Chapter 5: The Structure and Function of Large Biological Molecules - Vocabulary Flashcards

Vocabulary flashcards defining key biological terms, molecules, reactions, structures, and processes covered in Chapter 5: The Structure and Function of Large Biological Molecules.

Macromolecule

A large, complex biological molecule formed by the joining of smaller molecules, belonging to one of four main classes: carbohydrates, lipids, proteins, or nucleic acids.

Polymer

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

Monomer

The repeating subunit or single building block that serves as the monomeric unit for synthesized polymers.

Enzymes

Specialized macromolecules that speed up chemical reactions, such as those that synthesize or disassemble polymers.

Dehydration Reaction

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

Hydrolysis Reaction

A chemical process that breaks bonds between monomers by the addition of a water molecule, reversing a dehydration reaction.

Monosaccharides

The simplest carbohydrates, also known as simple sugars, which have molecular formulas that are usually multiples of $CH_2O$ and serve as fuel and structural raw material.

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 monosaccharide units by a dehydration reaction.

Polysaccharides

Macromolecules consisting of polymers of many monosaccharide sugar building blocks joined by glycosidic linkages, functioning as energy storage or structural support.

Starch

A storage polysaccharide produced by plants consisting entirely of glucose monomers linked together.

Glycogen

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

Cellulose

A structural polysaccharide made of glucose monomers that forms the tough primary component of plant cell walls.

Lipids

A diverse class of hydrophobic biological molecules consisting mostly of hydrocarbon regions that do not form true polymers.

Fat (Triacylglycerol)

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

Glycerol

A three-carbon alcohol containing a hydroxyl group attached to each carbon atom, serving as a precursor backbone for fats and phospholipids.

Fatty Acid

A organic molecule consisting of a carboxyl group attached to a long, nonpolar carbon skeleton.

Ester Linkage

The covalent bond formed between a hydroxyl group of glycerol and a carboxyl group of a fatty acid in a fat molecule.

Saturated Fatty Acid

A fatty acid whose carbon chain contains no double bonds, allowing it to hold the maximum possible number of hydrogen atoms; usually solid at room temperature.

Unsaturated Fatty Acid

A fatty acid possessing one or more double bonds in its carbon chain, creating a kink in its structure and rendering it liquid at room temperature.

Hydrogenation

The chemical process of converting unsaturated fats into saturated fats by adding hydrogen atoms across carbon-carbon double bonds.

Phospholipid

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

Lipid Bilayer

A double-layered arrangement of phospholipids that self-assembles in water, forming the fundamental structural unit of biological cell membranes.

Steroids

Lipids characterized by a hydrophobic carbon backbone composed of four fused carbon rings.

Cholesterol

A vital steroid molecule found in animal cell membranes and used as a precursor for the synthesis of other biological steroids.

Polypeptide

An unbranched polymer made of amino acids connected together by peptide bonds.

Protein

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

Amino Acid

An organic molecule possessing an amino group, a carboxyl group, an alpha carbon, a hydrogen atom, and a unique variable side chain (R group).

Peptide Bond

The covalent bond linking the carboxyl group of one amino acid to the amino group of another formed via a dehydration synthesis reaction.

Primary Structure

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

Secondary Structure

Repetitive coiling or folding patterns in a protein backbone maintained by hydrogen bonding between backbone constituents.

Alpha (\alpha) Helix

A helical coiling structure characteristic of protein secondary structure, held together by regular hydrogen bonding in the backbone.

Beta (\beta) Pleated Sheet

A protein secondary structure featuring parallel or antiparallel polypeptide strands linked side-by-side by hydrogen bonds.

Tertiary Structure

The overall three-dimensional shape of a polypeptide chain determined by interactions among variable amino acid side chains (R groups).

Disulfide Bridges

Covalent linkages created when sulfhydryl groups of two cysteine monomers interact, reinforcing protein tertiary structure.

Quaternary Structure

The higher-level protein conformation resulting from the structural association of two or more independent polypeptide chains.

Denaturation

A physical process in which a protein loses its specific three-dimensional conformation and biological activity due to disruptions in chemical bonding caused by factors like pH, temperature, or chemical exposure.

Gene

A discrete unit of hereditary information composed of a specific sequence of nucleotides in DNA that dictates the primary amino acid sequence of a polypeptide.

Gene Expression

The process where inherited genetic instructions in DNA direct messenger RNA synthesis, which subsequently controls protein construction ($\text{DNA} \rightarrow \text{RNA} \rightarrow \text{protein}$).

Polynucleotide

A nucleic acid polymer constructed from nucleotide monomers linked together in a long chain.

Nucleotide

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

Nucleoside

The structural portion of a nucleotide containing only the nitrogenous base covalently bonded to a pentose sugar, excluding phosphate groups.

Pyrimidines

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

Purines

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

Phosphodiester Linkage

A covalent bond formed by a phosphate group linking the $3'$ carbon sugar of one nucleotide to the $5'$ carbon sugar of an adjacent nucleotide in a nucleic acid chain.

Antiparallel

The structural arrangement of the two sugar-phosphate backbones in a DNA double helix, which run parallel to each other but in opposite $5' \rightarrow 3'$ directions.