Classification, Bacteria, and Viruses

1. Classification, Bacteria, and Viruses Biology 

2. Classification • Taxonomy is: • the science of naming and classifying organisms • Linnaeus developed a two-word naming systems called binomial nomenclature. • Each species is assigned a two-part scientific name. • Written in italic, with just the first word capitalized • First word: Genus • Second word: species • For examples, humans are Homo sapiens

3. Classification • Overtime, Linnaeus’s classification/taxonomy system expanded to organize living things further. This includes: • Kingdom • Phlyum • Class • Order • Family • Genus • Species

4. Classification

5. Classification • Cladogram- • a model used by evolutionary biologists to represent evolutionary history among species • Clade- a group of species that includes a single common ancestor and all descendants of that ancestor. • Derived character- a trait that arose in the most recent common ancestor of a particular lineage and was passed along to its descendants.

6. Classification

7. Classification • Classification has broaden beyond kingdoms to domains: • Bacteria • Archaea • Eukarya

8. Domain Bacteria • Characteristics: • Unicellular prokaryotes • Peptidoglycan cell wall, cell membrane, ribosomes • No membrane-bound organelles • Naked DNA, single circular chromosome • Asexual reproduction= binary fission • Heterotrophs, photoautotrophs, chemoautotrophs • Rods, spheres, spirals: Gram positive and gram negative

9. Domain Bacteria • Domain Bacteria • Examples include: Bacillus, E. Coli, Streptococcus

10. Domain Archaea • Characteristics • Unicellular prokaryotes • Cell wall (no peptidoglycans), cell membrane, ribosomes, no membrane-bound organelles • DNA + histone proteins, single circular chromosome • Asexual reproduction = binary fission • Extremophiles: halophiles, thermophiles, methanogens

11. Domain Archaea • Examples: • Methancoccus, Halobacterium, Thermoproteus

12. Domain Eukarya • Examples: • Animals, Plants, Fungi, Protists • *We will explore each Kingdom in more detail throughout the remainder of the year 

13. Prokaryotes • All bacteria are prokaryotes- • unicellular organism that lack a nucleus. • small cells (about 1-10 µm) that do not have membrane-bound organelles • Found in bacteria and archaebacteria

14. Prokaryotes • Bacteria • Surrounded by cell wall which contains peptidoglycan • Archaebacteria • Look similar to bacteria • Lack peptidoglycan in cell walls • Live in harsh environments

15. Bacteria • Prokaryotic Cell Structures: • Nucleoid region – • part of the prokaryotic cell where the DNA is found • Cell membrane – • innermost covering of the cell • Cell wall – • outside of cell membrane • Capsule – • outside of the cell wall, protective covering (not all bacteria have it)

16. Bacteria Prokaryotic Cell Structures (continued): • Flagella (sing. Flagellum) – • long, whiplike structure thatmoves bacteria • Endospore • A thick wall that encloses DNA; resistance structure enabling bacteria to survive harsh conditions • Pili – • short, hair-like projection used to stick to other surfaces and for conjugation (exchange of genetic materials between bacteria) • Cytoplasm – • jelly-like fluid that dissolves substances and holds organelles • Ribosomes – • organelles that make proteins in the cytoplasm

17. Bacteria

18. Bacterial cell walls • In bacteria, the cell wall consists of a protein/carbohydrate complex called carbohydrate called peptidoglycan. They are classified based on their cell walls: • Gram positive bacteria • More peptidoglycan in cell walls • Appear purple under the microscope after gram stain • Gram negative bacteria • Have less peptidoglycan in cell walls • Have outer membrane • Apper pink under the microscope after gram stain

19. Bacteria- shapes • Bacilli • Rod-shaped • Cocci • Spherical-shaped as either: • Staph- clusters • Strep-chains • Spirilla • Spiral-shaped

20. Bacteria-shapes

21. Bacteria- modes of nutrition • Heterotroph • Consume other organisms: Clostridium • Photoheterotroph • Consume other organisms and can use light energy: Rhodobacter • Photoautotroph • Use light energy to make carbon compounds; Cyanobacteria • Chemoautotroph • Use chemicals, like ammonia and hydrogen sulfide, to obtain energy; Nitrogen-fixing bacteria

22. Bacteria- Aerobic, Anaerobic, and Facultative Anaerobes • Aerobic • Need oxygen to live • Anaerobic • Cannot live with oxygen • Facultative anaerobes • Can live with or without oxygen

23. Bacteria- Binary Fission • Binary fission • Process by prokaryotes reproduce by cell division. • Steps: • Duplication of chromosomes and separation of copies. • Cell elongates • Divides into two daughter cells

24. Bacteria- Binary Fission

25. Bacteria and Disease • Pathology- the study of disease caused by pathogens (microorganism—viruses or prokaryotes– that cause disease)

26. Bacteria and disease • Bacteria cause disease by destroying living cells or by releasing chemicals that upset homeostasis. • Damaging host tissue • Releasing toxins

27. Bacteria and Disease • Bacteria can be controlled via: • Physical removal • Disinfectants • Food storage • Food processing • Sterilization by heat

28. Bacteria and Disease • Bacterial diseases can be treated via- • Antibiotics • Blocks the growth and reproduction of bacteria • Examples: penicillin, streptomycin, and tetracycline

29. Bacteria and Disease • Prevention of a bacterial disease via: • vaccine- • A preparation of weakened or killed pathogens or inactivated toxins that prompt the body to produce immunity to a specific disease upon injection.

30. Virus • Virus • A nonliving particle made of proteins and nucleic acids. • Can reproduce only by infecting living cells. • Have no cytoplasm or organelles • Cannot carryout metabolism or homeostasis • Can’t grow like cells.

31. Virus • Viruses consist of… • Capsid- protein coat surrounding a virus • Some viruses have an envelop that surrounds the capsid (Influenza) • Nucleic acids (either DNA or RNA)

32. Virus • Shapes • Helical- Tobacco Mosaic Virus (contains RNA) • Polyhedral- Herpes (contains DNA) , Chicken Pox (contains DNA), Polio (contains RNA) • Spherical (enveloped)- Influenza (contains RNA) • Bacteriophage- T4 (contains DNA) Spherical Bacteriophage Helical

33. Virus • Viral Infections- • In order to infect a cell, a virus must be able to recognize it. • Viruses must bind the proteins on their capsid specifically to the proteins on their specific host. • Viruses then “trick” the cell to take in its genetic material. • Viruses will then make multiple copies of themselves inside the cell, ultimately destroying the cell.

34. Virus • Viral Infections can take place in two ways- • Lytic infection • Lysogenic infection

35. Virus • Lytic Infection • The virus infects a cell, it replicates, and the new viruses burst or “lyse” from the cell.

36. Virus • Lysogenic Infection • host cell is not immediately taken over • The virus infects a cell, the viral DNA integrates with host DNA where it may stay for a long period of time. • The viral DNA multiplies as the host cells multiply. • Eventually, it will become lytic, and the viruses will burst from the cell.

37. Viruses and Disease • Viruses cause disease by directly destroying living cells or by affecting cellular processes in ways that upset homeostasis. Diseases include: • Common cold • Influenza • AIDS • Chicken pox • Hepatitis • Wes Nile Virus • HPV (Human papillomavirus)

38. Viruses and Disease • Ways to fight viruses- • Hygiene- • Washing hands, avoiding contact with sick individuals, coughing or sneezing into a tissue or your sleeve • Vaccinations • Exposure to inactive forms of the virus that prompt the body to produce immunity to a specific disease upon injection. • Vector control • West Nile Virus is carried by mosquitoes (the vector). Controlling the population mosquitoes could eliminate the spread of the virus. • Antiviral drug therapy • Attack virual enzymes that in turn slow down or stop the infection cycle of the virus.