Classification, Bacteria, and Viruses
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Transcript of Classification, Bacteria, and Viruses
CLASSIFICATION, BACTERIA, AND VIRUSES
Biology
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
Classification
Overtime, Linnaeus’s classification/taxonomy system expanded to organize living things further. This includes: Kingdom Phlyum Class Order Family Genus Species
Classification
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.
Classification
Classification
Classification has broaden beyond kingdoms to domains: Bacteria Archaea Eukarya
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
Domain Bacteria
Domain Bacteria Examples include: Bacillus, E. Coli,
Streptococcus
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
Domain Archaea
Examples: Methancoccus, Halobacterium,
Thermoproteus
Domain Eukarya
Examples: Animals, Plants, Fungi, Protists
*We will explore each Kingdom in more detail throughout the remainder of the year
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
Prokaryotes
Bacteria Surrounded by cell wall which contains
peptidoglycan Archaebacteria
Look similar to bacteria Lack peptidoglycan in cell walls Live in harsh environments
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)
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
Bacteria
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
Bacteria- shapes
Bacilli Rod-shaped
Cocci Spherical-shaped as either:
Staph- clusters Strep-chains
Spirilla Spiral-shaped
Bacteria-shapes
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
Bacteria- Aerobic, Anaerobic, and Facultative Anaerobes Aerobic
Need oxygen to live Anaerobic
Cannot live with oxygen Facultative anaerobes
Can live with or without oxygen
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
Bacteria- Binary Fission
Bacteria and Disease
Pathology- the study of disease caused by pathogens (microorganism—viruses or prokaryotes– that cause disease)
Bacteria and disease
Bacteria cause disease by destroying living cells or by releasing chemicals that upset homeostasis. Damaging host tissue Releasing toxins
Bacteria and Disease
Bacteria can be controlled via: Physical removal Disinfectants Food storage Food processing Sterilization by heat
Bacteria and Disease
Bacterial diseases can be treated via- Antibiotics
Blocks the growth and reproduction of bacteria Examples: penicillin, streptomycin, and
tetracycline
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.
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.
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)
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)
BacteriophageHelical
Spherical
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.
Virus
Viral Infections can take place in two ways- Lytic infection Lysogenic infection
Virus
Lytic Infection The virus infects a cell, it replicates, and
the new viruses burst or “lyse” from the cell.
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.
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)
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.