MIcro Exam 2

What are the functions of glycocalyx

1. helps with attachment to surfaces 2. resistant to dehydration 3. they provide a virulence factor (protects the bacteria against phagocytosis) 4. They provide a source of nutrients for the bacterial cell during times of scarcity.

Explain two mechanisms by which the capsule aids in protecting pathogenic bacteria from host defense systems.

1. protection-- prevents the bacteria from host cell phagocytosis due to the slippery exterior, and because of similar chemical composition to host cell, pathogen is often mistaken for host cells, thus making it undetectable. 2. prevents desiccation (drying out), due to the capsules hydrophilic nature (functional capacity to bind and retain water molecules) 3. colonization- glycocalyx can play a critical role in bacterial colonies attachment to host surface (examples: s. mutans and dental plaque ie biofilm)

Endospores

A thick-walled protective spore that forms inside a bacterial cell and resists harsh conditions.

What are anti-toxins?

Antibody made from immunocompetent source (may be human, likely not) These are premade antibodies used against a toxin Takes minutes to an hours to activate antibodies Usually injected They are antibodies that render toxins harmless.

How bacterial membrane differs from eukaryotic membranes?

Bacterial membranes:

What are the differences between bacterial and eukaryotic flagella?

Bacterial: Require energy (in the form of ATP) to move Eukaryotic: is made up of microtubules

True or false, mycoplasm sps have mycolic acid in the cell wall

False, MycoBACTERIUM are the ones with mycolic acid in its cell well.

True or false, anthrax pathogen capsule is made up of polymeric NAG and NAM units

False, anthracis has an unusual capsule that is made of up of poly d gluteanic acid. NAG/NAM structures are found in the cell wall not the capsule.

True or false, flagella is part of the envelop of bacterial cells?

False, flagella is an appendage of bacterial cells

True or false, slime layer is glycocalyx that is organized and attached tightly to the cell wall

False, slime layer is highly disorganized, loosely attached. A capsule is organized and tightly attached.

What is filament made up of?

Filament is made up on Flagellin. It is a globular protein.

What are examples of anti-septics?

For example, 70/30 alcohol water mixture is antiseptic

What is the structure of the cell wall of Gram positive bacteria

Gram +ve bacteria have thick outer layer of peptidoglycan (10-25 layers) outside plasma (phospholipid) membranes

What is the structure of the cell wall of Gram negative bacteria

Gram -ve bacteria have a thin wall of peptidoglycan (1-3 layers) in between phospholipid membranes

What are toxins?

Harmful substances made by some pathogenic bacteria species

What are Protoplasts and spheroplasts?

If you were to remove to the cell wall, but the cell is in an isotonic environment (solute concentration is same inside and outside of cell, there is no net movement into or out of the cell).

What is toxemia?

It is the presence of toxins in the blood. tox - emia (toxins in the blood)

How does mycoplasma pneumonia differ from other causes of pneumonia?

It is walking pneumonia

Action of lysozyme on cell wall and the specific targets

Lysozyme is found in eyes (tears), which adds to our own line of defense. - it breaks the carbohydrate back bone of the peptidoglycan cell wall (NAG/NAM bond backbone structure)

What are the functions of the peptidoglycan cell wall?

Maintain shape of cells protect cell and provide structural support (mechanical protection) Prevents cytolysis (bursting) in pure H20 Cytolysis = more solute inside the cell than fresh H20 (Ex. lack of cell wall on red blood cell)

How does the mycoplasm membrane differ?

Mycoplasma membrane has cholesterol in the cell membrane, but no cell wall

Why is penicillin more effective for Gram + than Gram - cells?

Penicillin is effective only against Gram-positive bacteria because Gram negative bacteria have a lipopolysaccharide and protein layer that surrounds the peptidoglycan layer of the cell wall, preventing penicillin from attacking.

What is the structure of the bacterial cell wall?

Peptidoglycan is made up of alternating NAG and NAM modified glucose units which are then attached by crossbridging on tetrapeptide amino acid tails, forming a 3-D cage around bacterial cell membrane. The structure of peptidoglycan provides rigidity and mechanical stability

Identify some situations when lipid a is released from cells.

Phagocytosis (macrophages, neutrophils) MAC (membrane attack complex) Antibiotic drugs

What is toxigenicity?

The ability to generate toxins.

When are antiseptics used?

They are applied directly to the infection. They are also not preventative. Kills microorganisms (including fungi, protozoa, etc.) on other living organisms (ok to use on living things)

When are antibiotics used?

They are applied directly to the infection. They are not preventative. They directly target bacterial growth on living things. They are okay to use on living organisms (ie, bacitracin, neosporin, etc)

What is a disinfectant?

They are used before bacterial growth to prevent infection. (dis v. anti) Kills microorganisms on nonliving/inanimate objects (i.e. medical devices developing biofilms) or cadavers Examples: lysol, bleach, hand sanitizer.

What is a taxoid?

Toxins that are used for making vaccines (they are altered or inactivated toxins) They are used to illicit a host immune response

True or false, 70% Alcohol targets bacterial membrane and lyses the cell.

True. 70% isopropyl alcohol works best for lysing the cell membrane because the water acts as a catalysts.

Action of vancomycin on cell wall and the specific targets

Vanco prevents cross-bridging, by binding to the 4th amino acid of the tail which prevents further cross bringing. Vanco should be administered IV because the pH of the stomach will destroy Vanco. It is more effective over gram positive than gram negative.

If we find flagellin in humans, could that be a pathogen associated molecular pattern (PAMP)?

Yes.

Plasma Membrane Destruction (toxin mode of action)

a) The toxin will poke a hole in the membrane causing an electrolyte imbalance, causing the cell to die. b) the cell will die, and the bacteria can get the nutrients

cytoskeleton alterations (toxins mode of action)

a) cytoskeletons contain microfilaments (made up of actin) and can slide, causing changes in the membrane shape b) macrophages and neutrophils are good at changing shape -- bacteria can enter and become enveloped during cell shape changes

Protein synthesis disruption without disrupting bacterial synthesis (in eukaryotes) (toxins mode of action)

a) diphtheria toxin b) shiga toxin

Disrupting signal transduction (toxins mode of action)

a) not a clever way to kill a cell b. stopping the cAMP (cyclic amp is a signal molecule)

PBP (penicillin binding protein) action is confined to

both gram positive and gram negative cells

What is the bacterial cell wall composed of?

composed of peptidoglycan

Cross bridges in gram negative bacteria is

direct

Tough, dormant bacteria that are resistant to dehydration, radiation, and toxins are known as?

endospores

Interrupting the exocytosis of vesicles

exocytosis-- release of vesicles; xxx fuses with a plasma membrane releasing neurotransmitters to the synaptic cleft and moves to the dendrites. examples of this: clostridium botulinum (botox) and clostridium tetani (tetanus)

Integral proteins

go all the way through the phospholipid bilayer (They penetrate) and can act as "gates", and allow for the membrane to be semi-permeable

Cross-bridges in gram positive cells in bacteria is

indirect

Bacteriodes

mycoBACTERIUM tends to undergo incomplete phagocytosis due to its slippery exterior and ability to look like a host cell. The bacteria becomes attached to the phagocyte where they are able to reproduce.

Lipid A of Gram positive bacteria are involved in what?

pathogenesis

What causes a fever?

pyrogens

What are some medical significances of lipid A and some clinical aspects of pathogenesis?

septic shock (endotoxic shock) DIC (disseminated intravascular coagulation) fever

Plasma membranes are?

symmetric, highly dynamic structures

The antigen specificity of gram positive cells is due to its

teichoic acid

Spheroplast

wall-less gram-negative cell