Lecture 29 & 30 - Bacterial Structure & Function Flashcards
when does disease occur in regard to bacteria
- when they are present in normally sterile places
- colonize host species not adapted
- have acquired toxins or host-damaging mechanisms
- are not controlled by the immune system
What are the 3 applications of veterinary bacteriology
- diagnosing and treating disease
- preventing transmission
- food safety and public health
what are external appendages on bacteria
- pili
- fimbriae
- flagellum
what is present in the membrane of gram + cells
teichoic acid
what is present in the membrane of gram - cells
lipopolysaccharide
what are the 3 broad categories for bacterial cell structures
- cytoplasm
- cell envelope
- surface structures
describe the bacterial genome
- large, circular DNA
- one per cell
- organized into a nucleoid
- mostly genes
describe the bacterial plasmid
- small
- autonomously replicating
- single or multiple copies
- virulence factors or antibiotic resistance
describe the nucleoid
chromosomal DNA organized to fit within the cell
what is MreB?
actin homolog; builds cytoskeleton inside-out and initiates FtsZ
What is FtsZ?
scaffold used to pinch cells in replication
what membrane structure is most rigid?
a. saturated FA
b. trans unsaturated FA
c. cis unsaturated FA
a. saturated FA
what is the difference between saturated vs unsaturated bonds
single vs. double
what is the difference between cis and trans unsaturated bonds
cis - H atoms on the same side
trans - H atoms on opposite sides
T/F: Branched-chain amino acids are present in gram + bacteria
TRUE
what gradient is present regarding the cytoplasm of bacteria and the external environment
chemiosmotic
what does disequilibrium drive
- proton motive force
- ATP synthesis
what is FALSE of peptidoglycan?
a. composes the cell wall
b. determines gram stain
c. thick in gram-negative bacteria
d. targeted by B-lactam antibiotics
c. thick in gram-negative bacteria
what is the role of iodine in the gram staining process
creates cross-links between the stain and peptidoglycan
describe a bacterial capsule
- extracellular polysaccharide matrix
- protects cell and mediates attachment
- “mucoid” colonies
describe flagella
- filamentous appendage originating from the cytoplasmic membrane
- confer motility using taxis
describe pili
- filamentous appendage
- mediate attachment to cells
- sex (conjugation) and type IV (twitching)
describe conjugation in 3 steps
- donor cell attaches to the recipient via sex pilus
- plasmid is replicated during transfer
- two cells with plasmid
what secretion system interacts with the host cell
T3SS
what secretion system is responsible for intra-bacterial interaction
T6SS
summarize the job of T3SS
- T3SS(1) intake of bacterial cells (invasion)
- T3SS(2) trafficking/maturation (modulate host processes)
summarize the job of T6SS
- recognition of immunity proteins as self or non-self
- kills non-self cells during bacterial competition
what is Diene’s phenomenon
zones of intense mutual destruction denoted by black lines in culture
mutants lacking T6SS are unable to do what
kill non-self cells
where is chromosomal DNA stored in bacterial cells?
nucleoid
how do most bacteria regulate membrane fluidity?
fatty acid desaturation
what structure allows bacteria to move in their environment?
flagella
Bacterial secretion systems:
a. can target other host cells
b. can target other bacteria
c. are large proteinaceous structures
d. all of the above
d. all of the above
Replication and transcription occur in what direction
5’ to 3’
what is the additive effect
the cumulative strength of individual, relatively weak hydrogen bonds
if the phosphodiester backbone of DNA has a net negative charge, then what does this suggest about the proteins that interact with them?
positively charged
what releases the tension of DNA unwinding during replication
gyrase (topoisomerase)
what inhibits gyrase
quinolone antibiotics
what happens during the transcription phase of replication
mRNA is derived from DNA template strand
what happens during the translation phase of replication
amino acid sequence is derived from mRNA (3:1)
what is RNA polymerase
sigma factor that binds to -35 and -10 regions in promoters
transcriptional activators ___ RNA polymerase while RNA repressors ___ binding
recruit; prevent
T/F: The half-life of mRNA is short
TRUE
summarize the two-component system in 4 steps
- membrane-bound histidine kinase senses signal
- phosphorylates itself then response regulator
- phosphorylated RR activates genes for response signal
- cellular processes regulated
define competent
bacteria capable of being transformed by integration of new DNA
what are transposable genetic elements
segments of DNA that move from site to site within or between chromosomes
*can encode AMR
what are modes of antimicrobial resistance
- efflux pump
- decreased import
- loss/mutation of target
- modification/detoxification
Describe how this antibiotic targets bacteria:
Penicillin
prevent the formation of bacterial cell wall
Describe how this antibiotic targets bacteria:
macrolide
prevent multiplication and protein synthesis
Describe how this antibiotic targets bacteria:
cephalosporins
prevent the formation of the bacterial cell wall
Describe how this antibiotic targets bacteria:
fluoroquinolones
prevent DNA synthesis
Describe how this antibiotic targets bacteria:
increased activity beta-lactams
increases activity and provides protection of penicillin/cephalosporin
Describe how this antibiotic targets bacteria:
tetracycline
prevent multiplication and protein synthesis
Describe how this antibiotic targets bacteria:
trimethoprim-sulfamethoxazole
inhibit folic acid synthesis and multiplication
Describe how this antibiotic targets bacteria:
urinary anti-infectives
kill or prevent DNA. protein, and cell wall synthesis
Describe how this antibiotic targets bacteria:
lincosamides
prevent multiplication and protein synthesis
bacteriophage
virus that infects bacteria
lytic or lysogenic
what are the two ways DNA is transferred from bacteriophage
- generalized - any portion of the host bacterium transferred
- specialized - DNA from specific region is transferred
CRISPR
- Clustered Regularly Interspaced Short Palindromic Repeats
- molecular scissors cleave foreign DNA
The central dogma of molecular biology says
DNA to RNA to protein
5’ to 3’ refer to what feature of DNA
carbons connected by phosphodiester backbone
RNA polymerase binds at which feature to regulate gene expression
promoter
which of the following describes a mechanism of antimicrobial resistance?
a. enzymatic modification/detoxification
b. increased efflux
c. mutations resulting in decreased binding to target protein
d. all of the above
d. all of the above
