Exam 1 Flashcards
What two things are needed to become an infection?
Growth and multiplication of a parasite
4 features that create areas that are difficult to clean
- shape and topography of teeth
- misalignment of teeth
- poor quality of restorations
- non-keratinized sulcular epithelium
What is the main phagocyte of gingival crevicular fluid?
neutrophils
What is the absolute requirement for all living organisms?
membrane
number of lipids compared to number of proteins in the plasma membrane?
more lipids than proteins
mass of lipids compared to mass of protein in plasma membranes
about the same
What is the bacterial version of cholesterol?
hopanoid (bacteriohopanetetrol)
What are inclusion bodies?
granules of organic or inorganic material stockpiles by cell for future use
Eukaryotic vs prokaryotic ribosomes
Eukaryotic: 80s
Prokaryotic: 70s
Ribosomes are made of…
protein and RNA
Is the prokaryotic chromosome single or double stranded? What aids in folding?
double stranded (one circular loop) (chromosome structure can vary
nucleoid proteins
The cell wall protects the cell from…
- osmotic lysis
- some toxic substances
Gram + vs Gram -
(+): purple, thick peptidoglycan layer
(-): pink, membrane -> thin peptidoglycan layer->membrane
What is in the periplasmic space of gram negative cells?
enzymes (nutrients, e- trans, peptidoglycan synth, modify toxins)
Why do gram positive bacteria secrete enzymes?
lack periplasmic space (same functions as neg)
What sugar group is linked to peptides in the peptidoglycan structure?
NAM (N-acetylglucosamine)
How does the cross linking in peptidoglycan layers of gram positive vs gram negative differ?
Positive: pentaglycine interbridge
Negative: direct link between D-Ala and DAP
Pentaglycine interbridge means what kind of bacteria?
gram positive
direct link between D-Ala and DAP means what kind of bacteria?
gram negative
Other main component of cell wall other than peptidoglycans?
Teichoic acids
Describe the structure of teichoic acids
alternating chain or glycerol/ribitol and posphate groups
What are gram negative cell walls lacking?
teichoic acids
What are the three parts of lipopolysaccharides in gram negative outer membranes?
- Lipid A: anchor in membrane
- Core Polysaccharide: heptose or keto-deoxyoctogenic acid
- O side chain (polysaccharide): antigen visible to immune system
What part of the LPS contributes to the negative charge of the cell surface?
Core Polysaccharide
What part of the LPS can act as an endotoxin?
Lipid A
What size molecules can pass through porin proteins in the outer membrane of gram - cells?
600-700 daltons
What is the function of fimbriae and how many are there?
mediate attachment to surfaces, and up to 1000/cell
Flagella are anchored in what parts of gram + and - cells?
Plasma membrane (gram + also have anchor in peptidoglycan and outer membrane)
What forms lysosomes?
Endoplasmic reticulum
What face of the golgi is associated with the ER?
The cis (forming) face
Pro vs Euk:
DNA complexed with histones?
Pro: no
Euk: yes
Pro vs Euk:
Presence of flagella?
Pro: submicroscopic, one fiber
Euk: microscopic, 20 microtubules
Pro vs Euk:
Peptidoglycan in cell walls?
Pro: chemically complex with peptidoglycan
Euk: chemically similar and lacking peptidoglycan
Pro vs Euk:
Size of Ribosome
Pro: 70s
Euk: 80s
What are the macoelements?
C, O, N, H, S, P
K+, Ca2+, Mg2+, Fe2+
What are the trace elements?
Mn, Zn, Co, Mb, Ni, Cu (mainly act as cofactors for enzymes
Lithotrophs vs organotrophs
Lithotrophs: reduced inorganic molecules needed as electron donors
Organotrophs: need organic molecules as electron donors
Autotrophs vs Heterotrophs
Autotrophs: CO2 as main source of carbon
Heterotrophs: reduced, preformed organic molecules
What nutritional classification are ALL pathogens?
Chemoorganotrophic heterotrophy
3 ways organisms are classified based on nutrient requirements
Source of Energy: photo/chemo trophs
Source of Reducing Equivalents: litho/organo trophs
Source of Carbon: auto/hetero trophs
What is the most medically relevant bacteria? What is special about them?
Facultative anaerobes: can perform respiration and fermentation
What are the 4 gram positive bacteria of the mouth?
Cocci/rod? Strict or Facultative anearobes?
- Streptococcus spp.: cocci, facult anaer
- Peptostreptococcus spp.: cocci, strict anaer
- Actinomyces spp.: rods, strict/facult anaer
- Lactobacillus spp.: rods, facult anear
What are the 7 gram negative. bacteria of the mouth? Cocci/rods/spirals? Strict anaerobes or capnophilic?
- Veillonella: cocci, st an
- Aggregatibacter: rods, capnophilic
- Capnocytophaga: rods, capnophilic
- Prophyromonas: rods, st an
- Prevotella: rods, st an
- Fusobacterium: rods, st an
- Spirochetes: spirals, st an
What two nutrient uptake mechanisms can become saturated?
- Ion-driven transport systems
- Binding protein dependent transport systems
What are siderophores?
chemical complexes that bind to nutrients to aid in cellular uptake from the environment.
Ex. Ferrichrome or enterobactin for Fe3+ uptake
Example of bacteria that can grow on many different mediums?
E. coli or pseudomonas
Two examples of nutritionally fastidious bacteria?
Staphylococci or streptococci
Example of an obligate intracellular parasitic bacteria?
Chlamydia
What ways can enzymatic activity be controlled?
- allosteric regulation
- regulation of enzyme synthesis
How do effector molecules act?
- change affinity of enzyme for substrate
2. change Vmax
Attenuation relies no the fact that in prokaryotes, __________ and _________ occur at the same time.
-transcription and translation
What stalls in the absence of leucine and then causes transcription to stop?
-the translation ribosome stalls in the absence of leucine, causing the DNA to base pair with itself which activates the terminator region, stopping production of mRNA.
What pathway is commonly linked to a repressor and an inducer?
Catabolic pathways (automatically off unless activated/induced)
What pathway is commonly linked to an inactive repressor and co repressor?
Anabolic pathways (growth is good unless we want it to turn off)
What is stopping transcription in catabolic pathway regulation?
What can start it?
- a repressor protein binding the O region of a gene (I gene -> lac repressor prot)
- an inducer that binds to the repressor protein and inactivates it so it cannot bind to the O region (allolactose)
We don’t need galactosidase enzyme to break down lactose if there is no lactose present. When lactose (or allolactose) is present, it will inactivate the lac repressor protein and induce transcription of the galactosidase gene.
Explain gene regulation by corepressors.
- inactive repressor is transcribed before it’s associated gene
- RNA polymerase is free to continue to transcribe the gene if no repression occurs.
- If a corepressor is present, it will bind to the inactive repressor and activate it.
- repressor/corepressor bind to O regulatory region and inhibit transcription of the gene.
What is the therapeutic index?
Antibiotics: ratio of toxic dose to therapeutic dose
What are the three factors influencing the effectiveness of antimicrobial agents?
- Ability of drug to reach site of infection
- Ability of drug to reach conc in body that exceed the MIC of the pathogen
- Susceptibility of pathogen to drug
Beta-lactams, glycopeptides, polypeptides, etc all affect what part of pathogens?
Disrupt the bacterial cell wall
What are the four main mechanisms of antibiotic action?
- Disruption of bacterial cell wall.
- Inhibition of protein synthesis.
- Inhibition of nucleic acid synthesis.
- Antimetabolites.
What makes up the two parts of the prokaryotic ribosome?
30s: 16s rRNA + 20 proteins
50s: 23s and 5s rRNA + 30 proteins
During what phase are tRNAs transferred to the ribosomal A site by EF-Tu?
Elongation phase
What is it?
-can promote their own transfer by conjugation
plasmids
What is it?
-can package non-phage DNA
transduction (transfer of non-page DNA through a bacteriophage)
What is it?
-hopping of genes into other genetic elements
-transposons
What is it?
-segments of DNA containing complete sets of genes found on plasmids, transposons, and bacterial chromosomes
integrons
What is a super infection? What causes it?
- development and spread of drug resistant strain of bacteria
- caused by loss of drug sensitive strains that were controlling growth of the resistant strain
Capusles, slime layers, and glycocalyx are all made of… Which one is easiest to remove?
- polysaccharides
- slime layer
4 functions of capsules/slime layers/glycocalyx?
- protect from viruses/other bacteria
- protect from chemicals
- motility of gliding bacteria
- protection from osmotic stress
What form of diffusion do pathogens use to take up nutrients and what carrier protein assists?
- Facilitated diffusion (down gradient and no energy needed)
- Permeases within the plasma membrane
gradient maintained by intracellular use of compound. Ex. glycerol -> glycerol-3-phosphate
What oral fluid is similar to blood serum?
GCF
What is the difference between humoral and cell mediated immunity?
Humoral: combats extracellular pathogens (B cells)
Cell Mediated: combats intracellular microbes/infected cells (T lymphocytes)
What is the difference between innate and adaptive immunity?
Innate: receptors recognize PAMPs and DAMPs
Adaptive: receptors recognize previously encountered pathogens
What is passive vs active immunity?
Passive: immunity from an outside source (mother/vaccine)
Active: immunity from a previous encounter with the pathogen (B cells)
TLRs detect…
bacterial cell wall lipids
NLRs detect…
bacterial cell wall lipids OR damaged host cells
RLRs detect…
viral DNA
CDSs detect…
microbial DNA in the cytosol of host cells
