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MicroBiology1
Exam 1
| Question | Answer |
|---|---|
| prokaryotic | Prokaryotes have no true nucleus, no membrane bound organelles and a single, circular strand of DNA |
| eukaryotic cells | Eukaryotes have a true nucleus and membrane bound organelles. |
| Who are the two men responsible for changing from the 5 kingdom classification to the 3 domains | Woese and Fox |
| Eukarya | Includes fungi and protists |
| Archaea | Unique rRNA, extreme environments, non-pathogenic, lack peptidoglycan |
| Bacteria | Single-celled prokaryotes, usually have peptidoglycan, some are pathogenic |
| Early micro observations (bees/weevils)Who? | Francesco Stelluti |
| Accurate, extensive observations Who? | Van Leeuwenhoek |
| Disproved Spontaneous Generation Who? | Louis Pasteur |
| 1st drawings of microorganisms Who? | Robert Hooke |
| Microorganisms cause disease Who? | Augustino Bassi |
| Developed 1st antiseptics Who? | Joseph Lister |
| What are Koch’s postulates ? | The microorganism must be present The microorganisms must be isolated3) The same disease must result when the isolated microorganism is inoculated into a healthy host.4) The same microorganism must be isolated again from the diseased host |
| What microrganisms were present in Koch's Postulate? | Mycobacterium tuberculosis and Bacillus anthracis |
| What is a pure culture and why was that important for Koch to prove his postulates? | A pure culture is a culture containing only 1 kind of microorganism and it creates a cause and effect relationship. |
| bright field microscope | A bright field microscope shows a dark image on a light background |
| dark field light microscopes | dark field is a dark background with a light specimen. |
| In what kind of microscopy do you observe live, unstained cells by changing the illumination | Phase contrast |
| What is resolution | The ability of a lens to separate or distinguish between small objects that are close together |
| Phase Contrast | Converts differences in refractive index & cell density to variations in light intensity |
| DIC | Detects differences in refractive indices and thickness; live, colored, 3-D specimens |
| Fluorescence | Exposes the specimen to UV or blue light |
| What is the process by which the internal and external structures of cells and microbes are preserved and fixed in position | Fixation |
| What happens to a cell during fixation? | Enzymes are inactivated and cell structures are toughened up so they don’t change upon staining. |
| What are the 2 types of fixation | Chemical and Heat |
| What are the 2 common features of stains | Chromophore groups and the ability to bind to cells. |
| Negative staining results in | a bright object on a dark background |
| Basic dyes use negatively charged groups to bind to | negatively charged groups |
| basic dyes | positive charged group that binds to negatively charged ion . methylene blue crystal violet, basic fuschin, safarin, malachite green |
| Acidic dyes | eosin, rose Bengal and acid fuchsin negatively charged groups binds to positive ion |
| A complex stain | uses multiple dyes to determine size, shape and arrangement of prokaryotic cells. |
| Differential staining is used to distinguish | organisms based on staining properties |
| A gram negative organism will stain | pink |
| A gram positive organism will stain | purple |
| Acid fast stains are an example of a | differential stain identifies Mycobacterium tubercleosis and M. leprae |
| Capsule staining is used to | reveals the prescence of a capsule |
| The Schaffer-Fulton method is used | to detect endospores malachite green |
| What is the purpose of a capsule | To fortify the cell making it harder for the immune system to fight the bacteria |
| What is the purpose of an endospore? | This allows a cell to live for prolonged periods of time under unfavorable conditions. |
| A Transmission Electron Microscope (TEM) looks at what | Looks inside the cell at internal structures |
| a Scanning Electron Microscope (SEM) looks at | Looks at the surface of the cell |
| Bacillus | rod shape can be found in chains cocco bacillius- short and wide |
| Vibrion | looks like a comma |
| Spirilla | tufts of flagella at one or both ends |
| Cocci | spherical -diplo, strepto, staph, microcaccus |
| Streptococci | chains |
| Microcaccus | two plains (division) |
| Diplococci | two spheres |
| Staphcocci | clusters |
| A pleomorphic prokaryote is variable | in its morphology (i.e. shape, size) |
| The average bacteria size | is 2-6um in size, but can range from the smallest at 0.2um to 0.05 to the largest at 500um long. |
| What is the purpose of the cell membrane? | It is the “gatekeeper” that offers protection and it is selectively permeable. |
| developed the fluid mosaic model. | Singer and Nicholson |
| integral protein | Integral proteins go all the way through and are insoluble in water |
| peripheral proteins | only loosely connected to the membrane and easily removed. |
| Amphipathic | polar and nonpolar ends |
| Hydrophobic | water-fearing |
| Hydrophilic | water-loving |
| What are the sterol-like molecules that prokaryotes have in their plasma membranes | Hopanoids |
| What is the advantage of having a convoluted surface (i.e. plasma membrane)? | It increases surface to volume ratio |
| Eukaryotes have | a nucleus |
| prokaryotic cell have | nucleoid region |
| Extrachromosomal DNA is also known as | as a plasmid |
| when a plasmid becomes integrated into host DNA it is called | an episome |
| What is the process of curing | The removal of a plasmid |
| What does the R in R-plasmid stand for? | Resistance |
| Bacteriocins | bacterial proteins that destroy other bacteria |
| Do gram positive or gram negative bacteria have a more complex cell wall? | Gram – because of the extra outer membrane |
| gram positive cell wall | Gram +: 20-80nm of peptiodglycan, more resistant to osmotic pressure |
| Gram negative cell wall | Gram -: 2-7nm of peptidoglycan, but it also has an outer membrane that is 7-8nm thick. |
| what makes up the cell envelope | The plasma membrane, cell wall and the capsule |
| what makes up the cell envelope | The plasma membrane, cell wall and the capsule |
| Other than peptidoglycan gram positive cell walls also | contain techoic acids |
| capsule | increases virulence as a layer outside the cell wall that is well organized and not easily washed off |
| slime layer | is an unorganized, diffuse layer that is easily removed. |
| What is a glycocalyx | A network of polysaccharides on the exterior of the cell |
| What are pili and used for respectively? | Pili- (sex) conjugation |
| What are fimbriae used for respectively? | Fimbriae- Motility (smaller and more numerous than pili) |
| Flagella are used for locomotion. They can occur in each of the following patterns | a. Monotrichous: Lophotrichous: Amphitrichous: Peritrichous: |
| Monotrichous: | one end (polar |
| Lophotrichous | Clusters at one or both ends |
| Amphitrichous | Single at each end |
| Peritrichous | spread over the whole surface |
| What does it mean to “run” and to “tumble?” | Run moving in an approximately straight line and tumbling is when they stop and change directions. |
| Chemotaxis | Movement away from chemical repellents and toward chemical attractants |
| What are the major membrane lipids? | Phospholipids, Sphingolipids, and cholesterol |
| What are microdomains? | They are involved in cell movement, signal transduction and entry of some viruses into cells. |
| What are the two types of endoplasmic reticulum | Smooth and rough endoplasmic reticulum |
| Smooth ER- Synthesizes | lipids, detoxify substances |
| Rough ER- Synthesize | proteins |
| What are cisternae and where are they found? | They flattened sacs that are found in the golgi apparatus and both types of ER |
| What does the Golgi Apparatus do? | Manufacture, sort and ship cell molecules |
| Lysosomes are responsible for intracellular digestion and have special enzymes called | hydrolases or lysozymes that help digest macromolecules |
| glycosylation | GLycosylation= adding a sugar to a protein |
| Ubiquitin | Ubiquitin is a polypeptide that tags the misfolded protein for degradation (break down |
| endocytosis | The process of bringing materials into the cell from the outside |
| Does the endocytic pathway concentrate materials before or after bringing them into the cell? | It concentrates materials outside the cell before bringing them inside |
| What types of cells use phagocytosis | Specific immune cells |
| What is phagocytosis | An invagination of the plasma membrane that encloses particles in a membrane delimited vacuole |
| What is autophagy | Cells selectively digest and recycle cytoplasmic contents |
| What is a residual body | A lysosome that contains undigested material |
| Mitochondria produce | ATP in cells |
| What do chloroplasts do and in what kind of cells are they found | They do photosynthesis and we find them in photosynthetic cells |
| What are plastids? Give an example of one. | Specialized cells that contain pigments like chlorophyll and complete photosynthesis and an example is chloroplasts |
| Chromosomes | These are tight |
| Chromatin | These are loose and in non-dividing cells |
| Euchromatin | Loosely organized, contain genes are expressed |
| Heterochromatin | These stain darker and are not genetically active |
| Nuclear envelope | pored structure that surrounds the nucleus |
| What is the noticeable, non-membrane bound structure inside the nucleus? | Nucleolus |
| Which are identical: sister chromatids or homologous pairs | Sister chromatids |
| mitosis | end up with the same # of chromosomes as the parent cell, identical to the parent cell and they’re diploid (2n) |
| Meiosis | Meiosis: only occurs in the sex cells, end up with ½ the # of chromosomes as the parent cells so they are haploid(n). |
| List and describe the steps in the cell cycle | G1: Growth Phase IS: Synthesizes DNAG2: Growth Phase IIM: Meiosis or MitosisCytokinesis: Division of the cytoplasm |
| What types of cells have a cell wall? | Photosynthetic organisms |
| What organisms contain a pellicle and what is its purpose | Protists have a pellicle and it is a rigid layer of components beneath the cell membrane. It helps support or reinforce the structure of the cell membrane. |
| What are the differences between cilia and flagella? | Cilia are more numerous than flagella and they’re smaller than flagella |
| types of chemicals used in fixation | ethanol, acetic acid, formaldehyde, and gluteraldehyde |
| gram stain | heat fixated smear. crystal violet 30 sec, rinse 5 sec, iodine, wash , than ethanol |
| cytoplasmic matrix | is the substance in which the nucleoid, ribosomes, and inclusion bodies are suspended |
| nucleoid | 60% dna, 30% rna, 10% protein |
| cell wall | outside plasma membrane, determines shape, contributes to pathogenicity, protects cell |
| flagellar movement | cell moves when helix rotates |
| bacterial endospore | dormant structure, developes in vegetative cells resisistant to environmental stresses(heat radiation,gamma radiation, chemical disenfectant, drying out. remain viable for long time |
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