SC 165/166 Microbiology
Text: Chapters 2-3 Review
Types of Bonds and Cellular
Structures
, Chapter 2: The Molecules of Life
• proton, neutron, electron
– Neutrons: uncharged particles
– Protons: positively charged particles (+)
– Electrons: negatively charged particles (-)
– Protons and neutrons make up the heaviest part of atom, the nucleus
• Electrons form a surrounding electron “cloud”
• # of protons = atomic number (seen at the bottom of an element’s
designation)
• # of protons and neutrons (added together) = mass number (top number in a
designation of an element
,Example: Hydrogen has 1 proton and no neutrons; its atomic number
and mass number are the same = 1
, Elements, Molecules, and Compounds
• Elements consist of only 1 type of atom
– Cannot be chemically separated into simpler parts
– Living matter primarily composed of 4 main elements – CHON (with
some phosphorus and sulfur)
• Element (1 kind of atom) vs Molecule (several elements bonded together)
vs Compound (consisting of more than one molecule)
– Ex: The element H (hydrogen), bonded as pairs as H2, added to O
(oxygen) as H2O (water)
– organic (contains C-H bonds) versus inorganic compounds
• Polarity (charge, strength of an atom’s affinity and attraction for an
oppositely-charged one);
– Water is the most polar (and thus a universal) solvent
Text: Chapters 2-3 Review
Types of Bonds and Cellular
Structures
, Chapter 2: The Molecules of Life
• proton, neutron, electron
– Neutrons: uncharged particles
– Protons: positively charged particles (+)
– Electrons: negatively charged particles (-)
– Protons and neutrons make up the heaviest part of atom, the nucleus
• Electrons form a surrounding electron “cloud”
• # of protons = atomic number (seen at the bottom of an element’s
designation)
• # of protons and neutrons (added together) = mass number (top number in a
designation of an element
,Example: Hydrogen has 1 proton and no neutrons; its atomic number
and mass number are the same = 1
, Elements, Molecules, and Compounds
• Elements consist of only 1 type of atom
– Cannot be chemically separated into simpler parts
– Living matter primarily composed of 4 main elements – CHON (with
some phosphorus and sulfur)
• Element (1 kind of atom) vs Molecule (several elements bonded together)
vs Compound (consisting of more than one molecule)
– Ex: The element H (hydrogen), bonded as pairs as H2, added to O
(oxygen) as H2O (water)
– organic (contains C-H bonds) versus inorganic compounds
• Polarity (charge, strength of an atom’s affinity and attraction for an
oppositely-charged one);
– Water is the most polar (and thus a universal) solvent
