Biochemistry Basics

Atoms and Elements

Atoms are the fundamental units of matter and make up all elements. Each atom consists of protons (positive charge), neutrons (neutral), and electrons (negative charge). The number of protons is constant for each element, while neutrons and electrons can vary, leading to isotopes and ions.

• Valence Electrons: Electrons in the outermost shell, crucial for chemical bonding.

• Electron Shells: Layers around the nucleus where electrons reside.

• Ions: Atoms that have gained or lost electrons, resulting in a charge.

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

Table: Common Positive and Negative Ions

Isotopes of Carbon

• Stable Isotopes: 12C and 13C are stable and commonly found in nature.

• Radioactive Isotope: 14C is radioactive and used in radiometric dating.

Molecules and Compounds

Molecules are formed when two or more atoms bond together. Compounds are molecules that contain more than one element. Molecular formulas describe the types and numbers of atoms in a molecule.

• Organic Molecules: Contain both carbon (C) and hydrogen (H).

• Inorganic Molecules: Lack either carbon or hydrogen.

• Isomers: Molecules with the same formula but different structures.

Functional Groups

Functional groups are specific groups of atoms within molecules that have characteristic properties and reactivity. They are common in biochemical reactions and often behave similarly across different molecules.

Acids, Bases, and pH

Acids and bases are substances that alter the concentration of hydrogen ions (H+) in a solution. The pH scale measures the acidity or basicity of a solution, ranging from 0 (most acidic) to 14 (most basic).

• Acid: Increases H+ concentration. Example:

• Base: Decreases H+ concentration. Example:

• Buffer: Stabilizes pH by absorbing or releasing H+ ions.

• Acidosis: Low blood pH.

• Alkalosis: High blood pH.

Types of Chemical Bonds

Chemical bonds are forces that hold atoms together in molecules. The main types are ionic, covalent (polar and nonpolar), hydrogen, and van der Waals bonds.

• Ionic Bonds: Electrons are transferred from one atom to another, creating charged ions. No sharing occurs.

• Nonpolar Covalent Bonds: Atoms share electrons equally; electronegativities are the same.

• Polar Covalent Bonds: Atoms share electrons unequally; electronegativities differ.

• Hydrogen Bonds: Attraction between hydrogen and an electronegative atom (e.g., oxygen or nitrogen).

• Van der Waals Forces: Weak attractions between regions of molecules with partial charges.

Water Affinity

Substances interact with water differently based on their chemical properties. Hydrophilic substances maximize contact with water, while hydrophobic substances minimize contact.

• Hydrophilic: Water-loving; readily dissolves in water.

• Hydrophobic: Water-fearing; does not dissolve in water.

Chemical Reactions

Chemical reactions involve the transformation of substances through breaking and forming bonds. Enzymes, which are proteins, act as catalysts to speed up these reactions.

• Synthesis Reaction: Two or more reactants combine to form a larger product.

• Decomposition Reaction: A substance is broken down into smaller components.

• Exchange Reaction: Molecules swap components.

• Endergonic Reaction: Requires energy input; products have higher energy than reactants.

• Exergonic Reaction: Releases energy; products have lower energy than reactants.

Macromolecules

Overview of Macromolecules

Macromolecules are large, complex molecules essential for life. They are built from smaller units called monomers, which join to form polymers.

• Carbohydrates: Sugars and starches; energy storage and structural roles.

• Proteins: Made of amino acids; perform a wide range of functions.

• Lipids: Fats and oils; energy storage and membrane structure.

• Nucleic Acids: DNA and RNA; store and transmit genetic information.

Carbohydrates

Carbohydrates are composed of monosaccharides (simple sugars) and polysaccharides (complex sugars). They serve as energy sources and structural components.

• Monomer: Monosaccharides (e.g., glucose).

• Polymer: Polysaccharides (e.g., starch, glycogen, cellulose).

• Examples:

  • Cellulose: Strengthens plant cell walls.

  • Starch: Stores energy in plants.

  • Glycogen: Stores energy in animals.

  • Chitin: Strengthens exoskeletons of insects and fungi.

Lipids

Lipids are hydrophobic molecules that include fats, oils, and phospholipids. They are important for energy storage, insulation, and forming cell membranes.

Proteins

Proteins are polymers of amino acids and are essential for structure, function, and regulation of the body's tissues and organs. Enzymes are a type of protein that catalyze biochemical reactions.

Nucleic Acids

Nucleic acids, such as DNA and RNA, are polymers of nucleotides. They store and transmit genetic information necessary for cell function and reproduction.

Summary Table: Macromolecules

Conclusion

Understanding biochemistry basics is essential for microbiology, as it provides the foundation for studying cellular processes, metabolism, and molecular interactions in microorganisms.