microbio chapter 3 Flashcards
Prokaryotic characteristics
- lack nucleus, lack various internal structures, very small
- composed of bacteria and archaea
- composed of phospholipid bilayer membrane
- biosynthesis can occur and put together polysaccharides
What can happen to the polysaccharides produced in a bacteria cell?
They can exit the cell and form a glycocalyx around the cell
Glycocalyx: capsule
- firmly attached to cell surface, may prevent bacteria from being recognized
- consistency of vaseline, interferes with the detection of bacteria cells
Glycocalyx: s-layer
- loosely attached to the cell surface, water soluble
- sticky later allows bacteria to stick to surfaces
- consistency of hand lotion
- prevents phagocytosis of bacteria by immune system
Glycocalyx: capsule and s-layer
- some bacteria make one or the other, some make none
- both prevent dehydration and can trap food
Flagella
- not present on all bacteria, will be produced in a water environment
- composed of a filament, hook, and basal body
Basal body of flagella
- anchors flagella into cell wall
- contains stator MOT A and B proteins
- contains hollow rod which has access to inside of cell and feeds into the hook
MOT A and B proteins
- in the stator of the basal body in flagella
- function as motor proteins to help propel flagella
Hook
extends from hollow rod, allows for rotational movement
- in correspondence with rod and ring proteins
Filament
- hollow shaft extending from the membrane, does not have additional membrane coverage
- composed of proteins made in the cell and push through the hollow rod to filament
- newest proteins are furthest from the cell
- rotation of filament is dependent on rotation of hook and stator
Monotrichous
Bacteria that have only one flagella
Amphitrichous
Bacteria with 2 flagella, one on each end
Lophotrichous
Bacteria with a bundle of flagella on one end
Peritrichous
Bacteria with flagella all over
Movement of flagella
-runs
-tumbles
-taxis
-memory based movement
Runs
- counterclockwise rotation of flagella
- propels flagella in a single direction
- interrupted by tumbles
Tumbles
- clockwise rotation where each filament rotates individually
- cell utilizes sensory perception to judge nutrient and toxin levels in order to recalibrate and make next movement
- recalibration of bacteria cell
Taxis
- movement in response to stimuli
- stimuli is usually light or chemicals
Movement of bacteria in taxis
- if a bacterium approaches a favorable stimulus, it increases duration of runs, runs are shorter with less sugar detection on surface
- unfavorable stimuli increases run in opposite direction of repellent
Memory based movement of bacteria
- bacteria moves in different directions based on what was around them
- increasing length of runs as they come closer to nutrients
- in comparison to how much sugar they had on their surfaced last time
Speed of bacteria
0.0001 mph or 60 body lengths/sec
- 670mph in a car
Primary active transport in bacteria cells
- direct contact with ATP on protein
- used to pump ions out of membrane and create a gradient
- creates a proton motor force
- ions can be taken back in and utilized for movement
Proton motor force
how bad an ion wants to move back into a cell after being pumped out by primary active transport
Secondary active transport
- movement of nutrients or molecules with the use of Na gradient, no direct contact with ATP
- utilizes ion equilibriumization to bring in nutrients
MOT A and B protein movement
- ions moved out with primary active transport can be used my MOT A and B proteins in stator to produce movement
- ion binding of ion on MOT B protein changes its shape and causes rotation
primary active and secondary active correlation
- primary active transport utilizes ATP to create an ion gradient
- secondary active transport relies on those ions to bring nutrients back into the cell
Axial filament
- found on spirochetes
- flagella on both ends that spiral tightly around bacteria body rather than protrude outward (endoflagella)
- endoflagella form axial filament
- wraps around cell between cytoplasmic and outer membrane
- rotation of endoflagella causes axial filament to rotate around cell causing corkscrew movement
Fimbriae
- stick, bristle like projections (hairlike velcro)
- used by bacteria to adhere to one another or hosts/substances
- serve an important function in biofilms
- fimbriae use s-layer to connect, making it hard to treat infection
- can be used in movement by anchoring and pulling
pili
- longer than fimbriae, shorter than flagella
- potentially evolved from hollow rod
- allow for genetic exchange between cells
- conjugation: sexual genetic exchange from one bacterium to another through pili
bacterial cell walls functions
- provide structure and shape
- protect cell from osmotic forces
- assists some cells attaching to cells or resisting antimicrobial drugs
bacterial cell wall composition
- composed of NAM and NAG interchanging pattern
- NAM and NAG are held together by an alanine bridge
- this is called peptidoglycan
NAG
N-acetylglucosamine
NAM
N-acetylmuramic acid
How are NAM and NAG made
- nutrients are brought into the cell
- nutrients are metabolized
- nutrients are catabolized
- NAG and NAM are made
- they can leave the cell and creating alternating pattern to form cell wall
Gram positive cell walls
- appear purple with gram staining
- thick layer of peptidoglycan (30ish layers)
- contain teichoic and lipoteichoic acid
- up to 60% mycolic acid that helps with survival of desiccation
Teichoic acid
- found in gram positive cell walls
- does not go into membrane
- have (-) charges and may play a role in ion movement through membrane
- covalently bonded to lipoteichoic acids
Lipoteichoic acid
- does go into membrane
- anchors petidoglycan to cytoplasmic membrane
Gram negative cell walls
- appear pink in gram staining
- thin layer of peptidoglycan
- have two membranes
Membranes of a gram-negative cell
- cytoplasmic phospholipid bilayer
- outer phospholipid and lipopolysaccharide membrane
Outer membrane of a G- cell wall
- made of lipopolysaccharides
- lipid a side: trigger for immune system
- o-side chain
-contains porin proteins that utilize a can be non-specific - decreases osmotic pressure by allowing only half of nutrients in at once
Inner membrane of a G- cell wall
- cytoplasmic membrane
- phospholipid bilayer
- contains very specific proteins that allow in half a nutrient
- proteins utilize active transport
- decreases osmotic pressure
- utilizes symport proteins to eat and antiport proteins to ger rid of wastes/toxins
Gram staining
- air dry
- heat fix
- crystal violet
- iodine
- destain, flow through
- safranine counter stain
cytoplasmic membrane of bacteria cells composition
- phospholipid bilayer
- associated proteins
- fluid mosaic model
Membrane processes
-diffusion; charged and small
- osmosis; water
- facilitated diffusion; can be specific or non-specific, allows movement of larger, charged molecules
cytoplasmic membrane functions
- energy storage, membrane permeability
- maintain electrical and [ ] gradient
- naturally impermeable to most substances
- harvest light energy on photosynthetic bacteria
Effects of solutions on cells
- bacteria have cell walls that prevent cytolysis
- isotonic; no water movement
- hypotonic; water moves into cell, cell wall prevents cytolysis
- hypertonic; water moves out of cell
Group translocation
- the substance transported across the membrane is chemically changed during transport
- saves energy for cells low on energy
- some bacteria utilized this over glycolysis because ATP is needed in first two steps of glycolysis but not group translocation
- group translocation allows for ATP usage at different stages
Group translocation process
- Enz 1 floats in cell and becomes phosphorylated by PEP
- Enz1-P phosphorylates HPr
- HPr-P is phosphorylated on aa 15 histamine, allows it to phosphorylate next protein
- HPr-P phosphorylates Enz 2A
- Enz 2A-P phosphorylates Enz 2B
- Enz 2B-P changes shape with phosphorylation, causing Enz 2C to change shape
- change of shape of Enz 2C allows glucose to enter cell
- glucose is chemically changed to g6P during transport by picking up phosphate on Enz 2B on its way in
- g6P can be used to make 7Fruc6P then Fruc1,6BP
On which aa is HPr phosphorylated to allow group translocation
aa 15, histamine
What does the presence of Fruc1,6BP do to group translocation
Increased levels of Fruc1,6BP activate HPr kinase which blocks the HPr 15, histamine bond
- HPr 15 is blocked because HPr kinase binds to aa 36, serine which in turn blocks any bonding to histamine aa 15
- cell switches from translocation to glycolysis
cytosol
liquid portion of cytoplasm, contains the nuclei
nucleoid
DNA packaged around protein/RNA core
Inclusions
- include reserve deposits of chemicals
- can form a polypeptide chain membrane around toxins (very rare)
- chemicals can be taken in and stored for later use
endospores
- constitute a defensive strategy against hostile and unfavorable conditions
- NOT reproductive structures
- a vegetative cell normally transforms when one or more nutrients are in limited supply
endospore formation
- cytoplasmic membrane invaginates to form forespore
- membrane grows and engulfs spore in a second membrane, DNA in vegetative cell disintegrates
- peptidoglycan is deposited between 2 membranes, dipicolinic acid and Ca accumulate with endospore
- endospore coat forms and matures, endospore is released
endospore to a new vegetative cell
- endospores contain specific enzymes that are utilized in transcription/translation this allows the eventual use of DNA to replicate and eventually make a new vegetative cell
-endospores can stay dormant for many years and still become vegetative
ribosomes
- sites of protein synthesis, float around cytosol
- composed of polypeptides and rRNA
cytoskeleton
- plays a role in forming the cells basic shape
-composed of 3-4 fiber protein types
plasmids
- non-chromosomal DNA, non-essential genes, may not be present in all bacteria cells
glycocalyx in archaea
- function in formation of biofilms
- adhere cells to cells or objects
flagella in archaea
-slower than bacteria, smaller, not hollow
- grow at base rather than at end
- powered by ATP
- all rotate together in both directions
fimbriae in archaea
- stick projections
- anchor cells to cells or surfaces
hami in archaea
- fimbriae like structures with prickles and hooks at the end
archaeal cell walls
- do NOT have peptidoglycan
- composed of polysaccharides and special proteins
- gram negative have an outer layer protein
- gram positive have a thicker cell wall
archaeal cytoplasmic membrane
- composed of lipids and branched hydrocarbons linked to glycerol by ether linkages
- ether linkages are stronger than ester linkages, allowing archaea to live in harsh conditions
archaeal cytoplasm - similarities to bacterial
- 70s ribosomes
- fibrous cytoskeleton
- circular DNA
archaeal cytoplasm - differences to bacterial
- different ribosomal proteins
- different ribosomal proteins to make RNA
- genetic code more similar to eukaryotes
What is the significance of Ca and dipicolinic acid in endospore formation
Ca and dipicolinic acid form a cortex around the first membrane of an endospore
- creates an extra layer of protection of DNA material inside
