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CLASSIFICATION, BACTERIA, AND VIRUSES Biology. Classification  Taxonomy is:  the science of naming and classifying organisms  Linnaeus developed a.

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Presentation on theme: "CLASSIFICATION, BACTERIA, AND VIRUSES Biology. Classification  Taxonomy is:  the science of naming and classifying organisms  Linnaeus developed a."— Presentation transcript:

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  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 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 that moves 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) Bacteriophage Helical Spherical

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.


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