Atoms and Isotopes in Medicine

Aims of Lecture

• Define atoms and study their structure
• Explain isotopes and their use in treatment and diagnosis
• Explain the main types of organic compounds (carbohydrates and proteins)

Atoms

• An atom is the smallest part of an element that displays its properties
• Atoms have a nucleus containing protons and neutrons
• Electrons orbit the nucleus
• Mass number is the total number of protons and neutrons
• Atomic number is the number of protons

Isotopes

• Isotopes are variants of an element that differ in neutron number
• All isotopes of an element have the same number of protons but different numbers of neutrons
• Examples of elements with common isotopes: carbon
• Isotopes are useful in treatment and diagnosis

Applications of Isotopes (in medicine)

• Treatment:
  • Iodine-131 is used in goiter treatment
  • Cobalt-60 is used to arrest cancer development
• Diagnosis:
  • Iodine-131 for locating brain tumors and thyroid disorders
  • Sodium-24 to locate blood clots and circulation problems
  • Iron-59 for diagnosing anemia and pregnancy disorders
  • Cobalt-60 for diagnosing cancer
  • Hydrogen-3 for measuring water content.

Low Levels of Radiation

• Radioactive isotopes are used in many medical applications
• After a patient drinks a solution with a small amount of 131I, it concentrates in the thyroid.

High Levels of Radiation

• Radioactive substances can damage DNA, cause cancer and harm cells
• Radiation can be used in the sterilization of food, and in cancer treatment

Organic and Inorganic Compounds

• Organic compounds contain carbon, inorganic compounds may or may not contain carbon
• Organic compounds are necessary for living organisms

Organic Molecules (macromolecules)

• Large organic molecules in cells are macromolecules formed via monomers joining together into polymers

Carbohydrates

• Are organic molecules composed of carbon, hydrogen, and oxygen atoms
• Serve as structural and functional components of cells
• Chemical formula: C₆H₁₂O₆ (glucose)
• Types of carbohydrates:
  • Simple carbohydrates include monosaccharides (e.g., glucose, fructose)
  • Complex carbohydrates (polysaccharides) are made from multiple linked monosaccharides, examples include starch, glycogen, cellulose, chitin

Proteins

• Proteins are linear polymers of 20 different amino acids
• Approximately 50% of the dry weight of living matter is protein
• Amino acids are linked together by peptide bonds to form chains(typically containing 100-300 amino acids)

Protein Denaturation

• Denaturation is a change in a protein's three-dimensional structure that might be reversible or irreversible.
• Agents include: heat, changes in pH, ultraviolet rays, X-rays, high salt concentration, and heavy metals
• Denaturing changes can lead to diseases like Alzheimer's, Parkinson's, Huntington's, Creutzfeldt-Jakob, etc.

Protein Structures

• Proteins have four levels of structure:
  • Primary: sequence of amino acids in a polypeptide chain.
  • Secondary: local folding of the polypeptide chain (e.g. alpha-helices, beta sheets).
  • Tertiary: three-dimensional structure of a single polypeptide chain.
  • Quaternary: structure of a protein consisting of multiple polypeptide chains.