Chapter 2: Chemistry and Organic Molecules (Biology Notes)

Vocabulary flashcards covering key chemistry concepts, bond types, macromolecules, reactions, and functional groups from the notes.

Element

A substance with unique chemical properties that cannot be broken down by ordinary chemical means.

Atom

The basic unit of matter; consists of a nucleus (protons and neutrons) with electrons around it.

Atomic number

The number of protons in an atom’s nucleus; defines the element.

Mass number

The sum of an atom’s protons and neutrons in the nucleus.

Proton

A positively charged subatomic particle located in the nucleus.

Neutron

A neutrally charged subatomic particle located in the nucleus.

Electron

A negatively charged subatomic particle orbiting the nucleus; held by attraction to protons.

Electron shell

An energy level where electrons are found; each shell has a capacity limit.

Valence electrons

Electrons in the outermost shell that determine chemical reactivity.

Lewis dot structure

A representation using dots to indicate the number of valence electrons.

Isotope

Atoms of the same element with the same atomic number but different mass numbers.

CHNOPS

Biologically important elements: Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, Sulfur.

Covalent bond

A bond formed by sharing one or more pairs of valence electrons.

Electronegativity

A measure of how strongly an atom attracts electrons in a bond.

Nonpolar covalent bond

A covalent bond in which electrons are shared equally due to similar electronegativity.

Polar covalent bond

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

Hydrogen bond

A weak attraction between a hydrogen atom in a polar molecule and an electronegative atom in another molecule.

Molarity

The concentration of a solution defined as moles of solute per liter of solution.

Solute

The substance dissolved in a solvent.

Solvent

The substance dissolving another substance; in biology, usually water.

Synthesis (chemical reaction)

Two or more reactants combine to form a larger product (A + B → AB).

Decomposition

A single compound breaks down into two or more products (AB → A + B).

Exchange reaction

Reactants trade components to form new products (AB + C → AC + B).

Redox (oxidation-reduction)

Reactions involving transfer of electrons between reactants; oxidation is loss, reduction is gain.

Oxidizing agent

A substance that accepts electrons and is reduced in a redox reaction.

Reducing agent

A substance that donates electrons and is oxidized in a redox reaction.

Enzymes

Proteins that bind substrates to speed up reactions by orienting them for bond changes.

Water (H2O)

A polar molecule with hydrogen bonding; oxygen is highly electronegative, leading to a network of bonds.

Hydrogen bond (in water context)

Weak attraction between a hydrogen of one molecule and an electronegative atom of another.

Hydrophilic

Water-loving; readily interacts with water.

Hydrophobic

Water-fearing; tends to repel or not dissolve in water.

Organic molecules

Compounds that contain carbon and are typically found in living organisms.

Macromolecule

Large polymers built from subunits (monomers) such as carbohydrates, lipids, proteins, and nucleic acids.

Monomer

A single subunit that can join with others to form a polymer.

Polymer

A large molecule made up of repeating monomer units.

Dehydration synthesis

A chemical reaction that removes a water molecule to form a covalent bond between subunits.

Hydrolysis

A chemical reaction that adds water to break covalent bonds between subunits.

Carbohydrates

Macromolecules made of monosaccharides; function as energy sources and structural components.

Monosaccharide

A simple sugar; the basic monomer of carbohydrates.

Lipids

Hydrophobic macromolecules involved in energy storage and membrane structure.

Proteins

Macromolecules made of amino acids; perform structural, enzymatic, signaling, and transport roles.

Nucleic acids

Macromolecules (DNA and RNA) made of nucleotides; store and express genetic information.

Nucleotide

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

DNA

Deoxyribonucleic acid; stores genetic information and directs protein synthesis.

RNA

Ribonucleic acid; participates in protein synthesis and often catalyzes reactions.

Functional groups

Specific groupings of atoms that impart characteristic properties to molecules.

Carboxyl group (-COOH)

Gives acids their properties; can donate H+ in solution.

Amino group (-NH2)

Can accept a proton and act as a base; found in amino acids.

Hydroxyl group (-OH)

Polar group found in alcohols; participates in dehydration synthesis and hydrolysis.

Aldehyde group (-CHO)

Carbonyl group at the end of a carbon skeleton; common in sugars.

Ketone group (C=O)

Carbonyl group within the carbon skeleton; common in sugars and other molecules.

Phosphate group (-OPO3H2)

Phosphate-containing group important in energy transfer (ATP) and nucleic acids.

Sulfhydryl group (-SH)

Thiol group that can form disulfide bonds, contributing to protein structure.

ATP (adenosine triphosphate)

Energy currency of the cell; stores and releases energy when phosphate bonds are broken.