Microbiology Exam Study Guide 1
Microbiology Exam Study Guide 1 10806197
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This 11 page Study Guide was uploaded by Alyssa Hilker on Friday January 22, 2016. The Study Guide belongs to 10806197 at Mid-State Technical College taught by Michael Silveira in Winter 2016. Since its upload, it has received 79 views. For similar materials see Microbiology in Natural Sciences at Mid-State Technical College.
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Date Created: 01/22/16
Microbiology Test One Study Guide One Weeks 1-3 Notes Intro to Microbiology o What is a Micro? Small, living organism too small to see o List four reasons we care about microbes. o Gene therapy: Virus is inserted into a gene to be transported to another human. Originally scientists thought: o Spontaneous generation: worms and other life forms arise from non- living materials o Francesco Redi: started the disapproval of “spontaneous generation” Meat in the jar experiment- 1668 The better the jar was covered, the less maggots grew on the meat. “All life from life” **What can we determine from these results? Maggots come from the fly (source) By covering the jars, we can control what and where things grow. o 1749- John Needham: sealed with a cork and used shot boiling time for sterilization Not a complete seal o 1776- Lazzaro Spallanzani: sealed flask by melting the neck and used long boiling time for sterilization Complete seal o 1861- Louis Pasteur: Father of modern Microbiology Swan-neck flask experiment- No microorganisms are able to get to the broth due to little are which promoted no growth in broth. o 1850’s- Semmelweis: introduced handwashing before visiting patients Naming Microbes: o Genus specific epithet The first letter of the Genus is always capital, specific epithet always lowercase and whole name is italicized or if handwritten, underlined. Example: Humans Homo sapiens o Microorganism names originate from four different sources: Descriptive Scientist’s name Geographic places Organizations Classifying microbes: o Prokaryote- no nucleus or Eukaryote- nucleus Prokaryotes Archaea and Bacteria Eukaryotes Eukarya Archaea more closely related to Eukarya Bacteria: Single celled, no nucleus, can have peptidoglycan cell wall. Archaea: Singe celled, no nucleus, no peptidoglycan cell wall, and often extremophiles. o Three main groups: Methanogens, thermophiles and halophiles. Eukarya: Have a nucleus, can be singled celled or multicellular. Viruses and prions: Non-cellular o Virus: Just a nucleic acid core surrounded by a protein coat o Prion: Malformed protein that can cause death o General Organization of a Bacterial Cell Make sure to know all of the functions and where they are located on the diagram!! o What two structures, in a bacterial cell, are essential for life? Shapes of Bacteria/Archaea: A. Coccus- Spherical B. Bacillus- Rod or cylinder C. Coccobacillus- Short rod D. Vibrio-Curved rod E. Spirillum- Spiral shaped F. Spirochete- Helical shape G. Pleomorphic- Bacteria able to vary Binary Fission: Formation of two new cells of approximately equal size as a result of parent cell division. Prokaryotic cells also divide by binary fission. Bacterial cell groupings: o Diplococci- Pairs o Streptococci- Chains o Division along two or three perpendicular planes form cubical packets. o Division along several random planes form clusters. Chemotaxis: movement based on concentration. o If chemical compound is nutrient- acts as attractant o If chemical is toxic- acts as repellant Peptidoglycan: (only in bacteria) o Rigidity of cell wall is due to peptidoglycan (PTG) o Basic structure: Alternating series of two subunits NAG & NAM which are sugars Lines of NAG and NAM held together by peptides This is not a boundary! Gram Positive Cell Wall: o Thick layer of PTG o PTG is permeable to numerous substances regardless of thickness. o In order for objects to enter, they need to travel through all layers of PTG Gram Negative Cell Wall: o Thin layer of PTG o PTG placed between Outer membrane and cytoplasmic membrane o Periplasm: gel like fluid between outer membrane and cytoplasmic membrane. All secreted proteins held in this area unless transported across outer membrane. o Outer cell wall membrane: Lipid bilayer Also called Lipopolysaccharide layer or LPS LPS serves as barrier to large number of molecules. Antimicrobials that interfere with the synthesis of PTG: o Penicillin- prevents proper bond formation of PTG o Lysozyme- Breaks bonds in PTG molecules, destroying structural integrity Gram Staining: o Gram Positive: stained purple o Gram Negative: Stained red or pink o What component in the cell wall determines what color the stain is? Endospore formation o Complex, ordered sequence o Bacteria sense starvation and begin sporulation o Growth stops o DNA duplicated o Cell splits o Cell splits unevenly o Larger component engulfs small component, produces forespore within mother cell o Forespore enclosed by two membranes o Forespore becomes core o PTG between membranes forms core wall and cortex o Mother cell proteins produce spore coat o Mother cell degrades and releases endospore Archaea are considered extremophiles because they can survive things such as extreme heat. Which is archaea most closely related to, eukaryotes or bacteria? What does archaea lack in its cell wall that eukaryotes have? Dyes and Staining: Acid fast stain; usually used for bacteria that resist typical stains Gram strain; uses two different stains, one for gram positive and one for gram negative Endospore stain; uses heat to enhance view of endospore Form and Function of the Eukaryotic Cell: Internal Structures o The Nucleus: The Control Center Structure-nuclear envelope, nucleolus, nuclear pores Contents-Chromosomes, histone protein o Endoplasmic Reticulum: Rough ER- ribosomes –protein synthesis Smooth ER-lacks ribosomes- lipid synthesis and detoxification o Golgi Apparatus: Processing and sorting center for newly synthesized proteins Protein modification-lipids added, carbohydrates added o Lysosomes- low pH, digestive enzymes o Vacuoles- plant cells only, storage of water, wastes, and poisons o Mitochondria: Energy Generators of the Cell Structure- outer membrane, inner membrane (cristae) and matrix DNA, ribosomes Aerobic respiration o Chloroplasts: Photosynthesis Structure- triple membrane, thylakoid membrane, stacks of grana Photosynthesis-light and carbon dioxide to form ATP and sugar o Ribosomes: Protein Synthesizers Eukaryotic 80S, a large (60S) and a small (40S) subunit Translation of codons into amino acids o The Cytoskeleton: A Support Network Cytoskeleton Actin filaments Microtubules Intermediate fibers o Protein Structures of Eukaryotic Cell : Structures that distinguish from Prokaryotic cells. Cytoskeleton Flagella Cilia 80s Ribosome o Plasma Membrane : Phospholipid bilayer with proteins proteins transport, maintain cell integrity and have receptors for cell signaling. Membrane contains sterols for stength. Animal cells contain cholesterol Fungal cells contain ergosterol Transport across eukaryotic membrane via transport proteins others taken in through endocytosis and exocytosis What seven membrane-bound organelles set eukaryotes apart from prokaryotic cells ? What four unique protein structures distiniguish eukaryotes from prokaryotic cells ? o Endocytosis : Process by which eukaryotic cells bring in material from surrounding environment. Pinocytosis : Pinch off small portions of own membrane along with attached material a. Creates endosome (vesicle) 2. Phagocytosis : The moment bacteria are present in parts of a human body where they would not normally be found, the phagocytes move toward them, enclose them by folding the membrane around bacteria and endocytosis takes place. Bacteria are eventually digested and destroyed. Phagocytes also clean up dead cells parts or other debris found in body fluids. o Exocytosis : Opposite of Endocytosis- transports material outside of cell. Fungi Mycology: Study of fungi o NOT photosynthetic or a plant Fungi include: o Yeast- single celled o Mold- filamentous fungi o Mushrooms- reproductive structures of fungi Fungi Cell Types: o Yeast cell- round/oval and uses asexual reproduction o Hyphae cell: long / thread like and can be used for sexual reproduction o Dimorphic: can differ depending on the growth conditions o Mycelium: visible mass of hyphae Mycelium is the visible mold on bread and hyphae is the microscopic mold that digs into the bread. Heterotrophic: o Fungi are heterotrophic – acquire nutrients from other substrates o Saprobes: get nutrients from remnants of dead organisms o Parasites: get nutrients from another living organism How Fungi Obtain Nutrients: o Secrete enzymes to the outside of cell o Break down (digest) substrate into small components that the fungal cell can absorb o Particle get absorbed by the fungal cell Fungal Reproduction: o Yeast cells “bud” off o -Similar to mitosis o Reproductive hyphae can produce spores Spore Types: o Sporangiospores: develop within a “sac” called a sporangium. Lots of cell divisions until it bursts out o Conidiospores: No “sac”. Form by segmenting or pinching off o Can be used to identify Fungal habitats o Can grow in condition that most bacteria could not survive: o Large pH range; grow better on acidic fruits/veggies than bacteria o Prefer 20 – 35 Celsius, could grow at below freezing o Can resist pasteurization o Most are aerobic o Some yeast: facultative anaerobes – make ethanol by fermentation Why is it important to know what kind of environment fungi grows best in? Mycoses o Mycoses = fungal infections o Can be parasitic, airborne allergies, or fungal toxin based Why can low toxic index be dangerous to a human? Classification of Fungi: Looking for drug target- -Plasma Membrane Synthesis and function: o Ergosterol: used for membrane structural support; found in fungi plasma membrane, not human plasma membranes! Action of Antifungal Drugs: o Polyenes- bind to ergosterol disrupt cell wall causing a hole cell guts leak out. o Azoles- inhibit intermediate steps in ergosterol synthesis accumulate toxic sterol intermediates defective membranes leak cytoplasmic components. o Allyamines- similar to azoles but inhibit much earlier steps in ergosterol synthesis cell can no longer build walls defective membrane leaks cytoplasmic components. -Nucleic Acid Synthesis (Difficult target due to similarities with human systems) o Flucytosine, is taken up by yeast cells and then converted by yeast enzymes into and active inhibitory form. o Flucytosine → phosphorylated and if incorporated into RNA → halts ribosome and therefore protein synthesis o Flucytosine → FdUMP → inhibits enzyme DNA synthesis because Uracil is precursor to Thymidine – effects DNA therefore effects Nucleus. o Selectivity due to rapid uptake by fungi over human cells Algae: typical eukaryote with chloroplasts o Red tide: overgrowth of particular algae makes sea look red these bacteria release toxins eaten by animals toxins build up in seafood and are harmful to humans Protozoa: o “Animal like” unicellular organism; typical eukaryote organism with no chloroplast. o Operate closer to organs and must have a water source to live o Reproduction Life cycle usually involved multiple habitats or hosts Polymorphic with a vegetative trophozoite (get nutrients from host) and a resting cyst Binary fission- formation of two new cells of approximately equal size as result of parent cell division. Schizogony: multiple fissions o Structure o Lack cell wall, maintain shape by using material lying underneath the plasma membrane o Not photosynthetic o Typical classification is based on mode of locomotion AND rRNA sequence o Malaria o African sleeping sickness o Toxoplasmosis o Amoebic dysentery African Sleeping Sickness (aka trypanosomiasis) o Caused by: Trypanosoma brucei o Uses insect vector: Tsetse fly o One of a few pathogens that can cross the blood-brain barrier. o When it get there it feeds off of the glucose supply Antiprotozoan Drugs o Targets of most antiprotozoan: Biosynthetic pathways interference Attacks enzyme of urea cycle protozoan metabolism no longer works it dies, human lives Neuromuscular function Helminths: o Tapeworms, flukes, and roundworms o Adult form usually can be seen with naked eye o Are multicellular o Microscope needed for eggs and larvae Helminth Life Cycle: o Egg larva adult o Usually additional hosts needed to complete life cycle Pinworm Life Cycle: o Person gets infected by swallowing eggs o Eggs hatch in the intestine o Larvae mature to adults in about a month, male and female adult mate in the intestine. o Female travels to anus to deposit the eggs o The eggs in anus cause itchiness (scratching) o Hands are now contaminated with eggs and spread to another person to digest Affects people world wide Tapeworms o One medication is Praziquantel o Anthelmintics – medicines that attack helminths o Causes intense muscle spasms in the tapeworm Increase permeability to Ca. o Tapeworm dislodges from intestine and gets broken down Why is the tapeworm affected by Praziquantel but the human is not?
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