Lecture Notes: Proteins, Nucleic Acids, and Large Biological Molecules (Vocabulary Flashcards)

Vocabulary flashcards covering major terms from proteins, enzymes, nucleic acids, and large biological molecules as presented in the notes.

Protein

A large class of biomolecules built from one or more polypeptides; functions include structural support, storage, transport, signaling, movement, and defense; account for more than 50% of the dry mass of many cells.

Polypeptide

A polymer of amino acids; a protein consists of one or more polypeptides.

Amino acid

Organic molecules with an amino group, a carboxyl group, and a distinctive side chain (R) that determines properties; 20 common types.

Peptide bond

Covalent bond linking amino acids; formed between the carboxyl group of one amino acid and the amino group of the next, creating a polypeptide backbone.

N-terminus

The amino (NH2) end of a polypeptide chain.

C-terminus

The carboxyl (COOH) end of a polypeptide chain.

Primary structure

The linear sequence of amino acids in a protein, determined by genes.

Secondary structure

Local folded structures of a polypeptide backbone, including alpha helices and beta pleated sheets, stabilized by hydrogen bonds.

Alpha helix

A right-handed coiled structure that is a common type of secondary structure.

Beta pleated sheet

A secondary structure with strands connected by hydrogen bonds, forming a folded sheet.

Tertiary structure

The overall three-dimensional shape of a single polypeptide, determined by interactions among R groups (hydrogen bonds, ionic, hydrophobic, van der Waals) and disulfide bridges.

Disulfide bridge

A covalent bond between sulfur atoms in cysteine side chains, strengthening the protein's structure.

Quaternary structure

Structure that results when a protein consists of multiple polypeptide chains (e.g., collagen, hemoglobin).

Sickle-cell disease

Inherited disorder caused by a single amino acid substitution in hemoglobin, leading to abnormal fiber formation and sickled red blood cells.

Denaturation

Unfolding of a protein and loss of native structure and function due to changes in pH, salt concentration, temperature, or other factors.

Chaperonin

A protein complex that assists the proper folding of other proteins; often forms a hollow cylinder with a cap.

X-ray crystallography

Technique to determine a protein’s structure by diffracting X-rays through crystals.

NMR spectroscopy

Nuclear magnetic resonance spectroscopy; determines protein structure without crystallization.

Gene

A unit of inheritance made of DNA that programs the amino acid sequence of a protein.

DNA

Deoxyribonucleic acid; a nucleic acid that stores hereditary information; typically double-stranded; sugar is deoxyribose; bases are A, C, G, T.

RNA

Ribonucleic acid; a nucleic acid involved in transcription and translation; typically single-stranded; sugar is ribose; bases are A, C, G, U.

Nucleotide

Monomer of nucleic acids consisting of a nitrogenous base, a sugar, and a phosphate group.

Nucleoside

Nitrogenous base bound to a sugar; lacks the phosphate group.

Purine

A two-ring nitrogenous base family including adenine (A) and guinine (G).

Pyrimidine

A single-ring nitrogenous base family including cytosine (C), thymine (T), and uracil (U).

Glycosidic linkage

Bond between a sugar and a nitrogenous base in a nucleotide.

Phosphodiester linkage

Bond linking the 3' hydroxyl of one sugar to the 5' phosphate of the next, forming the backbone of nucleic acids.

DNA double helix

Two polynucleotide strands wound around an axis in an antiparallel arrangement; base pairs A–T and G–C maintain hydrogen bonding.

Monosaccharide

A simple sugar (e.g., glucose, fructose), the basic unit of carbohydrates.

Disaccharide

Carbohydrate composed of two monosaccharides (e.g., lactose, sucrose).

Polysaccharide

Long polymer of monosaccharides; includes cellulose, starch, glycogen, and chitin.

Enzyme

A protein that acts as a catalyst to accelerate chemical reactions; can catalyze repeatedly.

Ribosome

Molecular machine where protein synthesis occurs; composed of RNA and proteins.

DNA as a tape measure of evolution

Similarity of DNA sequences between species reflects evolutionary relatedness and kinship.

List and describe the four major classes of

molecules

The major classes of molecules are carbohydrates, lipids, proteins, and nucleic acids

Describe the formation of a glycosidic linkage

and distinguish between monosaccharides,

disaccharides, and polysaccharides

forms when two monosaccharides join by dehydration, making disaccharides (two sugars) or polysaccharides (many sugars)

Distinguish between saturated and

unsaturated fats and between cis and trans fat

molecules

Saturated fats have no double bonds and are solid at room temp, while unsaturated fats have double bonds and are liquid; cis fats bend at the bond while trans fats are straight

Describe the four levels of protein structure

Proteins have primary (amino acid sequence), secondary (folding into α-helices/β-sheets), tertiary (3D shape), and quaternary (multiple chains) structures.

Distinguish between the following pairs:

pyrimidine and purine, nucleotide and

nucleoside, ribose and deoxyribose, the 5′

end and 3′ end of a nucleotide

Pyrimidines are single-ring bases while purines are double-ring; a nucleotide is a nucleoside plus phosphate; ribose has an -OH on carbon 2 while deoxyribose lacks it; the 5′ end has a phosphate group and the 3′ end has a hydroxyl group.