microbiology Flashcards
viruses are considered what?
obligate intracellular parasites
some viruses store ____ molecule in their capsid
ATP
Viral genome can be
DNA/RNA
Single/Double stranded
Linear/Circular
Viruses adaptations
- Carry very few genes
- rely on host-cell machinary
- encode for >1 protein in a given length of the host genome
How do viruses accomplish the encoding of greater than 1 protein in a given length of the host genome?
By utilizing more than 1 reading frame within a piece of DNA
Capsid
protein coat that surrounds the viral nucleic acid genome
Capsid head
contains the genome
Capsid tail fibers
attach to the surface of the host cell
Capsid Base Plate
attach to the surface of the host cell (check??)
Capsid Sheath
contracts using energy from ATP
injects genome into the host cell (check this??)
Envelope
Surrounds the capsid
Composed of phosopholipid, carbohydrates, proteins = from the host cell membrane and protein that is encoded by the virus
Naked Viruses can be distinguished by what?
They have NO envelopes
What is the first viral product?
What is its function?
Is an example of what?
hydrolase
degradation of host genome
early gene
lysozyme
destroys bacterial cell wall
Lysozyme can be found
in human tears, saliva, phages, mucas, milk
lysozyme is an example of a
late gene
without the cell wall
osmotic pressure no longer is counteracted –> bursting fo cell
naked virus infection is determined by
viral surface
Prophage
phage genome incorporated into bacterial genome
“pro - phage “ - used to indicate characteristics of the virus
Lysogen
Bacterial genome with prophage
“lysogenic bacterium” - term is used to describe the state of the bacterial cell
When a virus is considered a prophage, does it produce viral progeny?
No.
when a virus is considered a prophage what term would characterize its gene or gene expression?
silent except for the gene(s) that code for proteins that maintain prophage, such as for the phage-encoded repressor
How does a prophage silence its gene expression?
a phage-encoded repressor binds to specific DNA elements in phage promoters (operators)
Do viruses have promoters?
Yes
Can viral gene expression be regulated by the virus?
Yes, example of phage encoded repressor
How do you think the expression of genes is regulated?
universally with as a few protein products and dna sequences required to regulate expression
(remember viruses code for as few things as possible)
Transduction
process where the activation of a prophage leads to excision from the host genome
Animal viruses enter a target cell by
endocytosis
Productive cycle
Applies to animal viruses only
Similar to lytic cycle
Differs from lytic cycle in that it does not destroy host cell
How does an animal virus avoid destroying the host cell?
by budding instead of lysis
What property of the membrane allows an animal virus to exit without rupturing the membrane?
lipid bilayer can reseal itself
Provirus
dormant form of viral genome in lysogenic cycle of animal viruses (animal equivalent of a prophage)
RNA (+)
single stranded
is essentially viral mRNA
requires RNA(-) intermediate to generate new (+) strand genomes
RNA (-)
is essentially viral DNA equivalent (Note is not DNA itself_
is template for mRNA production
Retroviruses
MUST encode for reverse transcriptase
reverse transcriptase
is a RNA-dependent DNA polymerase (takes RNA –> DNA)
violates a big theme of molecular biology that information flows in a unidirectional manner from DNA –> RNA –> Protein.
List the 3 main retroviral genes and what they code for
gag - capsid
polt - reverse transcriptase
env - envelope
dsDNA virsuses
often encode enzymes for DNA replication and polymerization
some induce host cell to enter mitosis
can override cell inhibition for cell division –> cancerous cell
Bacteria do not contain what?
membrane bound organelles
What organelle does bacteria contain
ribosome
Bacterial genome is
circular
double stranded DNA
NOT associated with histones
We can differentiate between a bacterial genome and a human genome by?
bacterial genome would not have histones (proteins) in it while human genomes do.
Bacteria contain an extrachromosomal element called
a plasmid
Plasmid characteristics
circular piece of dsDNA
aka extrachromosomal genetic elements
may be capable of autonomous replication (replicating even though the genome is not)
Give the name for the following shaped bacteria:
round
rod-shaped
spiral shaped
- Round = Coccus / Cocci
- Rod-shaped = Bacillus/Bacilli
- Spiral-shaped = Spirochete, Spirillium, spirochetes, spirilla
The cell wall of bacteria is equivalent to what structure/process of animal cells that accomplishes the same function
cell wall of bacteria prevents lysis due to osmotic pressure
animal cells have pumps that pump out ions that accomplish the same function
Composition of bacteria cell wall
Peptidoglycan - Sugars & AA
contain D-Alanine (most AA are in L form)
What destroys peptidoglycan?
lysozyme
destruction of peptidoglycan results in a protoplast
Gram positive bacteria
thick peptidoglycan
Gram Stain - Dark Purple
gram negative bacteria
thin peptidoglycan
outer layer of Lipopolysaccharide
Gram Stain - Light Pink
where might enzymes that degrade antibiotics be found?
periplasmic space
endospores are formed by gram positive or gram negative bacteria?
gram positive (check??)
Endotoxin are a normal component of what type of bacteria?
Gram Negative
Where would an endotoxin be located on a gram negative bacteria
outer membrane
Are endotoxins inherently posionous? How do they cause us to get sick?
No.
They cause a severe immune reaction
Capsule
sticky layer of polysaccharide.
Surrounds bacterial cells & can also surround bacterial cell colony
enables bacteria to adhere to smooth surface
Capsule is a form of virulence
Virulence
evades immune system
Flagella
filaments
motility
structural components of a flagella:
filament, hook, basal structure
basal structure
anchor flagellum to the IM & OM of Gram negative bacteria
serve to rotate the rod & rest of attached flagellum in CW or CCW
describe the structure of eukaryotic flagella.
Eukaryotic cillia and flagella = 9+2 arrangement of microtubules. centrioles are 9+0 arrangement.
pili
long projections on bacterial surface involved in attaching to different surfaces
include the sex pilius
sex pilius is involved in
conjugation
Fimbraie
smaller structures involved in adherence to surfaces
what bacterial structures are involved in adherence?
Fimbraie and Capsule
Chemoautotrophs
energy - organic molecule
carbon source - organic molecule
Photoheterotrophs
energy - sun
carbon source - organic molecule
Obligate anaerobes
Poisoned by O2
why are obligate anaerobes poisoned by O2
because they lack a certain enzyme required for the detoxification of free radicals (free radicals form spontanously in the presence of O2)
what is the electron acceptor in respiration
O2
what is the electron acceptor in fermentation? what is the byproduct of fermentation?
pyruvate
Ethanol
Lactate
Bacterial mechanisms for the acquisition of new genetic material are
- transduction
- transformation
- conjugation
Carrying capacity is what? what is it specific for?
the max population @ stationary phase
specific for that environment
what is the prokaryotic flagella made from
flagellum
what is the eukaryotic flagella made from
microtubules
How many bacteria are produce per a spore? what does that inherently tell you about population growth?
1 bacterial cell per a spore
bacteria cannot increase in population through spore formation
germination
metabolic reactivation of endospore
Conjugation
F+ male –> F- female
F factor
single circular DNA
transferred unidirectionally
recombination –> integration
make cards for virulence, biofilms, read more about flagella
THIS IS A HIGH YIELD TOPIC YOU REALLY SHOULD LEARN AS MUCH AS YOU CAN IN REGARDS TO THIS TOPIC
