Microbiology Flashcards
How do viruses function?
They rely on host machinery to survive and are without activity outside the cell.
What is the structure of viruses?
A nucleic acid genome packaged in a protein shell, they are small and the exterior shell can’t expand to accommodate a larger genome
capsid
protein coat surrounding the viral nucleic acid
capsid head
where the genome is located
tail fibers
attach to surface of host cell along with base plate
sheath
injects genome into host through contraction using ATP
envelope
surrounds capsid, derived from host cell membrane, acquired when viruses bud through host cell membrane
adsorption
binding to the exterior of a bacterial cell
penetration
injection of viral genome into host cell, aka eclipse
lytic cycle
produces hydrolase, which degrades the host genome, and later on, lysozyme, which causes the host bacterium to burst after transcription and translation of the phage genome.
lysogenic cycle
phage genome enters bacterial genome, making the host a lysogen. Viral progeny is not produced, but every time the host cell reproduces, the prophage is reproduced and eventually enters the lytic cycle.
endocytosis
how most animal viruses enter cells, host cell engulfs virus and internalizes it.
productive cycle
similar to lytic cycle but doesn’t destroy host cells.
viruses that infect animal cells
sub viral particles
smaller and simpler than viruses, include prions and viroids
prions
misfolded versions of proteins that already exist, can cause TSEs, which are fatal.
viroids
consist of a short piece of circular single stranded RNA, have extensive self complementarity
What are the tenets of cell theory
- All living organisms are composed of one or more cells and their products
- Cells are the monomer for any organism
- New cells arise from pre existing living cells
What distinguishes prokaryotes from eukaryotes
Prokaryotes don’t contain membrane bound organelles
What are the types of prokaryotes
bacteria, archer, blue green algae
what are the three recognized domains
bacteria, archea, eukarya
polyribosome
ribosomes translating a single piece of mRNA, found in prokaryotes
plasmid
circular piece of double stranded DNA which is much smaller than the genome, an extrachromosomal genetic element
conjugation
bacterial exchange of genetic information
What is the bacterial cell wall composed of
peptidoglycan
gram positive vs gram negative bacteria
gram positive stain strongly and gram negative stain weakly. Gram negative bacteria has a periplasmic space, which offers it more protection from the environment.
capsule
sticky layer surrounding bacterial cell that makes bacteria more difficult for immune system cells to eradicate.
flagella
involved in bacterial motility
What is part of the structure of flagellum
a filament, hook, and basal structure
chemotaxis -
bacterial motion toward attractants or away from toxins via chemoreceptors
pili
long projections on bacterial surface involved in attaching to different surfaces
four types of bacteria
chemoautotrophs - build organic molecules from CO2 using chemical energy
chemoheterotrophs - require organic molecules such as glucose made by other organisms their carbon source and for energy
photoautotrophs - use only CO2 as a carbon source and obtain their energy from the Sun
photoheterotrophs. - get energy from the Sun but require an organic molecule made by another organism as their carbon source.
wild type bacteria
possesses all the characteristics normal to that particular species
auxotroph
bacteria that can’t survive on minimal medium, because It can’t synthesize a molecule it needs to live.
obligate aerobes vs obligate anaerobes
need oxygen vs poisoned by oxygen
binary fission
mode of replication in bacteria
stages of bacterial reproduction
lag phase to log phase to stationary phase to death phase
endospores
formed by gram + bacteria under unfavorable growth conditions
helps bacteria “Sleep through the bad times”
three bacterial mechanisms of acquiring new genetic material
transduction, transformation, and conjugation
F factor
key to bacterial conjugation, bacteria with F factor are male
transduction
process by which a virus transfers genetic material from one bacterium to another
when lysogenic viruses take pieces of host DNA with them when they excise and transfer it to the next host
retroviruses
inserts a DNA copy of its RNA genome into the DNA of the host cell it invades, changing the genome of the cell
the sequence of the nucleotide in the original viral genome will be the same as that of the transcribed mRNA
ex. HIV
