Microbiology Microbiology: The branch of biology that deals with microorganisms and their effects on other living organisms. Typically we study bacteria & protists. Virology studies the impact of viruses on organisms Viruses A. Virus General Information: 1. Non-living particles w/dna or RNA 2. viruses are not made of cells 3. viruses do not carry out respiration or grow 4. viruses only reproduce inside of a living host cell 5. Very small 1/1000 th the size of a bacteria 6. Examples: Influenza (flu), HIV, rabies, chicken pox, common cold B. Viral structure: 1. Inner layer: Made of DNA or RNA (nucleic acids) 2. Outer layer: Called capsid, it is a protein layer for protection *some viruses have an outer envelope of protection make them harder to destroy 3. Viral shape is specific, based on the type of cell it will invade
C. Viral invasion: 1) Virus attaches to host cell at a specific point in the cell s plasma membrane 2) Virus injects its DNA or RNA into the host cell 3) Viral DNA/RNA takes over the metabolism of the cell and causes it to produce viruses and releases them into the organism **Bacteriophage: special virus that invades a bacteria **NOTE: Antibiotics do not work on viruses. You must be given an antiviral drug to combat viruses. D. 2 Viral Cycles: 1) Lytic cycle: virus causes death of the host cell 2) Lysogenic cycle: virus takes over the cell without destroying it
Bacteria A. Bacteria General Information : 1) Members of Kingdoms Archaebacteria and Eubacteria 2) Prokaryotic cells 3) Unicellular 4) May be autotrophic or heterotrophic 5) Shapes part of their name a) Bacilli: rod-shaped b) Spirilli: spiral-shaped c) Coccus: sphere-shaped 6) Examples: Streptococcus pneumonia, Staphlococcus aureas, Bacillus cereus B. Bacterial structure: 1) Nucleoid: region where bacterial DNA is located 2) Cell Wall: protects bacterial cell, made of cellulose and surrounds the plasma membrane 3) Capsule: for protection 4) Plasma membrane: maintains homeostasis of the cell (allows substances to enter/leave the cell) 5) Pili: hair-like extensions of the plasma membrane to help the bacteria stick to surfaces and exchange DNA during sexual reproduction (conjugation) 6) Plasmid: circular DNA of the bacteria 7) Flagella: whip-like tail that enables bacteria to move
C. Gram Staining: used to distinguish different types of bacteria 1) Gram (+): thick cell wall, absorb lots of purple stain 2) Gram (-): thin cell wall, absorb little of the purple stain D. Bacterial reproduction: 1) Binary fission: asexual reproduction producing 2 identical bacteria a. no genetic variation - all are the same b. Chromosomes are copied and the bacteria divides 2) Conjugation: sexual reproduction where 2 bacteria exchange DNA thru pilli and then they divide a. causes genetic variation how bacteria get differences *** Antibiotics will kill bacteria by breaking down their cell wall and interfering with their metabolism and reproductive cycles E. Bacteria and oxygen: 1) Obligate aerobe: a. Bacteria that require oxygen to live b. Example: tuberculosis (TB) => attacks the lungs 2) Obligate anaerobe: a. Bacteria that does not require oxygen (will die in presence of oxygen) b. Example: botulism => spoiled canned foods
F. Concerns of bacteria: Why are bacteria bad?: 1) Disease: can cause diseases such as strep throat, infections 2) Food spoilage: can cause food to spoil and become poisonous G. Importance of bacteria: Why are bacteria good?: 1) Nitrogen fixation: Converts nitrogen from a gas in the air to a solid form that plants can use when growing a. Example: soybean plant w/ bacteria in roots 2) Decomposers: recycle nutrients a. Examples: decompose dead organisms and break down chemicals from oil spills 2) Make foods: a. Used to make cheeses, vinegar, yogurt 3) Medicines: a. Used to make medicines like bacitracin, neosporin Protists Kingdom Protista A. General Information: 1) Eukaryotes 2) Unicellular or multicellular 3) Autotrophic or heterotrophic 4) Have contractile vacuoles: vacuole that contracts to maintain water levels; pumps out excess water so the cell does not burst and die 5) Kingdom Protista is the most diverse kingdom B. 3 Types of Protists: 1) Protozoa: animal-like heterotrophs a. Amoeba: i. Pseudopod: moves using pseudopodia (false foot) as an extension of the cell membrane, ingests food by surrounding what it wants to eat ii. Reproduction method: asexually by binary fission b. Flagellates: i. Have flagella (long tail-like projection that assists the cell in moving
c. Ciliates: i. Move using cilia ii. Cilia: short hair-like extensions that are used for movement through fluids iii. Example: paramecium d. Sporozoans: i. No self-propulsion ii. Reproduces by producing spores iii. Many are disease-causing and parasitic iv. Example: Plasmodium (protist that causes Malaria) 2) Algae: plant-like organisms that carry out photosynthesis a. Euglena: i. use flagella to move ii. have eye-spots for detecting light sources iii. can be heterotrophic if the organism cannot find enough light to carry out photosynthesis b. Diatoms: i. have hard outer shells made of silicates (minerals) ii. Example: phytoplankton c. Dinoflagellates: i. have 2 flagella ii. usually these organisms produce poison (toxins) that cause fish kills iii. Example: Red Tide d. Kelp: i. multicellular algae ii. Example: Seaweed in sushi 3) Fungus-like protist: a. Examples: Slime molds, water molds, & downey mildew b. Damage to crops and food stores (Irish potato famine)
Fungus/Fungi A. Fungus General Information: 1) Unicellular or multicellular 2) Eukaryotic 3) Heterotrophic (decomposers) 4) Decompose decaying matter and recycle nutrients into the soil 5) Examples of fungus: Unicellular yeast (what makes your bread dough rise) Multicellular mushrooms, molds(like on month-old bread) 6) Fungus can grow anywhere: in air, water, gardens, basement walls, between your toes B. Structure of Fungal cells: 1) have cell walls made up of chitin this is different than plant cell walls or bacterial cell walls. C. Negative aspects of fungus: 1) Food spoilage: molds grow on aged foods making them ineatable 2) Diseases: a. Athlete s foot i. Scaly, itchy, flaky skin ii. Can spread to other areas iii. Treatment anti-fungal cream or orally with a pill b. Ringworm (not caused by a worm) i. Skin infection ii. Same treatment as Athlete s foot 3) Poison: deadly mushrooms D. Positive aspects of fungus: 1) Decomposers: recycles dead materials into nutrients that can be used by plants and bacteria 2) Medicines & foods : creation of penicillin, bleu cheese
E. Reproduction of fungus: 1) Sexually: through spores, cells released from parent that will grow into new organisms like the parent 2) Asexually: through budding where new individual pinches off from the parent