Download Microbiology bio 123

C-2
Categories of Life:
Kingdoms:
 Animal
 Plant
 Fungi
 Protista (single celled organisms)
 Monera (bacteria)
Eukaryotic cells have a nuclear membrane. They do have a nucleus: Eu – true nuclear
Prokaryotic cells do not have a nucleus membrane or organelles, but do have ribosomes. Has DNA but no
nucleus. Pro – Before nuclear.
Protista –Eukaryotic cell structure
Monera – Prokaryotic cell structure (no nucleus)
Animals – Eukaryotic cell structure
Plants – Eukaryotic cell structure
Fungi – Eukaryotic cell structure
There are also three new categories:
Domains:
 Archaea - believed to be the first life form on earth, most live in hostile environments. Hot springs,
polar caps, and other very hostile environments such as geothermal vents on the ocean floor.
 Eubacteria - Monera
 Eukaryotes – Protista, fungi, animals, plants
Domains – Example: Eukaryotes
Kingdoms - Example: Animal
Phylum – Example: Chordata
Class – Example: Mammalia
Order – Example: Primate
Family – Example: Hominid
Genus – Example: Homo (always capitalized)
Species – Example: sapiens (never capitalized)
In micro, we can have multiple strains of the same species. In all other species, there is only one thing in the
species.
Nomenclature: (How do we name things) Take the name of the Genus, then the name of the species. Always
capitalize the Genus, never capitalize the species. Either underline the complete name, or italicize the name if
typing. You can abbreviate the name by writing the first letter of the Genus and then writing the full name of
the species. When doing this, you must write it out completely the first time that it is mentioned. Morphology
must not be capitalized.
Homo sapiens
H. sapiens
Homo sapiens
H. sapiens
Staphylococcus aureus (Staphylo- is also morphology)
Coccus – spherical organism, like grapes
Aureus – gold, when on an auger plate, the bacteria looks gold
Streptococcus pyogenes
Strepto – forming chains
Genes – produce, pyo - pus
Escherichia coli
Escherichia – named after discoverer
Coli – intestinal
Major structures of a cell (Prokaryotic – bacteria)
 Ribosomes – on quiz they will look like small circles attached to a larger circle. They are necessary for
making proteins.
 Capsule – (or glycocalynx) purpose of the capsule is to prevent phagocytosis first layer
 Cell Wall – second layer, It protects the cell from osmotic pressure
 Cytoplasmic Membrane – third layer, normal function of the cell membrane, maintains homeostasis for
the cell
 Chromosome – only one chromosome and it is singular. Then it is compressed and looks like a bowl of
spaghetti. Does not have a nuclear membrane. Also called Nucleoid.
 Nuclear region  Storage Granule – Used to store molecules, in quiz, storage granules will look circular and grayed. Also
called cytoplasmic inclusions.
 Flagellum – used for movement; rotor-like
 Pili – (pilus) or fimbriae(a) – nothing to do with movement, used to attach to smooth surfaces. Also can
transfer DNA from one cell to another.
 Plasmid – not in all bacteria. Very important. They are extra-chromosomal pieces of DNA. Plasmids
mediate antibiotic resistance among bacteria. Will look like a little beaded bracelet on the quiz.
Square/cube law limits the size that a cell can eventually become. It is the ratio between the surface area and
the volume of the cell.
Bacteria are asexual, it is referred to as binary fission. One bacterial cell divides into two. It is similar to
mitosis in Eukaryotic cells.
When we refer to growth in bacteria, we refer to the increase in number not the increase in size (geometric
growth). Te length of time that it takes for bacterial cells to divide is referred to as the doubling time or the
generation time (approx. 15-20 min).
Incubation time is the time that it takes from when you acquire an organism to when you start showing
symptoms and is dependent of the doubling/generation time.
E-coli have about a 15 min doubling time.
Bacterial cell weighs 1x10-12g
Need to start with generation 0, not generation 1 (i.e. 0 has 10 bacteria, 1 has 20 bacteria, 2 has 40 bacteria, 3
has 80 bacteria, etc.)
With the bacterial growth curve, it is measured on a log. #, is divided into 4 phases,
1. Lag phase, introducing the bacteria to a new environment, may have a small dip in it due to the slight
amount of death as some cells do not adapt to the new environment, has a lot of metabolism, but no cell
division.
2. Log phase, greatest amount of growth, has exponential growth during this time. It is between the points
where the line starts going up and just before to when it levels out. The rate of growth has to be the
same along the entire length of this line. “Constant” rate of growth at this time.
3. Stationary phase begins at the point where the growth rate changes. At this point the cells are beginning
to run out of room, nutrients, and waste is accumulating. Equilibrium between rate of growth and rate of
death.
4. Death phase begins when the rate of death exceeds the rate of growth.
Pure culture – when you have bacterial cells that have all come from a single cell. They all have one ancestor.
What environmental conditions would cause a cell to continue to grow?
Factors necessary for bacterial growth:
1.
Gaseous (oxygen) requirements:
In a broth, if the bacteria grow near the surface of the broth, they require more molecular oxygen. These
bacteria are considered obligate aerobes. (Bacteria that causes tuberculosis)
In a broth, if most of the bacteria grow within the top third of the broth, they are considered
“microaerophilic” (i.e “Likes air”).
In a broth, if the bacterium grows evenly throughout the whole broth, they are considered facultative
anaerobes.
These bacteria are able produce enzymes to metabolize oxygen whether they are in an aerobic
environment or anaerobic. (i.e. E. coli)
In a broth, if the bacteria only grow near the bottom, they are considered obligate anaerobes. Several of
these are spore formers, when in the presence of o2 they are able to form spores. (i.e. Anthrax, tetanus,
botulinium)
2. Temperature requirements:

Psychrophiles (Optimal temperature 15 to 20 C degrees; Can survive in -10 to 20 C degrees,)

Mesophiles (Optimal temperature 25 to 40 C degrees; Can survive in 15 to 50 C degrees (cause
most human illnesses)

Thermophiles (Optimal temperature 45 to 60 C degrees; Can survive in 45 to 110 C degrees,)
At 70 degrees C. most proteins will denature; Thermophiles have the ability to keep their
proteins together with more hydrogen bonds so they are not as easy to denature.
3. Osmotic pressure (Tonicity)
Bacteria will die in saline (salt) solutions above 10% and sugar solutions above 50%.
We are most concerned with the cell losing water. Most of the time it does not kill the cell, it
inhibits the growth and activity of the cell. We use increased salt content to preserve meats and
other things; we use sugar solutions for fruits to prevent bacteria from growing.
4. PH requirements:
Most cells need to be between 4 and 9, with an optimal between 6.5 and 7.5 (Neutral – the same as
blood).
5. Nutritional requirements:

Energy source:
Radiant (sun) energy = Phototrophs
Oxidation of chemical Compounds= Chemotrophs

Carbon source:
Carbon dioxide as the source of carbon, (inorganic to organic) convert CO2 to C6H12O6
(glucose). Autotrophs are called autotrophs because they create their own glucose as an
energy source. Mostly green plants because they have photosynthesis. They are called
autotroph synthesizers.
Organic Carbon source required = Heterotrophs. Most utilize carbohydrates.

A nitrogen source:
Inorganic source – KNO3 or atmospheric N2, NH2
Organic source – proteins

A source of Sulfur and Phosphorus:
Inorganic – H2S or S; phosphates
Organic – Proteins

Metallic elements – trace amounts of Na, Ca, Fe, K, Mg, Mn
Metallic elements are called cofactors; they are needed to produce certain proteins.

Vitamins
Vitamins are called co-enzymes because they are needed to produce proteins.

Water