How does it move compared to Eukaryotes?
Stiff, coiled screw-like. Rotate instead of moving in an undulating pattern like in Eukaryotes
Instead of a nucleus, DNA chromosome is floating in cytosol in a compact ____
In prokaryotes, translation and transcription ___
occur in the same area/ are not seperated
Bacteria are diploid or haploid? Shape of bacterial DNA?
haploid. They only have one version of their chromosome(s)
bacterial DNA can be circular or linear
What are plasmids?
What do they carry?
when do they replicate?
double stranded DNA molecules, usually circular that are independent of the bacterial chromosome.
They carry genes that may be useful but are not necessary for basic living.
Replicate the same time as chromosome
What happens when a daughter cell does not inherit a plasmid?
What has to happen to a plasmid to ensure a 100% rate of passing it down to every daughter cell?
it will replicate at a faster rate bc it wont have copy plasmid DNA.
problem for people who are trying to copy useful genes with plasmids.
Plasmids can integrate with bacterial genome, in which case, daughter cells will recieve plasmid DNA
Most bacteria lack steroles T/F
mycoplasma because they do not have a cell wall and will steal eukaryotic sterols in order to survive better in harsher environments
Bacterial membrane contains:
It functions like ____ in eukaryotes
transport proteins for uptake/release of materials
ion pumps to create membrane potential
It functions like inner membrane of mitochondiria in eukaryotes (Undergoes oxidative phosphoylation)
bacteria secrete small signalling molecules to communicate. Detection of these molecules leads to a reponse from the cell iin the form of increased/decreased expression of various genes
made of 30S and 50S subunits
30S unit has important 16S rRNA
Locations of biochemical pathways in Prokaryotes:
Glycolysis, pentose phosphate, Entner Doudoroff, TCA, ETC,
Glycolysis, pentose phosphate, Entner Doudoroff, TCA -cytoplasmic matrix
ETC and oxidative phosphorylation: Cell membrane
ropelike propellers (hollow rigid helix)
made of helically arranged proteins called flagellin
powered by [H+] transmembrane gradient
spirochetes have what kind of flagella? What does this enable the bacteria to do?
are gram positive or gram negative
endoflagella rotate and cause spirochetes to have flexing and spinning movements
Pili and fimbriae
thinner than flagella
also extend beyond cell wall
slender tubes of helically arranged protein subunits (pilin)
pilin- bacterial sex, allows transfer of DNA (1-10 per cell)
Fimbrae- thin, used for adhesion of cell to surfaces (up to 1000 per cell)
How do prokaryotes secrete proteins and large molecules?
*Not vesicle based unlike Eukaryotes
transmembrane channels for large molecules
general secretory pathway
General secretory pathway
Why is this not enough in gram negative bacteria
transport unfolded proteins across cell membrane
similar to the trans ER membrane movement of proteins during translation by ER membrane ribosomes in Eukaryotes
In gram negative bacteria: protein leaves inner membrane and is folded using chaperone proteins in the periplasmic space. Another mechanism must be used to cross outer membrane
What is Eukaryotic exoskeleton made of? Do bacteria have this?
Eukaryotic exoskeleton made of tubulin and actin. Bacteria do not have this but recently tubulin and actin homologs were discovered
ubiquitus in bacteria/Archaea
key player in bacterial division
forms dynamic, helical filaments inside cell
Can segregate low copy plasmids to cell poles
E.g. In Escherichia coli (rod shaped)
Bacterial cell walls contain
Archaea have peptidoglycan?
Do they stain gram positive/negative?
Some bacteria have inclusion bodies, such as ____.
what do these form?
volutin granuoles (storage form of polyphosphate). These form a metachromatic material
stains a different color than that of the original dye
Glycocalyx is made of what?
Is is necessary for cell metabolism?
What is its function
it aids in the formation of ___
made of capsules and slime layers outside of the cell wall.
-It is not used in cell growth but increases the fitness of a bacterium inside host
-can form a barrier to detergents
-can be used to adhere to surfaces or bacteria
-aids in the formation of biofilms
Glycocalyx: capsules made of?
Capsules are loose and surround cell wall
They are made of polysaccharides
exception: Bacillus anthracis has capsule made of polypeptide
Glycocalyx: Slime layers
loosly adherent and nonuniform in thickness/density
organized layers of microbial cells. Can form on parts of body or surgically implanted prosthetics/ medical devices that may express differnt gene products than sigular bacteria due to quorum sensing
Quorum sensing regulates gene expression in response to ____
cell population density flucuations
chemical signal molecules
autoinducers increase in concentration as
cell density (population) increases
Gene expression in a dense population of bacteial cells may change if a ___ of autoinducers is detected
minimum stimulatory threshold concentration
What kind of bacteria use quorum sensing? (gram pos or gram neg)
What is quorum sensing used to regulate?
DNA uptake competance
autoinducers are used in signalling between whom?
within and between species. Autoinducers can incite specific repsonses from host organisms
Prokaryotic cell wall provides ____ and protects the cell from ____ forces.
It helps ___ to other cells and eluding ____
structure and shape
osmotic forces (20-30 ATM pressure inside cell, easily popped if not for cell wall)
Assists in attaching to other cells due to proteins on outer surface of cell wall and helps elude antimicrobial drugs (if drugs can't get past the wall they cant harm the bacteria)
Why is peptidoglycan important
It is unique to bacteria so we can target it with antibiotics to kill bacteria without causing harm to other cells
The cell wall is __. It protects the cell from ___.
a porous corset (water can enter/exit with ease)
protects cell from osmotic lysis
disaccharide that forms chains
form tetrapeptide bridges to conect together
may be covelently bonded (E.G. Eschericha coli)
may be held together by an additional connecting chain (peptide interbridge) (E.G Stphylococcus aureus)
Peptidoglycan forms a
rigid prous meshwork
NAG-NAM chains form peptide linkage
cleaves between NAG-NAM disaccharides
Precusor to peptidoglycan
pentapeptide attached to NAM
Diamino acid such as L-Lysine must be in the 3rd position for a cross link to form
bond between aa 4 and 5 broken in the pentapeptide
aa 3 binds with NH2 on a NAM on a parallel chain
Acid fast bacteria are gram ____ visually.
They are resistant to gram stains T/F
gram positive cell wall structure. However, cell wall 60% mycolic acid, which helps the bacteria survive, but cause it to grow slowly.
T. They are resistant to gram staining staining and we must use harsher staining methods to stain them.
Identity of the first 2 aas on NAM can vary between organisms t/f
The pentapeptide has many moeties not found in proteins T or F
D-glutamic acid, D-alanine, D-lactate, D-serine, and meso-diaminopimelic acid
D-amino acids protect against
Terminal dipeptide of pentapeptide is usually
but it can be D-alanine-D-lactate or D-alanine-D-serine
Synthesis of peptidoglycan best studied in
Gram positive Cell Wall
thickness/percent comp. of peptidoglycan?
thick layer (15-50 nm)
~50% cell weight pep[tidoglycan
Unique polysaccharides in gram positive cell walls
Some covelently linked to lipids= lipoteichoic acids
in gram positive cell walls
anchor cell wall to cell membrane
complex polysaccharides in gram positive bacterial cell walls that can be used to identify streptococci
Gram positve cell wals ___ crystal violet dye because ___. Cells appear ___ when stained.
retain; the thick peptidoglycan layer prevents it from being washed out. Cells appear purple
M protein of streptococci is a ____ protein. These associate with the peptidoglyccan layer and form _____.
virulence protein; attachment fimbrae
teichoic acid can covelently bind to
teichoic acid and lipoteichoic acid are antigenic, which means
what can the bacteria use them for
they can be used to distinguish bacterial serotypes (strains)
they are used to anchor the bacteria to other bacteria and to mammalian surfaces
Cell wall peptidoglycan composition? Where is attched?
Relatively thin (5-10% compostion). Attached to outer membrane via lipoprotein
Composition of outer membrane. What does it enclose
inner leaflet: phospholipids
outer leaflet: channel proteins (porins), lipopolysaccharides (LPS)
Outermembrane encloses periplasmic space
what is in the periplasmic space?
hyrolytic enzymes for digestion of macromolecules, many lytic virulence molecules, and ezymes that synthesize peptidoglycan layer
What is lipopolysaccharide also called? What effect does it have on immune system
Stimulates immune system and can cause fever and shock
Outer membrane function
(what can it keep out/protect the bacteria from?)
maintains cell structure and acts as permeabiltiy to large molecules and hydrophobic molecues. Can impeded entrance of hydrophillic antibiotics
barrier to lytic enzymes such as lysozyme
produced when outer membrane is disrupted and lysozyme gains access to peptidoglycan layer
Gram negative bacteria stain ____
pink. and it can be easily washed out
What is the toxic part of Lipopolysaccharide? Does killing the bacteria with antibiotics help the host
Lipid A is the toxic part
killing the bacteria will only release the toxin into the host organism. In humans this can lead to unfavorable immune response ( fever, vasodilation, inflammation, shock, blood clotting due to cytokines from immune cells)
Has lipooligosaccharide (LOS) that steadily releases as they grow.
Lacks O antigen.
Lipopolysaccharide is made of (3 parts). What parts can we use to identify bacteria?
O antigen + core + lipid A
O-antigen: distinguishes different serotypes (strains)
core: same for a species
Lipid A: same for related bacteria
strengthen outer membrane by linking phosphates of lipid A with the core
chaperone proteins help fold proteins/prevent protein folding where?
Prevent protein folding inside cell
aid proper protein folding after translocation across the membrane
What helps facilitate unfolded protein across membrane?
Protein complex that forms transmembrane channel
What happens to protein after it is folded outside the membrane in gram positive bacteria?
Gram negative bacteria?
Gram positive: Inserts into cell membrane or leaves the cell
Gram negative: proteins are folded in the periplasmic space by chaperone proteins (e.g. pilin)
Proteins can leave the periplasmic space by travelling through flagella or a syringe like (type III) secretion system (looks like flagella)
What can a type III syringe like system be used for?
Insert toxic proteins into eukaryotic cells
Basal body of flagella in gram negative bacteria can transport flagellin units through ___ which crosses ___ membranes
flagellin make a ____ that is attached to a ___ with a sharp bend just ___ the outer membrane
Where is the flagellin attached to the cell?
20 nm thick helical hollow tube called the filament, which often ends with a capping protein
basal body (surrounded by proteins that serve as a motor)
Basal body recieves ___ from the motor proteins and transfers it to the _____.
hook and filament
Where are the flagellum basal body rings of gram negative bacteria?
1. lipopolysaccharides of outer membrane (top leaflet)
2. peptidoglycan layer (cell wall)
3. embedded in plasma membrane (inner membrane)
4. attached to plasma membrane (inner membrane)
1. peptidoglycan layer
2. plasma membrane
Flaggelum used for:
motility and protein transport (type III transport)
How is a flagellum made? How is it powered?
components of flagellum transported through basal body and travel through the hollow tube, then get added on at the end (the tip)
rotation powered by [H+] gradient formed by oxidative phosphorylation & cell metabolism
Types of flaggelar arrangement
amphitrichous (bilateral arrangement)
lophotrichous (many on one side
petrichous (everywhere on cell body)
clockwise rotation =
counter clockwise =
Spirochetes move using
spiral movements of axial filaments
also called endoflagella or periplasmic flagella
Bacillus and Clostridium genus
gram positive soil bacteria
can form highly resistant endospores
defense mechanism for bacteria
Vegetative state —► Endospore
depletion of key nutrient (such as L-arginine)
-forms single endospore per mother cell (which disintegrates)
-only DNA and essential proteins in endospore
bacteria is growing
it has lower resistance to things that can kill it
no growth, resting state
highly resistant to environmental conditions (boiling, radiation, attack from most enzymes/ chemicals
high concentration of Ca2+ bound to dipicolinic acid
convered by inner membrane, 2 peptidoglycan layers, tough outer spore coat
spores are hard to decontaminate. Posts a problem in food/medical industries
Endospore —► Vegitative state
water + triggering nutrient (such as L-arginine)
once it starts, cell is no longer resistant
endospore positions aid