Module 1: Chemistry Foundations for Anatomy & Physiology (BIOL 121)

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Chemistry Foundations in Anatomy & Physiology

Introduction

Chemistry is fundamental to understanding biological processes in Anatomy & Physiology. This module covers atomic structure, elements, chemical bonds, water properties, pH, macromolecules, and chemical reactions, providing the essential background for cellular and physiological functions.

Atoms and Elements

Atomic Structure

Atoms are the basic unit of matter and the smallest unit that retains the properties of an element. All living and non-living things are composed of atoms.

Atom: Smallest unit of matter; basic level of organization.
Element: Substance made of only one type of atom; defined by the number of subatomic particles.
Subatomic Particles: Atoms contain protons (positive charge), neutrons (neutral), and electrons (negative charge).

Elements in the Human Body

Elements are classified by their atomic number, symbol, and mass. The human body is primarily composed of a few key elements.

Element	Symbol	Approximate % in Body
Oxygen	O	65%
Carbon	C	18%
Hydrogen	H	10%
Nitrogen	N	3%
Calcium	Ca	1.5%
Phosphorus	P	1%
Others	-	1.5%

Additional info: Trace elements such as iron (Fe), magnesium (Mg), and zinc (Zn) are also essential for physiological functions.

The Periodic Table

The periodic table organizes elements by atomic number and provides key information:

Atomic number: Number of protons (and electrons in a neutral atom).
Atomic symbol: Abbreviation for the element's name.
Atomic mass: Number of protons plus neutrons.

Atomic Structure and Electron Arrangement

Subatomic Particles

Protons: Positive charge, located in the nucleus.
Neutrons: No charge, located in the nucleus.
Electrons: Negative charge, orbit the nucleus in energy levels.

Example: Carbon atom has 6 protons, 6 neutrons, and 6 electrons.

Electron Energy Levels and Valence Electrons

Electrons occupy defined energy levels (shells): 1st, 2nd, 3rd, etc.
Valence electrons: Electrons in the outermost shell; determine chemical reactivity and bonding.

Chemical Bonds

Types of Chemical Bonds

Chemical bonds form when atoms interact to achieve stable electron configurations. There are three major types:

Ionic bonds: Formed by the transfer of electrons from one atom to another, resulting in oppositely charged ions that attract each other.
Covalent bonds: Formed by the sharing of electron pairs between atoms. Can be nonpolar (equal sharing) or polar (unequal sharing).
Hydrogen bonds: Weak attractions between polar molecules, especially involving hydrogen and electronegative atoms like oxygen or nitrogen. Vital for the structure of water, DNA, and proteins.

Example: In water (H2O), hydrogen bonds form between adjacent water molecules.

Properties of Water

Water as a Universal Solvent

Water dissolves many substances due to its polarity, making it essential for biological reactions.

Solvent: Substance present in greater quantity; dissolves solutes.
Solute: Substance dissolved in the solvent.
Solution: Combination of solvent and solute(s).

Other Properties of Water

High heat capacity: Absorbs and retains heat, helping regulate body temperature.
Lubrication: Reduces friction in joints and organs.
Cushioning: Protects organs from physical impact (e.g., cerebrospinal fluid around the brain).
Cohesion and adhesion: Water molecules stick to each other (cohesion) and to other surfaces (adhesion).
Hydrolysis: Water is required to break chemical bonds during digestion and metabolism.

pH and Acids/Bases

pH Scale

pH measures the concentration of hydrogen ions (H+) in a solution, ranging from 0 (acidic) to 14 (basic).

Acids: Release H+ ions; lower pH.
Bases: Remove H+ ions; raise pH.
Buffers: Prevent major shifts in pH, maintaining homeostasis.

Equation:

Macromolecules

Types of Macromolecules

Macromolecules are large organic molecules essential for life. They are classified into four categories:

Carbohydrates: Composed of C, H, and O. Monomers are monosaccharides; polymers are polysaccharides. Used for energy and energy storage.
Lipids: Composed of C, H, and O. Monomers are fatty acids; polymers include triglycerides and phospholipids. Used for long-term energy storage, cushioning, and cell membrane structure.
Proteins: Composed of C, H, O, and N. Monomers are amino acids; polymers are polypeptides. Serve structural, enzymatic, transport, and signaling functions.
Nucleic acids: Composed of C, H, O, N, and P. Monomers are nucleotides; polymers are DNA and RNA. Store and transmit genetic information.

Monomers and Polymers

Monomers: Small, repeating units.
Polymers: Large molecules made by bonding monomers (via dehydration synthesis).
Hydrolysis: Polymers are broken down into monomers by adding water.

Protein Structure

Protein function depends on its structure, which is organized into four levels:

Primary: Amino acid sequence.
Secondary: Hydrogen bonding forms alpha-helices and beta-sheets.
Tertiary: Further folding into a functional protein.
Quaternary: Association of multiple polypeptides (not present in all proteins).

Denaturation (loss of structure) leads to loss of function, caused by changes in temperature, pH, or chemicals.

Nucleic Acids

DNA: Double-stranded; stores genetic information. Bases: Adenine (A), Thymine (T), Cytosine (C), Guanine (G).
RNA: Single-stranded; involved in protein synthesis. Bases: Adenine (A), Uracil (U), Cytosine (C), Guanine (G).
Complementary base pairing: In DNA, A pairs with T, and C pairs with G.

Chemical Reactions

Types of Chemical Reactions

Chemical reactions involve breaking or forming bonds between atoms. Four main types:

Synthesis reactions: Combine smaller molecules into larger ones; anabolic and require energy.
Decomposition reactions: Break larger molecules into smaller ones; catabolic and release energy.
Exchange reactions: Bonds are both broken and formed.
Reversible reactions: Can proceed in both directions under certain conditions.

Enzymes

Enzymes are proteins that catalyze chemical reactions, increasing reaction rates and supporting life.

Enzymes do not make reactions occur that would not happen otherwise.
Enzymes are specific to their substrate.
Enzymes are not used up or permanently altered in the reaction.
Enzymes can catalyze reactions in both directions.

Example: ATP (adenosine triphosphate) is the molecule that provides direct energy for most cellular processes.

Summary Table: Macromolecules

Type	Monomer	Polymer	Main Functions
Carbohydrates	Monosaccharides	Polysaccharides	Energy source, energy storage
Lipids	Fatty acids	Triglycerides, phospholipids	Long-term energy, cushioning, cell membranes
Proteins	Amino acids	Polypeptides	Structure, enzymes, transport, signaling
Nucleic acids	Nucleotides	DNA, RNA	Genetic information, protein synthesis

Additional info: This module provides foundational chemistry concepts necessary for understanding cellular structure, metabolism, and physiological regulation in the human body.