PowerPoint 2 : Review of bacteria

Question 1

What type of bacteria has lipoteichoic acid?

Answer 1

Gram Positive

Question 2

Which bacteria has an outer membrane?

Answer 2

Gram Negative

Question 3

What is the role of adding iodide to the Gram stain?

Answer 3

Binds crystal violet and traps it in the peptidoglycan

Question 4

What is the purpose of alcohol in the Gram Stain?

Answer 4

Cells are de-stained

Question 5

Which cells retain the purple die?

Answer 5

Gram positive

Question 6

Why do we add safranin or Carbol Fushin?

Answer 6

Stains the gram negative cells pink

Question 7

Pili are found on most gram positive cells (T/F)?

Answer 7

False

Question 8

Teichoic acid is found on gram positive cells (T/F)?

Answer 8

True

Question 9

Lipopolysaccharides are found on gram positive cells (T/F)?

Answer 9

False

Question 10

What are lipopolysaccharides made of?

Answer 10

• lipid A
• core
• repeating oligosaccharide (O antigen)

Question 11

What is the polysaccharide layer that lies outside the cell envelope of bacteria?

Answer 11

Capsule

Question 12

Which organelle mediates attachment to other cells or surfaces?

Answer 12

Fimbrae and Pili

Question 13

What is an adhesin pili?

Answer 13

Pili with an adhesin protein that allows the cell to stick to human cells. Some mediate genetic exchange.

Question 14

Where are sex pili found?

Answer 14

On Enteric Bacteria

Question 15

On which bacteria is the sex pili coded for by a conjugative transmissible plasmid (F plasmid), which resides in the donor cell?

Answer 15

E.coli

Question 16

What is the stiff helical organelle of locomotion that protrudes from the cell surface and allows swimming?

Answer 16

Flagellum

Question 17

What is the capsule K antigen?

Answer 17

Capsular polysaccharide associated with cell surface non-covalently and protects bacteria from the host immune system.

Question 18

What is the lipopolysaccharide O antigen?

Answer 18

Also known as lipoglycan and endotoxin.

• A hydrophobic lipid section, lipid A, which is responsible for the toxic properties of the molecule
• A hydrophilic core polysaccharide chain, a
• A repeating hydrophilic O-antigenic oligosaccharide side chain that is specific to the bacterial serotype

Question 19

What is the protein antigen found on the surface of some gram-positive, and some gram-negative bacteria, rarely used in classification?

Answer 19

Fimbriae F antigen

Question 20

What is the antigen that based on the reaction with the flagellin protein arranges itself in a hollow cylinder to form the filament in a bacterial flaegellum?

Answer 20

Flagella H antigen

Question 21

What antigens is e.coli 157:H7 type based on?

Answer 21

O and H antigens

Question 22

What antigen is Listeria Monocytogenes based on despite the fact that the semantics are 1/2a, 1/2b, 4b, etc.?

Answer 22

Based on O and H antigens

Question 23

Although they are typed based on O and H antigens, what bacteria is given a name based on where it was discovered?

Answer 23

Salmonella

Question 24

For salmonella, instead of calling them serotypes what are they called?

Answer 24

serovars

Question 25

What pathogen is based of the O and K antigens (and O4:K12 is the most common cause of illness in Canada?)

Answer 25

Vibrio Parahaemolyticus

Question 26

What bacteria is based on toxins A,E, F?

Answer 26

Clostridium Botulinum

Question 27

In what type of media can injured cells grow?

Answer 27

non-selective media

Question 28

What type of cells can appear dead due to the use of selective media in termal studies, so then the thermal resistance will be underestimated and the the true kill values will be low?

Answer 28

Injured cells

Question 29

What type of cells make escape routine detection post-processing leading to faster spoilage or a safety problem?

Answer 29

Injured cells

Question 30

What are salt, organic acids, and suboptimal temperatures examples of?

Answer 30

Selective agents

Question 31

What requires de novo RNA and protein synthesis and is during the lag phase?

Answer 31

Recovery

Question 32

How can peroxide detox agent help in recovery?

Answer 32

Can help overcome damage caused by oxygen toxicity

Question 33

What is the state of the cell called when it cannot be cultured on any media even though their viability can be demostrated by non-culturable methods.

Answer 33

viable but not coluturable (VBNC)

Question 34

Salmonella, Campylobacter, Eschrichia, Shigella, Yersinia pestis, Vibrio, can exist in what type of state?

Answer 34

VBNC

Question 35

What is a survival strategy for non-sporulating species?

Answer 35

VBNC

Question 36

True or false: the VBNC state is morphologically the same form that of a normal vegetative cell.

Answer 36

false: its different

Question 37

Red fluorescent nucleic acid stains are incubated with cells, if they permeate what does it indicate?

Answer 37

The cells is dead

Question 38

What color will bacteria with intact membrane stain?

Answer 38

Intact membrane: green | Damaged membrane: red

Question 39

What is substrate responsive metabolism?

Answer 39

- can be used to detect viability - cells can be incubated with a nutrient (yeast extract) and an antibiotic that inhibits cell division (nalidixic acid, cirpofloxacin) - live cells elongate but do not divide

Question 40

What method can show listeria monocytogenes is viable?

Answer 40

substrate responsive metabolism

Question 41

What often induces VBNC state?

Answer 41

- nutrient limitation | - also salt concentration, exposure to chemicals, and temperature shifts

Question 42

T/F: VBNC can be resuscitated by temperature shifts and a gradual return of nutrients.

Answer 42

True

Question 43

Vibrio Vulnificus is commonly found in what type of food?

Answer 43

Shellfish such as oysters

Question 44

How many bacteria in the biosphere may be unculturable?

Answer 44

As many as 99%

Question 45

What regulates genes that would be superfluous to isolated cells but that are useful to large populations?

Answer 45

quorum sensing

Question 46

Quorum sensing is based on diffusion of a signal molecule produced in large amounts (T/F)?

Answer 46

true

Question 47

What type of response does quorum sensing elicit?

Answer 47

phenotypic response

Question 48

What is signal transduction?

Answer 48

two components regulatory system where one protein spans the membrane, picks up a signal and then reacts based on a response regulator protein.

Question 49

What is quorum sensing systems built on?

Answer 49

auto-inducers which diffuse through the cellular membrane to initiate a specific response when a certain population density has been reached

Question 50

What acts a signaling molecule in gram negative bacteria for quorum sensing?

Answer 50

N-acyl homoserine lactone (AHL) molecules

Question 51

How is probiotic bacteria thought to prevent infection by pathogenic bacteria?

Answer 51

Lactobacillus acidophilus prevents e.coli infection by produce small biologically active molecules that interfere with the quorum sensing system of e.coli. -this limits the pathogen's ability to adhere to tissues and cause lesions.

Question 52

What are the two components in signal transduction?

Answer 52

- Histidine Kinase Receptor | - Response Regulator

Question 53

What signal system does L.monocytogenes have?

Answer 53

Signal Transduction

Question 54

What signal system does s.aureus have?

Answer 54

Signal Transduction

Question 55

What signal system does lactic acid bacteria have?

Answer 55

Signal Transduction

Question 56

What signal system does S.enterica serovar typhimurium have?

Answer 56

Quorum sensing

Question 57

What signal system does enteropathogenic e.coli have?

Answer 57

Quorum sensing

Question 58

What signal system does v.cholerae have?

Answer 58

Quorum sensing

Question 59

What is a biofilm?

Answer 59

Aggregation of cells, often multiple species, into heterogeneous complex structures that are attached to a solid surface

Question 60

What is the purpose of defined boundaries in biofilms?

Answer 60

Allow fluid channels to run through the biomatrix. Critical for bringing in nutrients and carrying away waste. -resistant to heat, chemicals, sanitizers

Question 61

What are endospores?

Answer 61

Differentiated cells that are very resistant to heat and cannot be easily destroyed even by chemicals

Question 62

What are the two pathogens infamous for causing illness after consumption of food with germinated spores?

Answer 62

- clostridium botulinum | - bacillus cereus

Question 63

T/F: Bacterial chromosomes are plastic

Answer 63

True

Question 64

What is the geometry of Borelia burgdorferi and Giardia lamblia's chrosome?

Answer 64

Linear

Question 65

How many chromosomes does Giardia have?

Answer 65

Four

Question 66

What is the term that defines the genes that are shared by all members of a certain group?

Answer 66

Core Genome

Question 67

What is the term that includes the genes that are present in any member of a certain group?

Answer 67

Pangenome

Question 68

What is the term that describes the genes that are present in a subset of members of a certain group?

Answer 68

Accessory Genome

Question 69

What are the mobile genetic elements that contribute to diversity in bacteria?

Answer 69

- bacteriophage - plasmids - pathogenicity islands - transposons

Question 70

What is a prophage?

Answer 70

A bacteriophage or phage genome inserted and integrated into the circular bacterial DNA chromosome or existing as an extrachromosomal plasmid.

Question 71

What do prophages carry?

Answer 71

Genes for virulence factors or toxins required for pathogenesis by the pathogens they lysogenize

Question 72

What is the process by which a prophage converts a non-pathogenic bacteria into a pathogen?

Answer 72

Lysogenic Conversion

Question 73

What bacteria is not pathogenic until infected with a phage CTX that carries the gene for the cholera toxin?

Answer 73

Vibrio cholerae

Question 74

What are the vibrio cholerae serotypes that are pathogenic?

Answer 74

O1 and O139

Question 75

What are circular molecules (some exceptions) of double-stranded DNA called which are self-replicating?

Answer 75

Plasmids

Question 76

Do plasmids carry essential genes?

Answer 76

No. They carry genes which encode for products which can benefit the bacteria under certain circumstances (i.e AMR genes).

Question 77

What are pathogenicity islands and what do they allow?

Answer 77

- DNA elements integrated in the chromosome of some bacteria which contain genes that confer special properties - Allow the bacteria carrying them to occupy special ecological niches (i.e AMR genes).

Question 78

Are pathogenicity islands able to move from one bacteria to another, even in unrelated strains?

Answer 78

Yes

Question 79

What gene is essential to pathogenicity islands and allows them to integrate the host DNA?

Answer 79

Integrase Gene

Question 80

What is the role of the repeated sequence at the end of pathogenicity island's sequences?

Answer 80

Involved in integration

Question 81

What are DNA elements that can hop from one place in chromosomal DNA to another?

Answer 81

Transposon

Question 82

What does transposon DNA have that gives it the ability to hop each time it moves?

Answer 82

Transposase Gene

Question 83

What are the few types of bacterial transposons?

Answer 83

- Insertion Sequence (IS) Elements | - Composite Transposons

Question 84

What are Insertion Sequences (IS) Elements?

Answer 84

- smallest transposons - really only encode the transposon - can interrupt gene function by inserting in the middle of a gene - have Inverted Repeat (IR) at either end

Question 85

What are composite transposons?

Answer 85

When two IS elements bracket other genes and carry those other genes with them when they move. (i.e: Transposase Gene + 3 other genes + Transposase Gene)

Question 86

What is the transmission of DNA from mother to daughter cells called?

Answer 86

Vertical Gene Transfer

Question 87

What is intoxication?

Answer 87

Ingestion of bacterial or mould toxin, which must be present in its active form.

Question 88

What is infection?

Answer 88

Illness that occurs after the consumption of viable bacterial cells or viruses.

Question 89

What is a toxico-infection?

Answer 89

When illness occurs from the ingestion of a large number of viable cells of some pathogenic bacteria. -the bacteria cells either sporulate, colonize, or die, and release the toxins.