1. BACTERIA

2. Bacteria
Cells are prokaryotic and amongst the smallest known cells ( length µm ).
Lack a nucleus
DNA is naked, a single loop not bound in a chromosome
May contain plasmids (small circular fragments of DNA)
Have ribosomes, but no other organelles.
DNA present as a long circular molecule.

3. Structure of a Bacteria

4. Classification
All bacteria are prokaryotes, which can be placed in one of two kingdoms:
Archaebacteria: “Ancient Bacteria”
Archaebacteria “True Bacteria”

5. Archaebacteria “Archae” means primitive or early
Oldest organisms on the plant ~ 3 billion yrs old
Live in extreme conditions: Environments in which no other organisms can survive

6. Environments of Archaebacteria
These bacteria are characterized as living in extreme conditions that have:
High temperatures (Thermophiles)
Low temperatures (Psychrophiles)
High Salt concentrations (Halophiles)
High acidity
Environments with no oxygen (anerobic)

7. Archaebacteria Thermophilic bacteria thrive in volcanic vents
Halophilic bacteria thrive in salty lakes

8. Eubacteria All other bacteria.
Strong cell walls and less complicated genetic makeup.
Live in many habitats
Most common form of life on earth
Can be bad (pathogens) or good (digestion)
Organisms: Bacteria, Cyanobacteria

9. How to Classify Bacteria
Shape
Cell walls
How they move
How they obtain Energy

10. Spiral, called Spirilla or Spirochetes
Cell Shape
One way that bacteria can be identified is by their shape:
Enterococci: spherical
Lactobacilli: rod-shaped
Spirochaeta: spiral
Rod-shaped, called Bacilli
Spiral, called Spirilla or Spirochetes
Spherical

11. Coccus Spherical shaped bacteria are called Cocci
Single cells - monococci
Pairs - diplococci
Chains - streptococci

12. Bacillus Rod shaped Bacteria are called Bacilli
Exists as: Single Cells
In pairs (diplobacilli)
In chains (streptobacilli).

13. Spirilla Spiral shaped bacteria are called Spirilla
Spirillum (Singular)
Plural is spirilli.
Exist only as single cells.

14. Cell Wall
The chemical nature of a cell wall can be studied by a method known as Gram Staining
Hans Christian Gram: inventor of Gram Staining

15. Gram Staining Gram stains contain of two dyes
Crystal Violet (Purple)
Safranine (Red)
Gram-positive bacteria: cells with only 1 thick layer of carbohydrate and protein molecules took up the crystal violet dye.
Gram-negative bacteria: cells wall contains a second layer of lip and carbohydrate took up the crystal violet dye.

16. Appears red after Gram’s stain Appears violet after Gram’s stain
GRAM STAIN
It is the most important differential stain used in bacteriology because
it classified bacteria into two major groups:
b) Gram negative:
Appears red after Gram’s stain
Gram positive:
Appears violet after Gram’s stain

17. Bacterial Movement
Bacteria can be identified by studying how them move:
Some bacteria propel themselves by the means of 1 or more whip-like structures called a flagella
Some bacteria produce a thick layer of slime to glide about
Others remain stationary

18. How bacteria obtain Energy
Autotrophs: Organisms that make their own energy
Phototrophic Autotrophs: Bacteria that get there energy from sunlight
Chemotropic Autotrophs: Bacteria that obtain their energy from inorganic molecules
Inorganic molecules: Hydrogen sulphide, nitrites, sulphur and iron

19. Examples of Autotrophic Bacteria
Phototrophic autotroph: Cyanobacteria
Chemotrophic Autotrophs: Ecoli bacteria

20. How Bacteria obtain Energy
HETEROTROPHS: Energy is obtained from other organisms
Chemotrophic heterotrophs: obtain energy by dissolving and absorbing organic material
Phototrophic heterotrophs : obtain sunlight for energy, but need organic compound for nutrition.

21. Examples of Heterotrophic Bacteria
Chemotrophic heterotroph: Salmonella

22. Bacterial Respiration and Fermentation
Bacteria need a constant supply of energy to perform their life activities
Energy is supplied by the process of:
Respiration: A process that involves oxygen and the breakdown of food molecules to release energy
Fermentation: the process that enables cells to carry out energy production in the absence of oxygen

23. Bacterial Respiration
Bacteria can be classified into three categories based on their need for oxygen
1. Obligate aerobe: Must have O2 to live
2. Obligate anaerobes: Must live in O2 free environment
3. Facultative anaerobes: Can live with or without O2

24. RECAP QUESTIONS
How would this bacteria be classified according to shape?
Is this bacteria a Gram-positive or Gram-negative bacteria?