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

signs vs symptoms

signs: can be objectively measured

symptoms: subjective, reported by the patient

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/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 putative virulence genes in the Molecular Koch's Postulate?

is a gene responsible for the microbe’s ability to cause disease

1. The disease trait (symptom) must be found only in strains that have a specific gene.

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. Strong associations are more likely to be causal than weak ones.

what does the consistency criteria in Bradford Hill state?

If many studies in different settings find the same result, it's more likely to be real.

what does the specificity criteria in Bradford Hill state?

If a cause leads to a specific effect (and not many different effects), it's more likely causal.

what does the temporality criteria in Bradford Hill state?

The cause must happen before the effect

what does the biological gradient criteria in Bradford Hill state?

Dose-Response

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?

The findings should agree with what's already known from lab and science.

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 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, decomposing tissue)

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

bacteria shapes

• Cocci – Spherical

  • Diplococci – In pairs

  • Streptococci – In chains

  • Staphylococci – In grape-like clusters

  • Tetrads – Groups of 4 in a square

  • Sarcinae – Groups of 8 in a cube

• Bacilli – Rod-shaped

  • Coccobacilli – Short, rounded rods

  • Vibrios – Comma-shaped rods

• Spirilla – Spiral-shaped, rigid

• Spirochetes – Spiral-shaped, flexible

• Mycelium – Network of long, thread-like cells

• Pleomorphic – Can change shape or have many shapes

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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

archaea

glycerol diethers

NO peptidoglycan, often S layers

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

not in eukaryotes

NON-essential but can give selective advantage

episome: if it can integrate into chromosome

(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

bacterial structures

• Flagellum: A tail that helps bacteria move.

• Capsule: A sticky coating around some bacteria that protects them.

• Biofilm: A group of bacteria that stick together, often forming on surfaces like pipes or teeth.

• Plasmid: Small pieces of extra DNA in bacteria that can help them survive, like by making them resistant to antibiotics.

• Fimbriae: Tiny hair-like structures that help bacteria stick to surfaces.

• Pili: Longer than fimbriae, these also help bacteria stick to things and can be used to share DNA with other bacteria.

pBR322

plasmid vector, which means it's a tool used to insert and replicate genes in bacteria.

clone individual genes

Key Features of pBR322:

• Ampicillin resistance gene (AmpR): allows selection of bacteria that took up the plasmid.

• Tetracycline resistance gene (TetR): another selectable marker.

• Origin of replication (ori): lets the plasmid replicate in the host cell.

• Multiple cloning sites (MCS): areas where scientists can insert foreign DNA.

***what are the plasmids that carry antibiotic resistance genes?

R plasmids

**what are the plasmids that carry virulence genes?

virulence plasmids

what are some inclusion bodies in cytoplasm of bacteria?

1. Polyhydroxybutyrate (PHB) granules
   → Store carbon (like a backup energy supply).

2. Sulfur globules
   → Store sulfur, which some bacteria use for energy.

3. Gas vesicles
   → Help bacteria float or sink in water (buoyancy control).

4. Carboxysomes
   → Hold enzymes for carbon fixation (like RuBisCO), important in photosynthesis.

5. Magnetosomes
   → Contain magnetic particles; help bacteria align with Earth's magnetic field (for movement/navigation).

(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**

Bacteria group related genes together, so they can be turned on or off all at once. These genes are transcribed from one spot and make one long RNA.

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

The "start button" for making RNA. It's where the RNA polymerase (RNAP) attaches to begin copying the gene.

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

operator

A "control" switch. Proteins can attach here to turn the operon on or off, deciding if the genes should be copied.

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

Bacterial 70S ribosomes are _____ than eukaryotic 80S ribosomes and _____ enough that they can be targeted specifically by antibiotics

smaller; different

what are the 2 main targets of antibiotics on bacteria?

1. cell wall

2. ribosomes (translation)

ALSO:

transcription initiation —> Rifampcin

***where is gene expression regulated?

transcription PROMOTOR RECOGNITION

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?

ETC to create proton motive force (PMF) —> make atp

• respiration/photosynthesis

• 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

gram positive bacteria

thick cell wall

narrow periplasmic space (bw plasma membrane and peptidoglycan)

has techoic acids that are negatively charged

gram negative bacteria

thin peptidoglycan wall

wide periplasmic space

outermembrane that has an asymmetrical layer of phospholipids and LPS

what are sortases? and are they found on gram - or + bacteria.

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

peptidoglycan is a mesh glycan strands (______ and ______) cross linked via short (saccharides/lipids/peptides)

NAM, NAG, peptides

what proteins synthesize peptidoglycan?

PBPs (pencillin-binding proteins)

what are 2 advantages of peptidoglycan?

1. improves rigidity and ability to cope with osmotic stress

2. confers cell shape

the cell wall is composed of cross-linked strands of ______________ subunits forming a matrix, similar to a ________-________ fence

peptidoglycan, chain-link

the cell wall contains a peptide chain linked to the (NAG/NAM) subunit. this peptide (does/does not) vary by species.

NAM, does

(t/f) cross-linking peptides in the cell wall vary from species to species, but the way these peptides cross-link are all the same

false; cross-linking peptides in the cell wall vary from species to species and the way these peptides cross-link vary as well