1 / 37

Identifying and Classifying Bacteria

Identifying and Classifying Bacteria. Ch. 23 . What is a prokaryote?. Cells that lack a true nucleus . Cells that lack membrane-bound organelles . Most surrounded by a cell wall. Many secrete a protective slime capsule . How big is a prokaryotic cell?. 1- 5 micrometers

hector
Download Presentation

Identifying and Classifying Bacteria

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Identifying and Classifying Bacteria Ch. 23

  2. What is a prokaryote? • Cells that lack a true nucleus. • Cells that lack membrane-bound organelles. • Most surrounded by a cell wall. • Many secrete a protective slime capsule.

  3. How big is a prokaryotic cell? • 1- 5 micrometers • (1 millionth of a meter)

  4. Classification • Archaebacteria vs Eubacteria

  5. Archaebacteria • Surrounded by a cell wall lacking peptidoglycan. • Live in extreme conditions

  6. Examples of Archae • Methanogens: convert H2 and CO2 into methane gas for energy • Halophiles: love salt • Thermoacidophiles: love heat and acid

  7. Eubacteria: • Surrounded by a cell wall made of peptidoglycan. • Example: rhizobium- nitrogen–fixing bacteria

  8. Identifying Prokaryotes 1. Shape: • Coccus – spherical • Bacillus – rod-shaped • Spirillum – spiral • Vibrio – comma shape

  9. Bacillus Coccus Vibrio Spirillum

  10. Cocci and Bacilli may group together Prefixes for arrangements: Diplo – two Ex. Diplococcus

  11. Strepto – chain Streptococcus Streptobacillus

  12. Staphylo - clustered Staphylococcus

  13. 2. Motility: ability to move • Flagella: whip-like structure used to propel bacteria • Slime: glide along slime secretion • Spiral motion: cork-screw motion (spirillum)

  14. 3. Metabolism: Oxygen or NOT • Obligate Aerobes: Need oxygen • Obligate Anaerobes: cannot live in oxygen • Facultative anaerobes: can live with or without oxygen

  15. 3.Metabolism: Obtaining Energy Autotroph vs. Heterotroph • Photoautotroph- uses light energy for photosynthesis • Chemoautotroph- uses energy from inorganic chemicals for chemosynthesis

  16. Photoheterotrophs- uses photosynthesis and eats organic compounds • Heterotroph – consumes organic compounds

  17. review • What role do chemosynthetic bacteria have in the ecosystem? • http://www.youtube.com/watch?v=4lmwbBzClAc&NR=1

  18. Bacterial Reproduction

  19. Asexual: Binary fission • Circular DNA replicates • Cell membrane and cell wall divide • Identical daughter cells separate

  20. How fast does this happen? • http://www.youtube.com/watch?v=gEwzDydciWc&feature=related • approximately every 20 minutes

  21. Genetic recombination Sharing or exchanging of genetic material 3 types: • Conjugation • Transformation • Transduction

  22. 1. Conjugation • A temporary bridge forms between two cells. • A plasmid, a separate section of DNA, is transferred from one cell to the other. • Often the plasmid contains useful genes, like antibiotic resistance.

  23. 2. Transformation • Bacteria takes in DNA from the environment. • Dead bacteria may break apart and release DNA. • Other bacteria can pick up this DNA and become genetically different.

  24. 3. Transduction • Viruses can pick up small amounts of DNA from a host bacteria. • When it infects another bacteria, the new DNA is transferred into that cell.

  25. Disease • Pathology is the study of disease. • Pathogens: organisms that cause disease.

  26. Gram-staining Test • Gram-positive: bacteria contain lots of peptidoglycan in cell walls. Stains purple. • Gram- negative: bacteria contain little peptidoglycan in cell walls. Stains red.

  27. Exotoxins • Poisonous proteins that are released by some gram-positive bacteria.

  28. For example • Clostridium tetani secretes an exotoxin that causes tetanus. • Tetanus causes stiffness in muscles. • Clostridium botulinumproduces a very powerful exotoxin that causes the fatal disease, botulism. • 1 g of botulism toxin can kill 1 million people.

  29. Endotoxins • Lipids and carbohydrates in the cell membranes of some Gram-negative bacteria, that are poisonous. • They are released when the bacteria die.

  30. For example: • Most species of Salmonella, are endotoxin producing bacteria. • Salmonellatyphi, causes typhoid fever.

  31. Antibiotics • Antibiotics interfere with the bacteria’s cellular activities.

  32. For example: • Penicillin: blocks the building of the cell wall. “Accidently” discovered by Alexander Fleming in 1920s • Tetracyline: blocks protein synthesis.

  33. Where do antibiotics come from? • Antibiotics are naturally made by some fungi and bacteria. • Some are made synthetically in labs. • But most used in treatment still come from bacteria.

  34. Antibiotic-Resistance • Bacteria can quickly adapt to their environment because of their rapid rate of reproduction.

  35. Antibiotic-Resistance • If one bacterium mutates and becomes resistant, • then in the presence of antibiotics, bacteria not resistant die • Those with the resistance take over the population.

  36. Which diseases are preventable by better sanitation practice? • Cholera • Salmonella • Tetanus • Staph

  37. What are other ways that antibiotic resistance is passed? • Genetic recombination

More Related