UNIT 8:Chapter 19 Bacteria and Viruses

BACTERIA

The beautiful colors in this sulfur spring are caused by the bacteria that live in it. Bacteria can survive in extreme habitats.

Prokaryote Review No nucleus Mostly single -celled Circular chromosomes Cell walls Reproduce mostly asexually Anaerobic or aerobic Heterotrophic or autotrophic

Archaebacteria Methane producers – anaerobic Halophiles Thermophiles Halo = salt Philia = love Thermophiles Thermo = heat THESE BACTERIA CELLS HAVE PEPTIDOGLYCAN IN THEIR CELL WALLS TO PROTECT THEM FROM THE EXTREMELT HOT TEMPERATURES.

Hey you, Bacteria, I love your shape!!! (Eubacteria) Shapes: Cocci, Bacilli, and Spirilla How are these words associated with bacteria? Baking soda Yogurt Tooth decay Vitamins Road kill

Bacteria are Named by Shape Coccus (ball-shaped) Streptococcus mutans Bacillus (rod-shaped) Clostridium botulinum Spirilli (spiral-shaped) Treponema palladium

Prokaryotic Body Plan DNA capsule plasma membrane ribosomes in cytoplasm bacterial flagellum Figure 21.3 Page 348 pilus cell wall cytoplasm

Bacterial Shapes coccus bacillus spirillum In-text figure Page 348

Prokaryotic Fission - 1 Bacterium before bacterial chromosome DNA replication bacterial chromosome DNA replication begins Figure 21.7 Page 350

DNA replication completed Membrane growth moves DNA molecules apart Prokaryotic Fission - 2 parent DNA molecule DNA copy DNA replication completed Membrane growth moves DNA molecules apart Figure 21.7 Page 350

New membrane and cell-wall material deposited Cytoplasm divided in two Prokaryotic Fission - 3 New membrane and cell-wall material deposited Cytoplasm divided in two Figure 21.7 Page 350

Conjugation Transfer of plasmid Figure 21.8 Page 351 nicked plasmid in donor cell conjugation tube to recipient cell Conjugation Transfer of plasmid Figure 21.8 Page 351

Rhizobium

Bacteria Good?? BACTERIA CAN HELP THOSE WHO ARE INSULIN DEFICIENT (SOME DIABETICS). THIS IS DONE WHEN THE BACTERIA’S DNA COMBINES WITH INSULIN PRODUCING GENES FROM HUMAN.

VIRUSES

Are viruses alive? Only 1 characteristic of life: reproduction Can only reproduce inside a host cell! Process or reproduction = lytic cycle Like bacteria, viruses produce disease by disrupting the body’s normal equilibrium (homeostasis).

Figure 19-11 Viruses and Cells Section 19-2

Figure 19-10 Lytic and Lysogenic Infections

Diseases caused by viruses: Common Diseases Caused by Viruses Diseases caused by viruses: Section 19-3 Type of Virus Nucleic Acid Disease Oncogenic viruses Retrovirus Adenoviruses Herpesviruses Poxviruses DNA RNA Cancer Cancer, AIDS Respiratory infections Chickenpox Smallpox

Lysis of host cell is induced; infectious particles escape. Lytic Pathway Tail fibers and other parts are added to coats. Virus particles bind to wall of suitable host. Viral genetic material enters cell cytoplasm. Viral protein molecules are assembled into coats; DNA is packaged inside. Viral DNA directs host machinery to produce viral proteins and viral DNA. Stepped Art Fig. 21.20 Page 358

Viral DNA usually becomes integrated into the bacterial chromosome. Lysogenic Pathway Viral DNA is excised from chromosome and cell enters lytic pathway. Prior to prokaryotic fission, the chromosome and integrated viral DNA are replicated. After binary fission, each daughter cell will have recombinant DNA. Stepped Art Fig 21.20 (2) Page 358

Viral Body Plans Genetic material is DNA or RNA Coat is protein Complex virus (bacteriophage) Genetic material is DNA or RNA Coat is protein Helical virus Polyhedral virus Fig. 21.18 Page 356

LYTIC CYCLE-virus replication

Enveloped Virus (HIV) viral protein lipid envelope (derived from host) viral RNA reverse transcriptase Fig. 21.18 Page 356 viral coat (proteins)

Click the image to play the video segment. Lytic and Lysogenic Cycles Click the image to play the video segment. Video

Virus Nucleic Acid DNA viruses – stable, do not mutate rapidly Single-stranded or double-stranded Smallpox, Hepatitis B RNA viruses – mutate rapidly, unstable HIV, Rhinovirus

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

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

New Threats Emerging Pathogens Drug-resistant strains Food poisoning Ebola virus Monkeypox virus Drug-resistant strains Food poisoning E. coli Salmonella