Microbiology (Chp 4) Flashcards
virus
obligate intracellular parasites
- not considered alive (cant reproduce on their own, cant produce their own E)
bacteriophage
a virus that parasitizes a bacterium by infecting it and reproducing inside it
capsid
protein coat surrounding viral nucleic acid
bacteriophage life cycles
- attachment or adsorption
- penetration or eclipse
from here phage can follow one of two paths (lytic cycle or lysogenic cycle)
attachment
aka adsorption
binding to exterior of bacterial cell
penetration
aka eclipse
capsid remains on outer surface of bacterium while the genome disappears into the cell
lytic cycle of phages
- as soon as phage genome enters host cell, host polymerases and or ribosomes begin to transcribe/translate
- early genes: hydrolase - degrades host enzyme
- replicate viral genome
- late genes: lysozyme - destroys bacterial cell wall
>host bacterium lyses> releases progeny viruses
(timing of lysozyme is important - if too early phage wouldn’t have had time to replicate and assemble)
lysogenic cycle of phages
- phage genome is incorporated into the bacterial genome (phage now referred to as a prophage and bacterium as lysogen)
- phage is reproduced when bacterial genome is replicated
- phage is dormant until stressor
>excises itself from bacterial genome and enters lytic cycle
prophage
phage genome that has been incorporated into bacterial genome
transduction
foreign DNA is introduced into a cell by a virus or viral vector
endocytosis
animal viruses can enter cells through endocytosis - host cell engulfs the virus and internalizes it
productive cycle
animal cells only
similar to lytic cycle but doesnt destroy host cell
instead budding - virus aquires a coating of lipid bilayer (envelope) > host cell can’t differentiate btw itself and virus
+ RNA viruses
must ENCODE RNA dependent RNA pol (and do not have to carry it)
translation produces:
viral proteins
negative RNA (complimentary strand) - which RNA dep RNA pol can use to make more + RNA
- RNA viruses
must CARRY RNA dependent RNA pol (and encode it too)
template for RNA viral mRNA production
need RNA dep RNA pol to produce + RNA before can start producing more - RNA
retroviruses
must encode reverse transcriptase (req RNA dependent DNA polymerase)
ex: HIV
subviral particles
infectious agents even smaller and simpler than viruses
include:
prions viroids
prions
no DNA or RNA no membranes no organells v small extremely stable (can w/stand high T, extreme pH, strong salt conc., etc.)
self replicating proteins (don’t follow central dogma)
misfolding version of a protein that already exists > causes others of that protein to become misfolded
viroids
short piece of circular, single stranded RNA
don’t encode proteins
act as miRNA or siRNA to block translation
mostly found in plants (except hep D in humans)
Robert Hooke Cell theory
Cork
- all living orgs are composed of one or more cells and their products
- cells are the monomer for any org
- new cells arise from pre-existing living cells
primary difference between prokaryotes and eukaryotes
prokaryotes do NOT have membrane bound organelles
prokaryotes
means before the nucleus
- no membrane bound organelles
- contain all machinery required for life
- bacteria, archea, blue-green algae
plasmid
found in prokaryotes
circular piece of double stranded DNA (smaller than genome) that can contain advantageous info
-ex: antibiotic resistance genes
bacterial shapes
round - cocci
rod shaped - bacilli
spiral shaped - spirochetes/spirilla
cocci
found bacteria
singular: coccus
bacilli
rod shaped bacteria
singular: bacillus
spirochetes or spirilla
spiral shaped bacteria
singular: spirochete or spirillum
bacterial cell wall is composed of ____
peptidoglycan - complex polymer unique to prokaryotes
gram staining
method of classifying bacteria based on cell wall structure (degree to which it can be stained)
gram positive
dark purple (stain strongly) thick peptidoglycan layer outside the cell membrane and no other layers
gram negative
pink (stain weakly)
thin layer of peptidoglycan in the cell wall and additional out layer containing lipopolysaccharide
periplasmic space
intermediate space in gram negative bacteria between cell membrane and the outer layer
bacteria capsule
sticky layer of polysaccharide goo surrounding bacterial cell wall that makes them harder to be eradicated by immune system
flagella
filaments involved in bacterial motility
can be
monotrichous - 1 flagella
amphitrichous - two flagella
peritrichous - multiple flagella
mesophile
bacteria that prefer moderate temp
thermophile
bacteria that prefer hot temp
psychophile
bacteria that prefer cold temp
autotrophs
utilize CO2 as carbon source
heterotroph
rely on organic nutrients created by other organisms
chemotrophs
get E from chemicals
phototrophs
get their energy from light
auxotroph
bacterium that cant survive on minimal medium bc it cant synthesize a molecule it needs to live
ex: arg- = cant synthesize arg
obligate aerobes
bacteria that require O
anaerobes
do not require O
(3) subcategories:
1. facultative anaerobe - will use O when around but don’t need it
2. tolerant anaerobes - grow in presence or absence of O but do not use in their metabolism
3. obligate anaerobes - poisoned by O
binary fission
asexual reproduction in bacteria
conjugation
mechanism for exchanging genetic information in bacteria
bacterial mechanisms for acquiring new genetic material
- transduction - transfer or genomic DNA from one bacterium to another by a lysogenic phage
- transformation - bacterial cultures can internalize free DNA under certain conditions
- conjugation - bacteria make bridge between one another to exchange genetic info
F (fertility) factor in conjugation
male: have F Factor
female: don’t have F factor
males transfer replicated F Factor to females
parasite
causes damage to host cell
can be obligate (must be inside host cell to replicate) or facultative (can live and replicate inside or outside of a host cell)
viral life cycle steps
- attachment (aka adsorption)
2. injection (penetration)
