Biochemistry and Its Relevance to Anatomy & Physiology

Introduction to Biochemistry in A&P

Biochemistry is the study of the chemical processes and substances that occur within living organisms. It is fundamental to understanding cytology (cell biology), histology (tissue biology), and physiology (function of living systems).

• Biochemical molecules such as carbohydrates, lipids, proteins, and nucleic acids are essential for life.

• Each class of biomolecule is composed of specific elements: carbohydrates and lipids (C, H, O), proteins (C, H, O, N), nucleic acids (C, H, O, N, P).

Structure of Atoms

Subatomic Particles

Atoms are the basic units of matter, composed of three main subatomic particles:

Atomic Structure and Notation

• Atomic number: Number of protons in the nucleus (written as subscript to the left of the atomic symbol).

• Mass number: Total number of protons and neutrons (written as superscript to the left of the atomic symbol).

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

• Atomic weight: Average of the mass numbers of all isotopes of an atom.

Example: Carbon-12 (12C) has 6 protons and 6 neutrons.

Molecules and Compounds

Definitions

• Molecule: Two or more atoms chemically bonded together.

• Compound: A specific molecule that contains atoms of two or more different elements bonded together.

Compounds have unique properties that are different from the individual elements that compose them.

Atomic Models

Planetary Model

• Simplified and outdated; depicts electrons in fixed circular orbits around the nucleus.

• Useful for illustration but not accurate for electron behavior.

Orbital Model

• Current model; shows probable regions (orbitals) where electrons are likely to be found.

• Reflects the quantum mechanical nature of electrons.

Chemical Bonds: Role of Electrons

Valence Electrons and Energy Shells

• Chemical bonds are energy relationships between electrons of interacting atoms.

• Electrons occupy areas around the nucleus called electron shells (energy levels).

• The outermost shell is called the valence shell and contains electrons involved in chemical bonding.

• Electrons in the valence shell have the most potential energy and determine the chemical reactivity of the atom.

Example: Potassium (K) has one electron in its outermost shell, making it highly reactive.

Additional info:

• These notes cover foundational chemistry concepts essential for understanding biological molecules and processes in Anatomy & Physiology.

• Further topics such as types of chemical bonds, properties of water, acids and bases, and macromolecules (carbohydrates, lipids, proteins, nucleic acids) are typically included in a full biochemistry overview for A&P.