Bacterial Anatomy and Pathogenicity Pt 1

what term refers to a disease being transmittable between persons or species? what term refers to an individual who is capable of transmitting a disease or a disease that is transmissible by direct or indirect contact?

communicable; contagious

what term refers to microbes that frequently associated with disease production?

pathogens

what term refers to the mechanism a microbe uses to cause the disease state?

pathogenesis

what term refers to the replication of a pathogen in or on its host?

infection

specific ________ and __________ are associated with a specific disease

signs, symptoms

what are 5 things that can determine the host's susceptibility and resistance to infection?

1. immune status

2. age

3. other conditions

4. epidemiology

5. environment

primary vs opportunistic pathogens: tend to produce disease readily in healthy hosts

primary

primary vs opportunistic pathogens: cause disease when displaced to an unusual site

opportunistic

primary vs opportunistic pathogens: cause disease when the host has a weakened immune system

opportunistic

what are 3 things that causes opportunism for pathogens?

1. host defense failure

2. microbe in unusual location

3. microflora disturbance

what are the 4 components of Koch's Postulates?

1. microorganism must be found in abundance in all organisms suffering from disease, but not found in health organisms

2. microorganism must be isolated from a diseased organism and grow in a pure culture

3. cultured microorganism should cause disease when introduced in healthy organism

4. microorganism can be reisolated from inoculated, diseased host and identified to be identical to the original specific causative agent

what are 3 things used to validate the purative virulence genes in the Molecular Koch's Postulate?

1. the phenotype of a disease symptom must be associated with a specific genotype only found in pathogenic strains

2. symptom should not be present when the associated gene is inactivated

3. symptom should return when the gene is reactivated

what are the 9 components of the Bradford Hill criteria?

1. strength (effect size)

2. consistency (reproducibility)

3. specificity

4. temporality

5. biological gradient (dose-response relationship)

6. plausibility

7. coherence

8. experiment

9. analogy

what does the strength criteria in Bradford Hill state?

a small association does not mean that there is not a causal effect, though the larger the association, the more likely that it is a causal effect

what does the consistency criteria in Bradford Hill state?

consistent findings observed by different persons in different places with different samples strengthens the likelihood of an effect

what does the specificity criteria in Bradford Hill state?

causation is likely if there is a very specific population at a specific site and disease with no other likely explanation; the more specific an association between a factor and an effect is, the bigger the probability of a causal relationship

what does the temporality criteria in Bradford Hill state?

the effect has to occur after the cause; if there is an expected delay between the cause and expected effect, then the effect must occur after that delay

what does the biological gradient criteria in Bradford Hill state?

greater exposure should generally lead to greater incidence of the effect; however, in other cases, an inverse proportion is observed where greater exposure leads to lower incidence

what does the plausibility criteria in Bradford Hill state?

plausible mechanism between cause and effect is helpful

what does the coherence criteria in Bradford Hill state?

coherence between epidemiological and laboratory findings increases the likelihood of an effect

what does the experiment criteria in Bradford Hill state?

occasionally it is possible to appeal to experimental evidence

what does the analogy criteria in Bradford Hill state?

the use of analogies or similarities between the observed association and any other associations

what term refers to the subjective sensation that the person feels from the disorder?

symptom

what term refers to the objective evidence of disease as noted by an observer?

sign

what term refers to a specific group of signs and symptoms that accompany a disease?

syndrome

what term refers to a condition that is the consequence of a previous disease or injury?

sequelae

what is an acute disease?

symptoms develop rapidly

what is a chronic disease?

an ongoing disease characterized by long suffering

what is a subacute disease?

intermediate between acute and chronic

what is a latent disease?

disease with a period of no symptoms when the causative agent is inactive

what is a local infection?

pathogens are limited to a small area of the body

what is a focal infection?

when infectious agent breaks loose from a local infection and is carried to other tissues; this is what supports the hypothesis that an infection can cause a chronic disease

what is a systemic disease?

disease that affects the body as a whole

what is bacteremia?

bacteria in the blood

what is septicemia?

blood poisoning

what is viremia?

viruses in the blood

what is sapremia?

blood poisoning caused by toxins from putrefactive bacteria (like gangrene)

what is a primary infection?

initial infection

what is a secondary infection?

a different and opportunistic infection after a primary infection

what is a superinfection?

a second infection superimposed on an earlier one, especially by a different microbial agent of exogenous or endogenous origin

what is a mixed infection?

several microbes grow simultaneously at the infection site

what is a subclinical infection?

no symptoms or mild enough to go unnoticed

the Gram staining method uses a complex between the dyes _________ ________ and ___________ which is retained in the cell (membrane/wall) of the stained bacteria

crystal violet, iodine, wall

what does coccus mean?

spherical

what does spirillum mean?

spiral

what does bacillus mean?

rod shaped

what does vibrio mean?

curved rod

what does the prefix di- mean?

paired

what does the prefix strepto- mean?

chains

what does the prefix staph- mean?

grape-like clusters

what is a tetrad?

4 cocci in a square

what does sarcinae mean?

cubic configuration of 8 cocci

what are coccobacilli?

very short rods

what are spirochetes?

flexible spiral bacteria

what are mycelium?

network of long, multinucleate filaments

(t/f) bacteria have a membrane-bound nucleus

false; have a nucleoid that is usually not membrane bound

where are the chromosomes and their associated protein located in a bacteria?

nucleoid

the nucleoid is made of (multiple/one) (opened/closed) (circular/linear) (single/double) stranded (RNA/DNA) molecule

one, closed, circular, double, DNA

what are the 2 proteins found in the nucleoid that aid in folding (different from histones)?

1. supercoiling proteins

2. nucleoid proteins

what are plasmids?

extrachromosomal DNA; usually small, circular and closed

(t/f) plasmids can be found in bacteria, archaea, fungi, and eukaryotes

false; cannot be found in eukaryotes

(t/f) plasmids divide independently of the chromosome

true

(t/f) plasmids will not be inherited during cell division

false

what is an episome?

when a plasmid incorporates into the circular DNA of a bacterium

(t/f) plasmid genes are non-essential

true; but these genes do offer selective advantage to the host (drug resistance)

what are the plasmids that carry antibiotic resistance genes?

R plasmids

what are the plasmids that carry virulence genes?

virulence plasmids

what do polyhydroxybutyrate granules in bacterial cytoplasm store?

carbon

what do sulfur globules in bacterial cytoplasm store?

sulfur

what are the gas vesicles in the cytoplasm used for?

buoyancy control

what inclusion body in the cytoplasm is the location of carbon fixation reactions?

carboxysomes

what bacterial organelle is associated with direction finding?

magnetosomes

(t/f) similar to eukaryotes, bacterial transcription and translation happens in 2 different parts of the cell

false; in bacteria, transcription and translation occur in the SAME compartment

what is the name of the factor that is involved that associates with RNA polymerase to recognize promoters during transcription? when does it disassociate from RNA polymerase?

sigma factor; this factor then disassociates during elongation

at which step of bacterial transcription is where gene expression is most commonly regulated?

promoter recognition; transcription repressors and activators affect the sigma factors ability to recognize the promoter

what is the name of the antibiotic that can be used to prevent bacterial transcription initiation?

rifampicin

bacteria have operons. what are these?

groups of genes transcribed from one promoter on one long transcript

what are the 2 components of the operon?

1. promoter

2. operator

which component of the operon designates the RNA polymerase binding site and is the point at which RNA synthesis begins?

promoter

which component of the operon is the transcription factors binding site?

operator

what is the name of the operon found in E. coli that allows the bacteria to use lactose when glucose is unavailable?

lac operon

what is co-transcriptional translation?

as RNA is being transcribed from bacterial DNA, RNA is covered with ribosomes that bind to the RNA and start translating the proteins; transcription and translation happen at the SAME time

what is internal translation?

bacterial ribosome doesn't have to begin translating an mRNA molecule at the very beginning (5' end) but instead initiates at a point further downstream, within the mRNA sequence

what are the 2 main targets of antibiotics on bacteria?

1. cell wall

2. ribosomes (translation)

(t/f) not all cells will have a plasma membrane

false; all cells have a plasma membrane usually composed of a phospholipid bilayer and embedded proteins to separate the interior of the cell from the external environment

what are the sterol molecules some bacterial plasma membrane may have? what do they do?

hopanoids; helps with stability across temperature changes

how does O₂ and CO₂ cross the plasma membrane of the bacteria?

small enough to diffuse across the plasma membrane readily

how does H₂O cross the plasma membrane of the bacteria?

with aquaporin protein channels

how do sugars cross the plasma membrane of the bacteria?

with ATP-binding cassette (ABC) transporters

what is osmosis?

the flow of water across the plasma membrane toward the side with a higher solute (particle) concentration

what structure can help keep a bacterial cell during periods of extreme moisture (swelling) or extreme dryness (shriveling)?

a cell wall

what are 2 ways nutrients can cross the plasma membrane?

1. facilitated diffusion

2. active transport

what is facilitated diffusion?

using a protein channel to move particles with a concentration gradient; does NOT require energy

what is active transport?

using energy to move particles AGAINST a concentration gradient; e.g. symport/antiporters, ATP-binding cassette (ABC) transporters

what are 3 ways the bacterial plasma membrane can used captured energy?

1. ETC to create proton motive force (PMF)

2. respiration/photosynthesis

3. energy for motion (flagella)

proteins in the plasma membrane can be used to detect environmental changes. how does the bacteria respond?

detected changes can cause the bacteria to alter gene expression

(t/f) protein secretion from the bacteria only requires proton motive force

false; protein secretion from the bacteria requires proton motive force and ATP

gram negative vs positive: contains an inner and outer membrane

negative

what are sortases?

enzymes that anchor surface proteins to the cell wall, helping in adhesion, invasion, and immune evasion

gram negative vs positive: contains sortases

positive