Biological Molecules - Vocabulary Flashcards

Vocabulary-style flashcards covering key terms from the notes on carbon, carbohydrates, lipids, proteins, and nucleic acids.

Carbon

A central element to life; most biological molecules are built on a carbon framework due to carbon’s ability to form stable covalent bonds with many atoms.

Carbon framework

The structural backbone of most biological molecules formed by carbon atoms.

Covalent bond

A chemical bond formed by sharing electrons, enabling carbon to bond with many different atoms.

Valence (four for carbon)

Carbon’s outer shell has four electrons available for bonding, allowing up to four covalent bonds.

Hydrocarbons

Carbon-hydrogen compounds whose skeletons determine carbon chain length, branching, double bonds, and rings.

Functional groups

Groups of atoms that confer specific properties (such as reactivity or polarity) to carbon-based molecules.

Hydroxyl group (-OH)

A functional group that forms alcohols when attached to a hydrocarbon.

Carboxyl group (-COOH)

A functional group found in fatty acids and amino acids.

Amino group (-NH2)

A functional group found in amino acids.

Phosphate group (-PO4)

A functional group found in DNA, ATP, and other nucleotides.

Monomer

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

Polymer

A large molecule made by linking many monomers together.

Dehydration synthesis

A reaction that links monomers by removing water to form a polymer.

Hydrolysis

A reaction that breaks polymers into monomers by adding water.

Monosaccharide

A simple sugar; the monomer of carbohydrates (e.g., glucose).

Disaccharide

Two monosaccharides joined together (e.g., lactose, sucrose).

Polysaccharide

A large carbohydrate polymer (e.g., starch, glycogen, cellulose, chitin).

Glucose

A common monosaccharide; key energy source; formula C6H12O6; often drawn in ring form.

Lactose

A disaccharide composed of galactose and glucose.

Sucrose

A disaccharide (table sugar) composed of glucose and fructose.

Starch

A polysaccharide that stores carbohydrate in plants; polymer of glucose.

Glycogen

A polysaccharide that stores carbohydrate in animals; polymer of glucose.

Cellulose

A rigid structural polysaccharide in plant cell walls; polymer of glucose with a different (insoluble) linkage; most abundant biological molecule on Earth.

Chitin

A tough carbohydrate forming the external skeleton of arthropods.

Isomer

Organic molecules with identical molecular formulas but different arrangements of atoms.

Isomer (structural)

Isomers that differ in the arrangement of atoms (structure) rather than just the arrangement in space.

Lipids

A diverse group of hydrophobic molecules that do not dissolve in water and lack a single monomer/polymer structure.

Fat (triglyceride)

A lipid composed of glycerol and three fatty acids; a major dietary fat.

Fatty acid

A hydrocarbon chain that ends with a carboxyl group; can be saturated or unsaturated.

Saturated fatty acid

Fatty acid with all carbon bonds saturated with hydrogen (no double bonds).

Unsaturated fatty acid

Fatty acid with one or more C=C double bonds after which more hydrogen could bond.

Triglyceride

A lipid with a glycerol backbone attached to three fatty acids; the main form of fat in animals and foods.

Glycerol

The three-carbon alcohol that forms the backbone of triglycerides.

Phospholipid

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

Amphipathic

Molecule possessing both hydrophobic (nonpolar) and hydrophilic (polar) regions, as in phospholipids.

Polar head

The hydrophilic, phosphate-containing region of a phospholipid.

Nonpolar tails

The hydrophobic fatty-acid tails of a phospholipid.

Waxes

Lipids consisting of a single fatty acid attached to a long-chain alcohol; provide protective sealing.

Steroids

Lipids with a core of four fused carbon rings; examples include cholesterol and hormones like testosterone and estrogen.

Cholesterol

A steroid important for cell membranes and steroid hormone synthesis.

Testosterone

A steroid hormone; example of a steroid with a four-ring structure.

Estrogen

A steroid hormone; example of a steroid with a four-ring structure.

Proteins

A diverse class of biomolecules made of amino acids; perform enzymes, structural roles, and more.

Amino acid

The monomer of proteins; consists of a central carbon, amino group, carboxyl group, and side chain.

Peptide bond

Covalent bond linking amino acids in a polypeptide.

Polypeptide

A chain of amino acids that folds into a functional protein.

Enzyme

A protein that accelerates chemical reactions.

Protein functions (categories)

Enzymes, hormones, protective toxins, transport, contractile, structural, storage, and signaling roles.

Hemoglobin

A protein that transports oxygen in the blood.

Myosin and Actin

Proteins that interact for muscle contraction.

Fibrinogen

A protein that helps stop bleeding (clot formation).

Antibody

A protein that defends against microbial invaders.

Keratin

A structural protein in hair and nails.

Collagen

A structural protein in cartilage and connective tissue.

Ovalbumin

Egg white protein used as a nutrient source for embryos.

Glycoprotein

A protein with carbohydrate groups; receptors on cell surfaces.

Lipoprotein

A complex of lipids and proteins that transports lipids in the blood (HDL, LDL).

HDL (High-Density Lipoprotein)

A lipoprotein particle that transports cholesterol in blood; often termed “good” cholesterol.

LDL (Low-Density Lipoprotein)

A lipoprotein particle that transports cholesterol in blood; associated with fatty deposits in vessels.

Nucleic Acids

Polymers composed of nucleotides; DNA and RNA are the two main types.

Nucleotide

The building block of nucleic acids; consists of a sugar, a phosphate group, and a nitrogenous base.

Deoxyribose

The five-carbon sugar in DNA nucleotides.

Nitrogenous base

The base component of nucleotides; part of the code in DNA and RNA.

DNA (Deoxyribonucleic Acid)

Nucleic acid that stores genetic information in a cell; sequence of bases encodes proteins.

RNA (Ribonucleic Acid)

Nucleic acid that helps translate genetic information into proteins; includes mRNA, rRNA, and tRNA.

mRNA (Messenger RNA)

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

rRNA (Ribosomal RNA)

RNA that is a component of ribosomes and aids protein synthesis.

tRNA (Transfer RNA)

RNA that brings amino acids to ribosomes for protein assembly.

Double helix

The two-stranded, spiraled structure of DNA formed by base pairing and hydrogen bonds.

Hydrogen bond (in DNA)

Weak bonds between paired bases that stabilize the DNA double helix.

DNA vs RNA roles

DNA stores genetic information; RNA transmits that information to ribosomes for protein synthesis.