Introduction to Chemistry in Microbiology

This flashcard set covers the foundational chemistry concepts presented in Chapter 1 through Chapter 8, including atomic structure, chemical bonding, reactions, and the four major classes of organic macromolecules.

Chemistry

The study of interactions between atoms and molecules.

Atom

The smallest unit of matter that can enter into a chemical reaction.

Atomic Number

The number of protons in an element, which defines the element.

Atomic Mass

The sum of the number of protons and neutrons in an atom, representing the mass of the nucleus.

Isotopes

Forms of an element that differ in the number of neutrons.

Radioisotopes

High energy isotopes that release energy as they break down to a more stable form; used as biological tracers like $H^{3}$ and $C^{14}$.

Valence Electrons

The electrons located in the outermost electron shell that determine an atom's chemical reactivity.

Molecular Formula

The ratio of elements in a molecule, often written with subscripts such as $H_2O$.

Structural Formula

A representation that shows how the atoms in a molecule are bonded together.

Ionic Bond

A chemical bond formed by the attraction between a cation (positively charged ion) and an anion (negatively charged ion).

Cation

An atom that has lost an electron, resulting in a positive charge.

Anion

An atom that has gained an electron, resulting in a negative charge.

Covalent Bond

A strong bond formed when two atoms share one or more pairs of electrons.

Nonpolar Covalent Bond

A bond where electrons are shared equally between atoms, resulting in no net charge; typical of lipids.

Polar Covalent Bond

A bond where electrons are shared unequally due to differences in electronegativity, creating a slight electrical charge (e.g., water).

Hydrogen Bond

A weak attraction between polar molecules, such as the bond between the positive hydrogen of one water molecule and the negative oxygen of another.

Endergonic Reaction

A chemical reaction that requires an input of energy to occur.

Exergonic Reaction

A chemical reaction that releases energy.

Anabolism

The endergonic process of combining molecules or atoms to build more complex molecules.

Catabolism

The exergonic process of breaking down complex molecules into simpler subunits, releasing energy.

Organic Compounds

Molecules that always contain carbon, oxygen, and hydrogen.

Inorganic Compounds

Molecules that typically lack one of the three elements: carbon, hydrogen, or oxygen (e.g., water, salts, acids, bases).

Solvent

The dissolving medium in a solution; in biological systems, this is typically water.

Solute

The substance that is dissolved in a solvent.

Hydrophilic

Molecules that are polar or ionic and dissolve easily in water.

Hydrophobic

Molecules that are nonpolar and do not dissolve in water, such as oils.

Hydration Shell

The sphere of water molecules that surrounds an ion when it dissolves in water, disrupting ionic bonds.

Acid

A substance that dissociates into hydrogen ions ($H^+$) and anions, increasing the concentration of protons in a solution.

Base

A substance that dissociates into hydroxyl ions ($OH^-$) and cations, decreasing the acidity of a solution.

pH Scale

A logarithmic scale ranging from 0 to 14, where 7 is neutral, less than 7 is acidic, and greater than 7 is basic.

Functional Groups

Common groups of elements that have specific chemical functions regardless of the molecule they are attached to.

Hydroxyl Group

A hydrophilic functional group represented as $-OH$, commonly found in alcohols and carbohydrates.

Amino Group

A hydrophilic functional group represented as $-NH_2$, essential in the structure of proteins.

Carboxyl Group

An acidic functional group represented as $-COOH$, important in protein structure.

Phosphate Group

A high-energy functional group important in DNA, RNA, lipids, and ATP.

Polymer

A large molecule made of similar repeating subunits called monomers covalently bonded together.

Condensation Reaction

A reaction that joins monomers together to build a polymer, generating a water molecule; also known as dehydration synthesis.

Hydrolysis Reaction

A reaction that breaks down polymers into monomers by adding a molecule of water.

Polysaccharides

Large carbohydrate polymers made of monosaccharides like glucose; examples include starch, glycogen, cellulose, and chitin.

Triglycerides

Energy-storing lipids composed of one glycerol and three fatty acids.

Phospholipid

An amphipathic molecule with hydrophilic and hydrophobic portions that forms the bilayer of plasma membranes.

Sterols

Lipids consisting of four fused carbon rings; includes structural molecules like cholesterol and ergosterol, as well as hormones.

Enzymes

Proteins that act as chemical catalysts absolutely needed for cellular reactions.

Amino Acids

The 20 different monomers that make up proteins, each containing an amino group, a carboxyl group, and a unique side chain (R group).

Peptide Bond

The covalent bond that joins adjacent amino acids in a polypeptide chain.

Primary Structure

The first level of protein structure, identifying the number and specific order of amino acids in a polypeptide chain.

Secondary Structure

The folding or coiling of a polypeptide chain into pleated sheets or an alpha helix, held together by hydrogen bonds.

Tertiary Structure

The overall three-dimensional shape of a single polypeptide, held by hydrogen, ionic, disulfide, and hydrophobic interactions.

Quaternary Structure

The interaction and bonding between different polypeptides to form a functional protein (e.g., hemoglobin).

DNA (Deoxyribonucleic Acid)

A double-stranded nucleic acid that uses deoxyribose sugar and stores genetic information in the nucleus.

RNA (Ribonucleic Acid)

A single-stranded nucleic acid that uses ribose sugar and uracil ($U$); it aids in converting DNA instructions into proteins.

Complementary Base Pairs

The specific pairing of nitrogen bases: Adenine to Thymine ($A-T$) in DNA, and Cytosine to Guanine ($C-G$).

ATP (Adenosine Triphosphate)

A modified nucleotide with three phosphate groups that stores and releases energy through high-energy phosphate bonds.