Biology Fundamentals: Atoms to Organisms

Levels of Organization

• Atoms are the fundamental units of matter
• Molecules are specific arrangements of atoms
• Cells are the simplest units that show characteristics of life
• Tissues are many cells that perform a particular function
• Organs are many tissues that perform a particular function
• Organ systems are many organs that perform a particular function
• Organisms are independent living units, an individual

Biomolecules of Life

• Biomolecules are chemical compounds found in living organisms, composed mainly of carbon, hydrogen, oxygen, nitrogen, sulfur, and phosphorus
• They are the building blocks of life and perform important functions in living organisms

Proteins

• Proteins are large molecules made of polymers of amino acids
• They are found in every cell in the body and are involved in most of the body's functions and life processes
• The sequence of amino acids is determined by DNA

Amino Acids

• An amino acid contains a central carbon, an amine group, a carboxylic acid group, a hydrogen atom, and a variable side chain
• There are approximately 500 amino acids found in nature, but only 20 amino acids make up the proteins found in the human body
• Each type of amino acid differs in the composition of the variable side chain, which affects the protein's folding and function

Protein Structure

• Proteins are made up of chains of amino acids, classified by the number of amino acids in a chain (dipeptides, tripeptides, oligopeptides, polypeptides)
• Amino acids are covalently joined together via peptide bonds to form long chains called polypeptides
• The primary structure of a protein refers to the order of the amino acid sequence, which determines the way the chain will fold
• The secondary structure of a protein refers to the stable configurations that the amino acid sequence folds into, such as alpha helices and beta-pleated sheets
• The tertiary structure of a protein refers to the overall three-dimensional configuration of the protein
• Loss of protein structure and function is called denaturation, usually due to changes in pH or temperature

Learn about the basic units of life, from atoms to organisms, and discover the biomolecules that make life possible. Understand the hierarchy of organization in living things, from molecules to organ systems.