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Flashcards in Resistance Deck (33)
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1

what is recombination

breaking and joining of DNA in new combinations

2

type of recombination

-homologous (between similar/identical DNA)
-non homologous ("cut and paste" - transposition)

3

integration of DNA acquired by

transduction, conjugation, transformation

4

what are transposons

jumping genes

move from:
chromosome -> chromosome
chromosome -> plasmid

5

how do transposons move around within these sites

non‐homologous recombination: site‐specific recombinases (the transposase enzyme)

6

difference between structure of simple and complex transposon

in simple: no selectable genes (inverted repeat, transposase, inverted repeat which makes up the IS)

complex: IS, genes for eg. penicillin, IS

7

how do transduction, conjugation, and transformation transfer resistant regene

transduction - bacteriophage
conjugation - plasmid
transformation - DNA binding proteins

8

explain the process of transformation

bacterial cell dies and DNA is broken up, 2 strands of the DNA is grabbed by the DNA binding protein, 1 strand is degraded and 2nd is recombined and incorporated into competent cell

9

what are some competent cells for transformation

streptococci and haemophilus

10

what microorganisms carry out conjugation and why

gram negative bacteria because it requires production of pilus

11

what encodes the pilus

F-factor (plasmid)

12

what does the F factor plasmid contain

tra genes (transfer) and of course genes for pilus production

13

how are cells defined in conjugation

– F+ (have F‐factor plasmid)
– F‐ (lack F‐factor plasmid)

14

what is used to transfer plasmid from F+ donor cell to recipient cell

pilus

15

types of phages in transduction

virulent (lytic) - death of cell by lysis hence releasing new phage

temperate: phage DNA gets integrated with host cell DNA (prophage), cells replicate, then there's a change where cells them become virulent and begin to lyse and release new phages

16

what is it called when bacteria are carrying a prophage

lysogeny

17

what happens when alcohol concentration is greater than 50%

dissolve membrane lipids, disrupt cell surface
tension, affect membrane integrity

18

alcohol acts as a microbicial agent against what microorganisms

vegetative fungi, fungal spores, enveloped viruses

NOT BACTERIAL SPORES

19

what is the activity of halogen eg iodine

microbicidal and sporicidal (with longer exposure)

20

what are applications of halogens

chlorine: water tx
iodine: iodophors eg betadine

21

halogens as oxidizing agents affect what?

cellular enzymes

22

example of disinfectant

sodium hypochlorite (bleach)

23

how does steam heat (autoclave) work

it coagulates protein hence breaking hydrogen bonds

24

advantage of steam heat

will kill all microorganisms and most endospores within 15 mins

25

uses of steam heat

culture media, solution, dressings, instruments

26

what is steam heat not used for

heat sensitive items

27

what is ethylene oxide gas

chemical sterilizing agent when used in gaseous form

28

why is ethylene oxide gas considered a strong alkylator

reacts with guanine of DNA and functional groups of proteins

29

advantages and disadvantages of ethylene oxide gas

advantage - for all organisms and endospores, suitable for temp or moisture sensitive items

disadvantage - Longer treatment time compared to autoclaving: 16‐18 hours

30

used to disrupt DNA

Ionizing radiation e.g., gamma rays