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Micro Unit 2 of 14
Microbiology Study Guide for the CLEP Exam (Prokaraotic Structure)
Question | Answer |
---|---|
Define the bacterial morphology: Bacillus | rod shaped |
Define the bacterial morphology: Coccus | sperical shaped |
Define the bacterial morphology: Vibrio | comma shaped |
Define the bacterial morphology: Spirochete | helical shaped |
Define the bacterial morphology: Pleomorphic | can be more than one shape |
Define the cell cluster: Diplo- | linking of two cells |
Define the cell cluster: Tetra- | linking in fours |
Define the cell cluster: Staphylo- | clustered (like grapes) |
Define the cell cluster: Strepto- | in chains (like a necklace) |
Explain the functions of the cell (or cytoplasmic) membrane | The cytoplasmic membrane defines the inside and outside of a cell. It contains protien transporters that pump desirable chemicals into the cell usings the cell's energy resources. It also prevents undesirable chmicals from entering the organism. |
Describe the structure of peptidoglycan. | It's like a "fishnet" because the long polymers of glycan are cross-linked by shorter pieces of peptides |
Name two biologically active items that destroy the bacterial cell wall | Lysozyme and Penicillin |
What structural component is unique to gram-negative bacteria? | an outer membrane |
What major chemical is unique to the structure identified in gram-negative bacteria? | Lipopolysaccharide is chemically unique to the outer membrane of gram-negative bacteria |
What does peptidoglycan vary between gram-positive and gram-negative organisms? | Gram-positive organisms have many layers of peptidoglycan. Gram-negative organisms have only a few layers of peptidoglycan. |
What layer of gram-positive and gram-negative bacteria are the same? | The cytoplasmic membrane is the same. |
What layer of gram-positive and gram-negative are different? | The outer membrane is different because only gram-negative bacteria have one. |
What is step 1 of the Gram stain process and the functions of each | stain with the primary stain, crystal violet |
What is step 2 of the Gram stain process | fix the crystal violet with Gram's iodine so that it aggregates |
What is step 3 of the Gram stain process | wash the aggregates from the porous gram-neg bacteria with acetone-alcohol |
What is step 4 of the Gram stain process | counterstain with safranin so the gram-negative cells are readily visable |
What is the chemical makeup of the structure that coats a bacterium? | polysaccharide is the coating's chemical makeup |
What is the function of polysaccharide? | it's a coating that makes the bacterium slippery so that white blood cells cannot capture and destroy it |
Describe the cell cytoplasm | The cytoplasmic compartment contains all the degraditive and synthetic machinery to allow the cell to grow and make new copies of itself. it contains the cell's DNA, RNA, and protiens |
Distinguish the bacterial chromosone from plasmids | all chromosomes contain thousands of genes, Some contain plasmids which are often specialized like those that code for resistance to a specific antibiotic |
Define "plasmid" | small pieces of DNA usually encoding fewer than fifty genes. |
What are the sizes of a complete bacterial ribosome and its two major components in S units? Compare them to eukaryotic ribosomes | Prokaryotic ribosomes are 70S (one each 30S and 50S subunits; eukarotic ribosomes are 80S (one each 40S and 60S) |
Why do some bacteria harbor inclusions or granules? | The granules provide an energy source available for when cells have a special energy need. |
What are granules or inclusions composed of? | polysaccharides or polyphosphates that contain too much energy |
What are the most environmentally stable of all known life forms? | Spores |
What genera produces spores? | the gram-positive bacteria Clostridium and Bacillus |
What is a streak plate? | a dish containing nutrient agar |
What does a streak plate accomplish? | It is used to grow individual cells into colonies to obtain pure isolates |
What is a colony? | This results when a single cell is streaked onto a plate in a well seperated manner so that the progeny can grow into a clump until the are sufficiently numerous to be seen by the naked eye |
Why do we obtain isolated colonies? | because they yeild pure cultures in which every cell is identical so the organism can be recognized |
List four methods used in the identification of bacteria | (1) Biochemical tests (2) immunological tests (3) genetic tests (4) direct DNA or RNA testing for organism-specific sequences |
List possible bacterial appendages and their functions | the flagella aid in motility; the pili in gene transfer; and the fimbriae (holdfasts) attach to a given site |
List the three major components of bacterial flagella | filiment, hook, and basal body |
How do bacteria produce a propelling force? | by rotating their helical filiments against their watery environment |
Name two possible benefits of motility to a pathogenic organism | Motility allows pathogens to spread out and to escape capture by cells of the immune system |
What benefit does chemotaxis confer upon a bacterium? | it allows organisms to swim toward or away from chemicals |