secondary structure in proteins where the polypeptide chain folds back and forth, held together by hydrogen bonds between parallel or antiparallel regions.

Polymer

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

Polynucleotides

Polymers consisting of many nucleotide monomers in a chain, forming nucleic acids such as DNA or RNA.

Polypeptide

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

Polysaccharides

Polymers of many monosaccharides joined by glycosidic linkages, formed by dehydration reactions.

Primary structure

The level of protein structure referring to the specific linear sequence of amino acids in a polypeptide chain.

Protein

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

Purines

Nitrogenous bases found in nucleotides characterized by a six-membered ring fused to a five-membered ring, including adenine and guanine.

Pyrimidine

A nitrogenous base found in nucleotides characterized by a six-membered ring, including cytosine, thymine, and uracil.

Ribonucleic acid(RNA)

A type of nucleic acid consisting of nucleotide monomers with a ribose sugar and nitrogenous bases (A, C, G, U), usually single-stranded.

Ribose

The five-carbon sugar component present in RNA nucleotides.

Saturated fatty acid

A fatty acid in which all carbons in the hydrocarbon tail are connected by single bonds, maximizing hydrogen attachment.

Secondary structure

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

Starch

A storage polysaccharide in plants consisting entirely of glucose monomers joined by $\alpha$ glycosidic linkages.

Steroids

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

Tertiary structure

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

Trans fats

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

Unsaturated fatty acid

A fatty acid that has one or more double bonds between carbons in the hydrocarbon tail, reducing the number of hydrogen atoms attached.