Download BIOLOGY * CHAPTER 2

Microbiology – Chapter 2
BIOLOGICAL
CHEMISTRY
Do Now
 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
Atoms Activity
 Complete worksheet on atoms
 Finish for homework if not completed in class
Do Now
 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)
Matter Activity
 Complete “Composition of Matter” worksheet.
 Finish what you don’t complete for homework.
Do Now
 What is a compound?
 What is a covalent bond?
 What is an ionic bond?
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
ORGANIC CHEMISTRY
 LIVING THINGS DIFFER GREATLY FROM NON



LIVING THINGS
THERE MUST BE A BIG DIFFERENCE IN HOW
THEY ARE CONSTRUCTED
THEY ARE ACTUALLY CONSTRUCTED OF THE
SAME MATERIALS
THE ONLY DIFFERENCE IS IN HOW THEY ARE
ORGANIZED
ALL BIOLOGY HAS A CHEMICAL BASIS
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 are the simplest carbohydrates
 They are the building blocks for the larger
carbohydrates (polysaccharides)
 Glucose, galactose and fructose are examples of
isomers – they have the same chemical formula
C6H12O6
 But their structures and properties are different
A. CARBOHYDRATES
Glucose
 Represents the basic supply of energy in the world
 Half of the world’s carbon exists as glucose
GLUCOSE – UNIVERSAL ENERGY
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
Sucrose – table sugar and is the starting point in wine
fermentation and may be a cause of tooth decay
DISACCHARIDE – TWO MONOSACCHARIDES
Polysaccharides
 Complex sugars
 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
Polysaccharide animation
Polysaccharides Activity
 Complete polysaccharides color worksheet
 Finish for homework if not completed in class
Do Now
 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
 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 mistake changes the protein (mutations)
 Protein Structure:
 Primary – AA sequence
 Secondary – AA chain twists into a corkscrew pattern
 Tertiary – Protein folds back upon itself
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 can dissociate 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)

Acid Rain
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 strips
Acid Rain
 Acid rain is a rain or any other form of
precipitation that is unusually acidic (low pH)
 It can have harmful effects on plants, aquatic
animals, and infrastructure
 Acid rain is caused by emissions of compounds of
ammonium, carbon, nitrogen, and sulfur which react
with the water molecules in the atmosphere to
produce acids
 Formation results from both natural sources
(volcanoes, decaying vegetation) and man-made
sources (fossil fuel combustion)
Activity
 Complete Acids/Bases worksheet
 Finish for homework if not completed in class