Block 1 Flashcards
what is the general size scale of prokaryotes in micrometers
5
what is the general size scale of eukaryotic cells in micrometers
10
what are bacteriophages
viruses that infect bacteria
what are the 3 classes/shapes of viruses that can infect human cells
nonenveloped icosahedral
enveloped icosahedral
nonenveloped helical
in nonenveloped icosahedral viruses, what is used to attach to the surface of the host cell
capsomere protein
in enveloped icosahedral viruses, what is used to attach to the surface of the host cell
glycoprotein
in enveloped viruses, where does the envelope come from
the previous host cell
are enveloped or nonenveloped viruses more stable
nonenveloped
what are the 7 steps of virus replication
- attach
- penetrate
- uncoat (acidify vacuole)
- early mRNA synthesis (proteins to shut off host cell and replicate viral genome) and late mRNA synthesis (capsomeres and glycoproteins)
- posttranslational modification
- assembly of new virus
- release (nonenveloped by lysis, enveloped by budding)
what type of viral genome does the human immune system recognize
dsRNA
where do viruses with DNA genomes typically replicate
nucleus
where do viruses with RNA genome typically replicate
cytoplasm
what is the difference between + and - sense RNA
+ is in the proper orientation to be translated
- is in the opposite orientation
what does TLR4 recognize
lipid A of gram - bacteria
what does TLR3 recognize
virus (dsRNA)
located inside cell (not on surface)
what does TLR1:TLR2 recognize
bacterial lipoproteins
what are features of gram + bacteria
thick peptidoglycan
lipoteichoic acid (LTA)
stains purple with gram stain
what does TLR2 and TLR6 recognize
bacterial lipopeptides
what does NOD2 recognize
NAM
what are 5 features of gram - bacteria
outer membrane (outer= lipopolysaccharide made of lipid A and polysaccharide, inner= phospholipids)
thin peptidoglycan
porin proteins
periplasmic space between cell wall and outer membrane and plasma membrane and cell wall
stains pink with gram stain
how does the gram stain work
bacteria with thick cell walls (gram +) are able to hold the color tighter, showing a darker color (purple)
what type of bacteria can be visualized with Ziehl-Neelsen stain
acid fast
in Zeihl-Neelsen stain, acid fast bacteria stain what color
pink
what type of bacteria can form a capsule
gram + and -
what are the advantages of forming a capsule
avoid phagocytosis
protection against drying out
inhibition of effective immune response
are biofilms made by a single bacteria or groups of bacteria
groups
what additional advantages does biofilm formation have over capsule formation
antibiotic and antiseptic resistance
what does the prefix strepto- mean
chain
what does the prefix staphylo- mean
cluster
how are spirochete bacteria visualized
darkfield microscopy
monotrichous vs amphitrichous vs lophotrichous vs peritrichous
mono- one flagellum from one end
amphi- flagella on both poles
lopho- flagella from one side
peri- flagella all around
what does TLR5 recognize
flagellin
bacterial flagella are composed of a basal body attached to a flagellin filament. the innermost ring is attached to a mot protein. what does this mot protein resemble
ATP synthase
what causes a bacterial flagellum to spin
proton gradient
bacteria flagella spin counterclockwise and clockwise. what type of movement occurs when it is spinning clockwise vs counterclockwise
clockwise- tumble
counterclockwise- run
what is the type 3 secretion system used by bacteria for
uses a “needle” to inject proteins that restructure actin in host cells
the type 3 secretion system for injecting proteins is used by gram + or - bacteria
-
what are pili (fimbriae)
flexible extensions through the cell envelope that allows bacterial to attach, pull, then contract, pulling it along a surface
what are the 5 steps of bacterial cell division
- replicate DNA
- make new cell envelope material in the middle of the cell, cell lengthens
- pinch at septum with FtsZ
- new cell envelope material is made at septum where FtsZ is attached
- cell divides into 2
what occurs during the lag phase of a bacterial growth curve
cell adjusts and preps for division
what occurs during the log (exponential) phase of bacterial growth curve
cell division
where on the bacterial growth curve is generation time measured
mid log phase
what occurs during the stationary phase of bacterial growth curve
bacteria start running low on nutrients
toxic byproducts increase
replication stops
# of new bacteria=# of old bacteria
where on the bacterial growth curve are autolysins expressed
stationary phase
what occurs during the decline (death) phase of bacterial growth curve
nutrients decrease
toxic byproducts increase
autolysis
what are the 5 spore formation steps
- replicate DNA
- cytoplasm divides, PM folds over creating double membrane over replicated DNA
- peptidoglycan deposited between layers
- protein coat of dipicolinate deposited
- cell lyses, releasing spore
why do spore forming bacteria appear pink with gram stain when all spore forming bacteria are gram + rods
peptidoglycan was transferred to the spore
what stain allows direct visualization of spores
malachite green
during which phase of the bacterial growth curve are sporulation genes expressed at the highest
end of stationary
during which phase of the growth curve would there be the most spores
end of decline (death)
all human and pathogen bacteria are what class of bacterial
mesophiles
as you increase temperature, what happens to the content of AT vs CG
increase temp= more CG
as you increase temperature, what happens to the concentration of saturated vs unsaturated fats
increase temp= increase saturated fats
as you increase temperature, what happens to alpha helix vs beta sheet structure
increase temp= more beta sheets
what are obligate aerobes
require oxygen
what are obligate anaerobes
can’t have oxygen
what are facultative anaerobes
prefer oxygen but can live without
what are aerotolerant anaerobes
tolerate but don’t use oxygen
what are microaerophiles
use small amount of oxygen
what are the only anaerobe/aerobe class that is not catalase positive
obligate ananaerobes
aerobes use cellular respiration (aerobic respiration). anaerobes use __
fermentation
what are capnophiles
need CO2 (5-10%) to grow
what does catalase do
breaks down free radicals (hydrogen peroxide)
what is the purpose of a catalase test
used to visualize if bacteria form bubbles
bubbles are O2 as a result of catalase= aerobic bacteria
is anaerobic or aerobic respiration more efficient for generating ATP
aerobic
where does cellular respiration take place in eukaryotes
mitochondria
where does cellular respiration take place in prokaryotes
plasma membrane
what is always a product of fermentation
acid
besides acid, what are 2 other possible products of fermentation
gas
alcohol
what does phenyl red visualize
a change in pH as a result of fermentation
what is the color change produced with phenyl red
pH 7= red
acidic pH= yellow
what does it mean if phenyl red turned yellow
the bacteria uses fermentation, as an acid was produced, lowering pH
what does a durham tube allow us to visualize about bacteria
if a gas was produced, liquid will be displaced by a gas bubble
what does it mean if gas was produced in a durham tube
the bacteria uses fermentation, as gas is a byproduct of fermentation
what does it mean for a bacteria to be alpha-hemolytic
bacteria grows, partially lyses RBC
what does it mean for a bacteria to be beta-hemolytic
bacteria grows, completely lyses RBC
what does it mean for bacteria to be gamma-hemolytic
bacteria grows, doesn’t lyse RBC
satellite colonies grow only nearby other bacteria growth. what does this tell us
they need RBC to grow but can’t lyse them
what is chocolate agar used for
it contains RBC that have already been lysed to allow bacteria that need hemin from RBC to grow but can’t lyse RBC on their own
what are plasmids
small circles of DNA that can be shared among bacteria
what types of genes are often on plasmids
antibiotic resistance
virulence factors
what is bacterial natural transformation
bits of DNA in the extracellular environment are taken up and incorporated into the cell’s chromosome
what enzyme is required whenever a piece of DNA is incorporated into a chromosome
recombinase
what gene is required whenever a piece of DNA is incorporated into a chromosome
recA
what is bacterial artificial transformation
construction of a plasmid with a gene scientists want a bacterium to express and forcing the bacteria to take up the plasmid
can bacterial transformation (natural and artificial) be done with gram +, -, or both
both
what is bacterial conjugation
a plasmid from a donor cell is transferred to a plasmid - recipient
what bacterial can perform conjugation
gram - due to involvement of pili
genes located where on a plasmid are most likely to be shared during conjugation
near the OriP (plasmid origin of replication)
what is a high frequency of recombination plasmid (Hfr)
a plasmid with a palindrome that allows it to switch back and forth from being an independent plasmid to being incorporated into the bacterial chromosome
*when the plasmid comes out of the chromosome, it brings with it a piece of bacterial chromosome which may be transferred by conjugation
in what type of bacterial genetic exchange must the donor be alive
conjugation
in what type of bacterial genetic exchange must the DNA donor and recipient be closely related
conjugation
transduction
a phage that is only ever lytic is called a __ phage
virulent
what is the lytic cycle of a phage
phage turns bacteria into a virus assembly factory
what is the CRISPR-Cas system of bateria
immune system of phages
phage injects DNA, DNA is cut by Cas, palindrome fragment added to library of phage DNA to compare to in the future
what is the lysogenic cycle of a phage
phage DNA is incorporated into bacterial chromosome and suppressed lytic phage genes so bacterial cell is not harmed
a phage that can be lysogenic is called a ___ phage
temperate
what is lysogenic induction
triggering of a temperate phage to switch from lysogenic to lytic
what is a cause of lysogenic conversion
high population of bacteria
what stage of the bacterial growth curve does lysogenic conversion occur
end of log (exponential) due to increase in bacterial population size
what is bacterial generalized transduction
bacteriophage injects DNA and replicates
during assembly, some bacteriophages take in bacterial DNA instead of viral DNA
bacteriophage infects a new recipient
bacterial DNA that was taken up is incorporated into new bacteria chromosome
what is bacterial specialized transduction
bacteriophage injects and becomes lysogenic
DNA is incorporated into bacterial chromosome, bacterial cell undergoes cell division
phage becomes lytic
viral DNA removes from bacterial chromosome taking with it some bacterial genes, leave some viral DNA behind
*location of bacterial gene maters in how likely it is to be transferred (closer to viral= more likely to be transferred)
do regulated genes tend to have higher AT or CG content
CG due to being less likely to be transcribed
what is the trp operon
codes for genes to make tryptophan
is the trp operon usually on or off
on
low trp= repressor dissociates from sequence so RNA polymerase can bind
when is the trp operon off
when trp levels are increased
what is the lac operon
genes to break down lactose
is the lac operon usually on or off
off
when is the lac operon on
when lactose is present, it bind to the binding region, changing shape of the promotor so the repressor is unable to bind
what occurs with quorum sensing
as bacteria divide, they release autoinducers which are pumped out through an autoinducer pump
when bacteria population increases, autoinducer population increases, increasing the likelihood for an autoinducer to bind to an autoinducer receptor
when an autoinducer bind to an autoinducer receptor, the autoinducer is phosphorylated, causing a change in gene expression
what is a heat shock sigma factor
protein turned on in times of stress to help the bacteria survive
what type of bacterial have heat shock protein
all
what are polycistronic genes
a single mRNA codes for multiple proteins expressed simultaneously
how do polycistronic genes work
bacterial ribosome binds to shine delgarno sequence
moves until reaches a stop codon
ribosome reattaches to next shine delgarno sequence
what is bacterial transposition
a mutation in which a gene moves from one location in a bacterial chromosome to another
*may now be expressed with anew operon
what increases the likelihood of bacterial transposition
DNA palindromic sequences
what is the only PAMP small enough to form a concentration gradient
f-met
what are efflux pumps
modification of membrane proteins used to pump antibiotics out as soon as they diffuse into the cell
“is this food? No. Pump out”
what is siderophore
a molecule secreted by bacteria to collect iron from the environment and transport it to the bacterial cell
