BACTERIA  Characteristics  no membrane bound nucleus  single chromosome  reproduce by fission  great metabolic diversity

Archaebacteria Methanogens Extreme halophiles Extreme thermophiles

Eubacteria  Includes most familiar bacteria  Have fatty acids in plasma membrane  Most have cell wall; always includes peptidoglycan  Classification based largely on metabolism

Bacterial Behavior  Bacteria move toward nutrient-rich regions  Aerobes move toward oxygen; anaerobes avoid it  Photosynthetic types move toward light  Magnetotactic bacteria swim downward

 Photoautotrophic  Cyanobacteria  get e - and H + from H 2 O and release free O 2  light trapping pigments and e - transfer chains  Chemoautotrophic  Anaerobes  free oxygen kills them  get e - and H + from gaseous H 2, H 2 S and other inorganic compounds

 Chemoheterotrophic  saprotrophic  must consume organic molecules for energy and carbon  known as decomposers  Photoheterotrophic  use light for energy  must obtain their carbon in organic form

Eubacteria Examples of eubacteria

 Bacteria contain the following structures  DNA (circular)  cell wall (peptidoglycan)  thin plasma membrane  flagella  cilia

Gram Stain Gram stain

 Stained bacteria  Gram negative  red  double layer  Gram positive  purple  single layer

Bacterial Shapes  Cocci  round  Bacilli  rod  Spirilla  spiral

Bacterial Arrangements  Staphlo  Grape like clusters  Strepto  chains  Diplo  pairs

Bacteria ReproductionBacteria Reproduction:  Binary fission  bacteria divides into 2 identical cells

Prokaryotic Fission Prokaryotic fission

Genetic Variation  Conjugation  process by which bacteria exchange genetic information  It is not sexual reproduction because no new offspring are produced

Conjugation Prokaryotic conjugation

 Transformation  bacteria picks up free pieces of DNA

 Transduction  bacteriophages carry portions of bacterial DNA from one cell to another

 Spore Formation  allows bacteria to remain dormant when conditions are unfavorable to reproduce  has thick internal wall that protects DNA  dehydrated form

Bacterial diseases: What are they and what do they affect? Gram + infections :  Streptococcus  Strep throat  Staphylococci (staph infection)

 Diphtheria  membrane becomes inflamed over windpipe  Botulism  Food poisoning

 Tetanus  caused by deep puncture wound  produces poisons and toxins which over stimulates the nervous system  causes muscle spasms  commonly known as lock jaw

Gram – infections  E. Coli  found in  your intestine  helps digest fat and produce vitamin K  improperly processed meat Acid Fast infections  TB –(tuberculosis)  affects the lungs

 Leprosy (Hansen's Bacillus)  attacks and destroys nerves  causes deformities, even loss of parts

VIRUSES  What is a virus made of?  non cellular  DNA or RNA  protein coat

Properties / Characteristics  dormant unless in a host cell  reproduce only when in a host cell  all energy derived from host  smaller than a bacteria cell

Viral Multiplication - Basic Steps  Attach to host cell  Enter host (virus or just genetic material)  Direct host to make viral genetic material and protein  Assemble viral nucleic acids and proteins  Release new viral particles

Lytic Cycle of a Virus  Lytic Cycle  attaches to the cell  injects its DNA or RNA into cell  viral DNA programs cell RNA to produce viruses as a result shuts down cell activity  cell bursts and releases viruses

Lytic Pathway Virus particles bind to wall of suitable host. Viral genetic material enters cell cytoplasm. Viral DNA directs host machinery to produce viral proteins and viral DNA. Viral protein molecules are assembled into coats; DNA is packaged inside. Tail fibers and other parts are added to coats. Lysis of host cell is induced; infectious particles escape.

Lysogenic Pathway  Lysogenic Cycle  attaches to cell  DNA of virus enters cell and is inserted into the DNA of the host cell  does not kill its host outright  can lie dormant for many years

 becomes active because of stress or change in body  lytic cycle begins

Viral DNA usually becomes integrated into the bacterial chromosome. Prior to prokaryotic fission, the chromosome and integrated viral DNA are replicated. After binary fission, each daughter cell will have recombinant DNA. Viral DNA is excised from chromosome and cell enters lytic pathway.

 Viruses can be transmitted in 5 ways:  coughing  sneezing

 ingesting infected food  animal bites

 physical contact  bodily fluids

Viral Infections  Mononucleosis or Herpes 2  glands in your neck  tired, headaches  Corona virus  causes bronchitis

 Mumps  causes the swelling of the salivary glands,  can affect other organs as well  Measles  usually affects the skin  can affect the respiratory system, brain

 Chicken pox  Poliomyelitis (polio)  attacks the spinal cord

 Herpes 1  common cold sore  fever blisters  Conjunctivitis  pink eye

How are viral infections cured?  no known antibiotic or treatment  body’s is its own natural defense mechanism  must run its course  can only treat the symptoms  when body detects virus (antigen), body produces antibodies called plasmacytes  fight off viruses  remains in blood  a single attack of a virus usually results in lifelong immunity Can viral infections repeat themselves?

What is an immunization?  weakened or killed virus strain  cannot cause disease  helps to produce the stimulation of antibody production  immunizations are used against  Polio  Measles  Chicken pox  Mumps  Influenza (flu)

What is a retrovirus?  contains RNA instead of DNA  works backwards  example  HIV -- Aids

Nature of Disease  Contagious disease pathogens must directly contact a new host  Epidemic  Pandemic (AIDS)  Sporadic  Endemic

New Threats  Emerging Pathogens  Ebola virus  West Niles virus  SARS virus  Avian Influenza  H1N1  Drug-resistant strains  Food poisoning  E. coli  Salmonella

Impacts, Issues Video West Nile Virus Takes Off

Viroids  Smaller than viruses  Strands or circles of RNA  No protein-coding genes  No protein coat  Cause many plant diseases

Prions  Small proteins  Linked to human diseases  Kuru  Prion found in brain tissue  Causes nervous and brain  Creutzfeldt-Jakob disease (CJD)  Animal diseases  Scrapie in sheep  Bovine spongiform encephalopathy (mad cow disease)

Evolution and Disease  Host and pathogen are coevolving  If a pathogen kills too quickly, it might disappear along with the individual host  Most dangerous if pathogen  Is overwhelming in numbers  Is in a novel host  Is a mutant strain

Bacterial Genes  Bacteria have a single chromosome Circular molecule of DNA Circular molecule of DNA  Many bacteria also have plasmids Self-replicating circle of DNA that has a few genes Self-replicating circle of DNA that has a few genes Can be passed from one cell to another Can be passed from one cell to another