Chapter 4 prokaryotes Flashcards
Prokaryotes grouped based on
morphology- shape and size
-genetically determined
Monomorphic
one shape
Pleomorphic
many shapes- rare
Average pro. size
- 2-1.0 um x 2-8 um
- ten times smaller then eukary on average
surface area of cell membrane controls….
size of cell
Two most common shapes of pros
round-coccus
rod- bacillus
Third common shape of pros
spiral- has curve
Types of curved spiral cells
- vibrio-comma
- spirillum- true twist; 1 maybe 2 turns- rigid and un-flexible
- spirochete- really flexible; super curvy
Uncommon shapes
stella- star shaped bacteria- filamentous
haloarcula- rectangular bacteria- flat disks- most are aquatic bacteria-nutrient poor-adaptation for
How do cells form groupings?
cells adhere together after division
form characteristic arrangements
-depends on plane of division
-after binary fission; cells remain connected causing
clumpingHow do pros multiply
binary fission
Diplococci
2 round cells that divide in a central plane and remain together ex. Neisseria
-gonorrhea; bacterial meningitis
Streptococci
chain of round cells that divide in central plane
-ex. Enterococcus
Tetrad
4 round cells only in cocci that divide on 2 planes down the center ex. Micrococcus
Sarcinae
8 round cells that divide on 2 planes down the center and a third plane horizontally thru the middle ex. Sarcina
Staphylococci
large group of cells that divide on random planes causing a non definitive shape
single bacillus
one rod ex. Bacillus anthracis
Diplobacilli
2 rod shape cells together end to end
streptobacilli
chain of rod like cells ex. Bacillus megaterium
Coccobacillius
rod/round ex. Bordetella pertussis
Bacillus rarely divide on long plane, if do they go thru…
Snap division and look like Chinese letters
Structures found in all bacterial cells are..
- cytoplasm
- ribosomes
- plasma membrane
- nuleoid
Glycocalyx are made..
inside cell and excreted to surface
Functions of glycocalyx…
- protection-primary- covering of cell that prevents water loss and phagocytosis
- attachment-secondary-helps attach to host or environment-most dont reproduce unless attached
- motility- rare- gliders-sluglike
Glycocalyx can be made of…..
polysaccarides, proteins or both
Virulence Factors
any bacterial structure or physiological structure that aids in disease ex. glycocalyx, flagella
Capsule
- encloses cell(glycocalyx)
- chemical composition varies depending on species
- highly organized and firmly attached
Slime Layer
- disorganized
- loosely attached
- filamentous
Prokaryotes move with
flagella
Flagella are…
- naked filaments composed of flagellin
- rotate clockwise/counterclockwise
- runs and tumbles
- taxis-move in response of outide stimuli
Bacterial Flagella structure has 3 basic parts…
- filament-long tube like appendage
- hook- made of protein- encloses base of filament outside cell
- basal body- single rod through cell wall and membrane with 1 or 2 pairs of rings for anchorage
one flagella at one end of cell
polar- Monotrichous
no flagella
atrichous-non motile
multiple flagella at one end
polar- lophotrichous
flagella all over the surface of a bacteria
peritrichous
flagella at both ends
polar-amphitrichous-can have more then one at each end
Archael flagella
bunch of tiny filaments bundled together, much smaller and turns as one piece virulence factor
an axial filament is _________ and only occurs in____.
uncommon; bacteria
axial filaments are
bundles of endoflagella that spira- ex. Spirochete bacteria
- attached at both ends and spirals down body
- causes a corkscrew motion-filament contract and relax over and over- cell twist and move
Fimbriae are
in bacteria- short thin filaments of pilin protein for attachment to other cells and surfaces
Hami are
in archaea- hooked protein filament always present for attachment
Conjugation/sex pili are
pilin tubules used to attach to other cells to exchange DNA
Conjugation
the exchange of DNA
Cannulae
filaments in thermophilic archaea- extreme heat loving
Spinae
filament that connect cells over distances and creates mesh-like network in marine bacteria
Prokaryotic cell wall
- most have
- protection
- determines shape of cell
- protects from osmotic pressure
- anchor point for flagella
- contributes to virulence
- lots of variation
sugar found only in bacteria
peptidoglycan-PTG-murein
archaea never have sugars called
peptidoglycan- may have pseudomurein
basic structure of peptidoglycan
-disaccharide polymer-NAG-N-acetylglucosamin; NAM-
N-acetlymuramic acid
-Glycan chain held together by amino acids
-tetrapeptide chain
Protein crossbridges- may or may not be present
-mostly G+
Gram Positive cell wall has
- thick layer of PTG
- Teichoic acids
- Lipoteichoic acids-attached to cell membrane
- Wall teichoic acids- not attached to membrane
- may have external protein or sugar layer
- very rigid
- charged and helps movement
- determines antigenic specificity
Gram Negative cell wall
- little or no PTG- b/w 2 diff.membrane
- outer lipopolysaccharide membrane(LPS)-controls anti. specificity
- O-specific polysaccharide side chain
- Lipid A endotoxin - significant periplasmic space- 60% plasma- nutralizing and digesting enzymes-defense mechanism
- no techoic acids
- 2nd membrane is made of lipids and sugars-part of cell wall
Antigenic specificity
stimulates immune system
Gram Staining
gram pos and gram neg bacteria can be id’d by a gram stain
-PTG holds stain so pos. holds color
Gram positive flagella
have 2 rings of the basal body in the plasma membrane
Gran negative flagella
have a ring under the outer membrane, one in the PTG of the cell wall, and two in the inner plasma membrane
Gram+’s
- many rigid layers of PTG
- teichoic acids
- no outer LPS membrane
- 2 ring basal body for anchoring flagella
Gram -‘s
- little to no PTG
- no teichoic acids
- LPS outer membrane
- 4 ring basal body anchoring flagella
Atypical wall of Gram +
-Acid-fast cell walls-hold on to stain
-classified as gram positive
- mycolic acid bound to PTG
- Mycobacterium
- Nocardia
-Wall coated with a hydrophobic wax material
- resistant to acid, base, chemicals, heat, cold,
and antibiotics
Chlamydia
- classified as Gram neg with no PTG
- only ones
- cysteine-rich proteins
- layer of proteins instead of PTG
Mycoplasmas
- have no cell wall
- smallest free-living bacteria
- plasma membrane- unique
- sterols- lipids
- help protect from lysis(rupture)
Acid fast stain is used to id bacteria of the genus
Mycobacterium and pathogenic species of Nocardia
Cytoplasmic membrane
- delicate thin fluid structure
- defines boundary
- serves as a semi-permeable barrier
- selectively permeable
Fluid mosaic model
how cell membrane is asymbled
Phospholipid Bilayer
-polar heads - composed of phosphate group and glycerol that are hydrophilic- h2o soluble -non-polar tails composed of fatty acids that are hydrophobic-insoluble
Archaea may ______ cell walls or unusual_______ that are made of_________ and _______ but not PTG.
- lack
- cell walls
- polysaccarides
- proteins
Amphipathic
both ends of bilayer chemically hydrophobic
core- controls what moves in and out
Membrane is embedded with numerous____, for things like_____,____, and _____.
- proteins
- receptors,transport, and enzymes
Prokaryotes typically dont have membrane____.
Bacteria may have ______.
- sterols
- Hopanoids- ringlike to stabilize membrane
- do not use steroids
Photosynthetic pigment on in-flodings
chromatophores or thylakoids
In-foldings of cell membrane are to ______ surface area for ____.
- increase
- photosynthesis
Archaea have distinct membranes lipids
- ether linkage
- 2 diether or 4 tetraether linkages
- glycerol group enantiomer
- branched isoprenoid sidechain
- may form mono-layer with great rigidity
Selectively Permeable
- membrane is
- few molecules pass through freely
- movement involves active and passive processes
Passive processes
- no energy(ATP) required
- along gradient
- simple diffusion, facilitated diffusion, osmosis
Simple diffusion
the net movement of molecules or ions from an area of high concentration to an area of low concentration
Facilitated diffusion
integral membrane proteins function as channels or carriers that facilitate the movement of ions or large molecules across the plasma membrane
Osmosis
the net movement of solvent molecules across a selectively permeable membrane from an area with a high concentration of solvent molecules(low concentration of solute molecules) to an area of low solvent molecules(high concentration of solute molecules)
Isotonic Solution
-no movement of water- equilibrium
Hypotonic solution
- water moves into the cell to high conc. of solutes- can cause cells to burst- osmotic lysi
Hypertonic solution
-water moves outside of cell-high solutes outside cell - causes cytoplasm to shrink
Active processes
-energy required- active transport
Group translocation
- form of active transport that breaks apart molecules before the molecule can enter
- PEP is in the cell and loses a Phos in order to rephospholate the in coming molecule
Internal Structures essential for life
- chromosome
- ribosomes
Optional cell structures that may provide selective advantages
- cytoskskeleton
- plasmid
- storage granules
- endospores
Primary chromosome
- reside in nucleoid
- typically single circular chromosomes
- Archaea-histone proteins
- Bacteria-condensin proteins
- Asexual reproduction
- Binary fission, budding, fragmenting, spores
Plasmids
- small DNA molecules
- replicated independently
- nonessential information
- used in genetic engineering biotechnology
Ribosomes
- composed of large and small subunits
- made of riboprotein and ribosomal RNA
- differ in density from eukaryotic ribosomes
- 70s ribosomes
Inclusions
- metachromatic granules
- polysaccaride granules
- lipid inclusions
- sulfur granules
- carboxyzomes
- magnetosomes
- gas vesicles
Endospores
“resting cells”
- highly resistant - heat, desiccation, chemicals, and UV light
- not for reproduction
Formation of endospores thru sporulation/sporogenesis
- begins when a key nutrient ,C,N, becomes scarce
- a newly replicated bacterial chromosome and portion of cytoplasm are isolated by an ingrowth of plasma membrane
- ingrowth becomes a double-layered membrane that surrounds the chromo and plasm
- thick layers of PTG are put between the two membrane layers
- spore coat of protein surrounds the outside membrane
- original cell is degraded and the endospore is released
