L7, (Zandi) Structure/fcn Of Infectious Agents

Front 1

How many classes of infectious agents are there?

Back 1

Four
1. Prions.
2. Viruses
3. Prokaryotes (bacteria and archaebacteria)
4. Eukaryotes (algae, protozoa, fungi)

Front 2

Describe some structural components of a prokaryotic cell:

Back 2

PLasma membrane, Cell wall (peptidoglycan), No nucleus just DNA (usually circular), Plasmids (smaller circular DNA fragments)

Front 3

Whats different about eukaryotic cells from prokaryotes?
Whats a very IMPORTANT difference?

Back 3

They are more complex.
1. Have nucleus
2. Have many other structures performing specific functions. (mitochondria, ER,Golgi Apparatus)
3. Diploid genome!
IMPT Difference: Diploid genome.
"Having two copies of a gene serves as a safety mechanism for eukaryotes. In a bacteria, anything that is mutated affects the function. Evolution will occur very rapidly."

Front 4

Classifying bacteria: each organism is identified by two names. What are they?

Back 4

GEnus and species
eg. Escherichia Coli

Front 5

GRam Staining differentiates Gram + bacteria from Gram - bacteria on the basis of:

Back 5

Gram + bacteria have a thick cell wall (peptidoglycan layer) and thus are stained. Gram - bacteria have a thin cell wall and the stain is washed away in the process.

Front 6

IN pictures Gram + bacteria appear what color?

Back 6

Gram + bacteria look dark purple
Gram - bacteria dont look a little red.

Front 7

In general, bacteria have three outer layers. What are they?

Back 7

External Capsule (most outside), Cell Wall (peptidoglycan), Cytoplasmic membrane.
Not all bacteria have the capsule.

Front 8

The capsule around some bacteria is made up what macromolecules?
Why is having a capsule beneficial for the bacteria?

Back 8

loose polysaccharide and proteins.

Important for survival of bacteria against attack by our immune system. The capsule is poorly antigenic. It is very difficult for our immune system to generate antibodies against the capsule. Many bacteria with capsules cannot be phagocytosed.

Front 9

What type of capsules help bacteria attach to teeth enamel?

Back 9

Dextran (glucose polymers) and levan(fructose polymers)

Front 10

What is biofilm:What is produced by and whats its FCN

Back 10

Some bacteria produce a polysaccharide biofilm under some conditions, which establishes a bacteria community and protects from antibiotics and host defenses.

Front 11

Capsules help protect bacteria from..:

Back 11

phagocytosis by host system

Front 12

What is "glycocalyx"

Back 12

name given to capsule and slime layer

Front 13

Other than the thick peptidoglycan layer, what are some other important distinguishing components of gram + bacteria?

Back 13

1. Teichoic Acid
2. Lipoteichoic acid

Front 14

Other than a thin peptidoglycan layer, what are some othe rimportant features of gram - bacteria?

What is the structural arrangements of the components in the cell? Outer to inner.

Back 14

periplasmic space(contains multiple proteins), outermembrane, LPS.

Structural order from outside to inside:
Lipopolysaccharides (sticking out), outer membrane, Periplasmic space, Peptidoglycan, Cytoplasmic Membrane

Front 15

So why are Gram + bacteria sensitive to lysozymes but Gram - bacteria are not?

Back 15

Lysosymes break down polysaccharides and thus can break down peptidoglycan. Gram Negative bacteria have an outer membrane, shielding the peptidoglycan layer. Gram positive bacteria have their peptidoglycan EXPOSED

Front 16

Peptidoglycan synthesis occurs in the following three phases:

Back 16

(1) Peptidoglycan is synthesized from prefabricated units constructed and activated for assembly and transport inside the cell. (2) At the membrane the units are assembled onto the undecaprenol phosphate conveyor belt, and fabrication is completed. (3) The unit is translocated to the outside of the cell, where it is attached to the polysaccharide chain, and the peptide is cross-linked to finish the construction.

Front 17

Some antibiotics, like X?, try to interfere with peptidoglycan synthesis:

Back 17

penicillin

Front 18

What are endotoxins:

Back 18

is a virulence factor shared among aerobic and some anaerobic gram-negative bacteria. The activity of this toxin depends on the lipid A component of LPS,

Front 19

What are three components of LPS?

Back 19

Lipopolysaccharide has three different components. Lipid A, Core polysaccharide, o Antigen


Lipid A is responsible for the endotoxin activity of LPS. Lipid A is essential for bacterial viability!

Front 20

Where is energy produced in eukaryotes? Prokaryotes?

Back 20

Eukaryotes: mitochondrial membrane
prokaryotes: cytoplasmic membrane

Front 21

What is exosporium?

Back 21

Exosporium: (outer layer of a spore) Rigid structure with proteins and polysaccharides (protects the spore from heat, UV and many other things)

Front 22

What type of bacteria can make spores and in what condition.

Back 22

Some Gram + bacteria. If bacteria is placed in a nutrient deficient environment, bacteria will try to make spores.

Front 23

Can bacteria only USE glucose for metabolism?

Back 23

While bacteria basically need glucose; they are capable to change their metabolism. If no glucose available, they can break down fat or proteins.

Front 24

Featurse of a Capsule:
Why is it useful to be slimy?
How does it help to evade the immune system?
How else does it protect a bacteria (other than evading immune system)

Back 24

Slimy: Therefor hard to grasp and tear away when grabbed by a phagocyte
The capsule is poorly antigenic; hard to be recognized.

The capsule also protects bacterium from destruction within the phago-lysosome of a macrophage or leukocyte.

Front 25

What is opsonization?

Back 25

The process by which antigens are altered so that they are more readily and more efficiently engulfed and destroyed by immune cells.

More specifically: Capsulated bacteria are made more "palatable" through coating with antibodies (IgG) and complements C3b. Make phagocytosis more efficient.

Front 26

Bacteria have preventive measures to try to avoid phagocytosis by the host. What does leukocidin do? What is it?

What other feature of bacteria help them evade phagocytosis(structural)?

How does the host respond to bacterial evading techniques (capsul, leukocidin)?

Back 26

A leukocidin is a type of cytotoxin created by some types of bacteria that destroys phagocytic cells.

2. Structure of Capsule!

3. Host response: Opsonization. Make the antigen more 'detectable'

Front 27

Bacteria also have many survival methods once phagocytosis has occured. What are a few strategies for the bacteria:

How does a host cell respond to the survival strategies of bacteria?

Back 27

1. Prevention of phagosome and lysosome fusion.
2. Escape from phagolysosome and grow/multiply in cytoplasm
3. Resistance to acidification and production of toxic substances within the phagolysosome

Host Cell Response: T Cells activate macrophages

Front 28

Bacteria also have virulence factors that aim to destroy extracellular structures, damage cell membranes, intracellular targets and extracellular targets. What are these virulence factors called?

Virulence factors affect four categories. Name an example of an 'exotoxin' that would affect each category mentioned above

Back 28

Exotoxins!

Extracell structures: urease, protease, hyaluronidase

Cell membranes: elastase, phospholipase

Intracell Targets: choleria toxin, diphtheria toxin, tetanus toxin

Extracellular target: superantigens

Front 29

Diphtheria Toxin is a Dimeric A-B exotoxin. What does the A chain inhibit the fcn of?

Cholera toxin is also a dimeric A-B exotoxin. What does it cause?

Dimeric Tetanus Toxin. Action?

Dimeric Botulinum toxin. Action?

Back 29

It prevents protein synthesis, leading to cell death


Cholera toxin increases adenylate cyclas activity --> Increasing cAMP levels, leading to a loss of cell nutrients --> DIARRHEA!

Tetanus toxin: inhibits neurotransmitter release

Butulinum: blocks release of ACH from vessicles (stimulation blocked

Front 30

Some exotoxins are dimeric. The bacterial A-B toxins consist of a two chain molecule.
The B chain FCn is:
The A chain fcn is:

Back 30

B Chain: promotes entry of the bacteria into cells
A chain has inhibitory activity against some vital function. The biochemical targets of A-B targets include ribosomes, transport mechanisms and intracellular signaling

Front 31

Often 'superantigents' are released by bacteria and they bind simultaneous to a TCR and a MHC (class II) molecule on another cell without requireing antigen. What is dangerous about this?

Back 31

This nonspecific means of activating T cells can trigger life-threatening autoimmune-like responses by stimulating the release of large amounts of interleukins, such as IL-1 and IL-2.

Front 32

Endotoxins (LPS) binds to specific receptors (CD14 and TLR4) on macrophages, B cells, and other cells and stimulates the production and release

Back 32

acute-phase cytokines, such as IL-1, TNF-α, IL-6, and prostaglandins

Front 33

What two factors about a bacteria is essential for it to cause a pendemic?

Back 33

1. Lethal
2. Easy to transmit