Chapter 5: Major types of organic molecules

Vocabulary flashcards covering key terms and concepts from Chapter 5: Major types of organic molecules.

Macromolecule

A very large, complex molecule, typically a polymer made of many subunits.

Polymer

A large molecule built from repeating subunits (monomers), such as proteins from amino acids or nucleic acids from nucleotides.

Monomer

A small molecule that can join with others to form a polymer.

Carbohydrates

One of the four major classes of biologically important organic molecules; composed of C, H, O in a (CH2O)n ratio; used for energy storage and building materials.

Lipids

Biomolecules defined by solubility (not structure); include fats, phospholipids, cholesterol; mainly hydrophobic and used for membranes, signaling, and energy storage.

Proteins

Biological polymers made of amino acids; perform structural, catalytic, and signaling roles; have levels of organization from primary to quaternary.

Nucleic acids

DNA and RNA; polymers of nucleotides that store and transmit genetic information.

Monosaccharide

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

Disaccharide

Two monosaccharides joined by a glycosidic bond; formed via a dehydration reaction (e.g., maltose, sucrose, lactose).

Glycosidic linkage

Covalent bond joining carbohydrate monomers; typically formed during dehydration (e.g., 1→4, 1→2 linkages in disaccharides).

Dehydration (condensation) reaction

A reaction that joins monomers with loss of a water molecule.

Hydrolysis

A reaction that breaks polymers apart by adding water.

Aldose

Monosaccharide with an aldehyde group.

Ketose

Monosaccharide with a ketone group.

Ring forms (alpha and beta) of glucose

Cyclized glucose forms; alpha has the OH group below the ring at the anomeric carbon, beta has it above.

Starch

Plant storage polysaccharide made of α-glucose; mainly α1→4 linkages; amylose (unbranched) and amylopectin (branched).

Amylose

Unbranched component of starch.

Amylopectin

Branched component of starch (branches usually α1→6).

Glycogen

Animal storage polysaccharide; highly branched; highly water-soluble; stored in liver and muscle.

Cellulose

Structural polysaccharide in plants; made of β-glucose with β1→4 linkages; unbranched; forms microfibrils stabilized by hydrogen bonds.

Chitin

Structural polysaccharide in fungal cell walls and arthropod exoskeletons; made of N-acetylglucosamine.

Triacylglycerol

Also called triglyceride; glycerol backbone with three fatty acids; major energy storage lipid.

Glycerol

Three-carbon alcohol that forms the backbone of fats.

Fatty acid

Carboxyl group attached to a long hydrocarbon chain; can be saturated or unsaturated.

Phospholipid

Diacylglycerol with a phosphate group and an organic molecule; amphipathic and forms lipid bilayers in water.

Amphipathic

Molecule having both hydrophilic (polar) and hydrophobic (nonpolar) regions.

Cholesterol

Steroid lipid found in animal membranes; modulates membrane fluidity and is a precursor to other steroids.

Steroid

Lipids with four fused carbon rings; include cholesterol and steroid hormones.

Omega-3 fatty acids

Essential fatty acids not synthesized by the human body (e.g., ALA, EPA, DHA); important for growth and cardiovascular health.

Trans fats

Fats with trans double bonds formed by hydrogenation; associated with increased cardiovascular disease risk.

Amino acid

Monomer of proteins; contains an amino group and a carboxyl group, with a variable side chain.

Peptide bond

Covalent bond linking amino acids in a protein; formed by a dehydration reaction.

Polypeptide

Polymer of amino acids; a chain that folds into a protein.

Protein structure levels

Primary, secondary, tertiary, and quaternary structures describing the organization of a protein.

Nucleotide

Monomer of nucleic acids; consists of a sugar, a phosphate, and a nitrogenous base.

Phosphodiester bond

Bond that links nucleotides together in DNA and RNA.

DNA vs RNA

DNA uses deoxyribose and thymine; RNA uses ribose and uracil; DNA is typically double-stranded, RNA single-stranded; both have 5' to 3' directionality.

5' and 3' ends

Ends of nucleic acid strands; directionality of growth is from 5' to 3'.

Adenine, Thymine, Cytosine, Guanine, Uracil

Nitrogenous bases; A, T, C, G are in DNA (T); A, C, G, U in RNA (U replaces T).