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58 Cards in this Set
- Front
- Back
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What are the chief distinguishing characteristics of prokaryotes? (DNA)
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DNA not enclosed in a membrane, its 1 circular chromosome
DNA is not associated with histone proteins |
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What are the chief distinguishing characteristics of prokaryotes? (lack, cell wall, division)
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lack other membrane-enclosed organelles,
cell walls contain complex polysaccharide peptidoglycan. divide by binary fission |
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What majority of known bacteria is in what kingdom? including what other type of bacteria?
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photosynthesizing bacteria are in the Eubacteria
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What are the basic shapes of prokaryotes
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Coccus: spherical
Bacilli: rod-shaped Spiral |
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Diplococci
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Cocci that remain in pairs after dividing
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Tetrads
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Cocci that remain groups of 4
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Sarcinae
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Cocci that remain in cube-like groups of 8
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Streptococci
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Cocci that remain attached in chain like patterns
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Staphylococci
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Cocci that form grapelike clusters
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Diplobacilli
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Bacilli that appear in pairs
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Streptobacilli
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Bacilli that occur in chains
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Vibrios
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Bacteria that look like curved rods
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Spirilla
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have a helical shape, like a corkscrew, and fairly rigid bodies
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Spirochetes
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have a helical shape and flexible
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What are the structures external to the prokaryotic cell wall
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glycocalyx, flagella, axial filaments, fimbriae, and pili
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What kind of forms can the glycocalyx take? Describe them
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capsule: organized and firmly attached to cell wall
slime layer: unorganized and loosely attached to the cell wall |
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Function of capsule form of the gylcocalyx
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often protect pathogenic bacteria from phagocytosis
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Describe Streptococcus pneumoniae
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causes pneumonia when the cells are protected by a polysaccharide capsule
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Describe Bacillus anthracis
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causes anthrax when encapsulated with D-glutamic acid
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What can the glycocalyx also enable a cell to do? Example?
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adhere to surfaces
(ex: S. mutans which stick to teeth) |
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What is each flagellum
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a semirigid, helical rotor that moves the cell by rotating either clockwise or counterclockwise
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What are the 3 basic parts of a flagellum? (describe filament/basal body)
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Filament: intertwining chains of the protein flagellin
Protein hook Basal body: small rod inserted into rings |
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How do spirochetes move? Describe it
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Axial filaments are anchored at one end, spiral around the cell, and is similar to flagella structurally
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What does many gram-negative bacteria contain and consist of?
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hairlike appendages that are used for attachment rather than motility
consist of a protein called pilin |
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Fimbriae
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can be numerous, and are used for attachment
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Pili
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longer, only 1-2 per cell, and they join bacterial cells in preparation for the transfer of DNA from one cell to another
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Functions of a cell wall with water pressure
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prevent bacterial cells from rupturing when the water pressure inside the cell is greater than outside the cell
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What does the cell wall help maintain and what does it serve?
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maintain the shape of a bacterium, and serves as a point of anchorage for flagella.
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What is the bacterial cell wall composed of
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a macromolecular network called peptidoglycan
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What does Peptidoglycan consists of? What is its function
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repeating disaccharide attached by polypeptides to form a lattice that surrounds and protects the entire cell
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What does the cell wall in most gram-positive bacteria consists of?
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many layers of peptidoglycan linked by a peptide cross-bridge (short chain of amino acids)
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What does the cell wall of gram-positive bacteria include? What function does it provide?
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teichoic acid, which may function in cation transport and act as an antigen
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What does the cell walls of gram-negative bacteria consist of
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one or very few layers of peptidoglycan and an outer membrane
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Special function of the outer membrane of gram-negative (Charge)
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Its strong negative charge is an important factor in evading phagocytosis
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Special function of the outer membrane of gram-negative (Barrier)
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Less vunerable to certain antibiotics (ie. penicillin), digestive enzymes (ie lysozyme), detergents, heavy metals, bile salts, and certain dyes
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Special function of the outer membrane of gram-negative (Polysaccharide/lipid portion)
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polysaccharide portion functions as antigens, and the lipid portion is an endotoxin inside the host
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What does the nucleoid of a bacterial cell contain
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a single long circular molecule of DNA - the bacterial chromosome
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How does antibiotics utilize the size different in prokaryotic and eukaryotic ribosomes? Examples of the antibiotics
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tetracycline & chloramphenicol bind to prokaryotic ribosomes (blocking protein synthesis), but not to eukaryotic
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Endospores
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specialized “resting” cells formed by certain gram-positive bacteria when essential nutrients are depleted
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Describe the structure of endospores and where are they formed
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highly durable dehydrated cells with thick walls and additional layers; formed internal to the bacterial cell membrane
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What environmental factors can endospores survive through?
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extreme heat, lack of water, and exposure to many toxic chemicals and radiation
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How is germination of the endospores triggered?
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by damage to the endospore coat, water enters, and metabolism resumes (even after millions of years)
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What does the nutritional patterns of prokaryotes metabolism depend on?
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on their source of energy and their source of carbon
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What do phototrophs and chemotrophs use for energy?
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Photo: light
Chemo: redox reactions of inorganic or organic compounds |
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Carbon sources of autotrophs and heterotrophs
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Auto: use CO2 as their principal carbon source
Hetero: require an organic carbon source |
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Describe the oxygenic Photoautotrophs
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because they release oxygen; CO2 + H2O -> sugar+O2
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Describe the anoxygenic Photoautotrophs
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are anaerobes; CO2 + H2S -> sugar + S
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Describe the Photoheterotrophs (What do they use for energy and what is their source of carbon?)
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anoxygenic, use light and cannot use CO2,
Carbon source: use organic compounds (alcohols, acids, carbohydrates) |
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Where do Chemoautotrophs thrive and where they derive the energy for their life processes from?
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thrive in darkness;
from the oxidations of inorganic materials (eg. H2S, NH3, & H2) |
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What does Chemoheterotrophs include? They can be either what or what?
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most bacteria (omnibacteria) and are either saprobes or parasites
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Examples of where chemoautotrophic archaebacteria are found?
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Methanogens producing methane (swamp gas)
Inhabit warm sulfurous area region deep in ocean trenches, producing food for ecosystems |
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What does phototrophs use instead of chloroplast
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Chromoplasm: pigmented membranes within cytoplasm
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Examples of oxygenic & anoxygenic photoautotrophs, photoheterotroph, and chemoheterotrophs bacteria
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Oxy PAT: Cyanobacteria
Anoxy PAT: green & purple sulfur bacteria PHT: green & purple nonsulfur bacteria CHT: most bacteria (omnibacteria) |
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What causes Bacterial variation in what form?
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mutations and genetic recombination in the form of conjugation, viral transduction, and transformation
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What is conjugation, viral transduction, and transformation
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Conjugation: cell-to-cell, Transduction: virus-to-cell
Transformation: environment-to- cell |
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When does Generalized transduction occurs
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when lytic phages pack host DNA into their capsid instead of the original phage DNA
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When does Specialized transduction occurs
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when the prophage of a lysogenic phage excises itself and takes some host DNA with it
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Compare the how genes are transferred between cells between generalized and specialized transduction
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Generalized: virtually any gene can be transferred between cells
Specialized: few genes are transferred between cells |
