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 Archaebacteria 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 Cocci Spirilla Rod-shaped 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 Need oxygen to live Anaerobic Cannot live with oxygen Facultative anaerobes Can live with or without oxygen

Bacteria- 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) Spherical Bacteriophage Helical

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- Vaccinations 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.