Fundamental Chemistry Concepts for Anatomy & Physiology

Basic Atomic and Chemical Structures

Atoms, Ions, and Related Structures

Understanding the basic building blocks of matter is essential for studying Anatomy & Physiology. The following terms are foundational:

• Atom: The smallest unit of an element that retains its chemical properties. Composed of protons, neutrons, and electrons.

• Proton: Positively charged particle found in the nucleus of an atom.

• Neutron: Neutral particle found in the nucleus.

• Electron: Negatively charged particle orbiting the nucleus.

• Isotope: Atoms of the same element with different numbers of neutrons.

• Ion: An atom or molecule with a net electric charge due to the loss or gain of electrons.

• Cation: A positively charged ion (lost electrons).

• Anion: A negatively charged ion (gained electrons).

• Electrolyte: A substance that dissociates into ions in solution, conducting electricity.

Chemical Symbols of Key Elements

Familiarity with the chemical symbols of biologically important elements is crucial:

• Hydrogen (H)

• Carbon (C)

• Nitrogen (N)

• Oxygen (O)

• Sodium (Na)

• Phosphorus (P)

• Chlorine (Cl)

• Potassium (K)

• Calcium (Ca)

Chemical Bonds and Interactions

Types of Chemical Bonds

Chemical bonds are forces that hold atoms together in molecules and compounds:

• Ionic Bonds: Formed when electrons are transferred from one atom to another, resulting in oppositely charged ions that attract each other.

• Covalent Bonds: Formed when two atoms share one or more pairs of electrons.

• Hydrogen Bonds: Weak attractions between a hydrogen atom (already covalently bonded to an electronegative atom) and another electronegative atom.

• Van der Waals Forces: Weak, non-specific attractions between molecules due to transient dipoles.

Properties of Molecules

Hydrophobic, Hydrophilic, and Amphipathic

• Hydrophobic: Molecules that repel water ("water-fearing"); typically nonpolar.

• Hydrophilic: Molecules that interact well with water ("water-loving"); typically polar or charged.

• Amphipathic: Molecules that have both hydrophobic and hydrophilic regions (e.g., phospholipids).

Solutions and Catalysts

Solvent, Solute, and Solution

• Solvent: The substance in which a solute is dissolved (e.g., water in biological systems).

• Solute: The substance dissolved in a solvent.

• Solution: A homogeneous mixture of solute and solvent.

Catalysts

• Catalyst: A substance that increases the rate of a chemical reaction without being consumed in the process. In biology, most catalysts are enzymes.

Acids, Bases, and Buffers

pH Scale and Buffer Systems

• pH Scale: Measures the concentration of hydrogen ions ($[H^+]$) in a solution. Ranges from 0 (most acidic) to 14 (most basic).

• Acid: Substance that donates hydrogen ions ($H^+$) to a solution.

• Base: Substance that accepts hydrogen ions or donates hydroxide ions ($OH^-$).

• Buffer: A system that minimizes changes in pH by absorbing or releasing $H^+$ ions.

• Neutral pH: pH 7.0 (pure water).

• Expected pH for blood: Approximately 7.4 (slightly basic).

Formula:

$pH = -\log_{10}[H^+]$

Macromolecules and Their Building Blocks

Monomers and Polymers

• Monomer: A small molecule that can join with others to form a polymer (e.g., amino acids, nucleotides).

• Polymer: A large molecule made up of repeating monomer units (e.g., proteins, nucleic acids).

Lipids

• Fatty Acid Tail: Long hydrocarbon chain, hydrophobic in nature.

• Phospholipid: A lipid containing a phosphate group; forms the bilayer of cell membranes.

• Bilayer: Double layer structure formed by phospholipids in aqueous environments.

• Triglycerides: Composed of three fatty acids and one glycerol; main form of stored fat in the body.

• Phospholipids: Major component of cell membranes, with hydrophilic heads and hydrophobic tails.

Carbohydrates

• Monosaccharide: Simple sugar (e.g., glucose).

• Disaccharide: Two monosaccharides joined together (e.g., sucrose).

• Polysaccharide: Many monosaccharides linked together (e.g., glycogen, starch).

• Glucose: Primary energy source for cells.

• Glycogen: Storage form of glucose in animals, especially in liver and muscle.

• Usage in Body: Glucose is used for immediate energy; glycogen is stored for later use.

Nucleic Acids

• Nucleotide: Monomer of nucleic acids, composed of a sugar, phosphate group, and nitrogenous base.

• Deoxyribonucleic Acid (DNA): Stores genetic information.

• Ribonucleic Acid (RNA): Involved in protein synthesis and gene regulation.

Bases in DNA and RNA

• DNA Bases: Adenine (A), Thymine (T), Cytosine (C), Guanine (G)

• RNA Bases: Adenine (A), Uracil (U), Cytosine (C), Guanine (G)

• Base Pairing: In DNA, A pairs with T, and C pairs with G. In RNA, A pairs with U, and C pairs with G.

Type	Bases	Pairing
DNA	A, T, C, G	A-T, C-G
RNA	A, U, C, G	A-U, C-G

Proteins and Protein Structure

Protein Structure and Function

• Amino Acids: Monomers of proteins; 20 standard amino acids exist.

• Protein Structure: Proteins have four levels of structure: primary (amino acid sequence), secondary (alpha helices and beta sheets), tertiary (3D folding), and quaternary (multiple polypeptides).

• Functions: Enzymes, structural support, transport, signaling, immune response, etc.

Example: Hemoglobin is a protein that transports oxygen in the blood.