Bacteria and Viruses Lecture 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 Cocci Cocci~ Sphere-shaped bacteria Bacillus Bacillus~ Rod-shaped bacteria Spirillium Spirillium ~ Spiral-shaped bacteria

Bacteria and their energy  Autotrophs  Chemotrophs  Heterotrophs

Autotrophs  Photosynthesis- use sunlight to make their food. Four major groups w/ different photosynthetic pigments: a. Purple sulfur (O 2 free environment) b. Purple non-sulfur c. Green sulfur (O 2 free environment) c. Green sulfur (O 2 free environment) d. Cyanobacteria (Blue-green alage)

Cyanobacteria Bluish-greenish color Bluish-greenish color Carry out the process of photosynthesis Carry out the process of photosynthesis Do not contain the same type of chloroplasts as plants do Do not contain the same type of chloroplasts as plants do Can survive in extremely hot environments and even extremely cold environment Can survive in extremely hot environments and even extremely cold environment

Chemoautotrophs Make their own food Make their own food Remove e-’s from inorganic molecules such as ammonia & methane Remove e-’s from inorganic molecules such as ammonia & methane Live in the soil & are responsible for nitrification Live in the soil & are responsible for nitrification Ex: Nitrobacter Ex: Nitrobacter Ex: Archaebacteria Ex: Archaebacteria

Heterotrophs Obtain their own food Obtain their own food Decomposers- break down the bodies of dead organisms Decomposers- break down the bodies of dead organisms Ex: Rhizobium –live in lumps on legume roots. Ex: Rhizobium –live in lumps on legume roots. Ex: E-coli O157:H7- eats undigested nutrients in mammal intestines Ex: E-coli O157:H7- eats undigested nutrients in mammal intestines

Bacteria Structure: Cell Walls Two types of cell walls distinguished by Gram staining: Gram – or Gram + Two types of cell walls distinguished by Gram staining: Gram – or Gram + After staining, the color for Gram – is Red & Gram + is Purple. After staining, the color for Gram – is Red & Gram + is Purple. Gram stain helps determine which antibiotic would be most helpful in fighting an infection. Gram stain helps determine which antibiotic would be most helpful in fighting an infection.

Gram + and Gram – Bacterium 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

Cilia of a bacterium E. coli with pili

Bacteria Reproduction Binary Fission Binary Fission Steps of Binary Fission: Steps of Binary Fission: - DNA condenses to form a circular chromosome & it attaches to the cell membrane. - DNA condenses to form a circular chromosome & it attaches to the cell membrane. - The DNA is copied, resulting in 2 identical chromosomes (which are both attached to the cell membrane) - The DNA is copied, resulting in 2 identical chromosomes (which are both attached to the cell membrane)

Continuation of Reproduction The cell grow until it reaches TWICE the original size. The cell grow until it reaches TWICE the original size. The cell begins to divide and a new cell wall forms around the new cell membrane. The cell begins to divide and a new cell wall forms around the new cell membrane. The result are two identical daughter cells. The result are two identical daughter cells.

Conjugation Two bacteria swap genetic information, Enables bacteria to spread genes within a population Ex: a gene that allows resistance to penicillin

Spore Formation: Endospore  A type of dormant cell  Exhibit no signs of life  Highly resistant to environmental stresses such as: - High temperatures - Irradiation - Strong acids - Disinfectants - Disinfectants

Bacteria Respiration Obligate Anaerobes Obligate Anaerobes Facultative Anaerobes Facultative Anaerobes Obligate Aerobes Obligate Aerobes Live without Oxygen Live without Oxygen Can live with or without oxygen Can live with or without oxygen Cannot live without oxygen. Cannot live without oxygen.

Strep Throat Streptococcus pyogenes Gram + Sphere, Gram + Pneumonia Klebsiella pneumoniae Gram - Bacillus, Gram - Food-born illnessSalmonella sp. Gram - Bacillus, Gram - “Botox” or Food Poisoning Clostridium botulinum Gram + Bacillus, Gram +

CholeraVibrio cholerae Gram - Comma-shaped, Gram - LeprosyMycobacterium leprae Tuberculosis (TB) ( White Plague) Mycobacterium tuberculosis Kills 1.8 million people each year TetnusClostridium tetani Gram + Rod, Gram + Bubonic Plague (Black Plague) Yersinia pestis Gram - Rod, Gram - Lyme disease Borrelia burgdorferi Spiral,Gram - Spiral, Gram - MeningitisNeisseria meningitidis Gram - Diplococcal, 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 Virus Viruses are composed of a core of nucleic acid made of either DNA or RNA but never both. Viruses are composed of a core of nucleic acid made of either DNA or RNA but never both. The nucleic acid core is surrounded by a protein coat called a capsid. The nucleic acid core is surrounded by a protein coat called a capsid. Viruses are classified by differences in the structures of protien coats. Viruses are classified by differences in the structures of protien coats.

T4 Bacteriophage

Polyhedral Virus Herpes zoster virus

Rod-shaped viruses  Tobacco Mosaic Virus- damages tobacco crops

Rod- shaped Viruses Ebola 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 Bacteriophage The virus hijacks a living cell’s nucleus. Inserts it’s genetic material into the cell’s DNA. So the cell produces about 100 virus particles in 20 minutes.

Cycle of Lytic and Lysogenic

THE END

Vaccines ► Viruses grown on chicken embryos are attenuated vaccines ► Another type of vaccine is made by 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