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Servsafe Alcohol Exam Explained Questions With Correct Answers.
Typology: Exams
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Prokaryotes can be distinguished from eukaryotes by
The way their DNA is packaged (lack of nucleus and histones) → Bacteria & Archaea have genetic material that is free inside the cell - The makeup of their cell wall (peptidoglycan (Bacteria) and other unique chemicals (Archaea) providing sturdy cell walls) - Their internal structure (lack of membrane bounded organelles)
All bacterial cells possess:
cell membrane
Surrounds cytoplasm
cytoplasm
Water-based solution filling cell
Ribosomes
Sites of protein synthesis
Cytoskeleton
Encircle cell inside cell membrane contributing to the shape of the cell
One (or a few) chromosome(s)
Composed of condensed DNA molecules
•Most bacterial cells possess
cell wall
glycocalyx (surface coating)
cell wall
Semirigid casing providing structural support
Surface coating called a glycocalyx
Stored nutrient such as fat, phosphate, or glycogen
Endospores
Dormant body formed within some bacteria that allows for their survival in adverse conditions
prokaryotic cell
A type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles; found only in the domains Bacteria and Archaea.
•Most prokaryotes (talking primarily about bacteria) exist as unicellular organisms
Sometimes they can act as a group, in colonies or in biofilms (communicating with one another via chemicals that cause the, to behave differently than if they were living singly) - Also capable of communicating nanotubes or nanowires (appendages used for transferring electrons or other substances)
On average, prokaryotic cells are
1 mm (microns) - Can range from 0.05 - 0.2 mm ("nanobes") to 750 mm
•Cells of one species may vary in shape and size
This is pleomorphism caused by variations in cell wall structure
coccus (cocci)
berry-shaped bacteria/bacterium
rod/bacillus
cylindrical shaped bacteria
Vibrio
a curved, rod-shaped bacterial cell
Spirillum
Spiral-shaped bacterial cell (rigid)
Spirochetes
spiral-shaped bacteria that have flexible walls and are capable of movement
branching filaments
a few bacteria produce multiple branches off of a basic rod structure
Bacterial cells can also be categorized according to arrangement, or style of grouping. The greatest variety in arrangement occurs in cocci:
Monotrichous
Single flagellum
Lophotrichous
small bunches or tufts of flagella
Amphitrichous
flagella at both poles of the cell
Peritrichous:
flagella distributed over the entire cell
All spirilla, about half of the rods, and a small number of the cocci are
flagellated
Flagella are often difficult to see via light microscopy. However, because the primary function of flagella is motility, simply knowing is a microbe is motile or not can aid in
identification.
If the flagella are found on the ends of a cell, they are termed
polar
•Bacteria move in response to chemical signals
(chemotaxis) → Positive (moving towards) vs. Negative (moving away from)
•Receptors bind extracellular molecules, which triggers flagellum to
rotate
•The actual "fuel" for the flagellum to turn is a gradient of protons (hydrogen ions) that are generated by the metabolism of the bacterium and that bind to an detach from parts of the flagellar
motor
•Runs
Smooth linear movement toward a stimulus
•Tumbles
Flagellar rotation reverses, causing the cell to stop and change its course
Bound more tightly to the cell, denser and thicker than a slime layer • Visible by negative staining • Produces a sticky (mucoid) character to colonies • Encapsulated bacterial cells generally have greater pathogenicity.
Cell Envelope •Lies outside of the cytoplasm •Composed of two or three basic layers:
Cell wall - Cell membrane - Outer membrane in some bacteria • Although each envelope layer performs a distinct function, together they act as a single protective unit.
peptidoglycan cell wall
Repeating framework of long glycan (sugar) chains cross-linked by short peptide (protein) fragments → Provides the relatively rigid quality • Present in most bacteria • Provides strength to resist rupturing due to osmotic pressure (Antibacterial drugs operate on this premise, breaking down the peptide cross-links, leading to a weakened cell wall and ultimately lysis. Lysozyme acts similarly naturally in the body
Gram Positive Cell
Thick peptidoglycan → Several layers of peptidoglycan • Also contains teichoic acid, lipoteichoic acid (Tightly-bound, acidic polysaccharides) → Function in cell wall maintenance and enlargement during cell division • One membran
The differences in the peptidoglycan layer of the cell envelope is what is largely responsible for the designations of
gram-negative vs. gram-positive bacteria.
Gram Negative Cell
Thin peptidoglycan → One layer •Lipopolysaccharide •Two membranes •Porins
The Gram Stain: Developed by Hans Christian Gram (
Acid-Fast Bacteria
•Mycobacterium sp. and Nocardia sp. •Bulk of the cell wall is composed of mycolic acid (a wax) → Contributes to the pathogenicity of this group •Modified Gram-positive structure
Acid-Fast Bacteria is highly-resistant to certain chemicals and dyes, so they must use the acid-fast stain to ID important pathogens causing:
Tuberculosis - Leprosy
70 - 80% water → Serving as a solvent for the contents of the cell •Soluble proteins, salts, carbohydrates •Site of nearly all chemical reactions •Contains the DNA in the nucleoid •Some distinguish between the cytoplasm and the cytosol
•DNA of most bacteria exists in the form of a single circular
bacterial chromosome
•DNA is aggregated in a dense area of the cell called the
nucleoid (No nucleus, no nuclear membrane)
Many bacteria contain other, nonessential pieces of DNA called
plasmids (Exist as separate, doublestranded pieces of DNA) → Not essential to bacterial growth and metabolism, but do provide protective traits such as resisting drugs and producing toxins and enzymes
Prokaryotic Ribosome
•Site of protein synthesis •Often occur in chains called polysomes •Two subunits (30S and 50S) •Total size is 70S (versus 80S in eukaryotes) •60% rRNA and 40% protein •Translates mRNA into proteins
Inclusions or Granules: Storage Bodies
Non-membrane bound granules that respond to the environmental conditions of a bacteria • Usually for storage of nutrients, storage of gas, and even storage of crystals of iron oxide with magnetic properties
The Cytoskeleton
Peptidoglycan layer determines shape of many bacteria, but in some, the cytoskeleton contributes as well • Others use protein fibers composed of actin and tubulin to alter cell shape
Bacterial Endospores
Dormant bodies that can withstand hostile conditions and facilitate survival
sporulation when environmental conditions become challenging
Sporulation is not
a reproductive function for most bacteria
When spores of Clostridium sp. are embedded in a wound with dead tissue, they can
germinate, grow, and release toxins
A Typical Sporulation Cycle in Bacillus Species
e refers to representatives of a species that stimulate a distinct pattern of antibody (serum) responses in their hosts, because of distinct surface molecules