Organic Molecules, Carbohydrates, Lipids & Proteins – Key Vocabulary

Flashcards covering fundamental vocabulary from the lecture on organic molecules, carbohydrates, lipids, and proteins.

Organic Chemistry

Branch of chemistry that studies carbon-containing molecules found in living organisms.

Organic Molecule

Compound that contains both carbon and at least one hydrogen atom.

Carbon Backbone

The chain or ring of carbon atoms that forms the structural framework of an organic molecule.

Hydrocarbon

Simplest organic molecule consisting only of carbon and hydrogen; often used as fuel.

Functional Group

Specific cluster of atoms that confers characteristic chemical properties to an organic molecule.

Hydroxyl Group (-OH)

Polar functional group characteristic of alcohols; increases solubility in water.

Carbonyl Group (C=O)

Polar functional group; forms aldehydes when at chain end and ketones when internal.

Carboxyl Group (-COOH)

Acidic functional group that can release H⁺; found in fatty acids and amino acids.

Amino Group (-NH₂)

Basic functional group that can accept H⁺; present in amino acids.

Sulfhydryl Group (-SH)

Polar group able to form disulfide bonds important in protein structure.

Methyl Group (-CH₃)

Non-polar functional group that reduces polarity of molecules.

Phosphate Group (-PO₄²⁻)

Acidic, negatively charged group found in nucleic acids and ATP.

Hydrophilic

Describes molecules that interact well with water due to polarity or charge.

Hydrophobic

Describes non-polar molecules that avoid water.

Isomer

Molecules with the same molecular formula but different structural arrangement.

Macromolecule

Very large organic molecule composed of many smaller subunits.

Monomer

Small organic subunit that can join with others to form polymers.

Dimer

Molecule made of two covalently bonded monomers.

Polymer

Chain of three or more covalently bonded monomers.

Dehydration Synthesis

Anabolic reaction that joins monomers by removing a molecule of water; requires energy.

Hydrolysis

Catabolic reaction that splits polymers by adding water; releases energy.

Monosaccharide

Single sugar unit; carbohydrate monomer (e.g., glucose).

Disaccharide

Sugar composed of two monosaccharides linked by a glycosidic bond.

Polysaccharide

Long chain of monosaccharides; carbohydrate polymer such as starch.

Hexose

Six-carbon monosaccharide (e.g., glucose, fructose, galactose).

Pentose

Five-carbon monosaccharide (e.g., ribose, deoxyribose).

Glucose

Primary six-carbon sugar used by cells for ATP production; "blood sugar."

Fructose

Sweet six-carbon sugar found in fruits and honey; isomer of glucose.

Galactose

Six-carbon sugar present in milk; combines with glucose to form lactose.

Ribose

Pentose sugar found in RNA nucleotides.

Deoxyribose

Pentose sugar in DNA; lacks an oxygen on carbon-2.

Glycosidic Linkage

Covalent bond joining two monosaccharides after dehydration synthesis.

Starch

Plant polysaccharide of glucose used for energy storage; includes amylose and amylopectin.

Glycogen

Highly branched animal polysaccharide of glucose stored in liver and muscle.

Cellulose

Structural polysaccharide in plant cell walls; indigestible to humans.

Chitin

Nitrogen-containing polysaccharide forming fungal cell walls and arthropod exoskeletons.

Lipid

Hydrophobic organic macromolecule primarily made of C and H; includes fats, oils, waxes, steroids, phospholipids.

Triglyceride

Lipid consisting of glycerol bound to three fatty acids; main energy storage fat.

Glycerol

Three-carbon alcohol that forms the backbone of triglycerides.

Fatty Acid

Long hydrocarbon chain with a terminal carboxyl group; building block of fats.

Saturated Fatty Acid

Fatty acid with no carbon-carbon double bonds; straight chains, solid at room temp.

Unsaturated Fatty Acid

Fatty acid containing one (mono-) or more (poly-) C=C double bonds; liquid oils.

Cis Configuration

Arrangement where hydrogens attached to C=C are on the same side, producing a kink.

Trans Configuration

Arrangement where hydrogens on C=C are opposite sides; straighter chain, often in processed fats.

Hydrogenation

Industrial addition of hydrogen to unsaturated oils converting them toward saturated or trans fats.

Phospholipid

Amphipathic lipid with glycerol, two fatty acids, and a phosphate group; forms cell membranes.

Steroid

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

Wax

Lipid composed of long fatty acid chains linked to alcohols; protective and water-resistant.

Amphipathic

Molecule possessing both hydrophilic and hydrophobic regions (e.g., phospholipid).

Protein

Macromolecule of one or more polypeptides folded into a specific 3-D shape.

Amino Acid

Protein monomer containing amino group, carboxyl group, hydrogen, and variable R group.

Peptide Bond

Covalent bond between carboxyl of one amino acid and amino of another.

Primary Structure

Linear sequence of amino acids in a polypeptide.

Secondary Structure

Local folding into α-helices or β-pleated sheets via backbone hydrogen bonding.

Tertiary Structure

Overall 3-D folding of a single polypeptide driven by R-group interactions.

Quaternary Structure

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

Denaturation

Loss of a protein’s native shape (and function) due to heat, pH change, or salts.

Essential Amino Acid

Amino acid that humans cannot synthesize and must obtain from diet.

Disulfide Bond

Strong covalent linkage between two cysteine R groups that stabilizes protein structure.

Enzyme

Protein catalyst that speeds up specific biochemical reactions without being consumed.

Collagen

Fibrous structural protein providing strength to skin, bone, and connective tissue.

Hemoglobin

Quaternary protein in red blood cells that transports oxygen.

Hormone (protein)

Protein messenger, such as insulin, that regulates physiological processes.