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Bacteria, viruses and the immune system

Bacteria, viruses and the immune system. Biology. 2 Bacteria Kingdoms. Archaebacteria Harsh environment High temperatures High salinity Acidic. Eubacteria Found in normal environments. These are the type of bacteria that we come into contact with on a daily basis!!!.

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Bacteria, viruses and the immune system

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  1. Bacteria, viruses and the immune system Biology

  2. 2 Bacteria Kingdoms • Archaebacteria • Harsh environment • High temperatures • High salinity • Acidic • Eubacteria • Found in normal environments. • These are the type of bacteria that we come into contact with on a daily basis!!!

  3. General Structure of Bacteria •  Prokaryotic • No nucleus or membrane bound organelles • Lots of ribosomes • Thick cell wall • Circular chromosomes (DNA) • Some have a sticky capsid located outside the cell wall; this allows them to stick to surfaces…. like your teeth!! 

  4. General Structure of a Bacterial Cell

  5. Bacterial Reproduction • Reproduce by binary fission • Asexual reproduction • Makes an exact copy • Happens quickly

  6. Binary Fission in Bacterial Cells Bacteria Grows DNA replication occurs Cytokinesis occurs Two identical cells result

  7. Bacteria…Good, Bad or Both? • Bacteria is good! • food (yogurt) • medicines (insulin) • recycles nutrients • decompose • nitrogen fixation (in plants) • Bacteria is bad! • Decay/rot food • Rot teeth • Cause disease/ infections (strep throat)

  8. Antibiotics • Antibiotics are used to clear up bacterial infections. • Antibiotics put holes into bacterial cell walls causing them to burst and die.

  9. Viruses • Considered to be nonliving because it cannot reproduce on its own • General Structure • Protein coat on the outside • Nucleic acid on the inside (DNA or RNA)

  10. Virus Structure

  11. Examples of Viruses • Influenza- the flu • HIV- AIDS • Varicella- chicken pox & shingles • Polio virus- polio • Rubella or measles- measles • Rhinovirus- cold

  12. Reproductive Cycles Lytic Cycle • Virus DNA enters the host cell • Hijacks host to make DNA and protein • Host cell puts viruses together • Cell bursts and releases virus

  13. Lysogenic Cycle Lysogenic Cycle • Very similar to lytic cycle • Virus DNA is integrated into host cell • Cell eventually ruptures with new virus after several generations

  14. Examples of Viruses with a Lysogenic Cycle • HIV • Herpes Simplex I = Cold sores • Herpes Simplex II = Genital herpes • Varicella = Chicken pox/ Shingles

  15. Our Immune System • Responsible for protecting the body from diseases caused by bacteria and viruses

  16. Lines of Defense • 1st line: skin and mucus • Skin acts as a barrier • Mucus traps microorganisms • 2nd line: cells release chemicals • blood flow to invaded region increases (swelling) • Raises body temperature (fever)

  17. 3rd line: Special white blood cells attack invaders • foreign antigens are detected and Helper T white blood cells are alerted • Helper T cells “activate” white blood cells called B cells • B cells multiply and either become plasma cells or Memory B cells • Plasma cells produce antibodies that attach to the foreign antigens and “mark” them for destruction • Memory B cells stay in the body in case another infection arises

  18. Uh OH!!! • What if a cell is already infected?!?!?! • Helper T cells alert Killer T cells • Killer T cells poke holes in the infected cell to kill it

  19. Types of Immunity • Active Immunity • Exposed to disease • Develop disease and become immune • Longer lasting • Passive Immunity • Injected with antibody that another organism made • Not permanent Some vaccines have to be received every year because the pathogen that causes the illness is always mutating!!!

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