Unit 1: Biochemistry

Vocabulary flashcards covering key terms from Unit 1 Biochemistry.

Chemical Bond

An attraction between atoms that holds them together in compounds.

Ionic Bond

A bond formed by the electrostatic attraction between oppositely charged ions.

Covalent Bond

A bond formed when atoms share electrons to fill their octets.

Polar Covalent Bond

A covalent bond where electrons are shared unequally, creating partial charges.

Nonpolar Covalent Bond

A covalent bond where electrons are shared equally, resulting in no partial charges.

Single Bond

A covalent bond that shares two electrons between atoms.

Double Bond

A covalent bond that shares four electrons between atoms.

Triple Bond

A covalent bond that shares six electrons between atoms.

Hydrogen Bond

An attraction between a slightly positive H and a highly electronegative atom (F, O, N).

H2 Gas

Molecule with nonpolar covalent bonding; homonuclear diatomic molecules are nonpolar.

Ion

An atom or molecule with a net electric charge.

Anion

A negatively charged ion.

Cation

A positively charged ion.

Molecular Formula

A formula showing the number of atoms of each element in a molecule.

Molecular Structure

A diagram or formula showing how atoms in a molecule are bonded.

CHONPS

The six most abundant elements in living organisms: Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, Sulfur.

Isomer

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

Enantiomer

Isomers that are non-superimposable mirror images of each other.

Racemic Mixture

A mixture containing equal amounts of two enantiomers.

Polarity

Unequal sharing of electrons within a molecule, leading to partial charges.

δ+ / δ-

Partial positive and partial negative charges in polar molecules.

Water: High Specific Heat

Water’s ability to absorb a lot of heat with little change in temperature.

Water: High Heat of Vaporization

Water requires a lot of energy to convert from liquid to gas.

Water: Cohesion

Attraction between water molecules.

Water: Adhesion

Attraction between water and other substances.

Water: Surface Tension

Tension at the surface of a water interface due to cohesive forces.

Water: Universal Solvent

Water dissolves many substances because of its polarity.

Water: Density of Ice

Solid water (ice) is less dense than liquid water and floats.

CHO Elements

The primary elements (C, H, O) and others that form organic molecules.

Organic Chemistry

The study of carbon-containing compounds.

Carbon

Atom that forms four covalent bonds and underlies organic chemistry.

Functional Group

A specific group of atoms within a molecule that determines chemical behavior.

Hydroxyl

–OH group; polar, involved in hydrogen bonding (found in alcohols, sugars).

Amino

–NH2 group; basic; participates in hydrogen bonding.

Carboxyl

–COOH group; acidic and hydrogen-bonding capable.

Phosphate

–OPO3^2− group; acidic, negatively charged; important in nucleic acids and energy transfer.

Methyl

–CH3 group; nonpolar.

pH

A measure of how acidic or basic a solution is (0–14; -log[H+]).

Acidic

pH less than 7; excess H+ ions.

Basic

pH greater than 7; excess OH− ions.

Neutral

pH equal to 7; balanced H+ and OH−.

Dehydration Synthesis

A reaction that links monomers by removing water, forming a covalent bond.

Hydrolysis

A reaction that cleaves bonds by adding water, breaking polymers into monomers.

Monomer

A small subunit that can join with others to form polymers.

Polymer

A large molecule made of many monomers bonded together.

Glycosidic Bond

Covalent bond linking monosaccharides in carbohydrates.

Monosaccharide

Simple sugar; glucose, fructose, galactose; building blocks of carbs.

Disaccharide

Two monosaccharides joined by a glycosidic bond.

Polysaccharide

Large carbohydrate polymers (starch, glycogen, cellulose, etc.).

Glycogen

Polysaccharide used by animals for energy storage.

Starch

Polysaccharide used by plants for energy storage.

Cellulose

Polysaccharide used by plants for structural support in cell walls.

Chitin

Polysaccharide found in fungi and exoskeletons for support.

Peptidoglycan

Structural polymer in bacterial cell walls.

Glucose

C6H12O6; a common monosaccharide; isomers include fructose and galactose.

Fructose

Monosaccharide isomer of glucose.

Galactose

Monosaccharide isomer of glucose.

Lipids

Hydrophobic molecules primarily made of fatty acids; include fats, oils, phospholipids, steroids, waxes.

Fatty Acids

Long hydrocarbon chains ending in a carboxyl group; can be saturated or unsaturated.

Ester Bond

Bond formed when a fatty acid bonds to glycerol, releasing water.

Triglycerides

Glycerol + three fatty acids; major form of energy storage in animals.

Glycerol

Three-carbon backbone of triglycerides with three hydroxyl groups.

Saturated

Fatty acids with only single C–C bonds; usually solid at room temperature.

Unsaturated

Fatty acids with one or more C=C bonds; kinked; usually liquid at room temperature.

Phospholipids

Lipids with glycerol, two fatty acids, and a phosphate group; amphipathic; form cell membranes.

Amphipathic

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

Steroids

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

Cholesterol

Steroid important for membrane fluidity and as a precursor to hormones.

Waxes

Esters formed from fatty acids and alcohols; water-repellent protective coatings.

Nucleic Acids

Polymers that store and transmit genetic information (DNA and RNA).

Nucleotide

Monomer of nucleic acids: sugar, phosphate, and nitrogenous base.

DNA

Deoxyribonucleic acid; stores genetic information; usually double-stranded; bases A, T, G, C.

RNA

Ribonucleic acid; various roles in protein synthesis; bases A, U, G, C; usually single-stranded.

Adenine

Purine base that pairs with Thymine in DNA and with Uracil in RNA.

Thymine

Pyrimidine base in DNA that pairs with Adenine.

Cytosine

Pyrimidine base that pairs with Guanine in both DNA and RNA.

Guanine

Purine base that pairs with Cytosine.

Uracil

Pyrimidine base in RNA that pairs with Adenine.

A-T / A-U / C-G Pairing

Base pairing rules: A pairs with T (2 H bonds) in DNA; A pairs with U (2 H bonds) in RNA; C pairs with G (3 H bonds).

Antiparallel

DNA strands run in opposite directions (5' to 3' and 3' to 5').

5' End / 3' End

Ends of nucleic acid strands; 5' has a phosphate; 3' has a hydroxyl.

Phosphodiester Bond

Bond between the phosphate and sugar in the backbone of DNA/RNA.

ATP

Adenosine triphosphate; energy currency of the cell; energy released by hydrolysis.

Amino Acids

Monomers of proteins; central carbon with amino, carboxyl, hydrogen, and R group.

Peptide Bond

Bond between the carboxyl of one amino acid and the amino of the next.

Primary Structure

Linear sequence of amino acids in a protein.

Secondary Structure

Folds into alpha helices or beta-pleated sheets stabilized by hydrogen bonds.

Tertiary Structure

Three-dimensional folding of a protein stabilized by formation of hydrogen bonds, hydrophobic interactions, ionic interactions, and disulfide bridges

Disulfide Bond

Covalent bond between cysteine residues that helps stabilize protein structure.

Quaternary Structure

Protein structure comprising more than one polypeptide chain.

Globular / Fibrous

Globular: compact, soluble proteins; Fibrous: elongated, structural proteins.

Keratin

Fibrous protein in hair; strength partly due to disulfide bonds.

Denaturation

Unfolding of a protein due to heat or pH changes, disrupting function.