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Microbiology Chapter 3 Nester
Microscopy and Cell Structure
99
Biology
Undergraduate 2
01/20/2014

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Term
Capsule
Definition
A distinct, thick gelatinous material that surrounds some microorganisms
Term
Chemotaxis
Definition
Movement of a cell toward or away from a certain chemical in the environment.
Term
Cytoplasmic Membrane
Definition
A phospholipid bilayer embedded with proteins that surrounds the cytoplasm and defines the boundary of the cell.
Term
Endospore
Definition
An extraordinarily domrant cell produced by some bacteria
Term
Flagellum
Definition
A type of structure used for cell movement.
Term
Gram-Negative Bacteria
Definition
Bacteria that have a cell wall characterized by a thin layer of peptidglycan surrounded by an outer membrane; when gram stained, these cells are pink.
Term
Gram-Positive Bacteria
Definition
Bacteria that have a cell wall characterized by a thick layer of peptidoglycan and techoic acid; when Gram stained, these cells are purple
Term
Lipopolyshaccharide (LPS)
Definition
Molecule that makes up the out layer of the the outer membrame of a Gram-negative bacteria
Term
Peptidoglycan
Definition
A macromolecule that provides strength to the cell wall; it is found only in bacteria
Term
Periplasm
Definition
The gellike material that fills the region between the cytoplasmic membrane and the outer membrane of Gram-negative bacteria
Term
Pili
Definition
Cell surface structures tat allow cells to adhere to certain surfaces; some types are involved in a mcechanism of DNA transfer
Term
Plasmid
Definition
Extrachromosomal DNA molecule that replicates independently of DNA the chromosome.
Term
Ribosome
Definition
Structure involved in protein synthesis
Term
Transport Systems
Definition
Mechanisms used to transport nutrients and other small molecules across the cytoplasmic membrane
Term
Simple Staining
Definition
only one dye is used to stain the sample. It is an easy way to increase the contrast between otherwise colorless cells and a transparent background.
Term
Why are basic dyes typically used?
Definition
They carry a positive charge so they are attracted to the many negatively charged cellular components
Term
Negative Staining
Definition
The use of acidic dyes that color the background. Cells repel the negatively charged dye, allowing the colorless cells to stand out against the background. It can be done as a wet mount so no heat-fixing is needed
Term
Differential staining
Definition
used to distinguish the different groups of microorganisms from one another.
Term
Special Stains
Definition
Stain specific structures inside or outside of cells.
Term
Capsule Stain
Definition
These are often negative stains that take advantage of the fact that viscous capsules do not take up certain stains; the capsules stained out against a stained background
Term
Endospore Stain
Definition
Stains endospores, a type of dormant cell that does not readily take up stains. Endospores are produced by Bacillus & Clostridium species
Term
Flagella Stain
Definition
The staining agent adheres to and coats the otherwise thin flagella, making them visible with the light microscope.
Term
Fluorescent Dyes & Tags
Definition
absorb ultraviolet light and then emit light of a longer wavelength. They are used in conjunction with a fluorescence microscope. Can be used to observe total cells, a subset of cells or cells with certain proteins on their surface.
Term
Flourescent dyes
Definition
Some fluorescent dyes bind to compounds found in all cells; others bind to compounds specific to only certain types of cells.
Term
Fluorescent tags
Definition
Antibodies to which a fluorescent molecule has been attached are used to tag specific molecules.
Term
resolving power of light microscope
Definition
2 micrometers
Term
gram positive color
Definition
purple
Term
gram negative color
Definition
pink
Term
resolving power of electron microscope
Definition
0.3x10-3 micrometers
Term
spherical
Definition
coccus
Term
rod shaped
Definition
bacillus
Term
short curved rod
Definition
vibrio
Term
long helical cell with flexible cell wall and unique motility mechanism
Definition
spirochete
Term
characteristically vary in shape
Definition
pleomorphic
Term
greatest diversity in shapes found in
Definition
low nutrient aquatic environment - often large surface area to absorb nutrients
Term
how are archaea membrane lipids different from bacteria?
Definition
not linear fatty acids, are methyl branched isoprenoids
Term
what passes freely through cytoplasmic membrane?
Definition
oxygen, carbon dioxide, nitrogen, water & small hydrophobic molecules
Term
facilitated diffusion
Definition
does not require energy, cannot create a concentration gradient (rarely used by prokaryotes)
Term
active transport
Definition
energy is expended to accumulate molecules against a gradient (uses ATP or proton motive force)
Term
group translocation
Definition
molecule is chemically altered as it passes into cell (typically phosphorylation)
Term
why can't prokaryotes rely on facilitated diffusion?
Definition
typically grow in nutrient poor environments
Term
signal sequence
Definition
sequence of amino acids on a polypeptide that signal for it to be excreted (then when outside do work for cell - ex enzymes degrade macromolecules
Term
tetrapeptides are joined directly in ..
Definition
gram negative bacteria
Term
LPS - 2 notable parts
Definition
Lipid A- anchors as top of bilayer body recognizes as invading bacteria
O antigen - chain of sugar molecules
Term
what is major reason why gram-negative bacterias less sensitive to medication?
Definition
outer membrane serves as barrier to passage of materials
Term
periplasm
Definition
in negative, between 2 layers - gel like substance, proteins accumulate here unless moved out
Term
why do antibacterials have no effect on eukaryotes?
Definition
target peptidoglycan - euks have none
Term
penicillin effective against
Definition
Gram positive more than negative (outer layer prevents medication from reaching peptidoglycan layer)
Term
lysozyme
Definition
enzyme found in tears, saliva breaks bonds of subunits of glycan, destroys integrity
Term
graham positive cells are colored ___ and why
Definition
purple, crystal violet is retained in the cell because decolorizing agent dessicates peptidoglycan layer, trapping it
Term
graham negative cells are not colored, why
Definition
outer membrane easily damaged by solvent action of decolorizing agent, thin layer of peptidoglycan cannot retain
Term
some bacteria lack a cell wall - such as
Definition
mycoplasma, has sterols in the cytoplasm
Term
archaea have ___ layers
Definition
S layers- sheets of protein or glycoprotein subunits
Term
distinct gelatinous gel-like layer outside the cell wall
Definition
capsule
Term
diffuse, irregular gel-like layer outside the cell wall
Definition
slime layer
Term
glycocalyx
Definition
capsules & slime layers composed of polysaccharides
Term
example of biofilm
Definition
plaque
Term
flagella must work hard, viscosity equivalent of
Definition
maple syrup
Term
movement of bacterial cell is
Definition
not in a straight line
Term
peritrichous
Definition
flagella distributed over entire surface
Term
pili
Definition
also called fimbriae - allow cells to attach to specific surfaces
Term
what has pili to attach to small intestine?
Definition
E. coli
Term
storage granules
Definition
accumulation of high molecular weight polymers synthesized from a nutrient the cell has in excess (glycogen)
Term
gas vesicles
Definition
small rigide protein bound compartments that provide buoyancy to the cell. gases flow freely in
Term
germinate
Definition
exit the dormant stage
Term
vegetative cell
Definition
typical multiplying cell
Term
sporulation
Definition
endospore formation - complex sequence of changes when carbon or nitrogen limited, sense starvation
Term
sporulation steps
Definition
DNA duplicated, septum forms, larger side engulfs smaller, peptidoglycan laid down around forespore, mother cell degraded
Term
germination triggered by
Definition
exposure to heat or certain chemicals
Term
germination is when
Definition
after trigger, takes on water and swells, spore coat and cortex crack open, vegetative cell emerges
Term
in sporulation: one vegetative cell gives rise to
Definition
one endospore (not cell reproduction)
Term
inside of organelle bilayer similar to
Definition
outside of cell bilayer
Term
given receptor binds a specific molecule, its
Definition
ligand
Term
endocytosis
Definition
eukaryotic cells take in material by invaginating around it (pinocytosis with liquid)
Term
endosome
Definition
membrane bound compartment formed by endocytosis, fuses with lysosomes
Term
phagocytosis
Definition
armlike extensions of cell called pseudopods surround & enclose particulate material (like bacteria)
Term
endolysosome
Definition
endosomes fuse with lysosomes
Term
phagolysosome
Definition
phagosome/endosome/lysosome fusing
Term
ribosomes
Definition
structures involved in protein synthesis
Term
cytoskeleton
Definition
actin filaments,
microtubules
intermediate filaments
Term
actin filaments
Definition
polymers of actin, rapidly assemble & disassemble to cause motion
Term
microtubules
Definition
thickest, long hollow structures made of tubulin...form mitotic spindles, cilia/flagella
Term
intermediate filaments
Definition
provide mechanical support, like rope, resist physical stress
Term
flagella & cilia microtubule arrangement
Definition
9+2
Term
where is ribosomal RNA produced?
Definition
in nucleus
Term
nuclear envelope
Definition
2 lipid bilayer membranes
Term
chloroplasts
Definition
site of photosynthesis in eukaryotic cells
Term
smooth endoplasmic reticulum
Definition
lipid synthesis, degradation, calcium storage
Term
rough endoplasmic reticulum
Definition
synthesizes proteins not destined for cytoplasm
Term
golgi apparatus
Definition
membrane bound flattened compartments, where macromolecules modified before transport
Term
lysosomes
Definition
contain powerful degradative enzymes that could destroy the cell if not contained
Term
peroxisomes
Definition
oxygen helps breaks down lipids and detoxify chemicals (creates hydrogen peroxide and superoxide)
Term
penicillin
Definition
prevents peptidoglycan synthesis
Term
lysozyme
Definition
destroys structural integrity of peptidoglycan
Term
myxobacteria
Definition
move as a pack and form fruiting bodies
Term
which has greater variety of cell wall types? archaea or bacteria
Definition
archaea
Term
mitochondria
Definition
use energy released during degradation of organic compounds to generate ATP
Term
mycoplasma causes
Definition
pneumonia
Term
mycoplasma does not have a ___ and is not affected by
Definition
cell wall, penicillin or lysozyme
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