Bacteria and Bacteria and VirusesViruses

Lecture Notes for May 12, 2011Lecture Notes for May 12, 2011

Bacteria Are prokaryotes- do

not have a nucleus & membrane-bound organelles.

Are placed in either kingdom Eubacteria or kingdom Archebacteria

All bacteria are single cells. Some bacteria can stick together or may form strands.

Bacterium Shapes

CocciCocci~ Sphere-shaped bacteria BacillusBacillus~ Rod-shaped bacteria SpirilliumSpirillium ~ Spiral-shaped bacteria

Bacteria and their energyBacteria and their energy

AutotrophsAutotrophs ChemotrophsChemotrophs HeterotrophsHeterotrophs

AutotrophsAutotrophs PhotosynthesisPhotosynthesis- use sunlight to make - use sunlight to make

their food. their food.

Four major groups w/ different Four major groups w/ different photosynthetic pigments:photosynthetic pigments:

a. a. Purple sulfurPurple sulfur (O (O22 free environment) free environment)b. b. Purple non-sulfurPurple non-sulfur

c. c. Green sulfurGreen sulfur (O (O22 free environment) free environment)d. d. CyanobacteriaCyanobacteria (Blue-green alage) (Blue-green alage)

CyanobacteriaCyanobacteria Bluish-greenish Bluish-greenish

colorcolor Carry out the Carry out the

process of process of photosynthesisphotosynthesis

Do not Do not contain the contain the same type of same type of chloroplastschloroplasts as plants doas plants do

Can survive in Can survive in extremely extremely hothot environments environments and even and even extremely extremely cold cold environmentenvironment

ChemoautotropChemoautotrophshs

Make their own Make their own foodfood

Remove e-’s Remove e-’s from inorganic from inorganic molecules such molecules such as ammonia & as ammonia & methanemethane

Live in the soil & Live in the soil & are responsible are responsible for for nitrificationnitrification

Ex: Ex: NitrobacterNitrobacter Ex: Ex:

ArchaebacteriaArchaebacteria

HeterotrophsHeterotrophs Obtain their own Obtain their own

foodfood Decomposers- break Decomposers- break

down the bodies of down the bodies of dead organismsdead organisms

Ex: Ex: RhizobiumRhizobium –live –live in lumps on legume in lumps on legume roots.roots.

Ex: Ex: E-coli O157:H7-E-coli O157:H7- eats undigested eats undigested nutrients in mammal nutrients in mammal intestines intestines

Bacteria Structure: Cell Bacteria Structure: Cell WallsWalls Two types of cell walls distinguished by Gram Two types of cell walls distinguished by Gram

staining: Gram – or Gram +staining: Gram – or Gram + After staining, the color for After staining, the color for Gram –Gram – is Red & is Red &

Gram +Gram + is Purple. is Purple. Gram stain helps determine which antibiotic Gram stain helps determine which antibiotic

would be most helpful in fighting an infection.would be most helpful in fighting an infection.

Gram + and Gram – Gram + and Gram – Bacterium Cell WallsBacterium Cell Walls

Movement of Bacteria• Flagella ~ Tail like structure the

whips around to propel the bacterium

• Cillia ~ Miniature flagella surround the cell that help to “swim”

• Pili ~ short hair-like protein structures that help it to stick to surfacces

CiliaCilia of a bacteriumof a bacterium

E. coliE. coli with pili with pili

Bacteria ReproductionBacteria Reproduction Binary Fission Binary Fission Steps of Binary Fission:Steps of Binary Fission: - DNA condenses to form a - DNA condenses to form a

circular chromosome & it circular chromosome & it attaches to the cell membrane.attaches to the cell membrane.

- The DNA is copied, resulting in - The DNA is copied, resulting in 2 identical chromosomes (which 2 identical chromosomes (which are both attached to the cell are both attached to the cell membrane)membrane)

Continuation of Continuation of ReproductionReproduction

The cell grow until it reaches The cell grow until it reaches TWICE the original size.TWICE the original size.

The cell begins to divide and The cell begins to divide and a new cell wall forms around a new cell wall forms around the new cell membrane.the new cell membrane.

The result are two The result are two identicalidentical daughter cellsdaughter cells..

ConjugationConjugation

Two bacteria swap genetic information,

Enables bacteria to spread genes within a population

Ex: a gene that allows resistance to penicillin

Spore Formation: Spore Formation: EndosporeEndospore A type of A type of dormantdormant cell cell Exhibit Exhibit no signs of no signs of

lifelife Highly Highly resistant toresistant to

environmental environmental stressesstresses such as: such as:- - High temperaturesHigh temperatures- Irradiation- Irradiation- Strong acids- Strong acids

- Disinfectants- Disinfectants

Bacteria RespirationBacteria Respiration Obligate AnaerobesObligate Anaerobes

Facultative Facultative AnaerobesAnaerobes

Obligate AerobesObligate Aerobes

Live without Live without OxygenOxygen

Can live with or Can live with or without oxygenwithout oxygen

Cannot live without Cannot live without oxygen. oxygen.

Strep ThroatStreptococcus pyogenesSphere, Gram +Gram +

PneumoniaKlebsiella pneumoniaeBacillus, Gram -Gram -

Food-born illness Salmonella sp. Bacillus, Gram -Gram -

“Botox” or Food Poisoning

Clostridium botulinumBacillus, Gram +Gram +

Cholera Vibrio cholerae Comma-shaped, Gram -Gram -

Leprosy Mycobacterium leprae

Tuberculosis (TB)(White Plague)

Mycobacterium tuberculosisKills 1.8 million people each year

Tetnus Clostridium tetaniRod, Gram +Gram +

Bubonic Plague(Black Plague)

Yersinia pestis Rod, Gram -Gram -

Lyme diseaseBorrelia burgdorferiSpiralSpiral,, Gram -Gram -

Meningitis Neisseria meningitidisDiplococcal, Gram -Gram -

Parasitism

Bacteria exploit the host cell, injuring them

Eg. Mychobacterium tuberculosis

What are Viruses?

A virus is a non-cellular particle made up of genetic

material and protein that can invade living cells.

The Structure Of a VirusThe Structure Of a Virus Viruses are composed of Viruses are composed of

a a core of nucleic acidcore of nucleic acid made of either made of either DNA or DNA or RNARNA but never both. but never both.

The nucleic acid core is The nucleic acid core is surrounded by a surrounded by a protein coatprotein coat called a called a capsid.capsid.

Viruses are classified by Viruses are classified by differencesdifferences in the in the structures of protien structures of protien coats.coats.

T4 BacteriophageT4 Bacteriophage

Polyhedral Polyhedral VirusVirus

Herpes zoster virusHerpes zoster virus

Rod-shaped virusesRod-shaped viruses

Tobacco Mosaic Virus- damages tobacco Tobacco Mosaic Virus- damages tobacco crops crops

Rod- shaped VirusesRod- shaped Viruses

Ebola virusEbola virus

Are viruses living or nonliving?

They have genetic material that is passed on to future generations

This material can change over time, therefore viruses can evolve

BUT, viruses are not made of cells, they cannot make proteins, cannot use energy (no metabolism), and cannot reproduce.

Multiplication of a Multiplication of a BacteriophageBacteriophage

The virus hijacks a living cell’s The virus hijacks a living cell’s nucleus. Inserts it’s genetic material nucleus. Inserts it’s genetic material

into the cell’s DNA. So the cell into the cell’s DNA. So the cell produces about 100 virus particles in produces about 100 virus particles in

20 minutes. 20 minutes.

Cycle of Lytic and LysogenicCycle of Lytic and Lysogenic

THE END

Vaccines Vaccines ►Viruses grown on chicken embryos are Viruses grown on chicken embryos are

attenuated vaccinesattenuated vaccines►Another type of vaccine is made by Another type of vaccine is made by

heat killing the virus heat killing the virus

Retrovirus

Change DNA into RNA.

Example of a Retrovirus is HIV

A typical, "minimal" retrovirus consists of: •an outer envelope which was derived from the plasma membrane of its host •many copies of an envelope protein embedded in the lipid bilayer of its envelope •a capsid; a protein shell containing •two molecules of RNA and •molecules of the enzyme reverse transcriptase