ABXR 1

Question 1

plasmid

Answer 1

episome

• autonomous
• self replicating
• extrachromosomal
• double stranded
• small (kilobases)
• usually circular
• genes for antibiotic resistance (r plasmids) and genes for virulence factors
• easily transferred from host to host

Question 2

chromosomal

Answer 2

• large, megabases
• double stranded DNA
• tightly packed in nucleoid
• haploid, circular or linear

-can encode for certain antibiotic resistance and virulence factors usually within pathogenicity islands

Question 3

What are conjugative plasmids vs non conjugative plasmids?

Answer 3

conjugative transfer from host to host within or between species
-spread of multiple antibiotic resistances

non conjugative:

• cannot transfer themselves, but can be transferred by conjugative plasmids
• used for genetic engineering

Question 4

Bacterial virus genome

-bacteriophage, phage

Answer 4

RNA or DNA

• double or single stranded
• linear or circular
• 3-300 kilobases
• can carry virulence factors
  ex. diphtheria beta toxin cholera toxin ( toxin gene encoded by bacteriophage)

Question 5

lytic infection vs lysogenic infection

Answer 5

lytic :phage replicates itself, lyses host cell, releases progeny phage

lysogenic: phage becomes latent doesn’t replicate
- circularize or integrate into the host chromosome -latent genome called prophage

Question 6

transposable elements

Answer 6

jump from genome to genome within the SAME cell

• major carrier of antibiotic resistance genes
• evolution of R plasmids

Question 7

What are two types of transposable elements?

Answer 7

1. insertion sequence elements

2. transposons

Question 8

What are insertion sequence elements?

Answer 8

cary only genes for transposition

1. recombinase (transposase)
   - transposition enzyme
2. inverted repeats
   - recombinase recognition sites

-insertion into a gene causes mutation

Question 9

What are transposons?

Answer 9

• transposable element that carries genes for
  1. transpostion
  2. other functions

-genes between two insertion sequences

_multiple Insertion sequences joined

Question 10

Transposon contain what genes?

Answer 10

resistance

Question 11

Transposable bacterialphage contain wha genest?

Answer 11

phage genes

• phage genome between two insertion sequences
• when lysogenic phage can transpose, i.e. jump from phage genome to chromosome or plasmid

Question 12

conjugal transposon contain what genes?

Answer 12

transfer genes

-can also contain resistance genes

Question 13

What are r plasmids?

Answer 13

carry multiple antibiotic resistance genes

-often encode enzymes that inactivate antibiotics or reduce permeability to antibiotics

Question 14

What type of bacteria are many r plasmids found on?

Answer 14

-gram negative