The Structure and Function of Large Biological Molecules — Vocabulary Flashcards (Carbohydrates, Lipids, Proteins, Nucleic Acids)

Vocabulary-style flashcards covering core biomolecules and related chemistry concepts from the notes (carbohydrates, lipids, proteins, nucleic acids, and foundational biochemistry).

Carbohydrate

Biomolecule class with formula Cx(H2O)x; includes sugars and polysaccharides; primary role is energy storage and, in some organisms, structural support.

Monosaccharide

Simple sugar; basic unit of carbohydrates (e.g., glucose, fructose).

Disaccharide

Two monosaccharides linked by a glycosidic bond (e.g., sucrose, lactose, maltose).

Polysaccharide

Polymer of many monosaccharides; can be storage (starch, glycogen) or structural (cellulose, chitin).

Glycosidic linkage

Covalent bond between two monosaccharides formed by dehydration synthesis; can be alpha or beta depending on orientation.

Alpha glycosidic linkage

Glycosidic bond where the linked OH group is below the ring plane; common in starches.

Beta glycosidic linkage

Glycosidic bond where the linked OH group is above the ring plane; common in cellulose.

Starch

Plant storage polymer of glucose; consists of amylose (unbranched) and amylopectin (branched); has alpha linkages.

Amylose

Unbranched component of starch.

Amylopectin

Branched component of starch.

Glycogen

Animal storage polymer of glucose; highly branched; stored mainly in liver and muscles.

Cellulose

Structural polysaccharide in plant cell walls; beta-1,4 glycosidic linkages; humans cannot digest it.

Chitin

Structural polysaccharide in fungal cell walls and arthropod exoskeletons; amino sugar monomers with beta linkages.

Lipid

Large, nonpolar biomolecules that do not mix well with water; include fats, phospholipids, and steroids.

Fat (triglyceride)

Glycerol bound to three fatty acids via ester bonds; major energy-storage molecule and insulator.

Fatty acid

Carboxylic acid with a long hydrocarbon chain; can be saturated or unsaturated.

Saturated fatty acid

Fatty acid with only single bonds between carbons; typically solid at room temperature.

Unsaturated fatty acid

Fatty acid with one or more carbon–carbon double bonds; typically liquid at room temperature.

Trans fat

Unsaturated fat with one or more trans double bonds; often produced by hydrogenation; associated with health risks.

Phospholipid

Lipid with glycerol, two fatty acids, and a phosphate group; amphipathic; major component of cell membranes.

Steroid

Lipid with four fused carbon rings; includes cholesterol and many hormones.

Cholesterol

Steroid important for animal cell membranes; precursor to other steroids.

Protein

Polymers of amino acids folded into a functional three-dimensional structure; perform many cellular roles.

Amino acid

Monomer of proteins; contains an amino group, a carboxyl group, and a variable R group.

Peptide bond

Covalent bond linking amino acids via dehydration synthesis.

Primary structure

Linear sequence of amino acids in a protein.

Secondary structure

Local folding patterns (alpha-helix, beta-pleated sheet) stabilized by backbone hydrogen bonds.

Alpha-helix

Right-handed coiled secondary structure common in proteins.

Beta-pleated sheet

Secondary structure with sheet-like arrangement stabilized by backbone hydrogen bonds.

Tertiary structure

Overall three-dimensional shape of a protein caused by R-group interactions (hydrophobic, ionic, hydrogen bonds, disulfide bridges).

Quaternary structure

Association of two or more polypeptide chains into a functional protein.

Denaturation

Loss of a protein’s native shape due to disruption of weak chemical bonds (e.g., by pH, salt, or heat).

Sickle-cell anemia

Genetic disease caused by a single amino acid substitution (Val for Glu) in beta-globin; deforms red blood cells and impairs oxygen transport.

Enzyme

Protein that acts as a catalyst to speed up chemical reactions without being consumed.

Active site

Region of an enzyme where substrate binds and catalysis occurs.

Substrate

Reactant that binds to an enzyme.

Induced fit

Model in which an enzyme changes shape to better embrace its substrate.

Cofactor

Nonprotein component required for enzyme activity (can be inorganic ion or organic molecule).

Coenzyme

Organic cofactor that assists enzyme activity.

Competitive inhibitor

Substance that competes with the substrate for access to the active site; effect can be overcome by increasing substrate concentration.

Noncompetitive inhibitor

Inhibitor that binds to a site other than the active site, altering enzyme shape and reducing activity.

Allosteric regulation

Regulation of an enzyme by binding a molecule at a site other than the active site, affecting activity at another site.

Cooperativity

Substrate binding to one subunit increases catalytic activity of other subunits (e.g., hemoglobin).

ATP

Adenosine triphosphate; energy currency of the cell; three phosphate groups; drives energy-requiring reactions.

Nucleic acid

Polymers (DNA and RNA) composed of nucleotides; store and transmit genetic information.

Nucleotide

Nucleic acid monomer: sugar + nitrogenous base + phosphate.

Nucleoside

Sugar + nitrogenous base; lacks phosphate group.

Purine

Broad, two-ring nitrogenous bases (adenine and guanine).

Pyrimidine

Single-ring nitrogenous bases (cytosine, thymine, uracil).

DNA

Deoxyribonucleic acid; double helix with two antiparallel strands; sugar is deoxyribose; bases A–T and C–G pair via hydrogen bonds.

RNA

Ribonucleic acid; typically single-stranded; sugar is ribose; bases A–U, C–G.

Base pairing

A pairs with T (or U in RNA) via two hydrogen bonds; C pairs with G via three hydrogen bonds.

Double helix

Three-dimensional structure of native DNA with two antiparallel polynucleotide strands coiled around an axis.

Human Genome Project

Large-scale project (1990–2003) to sequence the entire human genome.

Genomics

Study of whole genomes and their structure, function, and evolution.

Proteomics

Study of the full set of proteins (and their sequences) produced by an organism.

Bioinformatics

Use of computer software and computational tools to analyze large biological data sets.