MICROBIO (Lecture 2)

• Chemistry is essential to understand how microorganisms function and their impact on humans and the environment
• Chemical building blocks:

  • Atom: smallest chemical unit of matter
  • Element: fundamental kind of matter
  • Molecule: consists of two or more atoms that are chemically combined
  • Compound: formed by two or more elements that are chemically combined
• The most common elements in all forms of life are carbon (C), hydrogen (H), oxygen (O), and nitrogen (N)
• Atomic structure:

  • Atom comes from the Greek word "atomos" meaning "incapable of being divided"
  • Subatomic particles: protons (positive charge), electrons (negative charge), neutrons (neutral charge)
  • The number of protons in an atom is equal to its atomic number
  • The total number of protons and neutrons determines the atomic weight of an element
• Chemical bond: formation of atoms through interaction to form molecules by sharing or transferring their outermost electrons
• Types of chemical bonds:

  • Ionic bonds: electrons are completely transferred from one atom to another
  • Covalent bonds: atoms share one or more pairs of electrons
  • Hydrogen bonds: weak attractions between polar regions of hydrogen atoms and oxygen or nitrogen atoms
• Chemical reaction is the formation or breaking of chemical bonds between atoms, ions, molecules, or compounds
• Classification of chemical reactions:

  • Synthesis: new compound formed by the combination of simpler reactants (A + B → AB)
  • Decomposition: reactant breaks down into simpler products (AB → A + B)
  • Exchange reaction: combination of a decomposition reaction and a synthesis reaction (AB + C → AC + B)
• Water is a polar compound, acts as a solvent, and participates in many chemical reactions
• Solutions are mixtures with one or more solute evenly distributed throughout a solvent, while colloids contain particles too large to form a true solution
• Acids release H+ ions, bases accept H+ ions (or release OH- ions), and the pH scale measures the acidity or alkalinity of a solution
• Organic Chemistry studies carbon-containing compounds like alcohols, aldehydes, ketones, organic acids, and amino acids identified by their functional groups
• Carbohydrates include sugars and starches, serving as an immediate source of chemical energy in living systems
• Monosaccharides are the simplest carbohydrates, while disaccharides are formed by joining two monosaccharides, and polysaccharides consist of many monosaccharides bound in long chains
• Lipids are substances that dissolve in nonpolar solvents, with triglycerides, phospholipids, and steroids being the most abundant lipids in the body
• Proteins account for over 50% of the organic matter in the body and have diverse functions, with amino acids being their building blocks
• Biological functions of proteins include catalytic function, coordinated motion, transport and storage, structural support, defense, nerve impulse generation, growth control, and differentiation
• Nucleic acids make up genes, providing the blueprint of life, with DNA and RNA being the major types, and nucleotides being their building blocks
• Enzymes are protein catalysts that control the rate of chemical reactions in cells, with an active site where they combine with substrates
• CHEMICAL BOND -

  formation of atoms through interaction between

  them to form molecules by either sharing or

  transferring their outermost electrons.

  VALENCE ELECTRONS - electrons in the outermost

  shell

  OCTET RULE - the tendency of atoms to combine

  with other atoms until each has 8 electrons in its

  valence shell
• CHEMICAL REACTION - is the formation or breaking of chemical bonds between atoms,ions,molecules,or compounds.

  CATABOLISM - the breaking down of

  molecules.

  EXERGONIC - release energy

  ANABOLISM - the synthesis of larger

  molecules

  ENDERGONIC - require energy
• A pH of 7 is neutral, below 7 is acidic, and above 7 is basic,or alkaline
• MONOSACCHARIDES - simplest carbohydrates also referred to as “simple sugars" Monosaccharides in the body:

  Glucose - blood sugar

  Fructose and galactose - converted to glucose for use by body cells

  Ribose and deoxyribose - form part of the structure of nucleic acids
• Important disaccharide s in the diet: sucrose (glucose-fructose)-cane sugar

  lactose (glucose-galactose) found in milk

  maltose (glucose-glucose) malt sugar
• Polysaccharides in the body: Starch -is the storage polysaccharides formed by plants Glycogen -polysaccharide found in animal tissues
• STEROIDS Cholesterol -the basis of all body steroids Bile - salts released by the liver into the digestive tract, where they aid in fat digestion and absorption Vitamin D - necessary for normal bone growth and function Sex hormones - necessary for normal reproductive function
• BIOLOGICAL FUNCTIONS OF

  PROTEINS

  Transport and Storage

  Hemoglobin transports oxygen in erythrocytes

  Myoglobin carries & stores oxygen in muscle

  Albumin transports free fatty acids in blood.

  Transferin transports iron in blood
• NUCLEOTIDES Subunits/monomer/building

  blocks of DNA/RNA

  
  

  Three Components:

  - a 5-carbon sugar molecule (deoxyribose)

  - phosphate group

  - a nitrogenous base（A,G,C,OR T）