Video Notes: Levels of Organization and Biochemistry (Vocabulary)

This set covers key terms from the notes on chemical levels of organization, bonds, water, pH, biomolecules, and basic cellular biochemistry.

Element

A substance that cannot be broken down by ordinary chemical means; defined by its unique properties.

Atom

The smallest unit of an element that retains its properties.

Molecule

Two or more atoms bonded together.

Compound

Two or more different atoms joined together.

Protons

Positively charged subatomic particles in the nucleus.

Neutrons

Electrically neutral subatomic particles in the nucleus.

Electrons

Negatively charged subatomic particles orbiting the nucleus.

Nucleus

The center of an atom where protons and neutrons reside.

Orbital

Region around the nucleus where electrons are likely to be found.

Electron Shell

Energy levels around the nucleus that contain electrons.

Atomic Number

Number of protons in the nucleus; defines the element.

Mass Number

The average mass of all naturally occurring isotopes; protons plus neutrons.

Isotope

Atoms of the same element with a different number of neutrons.

Radioisotope

A radioactive isotope.

Half-life

Time required for a radioisotope to decay to half its mass.

Ion

Atom with a different number of electrons than protons, giving a net charge.

Cation

Positively charged ion formed by loss of electrons.

Anion

Negatively charged ion formed by gain of electrons.

Ionization

Process of gaining or losing electrons to become stable.

Ionic Bond

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

Covalent Bond

Bond formed by sharing electrons between atoms.

Polar Covalent Bond

Covalent bond with unequal sharing of electrons, creating partial charges.

Nonpolar Covalent Bond

Covalent bond with equal sharing of electrons.

Hydrogen Bond

Weak attraction between polar molecules involving hydrogen.

Van der Waals Force

Weak intermolecular forces due to momentary dipoles.

Hydrophobic Interaction

Attraction between nonpolar molecules in water.

Inorganic Compound

Typically lacks carbon and is structurally simple.

Organic Compound

Contains carbon and usually hydrogen; covalent bonds; more complex.

Water

Polar solvent; universal solvent with high cohesion and high heat capacity.

Hydration Shell

A layer of water surrounding dissolved ions or molecules.

pH

A measure of hydrogen ion concentration on a scale of 0 to 14.

Buffer

A system that resists changes in pH.

Acid

Proton donor; increases H+ concentration in solution.

Base

Proton acceptor; decreases H+ concentration in solution.

Salt

Dissociates into ions in water.

Monosaccharide

Simple sugar; basic carbohydrate unit.

Disaccharide

Two monosaccharides linked together.

Polysaccharide

Large carbohydrate polymer.

Carbohydrate

Organic biomolecule with CH2O ratio; major energy source.

Glycogen

Animal storage polysaccharide in liver and muscle.

Starch

Plant storage polysaccharide.

Cellulose

Plant structural polysaccharide.

Lipids

Hydrophobic biomolecules involved in energy storage and membranes.

Triglyceride

Lipid with glycerol backbone and three fatty acids.

Saturated Fat

Fat with only single bonds; tightly packed and solid.

Unsaturated Fat

Fat with one or more double bonds; kinked and usually liquid.

Trans Fat

Hydrogenated unsaturated fats; often unhealthy.

Phospholipid

Lipid with glycerol, two fatty acids, and a phosphate head; amphipathic.

Steroid

Lipid class with carbon rings; includes cholesterol and hormones.

Cholesterol

Sterol component of animal cell membranes and precursor to steroids.

Eicosanoid

20-carbon fatty acid derivatives used in signaling.

Prostaglandin

Eicosanoid class involved in inflammation and signaling.

Prostacyclin

Eicosanoid class involved in vascular function.

Thromboxane

Eicosanoid class involved in platelet aggregation.

Leukotriene

Eicosanoid class involved in inflammatory responses.

Nucleotide

Monomer of nucleic acids; base, sugar, and phosphate.

Nucleic Acid

Polymer of nucleotides; DNA or RNA.

DNA

Deoxyribonucleic acid; genetic material; typically double-stranded.

RNA

Ribonucleic acid; usually single-stranded; uracil replaces thymine.

Adenine

Purine base; pairs with thymine in DNA or uracil in RNA.

Thymine

Pyrimidine base in DNA; pairs with adenine.

Guanine

Purine base; pairs with cytosine.

Cytosine

Pyrimidine base; pairs with guanine.

Uracil

Pyrimidine base in RNA; replaces thymine.

mRNA

Messenger RNA; carries genetic code from DNA to ribosomes.

rRNA

Ribosomal RNA; structural component of ribosomes.

tRNA

Transfer RNA; brings amino acids to ribosomes.

Amino Acid

Building block of proteins; contains amino group, carboxyl group, and side chain.

Amino Group

NH2 functional group in amino acids.

Carboxyl Group

COOH functional group in amino acids.

Side Chain

Variable group attached to the alpha carbon in amino acids.

Primary Structure

Linear sequence of amino acids in a protein.

Secondary Structure

Alpha-helix or beta-pleated sheet stabilized by hydrogen bonds.

Tertiary Structure

Three-dimensional folding of a protein; globular or fibrous.

Quaternary Structure

Protein structure with multiple polypeptide chains.

Globular Protein

Spherical, functional proteins formed by tertiary/quaternary structure.

Fibrous Protein

Elongated proteins forming structural components.

Disulfide Bond

Covalent bond between sulfur atoms in cysteine; stabilizes structure.

Hydrogen Bond (Proteins)

Hydrogen bonds stabilizing protein structure.

Ionic Bond (Proteins)

Electrostatic interactions between charged side chains in proteins.

Denaturation

Loss of a protein’s 3D structure and function.

Carbon Skeleton

The carbon framework of an organic molecule.

Functional Group

Group of atoms that imparts characteristic properties.

Amphipathic

Molecule with both hydrophilic and hydrophobic regions.

Phospholipid Bilayer

Two-layer cell membrane with polar heads and nonpolar tails.

Water as Solvent

Water’s polarity allows it to dissolve many substances.

Hydration Sphere

Shell of water around dissolved ions.

Suspension

Mixture with large particles that do not stay evenly mixed.

Colloid

Mixture with particles that remain dispersed in water.

Solution

Mixture in which solute is dissolved in solvent.

Emulsion

Forced suspension of immiscible liquids in water.

Acid (in water)

Proton donor; increases H+ concentration.

Base (in water)

Proton acceptor; decreases H+ concentration.

Salt (in water)

Dissociates into ions in water.

Buffer System

System that resists pH changes.

Gastric Juice pH

pH of stomach fluid (about 1.2–3.0).

Blood pH Range

Normal blood pH around 7.35–7.45.

Bicarbonate Buffer

Carbonic acid–bicarbonate buffering system.

Glycogen

Animal storage polysaccharide in liver and muscle.

Starch

Plant storage polysaccharide.