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Oral Microbiology > Overview 1 (Test 1) > Flashcards

Overview 1 (Test 1) Flashcards

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1
Q

What are pathogens?

A

Organisms with unique, genetically endowed capacities to

1) colonize host
2) overcome host immunity
3) replicate within the host environment and/or cause host tissue damage

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2
Q

-What are virulence factors?

Examples?

A

-The molecules or activities that permit the action of colonizing, overcoming immunity, and replicating/causing tissue damage.

Examples:

1) Adherence factors
2) toxins
3) inflammatory mediators
4) anti-host enzymes
5) Bacterial capsules

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3
Q

Usually most pathogens posses multiple factors that endow pathogenic activity, Opportunists are_______?

A

Non-pathogenic “normal flora” that cause disease only under ABNORMAL host conditions like:

1) DECREASED competition form other microbes,
2) DECREASED host innate/adaptive immunity, or
3) Colonization of new sites where they can cause disease.

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4
Q

What are the 2 types of cells that exist?

A

1) Eukaryotic- Make up ALL NON-MICROSCOPIC life:
Mammals, fungi, algae, plants as well as some microscopic life such as protozoa.

2) Prokaryotic- Include AL BACTERIA as well as ARCHAEA.

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5
Q

How were eukaryotes formed?

A
  • By fusion of prokaryotic cells “a long time ago”
  • The typical bacterial plasma membrane carries out some of the functions of the organelle membranes in eukaryotic cells.
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6
Q

What is the difference between eukaryotic and prokaryotic genes?

A 
Eukaryotes = 25,000 genes
Bacteria= less than 5,000 genes
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7
Q

How do bacteria differ from human cells?

A
  • Bacteria are about 1/1000 the volume of our cells and lack internal membrane-defined organelles such as the nucleus, golgi, endosomes, mitochondria, chloroplasts, etc.
  • Almost all bacteria have a unique CELL WALL that covers the cell plasma membrane, and PROTECTS it from OSMOTIC LYSIS.
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8
Q

How is relationships between life forms measured?

A

By genetic similarity

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9
Q

What are some of the major infectious agents of humans?

A

1) Eukaryotes
2) prokaryotes -bacteria & archaea
3) viruses
4) prions

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10
Q

Which eukaryotic pathogens can humans be infected by?

A

1) fungi
2) helminths
3) protozoa

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11
Q

What are the kinds of viruses?

A

-enveloped(LESS HARDY) and non-enveloped

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12
Q

What are prions?

A

Small INFECTIOUS PROTEINS that mode of action is poorly understood

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13
Q

Where are Archaea found in humans?

A

1) Colon
Anaerobic in colon, associated with inflammation with IBS or colitis

2) Deep perio pockets
(anaerobic with lots of acid. Mostly found here in periodontal disease.

3) Infected tooth pulp chambers
- Anaerobic harsh environments, associated with pulp infections

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14
Q

Describe some characteristics of bacteria?

A

-They have 1000X smaller volume than typical human cell
-Prokaryotic
-Contain NO MEMBRANE BOUND ORGANELLES
(everything within cell or plasma membrane is in cytoplasm)

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15
Q

Where is bacterial genetic material contained?

A

In ONE circular dsDNA molecule

-There may also be one or more self-replicating plasmid DNA molecules present

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16
Q

How can bacteria quickly respond to environmental changes?

A

Since bacterial mRNA is transcribed directly in the presence of ribosomes, there is little lag in protein production after mRNA is produced

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17
Q

What is the difference between bacterial and eukaryotic ribosomal subunits?

A

1) Bacterial have 70 S ribosomes

2) Eukaryotic have 80 S and are target for some antibiotics

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18
Q

Other than ribosomes what is another target for some antibiotics?

A

Bacteria have a regular bi-lipid cell membrane around which is a RIGID CELL WALL

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19
Q

What are PILI(Fimbrae) ?

A
  • They are ANCHORED in the CELL MEMBRANE or CELL WALL.

- They are used for attachment and conjugation

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20
Q

What are Flagella used for?

A

For locomotion

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21
Q

What are capsules used for?

A

To protect from phagocytosis (capsules are usually carbohydrate polymers)

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22
Q

What is an LPS (lipopolysaccharide)?

A

A MAJOR virulence factor, found in the OUTER MEMBRANE of gram - bacteria.

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23
Q

Why must bacteria SECRETE many DIGESTIVE ENZYMES?>

A

Because only SMALL molecular weight molecules can pass thru the cell wall and cell membrane (s)

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24
Q

What can the DIGESTIVE ENZYMES that bacteria secrete do?

A
  • Cause pathology by damaging human tissues.

- These will break carbohydrates and proteins into small sugars and a.a respectively. (Can be taken in thru pores)

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25
Q

What do bacteria often steal from the host?

A

ESSENTIAL MOLECULES (e.g, iron)

26
Q

What happens when BACTERIA release their waste into their immediate environments?>
-What are biofilms?

A

-One bacterium’s waste is often another bacteria’s bread.
In their normal niche bacteria typically live in complex ecological BIO-SYSTEMS (just like their target hosts) Termed BIOFILMS

27
Q

What is the difference between Gram + and - ?

A

1) Gram + have a THICK OUTER CELL WALL and a SINGLE INNER PLASMA MEMBRANE (often the bacteria is 50% dry weight)

2) Gram - have a THIN CELL WALL sandwiched between 2 membranes, the outer of which contain a major virulence factor- LPS (lipopolysaccharide)
* *Unique outer membrane

28
Q

Linked to the cell wall and membranes most bacteria have structures such as?

A
  • Falgella, pilli, fimbrae, etc.

- Bacteria secrete some sort of loose ‘slimy’ material that surrounds them in a CAPUSLE.

29
Q

What protects the bacterial cell from PMNs and macrophages?

A

Capsules often have STONG ANTI-PHAGOCYTIC PROPERTIES

30
Q

What is the bacterial cell wall?

A

An essential, ALL ENCLOSING, RIGID, POROUS, PROTECTIVE GIRDLE, that surrounds the bacterial cell.

31
Q

What wraps around the plasma membrane and protects it from damage?

-What happens when penicillin is used against bacteria?

A

This cell wall wraps completely around the facile balloon-like plasma membrane and PROTECTS the plasma membrane from OSMOTIC PRESSURE within the cytoplasm by preventing the bacterial cell from swelling up and breaking open.

Note: THIS is what occurs when the outer wall is DAMAGED by certain antibiotics (penicillin)

32
Q

What is the cell wall made up of?

A

A ridged mesh rope like, linear, polysaccharide chains which are formed by repeating, modified (added acetylated amine groups) GLUCOSE-DIMERS = N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)

33
Q

Where does cell wall synthesis start?

A

1) In the cytoplasm when a short peptide is bound to each NAG-NAM disaccharide. Then the peptide disaccharide (NAG-NAM peptide) is transported out of the cell thru the bacterial membrane & joined to a growing peptidoglycan chain by a transport enzyme complex.
2) After 20 or so these dimers are linked into a “structural girder” (outside cell membrane) they FALL OFF the transport ENZYME complex & bump into the inside of the existing cell wall.

34
Q

What are transpeptidases?

A

Membrane bound enzymes that spot-weld these girders into place by cross linking the peptides hanging from the girders to peptides dangling from the existing wall.

35
Q

What is peptidoglycan?

A

This wall molecule is a continuous complex around the cell.

-Peptidoglycan is CONSTANTLY synthesized and degraded by autolysins (think bone remodeling)

36
Q

What is an endotoxin?

A

The outer leaflet of the outer membrane of a Gram - bacteria that contain a toxic lipopolysaccharide

37
Q

What is the difference in the staining of gram - and +?

A

Thee difference is the 2 results from the different wall sizes.

  • Both bacteria take up crystal-violet, but only the gram - are de-stained by the brief alcohol/acetone to diffuse through quick enough)
  • Some might say A gram - bacteria can’t hold its alcohol.
38
Q

In small amounts LPS is excellent at __________?

In large amounts _________?

A
  • Small amounts= Activating the innate immune reaction

- Large amounts = Especially systemically = serious problems

39
Q

What can LPS in large amounts do to the blood vessels?

A

1) It can Activate the clotting system, leading to disseminated intravascular coagulation.
2) Complete obstruction blood flow in the affected blood vessels, causing damage or death to the underlying tissues.
3) Macrophages can response in their environment by becoming activated.

40
Q

When Macrophages are activated by large amounts of LPS what do they secrete(drool) and produce ?

A

1) Various noxious compounds (PROTEASES- which breakdown the extracellular matrix, like collagen,etc) onto the surrounding tissues
2) They ALSO PRODUCE pro-inflammatory mediators such as PGE2 (prostaglandin- E2) and TNF (Tumor Necrosis factor)

41
Q

What can PGE2 activate?

A

osteoclasts to resorb bone

42
Q

What does TNF do?

A

Signals endothelial cells to produce more NO (nitric oxide) which causes pre-capillary sphincters to relax (i.e., inflammation)

43
Q

What happens when there is too many capillaries in the body opened up at one time ?

A

Causes the BP to FALL dramatically and can even lead to HYPOVOLEMIC SHOCK ( SEPTIC SHOCK)

44
Q

Describe LPS local pathology

A

Gm - bacteria release LPS–> platelets fibrinogen & Macrophages release TNF, PGE2 and collagenase (proteins enzyme)

  • TNF–> Endotheial cells –> NO
  • PGE2 (lipid mediator)–> Osteoclasts activated bone resorbed
  • Collagenase–> Collagen fibers destroyed
45
Q

Describe systemic LPS pathology

A

Gm - bacteria release LPS–> platelets fibrinogen–> Disseminated intravascular coagulation–> blocks blood flow

-Pre capillary smooth muscle sphincter relaxes–>Endothelial cells–> DECREASE BP –>Hypovolemic shock

46
Q

In nature LARGE GLUCOSE POLYSACCHARIDES form?

Major functions?

A
  • Very useful molecules.

- 2 major functions: Structural and /or food storage

47
Q

What are ways to store excess glucose for future use?

A 
Starch= plants
Glycogen= animals
48
Q

What are the linkages for starch, glycogen, cellulose, chitin, peptidoglycan?

A 
cellulose=  Beta 1-4 linkages 
chitin=  Beta 1-4 linkages 
peptidoglycan= Beta 1-4 linkages 
starch= alpha 1-4 linkages 
glycogen= alpha 1-4 linkages
49
Q

What do plants, animals and insects use form very strong resistance structural competent of the organism?

A 
Cellulose = plants
chitin= animals & insects
50
Q

What do bacteria use glucose polymers for?

A
  • BOTH energy storage and structure.

- Many bacterial species can store glucose energy stores as glycogen inside the cell, or DEXTRANS outside of the cell.

51
Q

What are HEME-PROTEINS?

A

Bacteria have this to deal with oxygen by RESPIRATION-Turning sugars and oxygen INTO CO2 + WATER. (our mitochondria do this)

Note- without it bacteria cannot respire

52
Q

What are the different kinds of oxygen environments for bacteria?

A

Obligate aerobes- MUST have O2 to live

Facultative- Respire if oxygen is present but can survive on FERMENTATION if oxygen is absent (GAINING energy by partiality breaking down substrate to other organic molecules like lactic acid or alcohol)

Aerotolerant anaerobes- Not killed by oxygen but can only ferment substrate

Microaerophic aerobes- Compete best in environments with only very SMALL levels of oxygen

Anaerobes- Killed by Oxygen

53
Q

Living in an oxygen environment comes at a price for bacteria what doe they have to deal with?

A

Toxic oxygen radicals

54
Q

What are the 2 enzymes the are utmost importance in neutralizing these oxygen radicals?

-Which oxygen environment has these conditions?

A

1) Superoxide dismutase (SOD) - produces the else toxic hydrogen peroxide (H2O2) from the very toxic O2-
2) Catalase (CAT) further converts H2O2 to water and oxygen

***Obligate aerobes and facultative aerobes have BOTH enzymes

55
Q

Which bacteria type only have SOD and can tolerate small amounts of oxygen?

A

Microaerophilic bacteria

56
Q

Which bacteria type only have neither enzymes for oxygen and therefore die in the presence of oxygen?

A

Strict anaerobe

57
Q

What is Supra-gingival plaque mostly made up of?

A

Microaerophilic and facultative bacteria while sub-gingival plaque is primarily facultative and anaerobic (more of the later in the deeper pockets)

58
Q

What is the periodontal practice aimed at reducing?

A

Anaerobic conditions in the sub-gingival area to prevent the growth of virulent anaerobic pathogens

59
Q

How do bacteria replicate?

A

In 20 minutes by Binary fission as do much eukaryotes (less complex and faster)

60
Q

How is the bacterial chromosome molecule?

A
  • Circular and double-stranded DNA (dsDNA)

- haploid

61
Q

What are plasmids?

A
  • Other small extra chromosomal strands of circular DNA present in cells
  • They may insert into bacterial host chromes and come out again!
  • Carry GENES that can HELP bacteria and HARM humans; Genes that code for TOXINS, ANTIBIOTIC RESISTANCE, etc.

Oral Microbiology (11 decks)

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