Chapter 2: The Chemical Level of Organization (BIO 141) – Study Notes

Chapter 2: The Chemical Level of Organization

Introduction

This chapter explores the fundamental chemical principles underlying anatomy and physiology. Understanding the chemical level of organization is essential for comprehending how the body functions at the molecular and cellular levels.

Learning Outcomes

• Describe atomic structure and how it relates to chemical bonding.

• Explain the types of chemical bonds and their physiological significance.

• Discuss the major types of chemical reactions important to physiology.

• Describe the role of enzymes in metabolism.

• Differentiate between inorganic and organic compounds and their roles in the body.

• Explain the chemical properties of water and its importance in physiology.

• Describe the structures and functions of carbohydrates, lipids, proteins, and nucleic acids.

• Discuss the structure and function of energy compounds.

The Basic Particles of Matter

Definitions and Key Concepts

• Chemistry: The science that deals with the structure of matter.

• Matter: Anything that takes up space and has mass.

• Mass: The amount of material in matter.

• Atom: The smallest stable unit of matter.

Subatomic Particles

• Proton: Positively charged particle found in the nucleus.

• Neutron: Neutral particle found in the nucleus.

• Electron: Negatively charged particle found in the electron cloud surrounding the nucleus.

Atomic Structure

• Atomic Number: The number of protons in an atom, which determines the element.

• Electron Cloud: The region around the nucleus where electrons are likely to be found.

• The arrangement of electrons determines the chemical properties of an atom.

Elements and Isotopes

• Element: A pure substance composed of atoms of only one kind; cannot be changed or broken down into simpler substances by ordinary chemical means.

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

• Mass Number: The total number of protons plus neutrons in an atom.

• Radioisotope: Isotopes with unstable nuclei that undergo radioactive decay.

• Half-life: The time required for half of a given amount of a radioisotope to decay.

Atomic Weights

• Actual Mass: The actual mass of an atom of a specific isotope.

• Atomic Weight: The average mass of all the isotopes of an element, weighted by their relative abundance.

• Dalton (amu): Standardized unit of measurement for atomic mass (atomic mass unit).

Atoms and Energy Levels

Electrons occupy energy levels (shells) around the nucleus. The arrangement of electrons in these shells determines how atoms interact and bond with each other.

• The first energy level can hold up to 2 electrons.

• The second and third energy levels can each hold up to 8 electrons.

• Atoms are most stable when their outermost energy level is full.

Example: Hydrogen (1 electron), Helium (2 electrons), Lithium (3 electrons), Neon (10 electrons).

Elements of the Human Body

The human body is composed of several essential elements, each with specific physiological roles.

Element	Significance
Oxygen (O)	Component of water and other compounds; essential for cellular respiration.
Carbon (C)	Found in all organic molecules.
Hydrogen (H)	Component of water and most other compounds in the body.
Nitrogen (N)	Found in proteins, nucleic acids, and other organic compounds.
Calcium (Ca)	Found in bones and teeth; important for membrane function, nerve impulses, muscle contraction, and blood clotting.
Phosphorus (P)	Found in bones and teeth, nucleic acids, and high-energy compounds.
Potassium (K)	Important for proper membrane function, nerve impulses, and muscle contraction.
Sodium (Na)	Important for blood volume, membrane function, nerve impulses, and muscle contraction.
Chlorine (Cl)	Important for blood volume, membrane function, and water absorption.
Magnesium (Mg)	Cofactor for many enzymes.
Iron (Fe)	Essential for oxygen transport and energy capture.
Iodine (I)	Component of hormones of the thyroid gland.
Trace elements	Some function as cofactors; the functions of many trace elements are poorly understood.

Additional info: Trace elements include elements such as zinc (Zn), copper (Cu), selenium (Se), and others, which are required in very small amounts but are vital for health.