Chapter 3-Cell Structure of Prokaryotes Flashcards
How do Prokaryotes differ from Eukaryotes?
in size and simplicity
most prokaryotes lack a _____________
internal membrane system
prokaryotes are divided into _____________
bacteria and archaea
describes cell shape
morphology
what are the 3 major cell morphologies? (there are variations from the main 3)
coccus (cocci), bacillus (bacilli), spirillium
2 cocci
diplococcus
chains of cocci
streptococcus
4 cocci
tetrad
8 cocci
sarcinae
many cocci
staphylococcus
diplobacilli
2 bacilli
chains of bacilli
streptobacilli
several parallel cells along long axis
pallisade
rods
bacilli
very short rods
coccobacilli
resemble rods, comma shaped
vibrios
rigid helices
spirilla
flexible helices
spirochetes
network of long, multinucleate filamentous cells
mycelium
organisms that are variable in shape
pleomorphic
Why is it advantageous for a cell to be small?
small cells have a higher SA to volume ratio than large cells, allows for greater nutrient exchange per unit of cell volume
what makes up the cell envelope?
(1) structures exterior to the cell wall
(2) cell wall
(3) cell membrane
What are the functions of the cell membrane?
maintain cell integrity, regulate transport, protein attachment, receptors for detection of/response to chemicals in surroundings, energy metabolism in prokaryotes
describes the cell membrane as somewhat fluid, somewhat solid, lipid bilayer with floating proteins
fluid mosaic model
phospholipid bilayer with proteins, no sterols, but contains hopanoids (both hydrophobic and hydrophilic components), many variations to glycerol backbone
composition of cytoplasmic membrane
loosely connected membrane protein on cytoplasmic side, easily removed
peripheral protein
embedded with membrane, project outward and inward, amphipathic, control important functions and microdomains
integral proteins
completely cross membrane
transmembrane protein
What are two cell membrane strengthening agents?
(1) sterols
(2) hopanoids
rigid and planar, found in eukaryotic membranes, strengthen membrane, only found in a very few prokaryotes
sterols
structurally similar to sterols, present in membranes of many Bacteria
hopanoids
liquid crystal, rigid and temperature dependent
cell membrane
What happens when the cell membrane gets too cold?
solidification occurs, gelling, Van der Waals forces pull tails together
What happens when the cell membrane gets too warm?
thermal lysis, cell death
How is the correct fluidity of a cell membrane obtained?
adjust fatty acid composition
if cold: more unsaturated fatty acids, minimize VDW forces
if hot: more saturated fatty acids, minimize VDW forces
transport which does not require ATP or other cellular energy to be used by the cell
passive transport
transport which require the cell to extend its own energy in the form of ATP
active transport
transport that doesn’t require a transport protein
simple transport
transport which requires a transport protein
facilitated transport
the movement of a molecule due to inherent kinetic energy from high concentration to low concentration
diffusion
the diffusion of water across a membrane
osmosis
What are the factors that determine transport across a cell membrane?
(1) Charge of the molecule
(2) Size of the molecule
(3) Shape of the molecule
What are the factors that determine movement across a cell membrane?
non-polar or small polar between phospholipids, all ions and all polar substances allowed through transport protein
ligand binds specific proteins, slow saturation effect, highly specific
receptor mediated transport systems
simultaneous transport and chemical modification of transported substance
group translocation
exterior to cell membrane, rigid and mostly structural polysaccharide and peptide/protein, prevent osmotic lysis in colonial prokaryotes
cell wall
pressure from water entering the cell, causes a rupture of the cell membrane and death of the cell
osmotic lysis
solute concentration outside is less that inside, water moves into cell and cell swells, cell wall protects from lysis
hypotonic environment
solute concentration outside the cell is greater, water leaves the cell, plasmolysis occurs
hypertonic environment
What will happen to a cell wall in hypotonic solution if no lysozyme or penicillin is present?
the cell will lyse
protoplasts are ___________
gram positive
spheroplasts are ____________
gram negative
purple stain, thick layer of peptidoglycan
gram positive
pink or red stain, thin peptidoglycan
gram negative
the structural polysaccharide in the cell walls of domain Bacteria prokaryotes, mesh like polymer of identical sub units forming long strands, 2 alternating sugars, alternating D & L amino acids
peptidoglycan
peptidoglycan strands have a ________shape, and are cross-linked by ____________
(1) helical
(2) covalent bonds
almost 90% peptidoglycan, have large amounts of teichoric acid (maintain cell envelope, bind to host cell, attract cations) may have layer of proteins on surface
gram positive cell wall
thin layer of peptidoglycan, outer membrane composed of phospholipids, lipoproteins, and lipopolysaccharide, Braun’s lipoprotein crosses from outer membrane to peptidoglycan
gram negative cell wall
have 3 parts (lipid A, a core polysaccharide, and an O side chain), place negative charge on cell surface, stabilize outer membrane structures, helps to create a permeability barrier, protects from host defenses
lipopolysaccharides
a gram negative outer membrane is more permeable than a plasma protein due to the presence of ____________ and ___________
porin proteins and transfer proteins (allow small molecules to pass)
polysaccharide rich material exterior to the cell wall, has multiple protein components
glycocalyx
a dense, tightly attached, regular arrangement of polysaccharides that sits exterior to the cell wall, visible to a light microscope, most are gram +
capsule
a diffuse, loosely attached irregular arrangement of polysaccharides, attach to solid surfaces and prevent virus attachment
slime layer
regularly structured layers of protein and glycoprotein that self assemble, gram (-) adhere to outer membrane, gram (+) associate with peptidoglycan surface
s-layers
What are the functions to the s-layer?
(1) protect from ion/pH/osmotic pressure
(2) maintain shape and rigidity
(3) promote adhesion to surfaces
(4) protect from host defenses
short, thin, hairlike proteinaceous appendages that mediate attachment to surfaces
fimbriae and pili
similar to fimbriae but longer, thicker and less numerous, genes for formation found on plasmids
sex pili
threadlike locomotor appendages that extend outward from plasma membrane, attach to surfaces and provide motility and a swarming behavior
flagella
one flagellum
monotrichous
flagellum at end of cell
polar flagellum
one flagellum at each end of cell
amphitrichous
cluster of flagella at one or both ends
lophotrichous
spread over entire surface of cell
peritrichous
What are the three parts of flagella?
(1) filament
(2) hook
(3) basal body
part of flagella, extends from cell surface to the tip, a hollow and rigid cylinder, composed of the protein flagellin
filament
part of flagella, links filament to basal body, made of protein
hook
part of flagella, series of rings that drive flagella motor
basal body
directed cell movement in response to some stimulus
taxis
movement toward chemical attractants such as nutrients and away from harmful substances
chemotaxis
a flagellum rotates like a ______________
propeller
Spirochetes have a ____________ shape which allows for movement in a viscous media.
corkscrew
a movement described as short, intermittent jerky motions
twitching
moving in smooth motion and movement
gliding
material bound by the plasmid membrane, 95% water, dissolved solutes, contains cytoskeleton, enzymes and ribosomes
cytoplasm
network of fibrous proteins within the cytoplasm, important in cell division and determine cell shape
cytoskeleton
What are two types of intracytoplasmic membranes?
(1) cell membrane infoldings
(2) anammozosome in planctomycetes
membrane bound storage structures containing granules of in/organic material that are stockpiled by the cell for future use, glycogen and carbon storage, amino acids and other nutrients
inclusions
not bound by membranes but compartmentalized for a specific function (CO2 fixing bacteria)
microcompartments
an inclusion found in aquatic, photosynthetic bacteria and archaea, provide buoyancy in gas vesicles
gas vacuoles
found in aquatic bacteria, orientate themselves based on the Earth’s magnetic field, help make protein
magnetosomes
have a complex structure, site of protein synthesis, larger in eukaryotes than bacteria
ribosomes
archaeal __________ are more similar to eukarya than bacteria
ribosomes
no nucleus, no membrane around DNA, found in an irregularly shaped region, 10-15% of cytoplasmic volume, DNA is circular and supercoiled
nucleoid
extrachromosomal DNA, found in bacteria, archaea and some fungi, small closer, circular DNA molecules, exist and replicate independently of chromosome, exist in many copies within cell, contain four genes that are non-essential
plasmids
complex, dormant structure formed by some bacteria, function is to survive extreme environments for organism, resistance to numerous environmental conditions (heat, radiation, chemicals)
bacterial endospore
thick covering of exosporium, and spore coat make up the ____________
endospore structure
process of endospore formation, occurs in only a few hours, ends when growth ceases b/c of lack of nutrients, complex, multistage process
sporulation
How is an endospore resistant?
calcium (complex with acid), small, acid soluble DNA binding proteins, spore coat and exosporium to protect
a multistage process that transforms an endospore into a vegetative cell complex
germination
prepares spores for germination, often results from treatments like heating
activation formation of a vegetative cell
occurs when environmental nutrients are detected, spore swelling and rupture of spore coat, loss of resistance, increased metabolic activity
germination formation of vegetative cell
