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BACTERIA. BACTERIA. are microscopic prokaryotes .  (“before nucleus ”) they are adapted to living in all environments – they exist EVERYWHERE. Bacteria are classified into two kingdoms :. Eubacteria (true bacteria ) The larger kingdom Huge variety

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  • are microscopic prokaryotes.  (“before


  • they are adapted to living in all

environments – they exist EVERYWHERE


Bacteria are classified into two kingdoms:

  • Eubacteria(true bacteria)
  • The larger kingdom
  • Huge variety
  • Have a Cell wall has peptodoglycan(a carbohydrate) and a cell membrane so are very resistant to damage
  • 2. Archaebacteria (Ancient Bacteria)
  • no peptodoglycan in the cell walls
  • often found in harsh environments
  • some key DNA sequences resemble
  • eukaryotes

a. The cell wall may be surrounded by an organized capsule called a glycocalyx and/or by a loose gelatinous sheath called a slime layer. b. In parasitic forms, these outer coverings protect the cell from host defenses.

1. Outside the plasma membrane of most cells is a rigid cell wall that keeps the cell from bursting or collapsing due to osmotic changes by peptidoglycan, a complex molecule containing a unique amino disaccharide and peptide fragments. 

i bacteria structure

2. Flagella is used for movement

3.  Pilli (Fimbrae) help bacteria cling to surfaces

4. Prokaryotes do not have organelles or a membrane bound  nucleus!

I. Bacteria Structure

5.  Nucleoid region contains a circular loop of DNA

6.  Plasmids are rings of DNA, used in reproduction

7.  Ribosomesin cytoplasm synthesize proteins


Cell Membrane – regulates what comes in and out of the cell

Cell Wall – maintains shape and form

Capsule – found in virulent bacteria, helps evade immune system


II.  Reproduction in Prokaryotes

Binary fission is the splitting of a parent cell into two daughter cells; it is asexual reproduction in prokaryotes. I


In bacteria, genetic recombination can occur in three ways.

a. Conjugation occurs when a bacterium passes DNA to a second bacterium through a tube (sex pilus) that temporarily joins two cells; this occurs only between bacteria in the same or closely related species. b.Transformationinvolves bacteria taking up free pieces of DNA secreted by live bacteria or released by dead bacteria. c. In transduction,bacteriophages transfer portions of bacterial DNA from one cell to another. Plasmids can carry genes for resistance to antibiotics and transfer them between bacteria by any of these processes


Plasmid – an extra bit of DNA, used in sexual reproduction


Plasmids are also used in genetic engineering


III.  Prokaryotic Nutrition

1.   Bacteria differ in their need for, and tolerance of, oxygen (O2).

a.   Obligate anaerobes are unable to grow in the presence of O2; this includes anaerobic bacteria that cause botulism, gas gangrene, and tetanus.

staphylococcus is a gram-positive, facultative anaerobe

b.   Facultative anaerobes are able to grow in either the presence or absence of gaseous O2.

c.   Aerobic organisms (including animals and most prokaryotes) require a constant supply of O2 to carry out cellular respiration.

2.   Autotrophic Prokaryotes

a.   Photoautotrophs are photosynthetic and use light energy, water and CO2 to assemble the organic molecules they require.

b.   Chemoautotrophsalso use CO2 and make organic molecules but use energy from enviromental chemical reactions involving ammonia, sulfur, iron, etc. (methanogens)


THERMOACIDOPHILE – the red stuff on the rocks

This is an archaebacteria.


3.Heterotrophic Prokaryotes

a. Most free‑living bacteria are chemoheterotrophstake in organic nutrients for energy and carbon.

b.    There is probably no natural organic molecule that cannot be broken down by some prokaryotic species.

c.    Detritivores (saprophytic bacteria)are critical in recycling materials in the ecosystem; they decompose dead organic matter and make it available to photosynthesizers.

Bacteria have an important role to play in breaking down materials in the environment.

Some are harmful and break down material we'd rather keep, like this image of an infection of necrotizing fasciitis (flesh-eating bacteria)

bacteria shapes

IV. Bacteria Shape & Naming

Bacteria Shapes

Cocci – spheres

Bacilli – rods

Spirilla - spirals

gram staining

The Gram stain procedure (developed in the late 1880s by Hans Christian Gram) differentiates bacteria.a. Gram‑positive bacteria stain purple, whereas Gram‑negative bacteria stain pink.b. This difference is dependent on the thick or thin (respectively) peptidoglycan cell wall.

Gram staining



Gram Negative, Bacillus



Gram Positive Staphylococcus

bacteria and you
Bacteria and You

You will be viewing many types of bacteria with slides and slide viewers.  Your main task is to identify by shape and gram stain.  

You will also need to know specific names (and appearance) of bacteria that cause disease in humans.

*Don't forget, you can review this presentation online anytime.



These Strains are responsible for strep throat, and flesh eating bacteria



These Strains are responsible for strep throat, and flesh eating bacteria

staphylococcus aureus

Staphylococcus aureus

Staph means “bunch of grapes” in greek.

bacillus subtilis
Bacillus subtilis

Easy to grow in the lab, not harmful

Gram Positive

*this is an example of a "poor" stain, it looks both pink and purple. 

Gram staining takes practice



Rigid muscles from tetanus infection

Also known as “lockjaw”

clostridium botulism
Clostridium botulism

Gram positive

Causes food poisoning that is sometimes fatal

All forms lead to paralysis that typically starts with the muscles of the face and then spreads towards the limbs.[1] In severe forms, it leads to paralysis of the breathing muscles and causes respiratory failure. In view of this life-threatening complication, all suspected cases of botulism are treated as medical emergencies, and public health officials are usually involved to prevent further cases from the same source.[1]

A form of botulism is used in BOTOX treatments, as it paralyzes the muscles of the face and effectively smooths wrinkles.

Results may vary.

yersinia pestis
Yersinia Pestis

The black plague, this bacteria was carried on the fleas of rats.  It was responsible for the deaths of thousands of Europeans from the 8th to the 14th century.


Causes pneumonia

Rickettsia rickettsi

Rocky Mountain Spotted Fever, carried by ticks

name this bacteria1

Name this Bacteria

Answer: Staphylococcus

plush germs

Plush Germs


E. Coli



The Plague (Black Death)

1 determine if the form is circular filamentous irregular or rhizoid
1. Determine if the form is circular, filamentous, irregular or rhizoid
  • circular form will appear perfectly round
  • filamentous form look like several tiny fibers over lapping one another
  • irregular form will have several branching paths that give it unnameable shape
  • rhizoid form resembles several thick strings overlapping one another.

2. Double-check the agar plate for multiple colony forms; if more than one type of form appears then the agar plate is being colonized by more than one type of bacteria. Make separate observations for both bacteria types if this is the case.

3. Examine the surface of the bacteria colony. Determine whether it is smooth, dull, rough or glistening.

4. Examine the pigmentation and color of the bacteria.


5. Determine the elevation Turn the agar plate on its side and flash a light at the bottom of the bacterial colony and examining it for a raised, convex, crateriform, umbonate or flat shape

  • raised elevation will look like as the bacteria grew uniformly
  • convex elevation resembles a tall dome
  • crateriform elevations appear raised except there will be several small craters on the surface
  • umbonate elevation will look raised except there will be several tiny bubbles growing on the surface
  • flat elevation seems as if the bacteria is flush with the bottom of the agar plate.

umbonate elevation

raised elevation

flat elevation


6. Examine the opacity of the colony by determining where it is transparent, translucent, opaque or iridescent

  • transparent opacity will be completely see-through
  • translucent opacity appears cloudy but will allow light to pass through
  • opaque opacity is not see-through at all
  • iridescent opacity will appear as luminous colors that change with the vantage point.

7. Place the agar dish beneath a microscope's 40x observation lens and examine the edge of the bacterial colony. Determine if the edge has a filiform, undulate, lobate, curled or entire shape

  • filiform edge will appear like tiny string fibers
  • undulate edge will appear like tiny, short bumps
  • lobate edge will appear as long several fingers
  • curled edge will appear as closely compacted waves
  • entire edge will appear perfectly smooth

Match the observed characteristics of the bacteria in the agar plate to the characteristic of bacteria in Bergey's Manual of Determinative Bacteriology