Microbiology – Chapter 2
BIOLOGICAL
CHEMISTRY
Interactive Notebook: Left Side
 What is an atom?
 What is an element?
 What is the name of the table that keeps track of all
the elements?
Why do biologists study chemistry??
 Chemical changes in matter are essential to all life
processes
 All living things are made of the same kinds of
matter that make up non-living things
 If you learn how changes in matter occur you will
understand the life processes of organisms
Elements
 Elements – pure substances that cannot be broken
down chemically into simpler kinds of matter
 Of more than 100 elements fewer than 30 are
important to livings
 More than 90% of the mass of living things is
composed of combinations of just:

O, C, H and N
Elements
 Chemical Symbol – usually part of the element’s
name or the Latin word for the element
 Organized into the periodic table of elements
 There are 118 elements, 94 are naturally occurring, the rest are
synthetic (made in particle accelerators)
 Elements listed by increasing atomic number
 Columns – groups of elements with similar properties because
of the number of electrons in their outer shell
 Rows - periods
Atoms – basic units of matter
-Atoms are the simplest particles of an element
that retain all the properties of that element
-Atoms are so small that their true structure has
not been observed
-Models of the atom help us understand their
structure enough to predict how they will act in
nature
Atoms
Structure – net electrical charge of zero
a. Protons (charge +) 1 AWU
b. neutron (charge 0) 1 AWU
c. electrons (charge -) .008 AWU
AWU – atomic weight unit
Nucleus – central mass of an atom,
contains protons and neutrons
Atoms
 Electrons – high energy particles that move
about the nucleus at high speeds in one of
several different energy levels
- Electrons in outer energy levels have more
energy than those in inner energy levels
- Each energy level can only hold a certain
number of electrons
- 1st energy level can hold 2 electrons
-2nd energy level can hold 8 electrons
- In most elements, the outer energy level is
not filled
Atom
Number of Protons?
Atom
 animation of an atom
Atomic number – the
number of protons in
the nucleus of the atom
Atomic mass – the
number of protons plus
neutrons in the nucleus
of the atom
Isotopes
Isotope – A different form of an element
which has the same number of protons and
electrons, but has a different number of
neutrons
Carbon (C):
-atomic number is 6 - it has 6
protons
-mass number is 12 – it has 6
protons and 6 neutrons
-C14 – isotope that has 8 neutrons
Hydrogen Isotopes
Isotopes
Radioisotopes – radioactive element
forms whose nuclei can undergo
spontaneous change in which charged
particles and radiant energy are
released
Interactive Notebook: Left Side
 What is the positively charged particle in an atom
called?
 What is the negatively charged particle in an atom
called?
 What is the neutral particle in an atom called?
 What is an isotope?
Compound
1. A pure substance made up of two or more
elements combined chemically
2. The properties of compound differ from the
elements it is composed of – H2O vs. H and O
3. The proportion of each kind of element are
fixed – Water always H2O
4. Elements combine and form compounds to
become more stable
5. Elements are more stable when their outer
electron shells are filled
Bonds
Chemical bonds – forces link two or more atoms
a. Covalent bonds – sharing of electrons (water
H2O)
b. Ionic bonds – transfer of electrons (sodium
chloride NaCl)
Chemical Bond Animation
Molecules
 A molecule is the simplest part of a substance that
retains all of the properties of that substance and
that can exist in a free state
 Hydrogen
gas (H2)
 Water (H2O)
2. INORGANIC CHEMISTRY
 STUDY OF COMPOUNDS THAT DO NOT
CONTAIN THE THREE ELEMENTS C, H, & O AT
THE SAME TIME.
 CAN CONTAIN TWO OF THOSE THREE AND ANY
OF OTHER ELEMENTS
 EXAMPLES OF INORGANIC COMPOUNDS:
 SODIUM CHLORIDE (SALT) NaCl, SULPHUR
DIOXIDE SO2
Interactive Notebook: Left Side
IF LIVING ORGANISMS CONTAIN THE SAME
CHEMICALS FROM THE PERIODIC TABLE AS
NON-LIVING THINGS:
 WHAT MAKES LIVING ORGANISMS DIFFERENT?
3. ORGANIC CHEMISTRY
 STUDY OF CARBON COMPOUNDS - CHEMICAL
BASIS FOR LIVING CELLS



ALWAYS C, H, & O
SOMETIMES NITROGEN & PHOSPHORUS
USUALLY SMALL AMOUNTS OF METALS
 THERE ARE “FOUR” DIFFERENT CLASSES OF
ORGANIC COMPOUNDS




Carbohydrates
Lipids
Proteins
Nucleic Acids
Carbohydrates
 Organic compounds of C, H and O
 Used as energy sources in cells
 Also found in several cellular structures such as
bacterial capsules
 They are synthesized from water and carbon dioxide
during photosynthesis
Carbohydrates
 Monosaccharides (simple sugars) are the simplest
carbohydrates
 They are the building blocks for the larger
carbohydrates (polysaccharides) like starch or
cellulose.
 Glucose, galactose and fructose are examples of
isomers – they have the same chemical formula:
C6H12O6 but the way the elements are put together
and their properties are different
Simple Sugars C6H12O6
GLUCOSE
Is the main source of energy for most living organisms
Half of the world’s carbon exists as glucose
Disaccharides
 Double sugars – composed of two monosaccharides
held together by covalent bonds
 They are made from glucose molecules through
dehydration synthesis – water is removed as the new
bonds are formed
 Examples are:



maltose – found in barley and used to ferment beer
lactose – found in milk and digested by bacteria to form
yogurt, sour cream and cheese
sucrose – table sugar and is the starting point in wine
fermentation and may be a cause of tooth decay
DISACCHARIDE – TWO MONOSACCHARIDES
Polysaccharides
 Large compounds formed by joining together 100’s
or 1000’s of glucose molecules


Starch – used by bacteria as an energy source
Cellulose – a component of the cell walls of plants and molds
and also used as an energy source by microorganisms
Polysaccharide animation
Interactive Notebook: Left Side
 What are the 4 classes of organic compounds?
 What 3 elements are carbohydrates made up of?
 What carbohydrate is considered a universal source
of energy?
B. LIPIDS
 Dissolve in organic solvents, but not in water
 Like carbohydrates, they are composed of C, H, and O,
but with much less O
 The best known lipids are fats
 Fats are important long-term energy sources for living
things they provide more calories than carbohydrates or
proteins
 Fats are also components of cell membranes
LIPIDS
 cell membrane animation
LIPIDS
 Fats consist of a 3 carbon glycerol molecule and up
to 3 long-chain fatty acids
 2 major types of fatty acids:
 Saturated
– contain the maximum number of H
atoms
 Unsaturated – contain less than the maximum
number of H atoms
 Unsaturated fatty acids are good for us – they
lower the levels of cholesterol in the blood
LIPIDS
 Other types of lipids:
Waxes – long chains of fatty acids
 Bee’s wax
 Plant leaves
 Phospholipids – contain a phosphate group
 Cell membranes
 Steroids – composed of several rings of carbon atoms
with side chains
 Cholesterol
 Estrogen
 Testosterone

C. PROTEINS
 Most abundant organic compounds of living things
 They can be:


Structural
Enzymes – regulate the rate of chemical reactions
 They are composed of chains of amino acids
 Each amino acid contains




Carbon atom
Amino group (NH2)
Carboxyl group (COOH)
Another side group
Amino Acids – there are 20
Proteins
 Amino acids are joined together by peptide bonds
 The sequence of amino acids is extremely important
 One change can alter the protein (mutations)
 Protein Structure:
 Primary – AA sequence (straight line)
 Secondary – AA chain twists into a corkscrew pattern ( 2-D)
 Tertiary – Protein folds back upon itself (3-D)
Proteins
Protein structure animation
D. NUCLEIC ACIDS
 Some of the largest molecules found in organisms
 DNA – genetic material of the chromosomes that carries the
genetic code
 RNA – cell messenger that functions in protein construction
 Composed of nucleotides
 Carbohydrate molecule (ribose or deoxyribose)
 Phosphate group
 Nitrogenous base
DNA – adenine, guanine, cytosine, thymine
 RNA – adenine, guanine, cytosine, uracil

Nucleic Acids
 DNA is located in the chromosomes of the cell
 It passes on the genetic information and directs protein
synthesis
 DNA molecule consists of 2 single strands of DNA in
opposite directions arranged in a double helix ladder
 Nucleic acids can not be altered without disrupting or
killing the organism – this can help us control
microorganisms
DNA Structure
Animation
Acids and Bases
Degree of acidity or alkalinity is very important to
living systems
You may hear the term pH a lot
What does this mean?
Acids and Bases
 Water molecules can dissociate (separate) into:

Hydroxide Ions OH-

Hydronium Ions H3O+
Acids and Bases
- pH is a measure of a solution’s hydronium ion
concentration
-pH is a scale of 0-14
- an acid = more hydronium ions (H3O+)
- a base = more hydroxide ions (OH-)
Acids and Bases
 Acids :
 Have more hydronium ions
 Have a sour taste
 In concentrated forms can be very corrosive

Example:

Strong acid – HCl (hydrochloric acid)
Weak acid – CH3COOH (vinegar)

Acids and Bases
 Bases :
 Have more hydroxide ions
 Have a bitter taste
 Tend to feel slippery because they react with the oil on our skin
to form soap

Example:

Strong base – NaOH (sodium hydroxide)
Weak base – NH4 (ammonia)

Acids and Bases
 pH scale ranges from 0 – 14:




Solution with a pH of 0 is very acidic
Solution with a pH of 14 is very basic
Solution with a pH of 7 is neutral
pH can be measured with pH paper or a pH meter