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

Vocabulary flashcards covering macromolecules, polymers, and key biomolecular concepts from the lecture notes.

Macromolecule

A very large molecule such as carbohydrates, lipids, proteins, or nucleic acids, built from smaller units and often with thousands of covalently bonded atoms.

Polymer

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

Monomer

A small molecule that serves as a building block for polymers.

Dehydration reaction

A chemical reaction where two monomers are joined by removing a water molecule, forming a covalent bond.

Hydrolysis

A reaction that breaks covalent bonds by adding water, splitting polymers into monomers.

Enzyme

A protein or RNA that speeds up chemical reactions in cells.

Carbohydrate

A macromolecule class including sugars and their polymers; major source of fuel and carbon.

Monosaccharide

The simplest carbohydrate; a single sugar unit such as glucose.

Disaccharide

A carbohydrate formed by two monosaccharides linked by a glycosidic bond (e.g., sucrose, maltose, lactose).

Polysaccharide

A polymer of many monosaccharides; function in storage or structural roles (e.g., starch, cellulose, glycogen).

Aldose

A monosaccharide with an aldehyde functional group.

Ketose

A monosaccharide with a ketone functional group.

Hexose

A six-carbon monosaccharide (e.g., glucose).

Pentose

A five-carbon monosaccharide.

Triose

A three-carbon monosaccharide.

Glycosidic linkage

A covalent bond formed between monosaccharides during a dehydration reaction.

Amylose

Unbranched component of starch, a polymer of glucose.

Amylopectin

Branched component of starch.

Starch

Storage polysaccharide in plants composed of glucose monomers.

Glycogen

Animal storage polysaccharide; highly branched polymer of glucose.

Cellulose

Structural polysaccharide in plant cell walls; polymer of glucose with beta linkages.

Alpha (α) glucose

Form of glucose used in starch; forms helical structures due to α linkages.

Beta (β) glucose

Form of glucose used in cellulose; forms straight, rigid fibers due to β linkages.

Microfibril

Bundle of cellulose molecules grouped to form strong plant cell-wall material.

Chitin

Structural polysaccharide in arthropod exoskeletons and fungal cell walls; like cellulose but with a nitrogen-containing appendage.

Lipid

A diverse group of hydrophobic molecules not forming polymers; mostly hydrocarbons.

Glycerol

A three-carbon alcohol that forms the backbone of fats.

Fatty acid

Carboxyl-bearing hydrocarbon chain; can be saturated or unsaturated.

Ester linkage

Bond linking glycerol to fatty acids in fats.

Triglyceride

A fat composed of three fatty acids attached to glycerol.

Saturated fatty acid

Fatty acid with no carbon–carbon double bonds; typically solid at room temperature.

Unsaturated fatty acid

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

Hydrogenation

Addition of hydrogen to unsaturated fats to make them more saturated; can produce trans fats.

Trans fats

Unsaturated fats with trans double bonds; associated with higher risk of heart disease.

Omega-3 fatty acids

Essential fatty acids that must be obtained from the diet; a type of unsaturated fat.

Phospholipid

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

Phospholipid bilayer

Two-layer arrangement of phospholipids with hydrophilic heads outward and hydrophobic tails inward, forming a cell membrane.

Cholesterol

A steroid molecule important in animal cell membranes and a precursor to other steroids; can affect heart disease risk at high levels.

Steroid

Lipid with four fused carbon rings; includes cholesterol and hormone molecules.

Protein

A large, diverse class of biomolecules made of one or more polypeptides; functions include catalysis, structure, transport, signaling, and defense.

Amino acid

Organic molecule with an amino group, a carboxyl group, a hydrogen, and an R group attached to a central (α) carbon.

R group (side chain)

Variable group attached to the α carbon of an amino acid; determines its properties (nonpolar, polar, or charged).

Peptide bond

Covalent bond formed by a dehydration reaction between the carboxyl of one amino acid and the amino of another.

Polypeptide

A chain of amino acids; a protein is one or more folded polypeptides.

Primary structure

Linear sequence of amino acids in a protein.

Secondary structure

Hydrogen-bonded shapes within a polypeptide, including α helices and β pleated sheets.

α helix

Right-handed coiled secondary structure stabilized by hydrogen bonds every fourth amino acid.

β pleated sheet

Secondary structure where portions of a polypeptide lie side by side and are linked by hydrogen bonds.

Tertiary structure

Three-dimensional shape of a single polypeptide, determined by interactions among R groups.

Disulfide bridge

Covalent bond between cysteine residues that helps stabilize a protein’s structure.

Quaternary structure

When two or more polypeptide subunits assemble into a functional protein.

Chaperonin

Protein complex that assists the folding of other proteins by providing a protected environment.

Denaturation

Loss of a protein’s native structure and function due to heat, pH, or chemicals.

Renaturation

Return of a denatured protein to its functional conformation (not always possible).

Nucleic acid

Polymers made of nucleotides; store, transmit, and express hereditary information.

Nucleotide

Nucleoside attached to one or more phosphate groups; monomer of nucleic acids.

Nucleoside

Nitrogenous base attached to a sugar; without the phosphate.

Purine

Nucleic acid base with a two-ring structure (adenine and guanine).

Pyrimidine

Nucleic acid base with a single-ring structure (cytosine, thymine, and uracil).

Ribose

Five-carbon sugar in RNA.

Deoxyribose

Five-carbon sugar in DNA lacking the 2' hydroxyl group.

Phosphodiester bond

Covalent bond linking nucleotides between the 3' hydroxyl and the 5' phosphate.

5' end

End of a nucleic acid strand with a phosphate attached to the 5' carbon.

3' end

End of a nucleic acid strand with a hydroxyl group on the 3' carbon.

Double helix

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

Antiparallel

Two DNA strands run in opposite 5' to 3' directions.

Complementary base pairing

A pairs with T (or U in RNA) and G pairs with C, enabling exact copy and transcription.

Central dogma

DNA -> RNA -> protein; flow of genetic information in cells.

Genomics

Study of whole genomes to understand structure, function, and evolution.

Proteomics

Study of the full set of proteins (proteome) in a cell or organism.

Bioinformatics

Use of computer tools to analyze and interpret biological data, such as sequences and structures.

Genome

Complete set of genetic material present in an organism or cell.

mRNA (messenger RNA)

RNA that carries genetic information from DNA to the ribosome for protein synthesis.

tRNA (transfer RNA)

RNA that delivers amino acids to the ribosome during translation.