Chemical Principles and Molecules of Microbiology

Chemical Principles of Microbiology

Basic Concepts of Matter

Matter is fundamental to all biological systems, including microorganisms. Understanding its properties is essential for studying microbiology.

• Matter: Anything that occupies space and has mass.

• Atom: The smallest chemical unit of matter.

• Atomic Structure:

  • Electrons (-): Negatively charged, found in electron shells.

  • Protons (+): Positively charged, located in the nucleus.

  • Neutrons (0): Neutral, also in the nucleus.

• Nucleus: Contains heavy protons and neutrons.

• Electron Shells: Lighter electrons orbit the nucleus at different energy levels.

Molecules and Compounds

Atoms combine to form molecules and compounds, which are essential for cellular structure and function.

• Molecule: Two or more atoms held together by chemical bonds.

• Compound: A molecule containing two or more different elements.

• Chemical Bonds: Hold atoms together, resulting from electron interactions. Bonds vary in strength and arrangement.

• Valence Shell: The outermost electron shell; atoms prefer filled shells for stability.

• Bond Types:

  • Some atoms share electrons (covalent bonds).

  • Some atoms transfer electrons (ionic bonds).

Solutions and pH

Solutions are mixtures crucial for biological reactions. The pH scale measures acidity and basicity, which affects microbial growth and metabolism.

• Solution: A mixture in which two or more substances are distributed evenly (e.g., sugar dissolved in water).

• Solvent: The dissolving agent (e.g., water).

• Solute: The substance that is dissolved (e.g., sugar).

• Aqueous Solution: A solution where water is the solvent.

• Acidity and Basicity:

  • Too many hydrogen ions (H+): Acidic

  • Too many hydroxide ions (OH-): Basic

  • Buffers: Help neutralize solutions, maintaining stable pH.

pH Scale

pH Range	Description
0 - 6	Acidic
7	Neutral
8 - 14	Basic

Example: Many biological molecules (e.g., DNA, proteins) function optimally at specific pH levels.

Molecules of Microbiology

Micromolecules and Macromolecules

Microbial cells are composed of various molecules, each with specific roles in structure and function.

• Micromolecule: Small molecules such as saccharides (sugars).

• Saccharide: Sugar molecule, classified by the number of sugar units.

• Monosaccharide: Single sugar molecule (e.g., glucose).

• Functions:

  • Enzymes (catalysts for biochemical reactions)

  • Structural components (ribosomes, flagella, peptidoglycan)

  • Transportation (membrane transport proteins)

  • Gene regulation

  • Toxins (produced by some microbes)

• Amino Acids: Building blocks of proteins (macromolecules).

• Nucleotides: Building blocks of nucleic acids, held together by phosphodiester bonds.

Nucleic Acids: DNA and RNA

Nucleic acids store and transmit genetic information in all living organisms, including microbes.

• DNA: Contains four nitrogenous bases:

  • Adenine (A)

  • Thymine (T)

  • Guanine (G)

  • Cytosine (C)

• RNA: Contains four nitrogenous bases:

  • Adenine (A)

  • Guanine (G)

  • Cytosine (C)

  • Uracil (U)

• Purines: Adenine (A) and Guanine (G)

• Pyrimidines: Cytosine (C) and Thymine (T) (in DNA); Uracil (U) replaces Thymine in RNA

• Phosphodiester Bonds: Link nucleotides in nucleic acids.

Example: DNA and RNA are essential for genetic structure, cell wall structure, and energy metabolism in microbes.

Additional info:

• Microbial molecules can be broken down into simpler molecules to provide energy (NRG).

• Common food sources, genetic structure, and cell wall structure are all related to these molecules.