Bacterial Genome

Question 1

What is a nuceloid?

Answer 1

composed of a single chromosome of circular DS DNA

Question 2

What are plasmids?

Answer 2

• usually circular
• replicate independently of nucleoid

Question 3

What do plasmids usually code for?

Answer 3

virulence factors or antibiotic resistance genes

Question 4

What are operons?

Answer 4

genes that are transcribed together

Question 5

What is a lac operon?

Answer 5

codes for 3 genes that help bacteria take up and metabolize lactose

Question 6

What prevents the polymerase form binding to the promoter?

Answer 6

repressor

Question 7

What prevents the repressor from working?

Answer 7

allolactose

Question 8

What are the characteristics of pathogenicity islands?

Answer 8

• code for virulence factors
• present in genome of pathogenic bacteria
• different nucleotide & codon structure
• include mobility genes -> transposases & integrases

Question 9

What is transformation?

Answer 9

bacteria pick up bacteria from the environment

Question 10

What is transduction?

Answer 10

bacteriophage-mediated info transfer

Question 11

What are the 2 types of transduction?

Answer 11

• specialized -> only transfers genes adjacent to site of integration
• generalized -> random excision & packaging of genes

Question 12

What is conjgation?

Answer 12

genetic material is transferred via pili or physical contact

Question 13

What is the cause of lysis of infected bacteria?

Answer 13

lytic phages

Question 14

What are lysogenic phages?

Answer 14

integrate into host DNA

Question 15

What is a toxin coded for by a lysogenic phage?

Answer 15

diphtheria

Question 16

What are transposons?

Answer 16

• mobile geentic elements in bacterial genome
• can move within chromosome, b/w plasmids & chromosomes
• complex ones can code for antibiotic resistance

Question 17

How can antibiotic resistance be developed?

Answer 17

from over - prescription

Question 18

What is the highly antibiotic resistant bacteria?

Answer 18

methicillin resistance staph. aureus

Question 19

Why does beta-lactam resistance occur?

Answer 19

• mutations in penicillin binding protein
• mutations in porins
• beta-lactamase -> in periplasm of gram - bacteria or outside gram + bacteria

Question 20

How does culture work to detect a bacterial infection?

Answer 20

• isolation & identification of bacteria from diseases tissues
• aka “gold standard”

Question 21

How can you diagnose a bacterial infection?

Answer 21

• identify/isolate an organism/part of an organism -> culture, swab test, PCR
• identify evidence of immune response to infection -> ELISA

Question 22

What are the types of media for bacteria?

Answer 22

• solid media -> agar plates
• liquid media -> used in bloodculture bottles
• selective media -> inhibits unwanted bacteris for culturing nonsterile specimens
• differential -> biochemically differenciates specific bacteria
• cell culture -> obligate intracellular bacteria

Question 23

What is the best type of stain to identify bacteria?

Answer 23

gram

Question 24

What are the steps of gram staining?

Answer 24

1. crystal violet
2. potassium ionide -> fixation
3. decolorizer -> alcohol
4. safarin red -> counterstain
   * gram + -> purple
   * gram - -> red/pink

Question 25

What stain is used for tuberculosis?

Answer 25

immunofluorescence

Question 26

What are examples of shape and arrangement identification?

Answer 26

• cocci in clusters
• bacilli in pairs

Question 27

What are examples of biochemical analysis identification?

Answer 27

• carbohydrate usage
• enzyme activity
• chemical composition

Question 28

What are examples of genomic structure identification?

Answer 28

• PCR
• nucleic acid probes
• sequence analysis

Question 29

What is sandwhich ELISA?

Answer 29

• direct direction of bacteria
• rapid Ag detection
• Ab binds to bacterial Ag, then another Ab binds & is detectable

Question 30

What is indirect ELISA?

Answer 30

• PCR
• nucleic probes
• detects Abs to bacteria in blood serum