Plasmids and DNA transfer

Question 1

describe virus structure

Answer 1

protein coat

single/double stranded DNA/RNA

Question 2

describe how virus functions

Answer 2

only inside cells - not outsides

Question 3

describe genomic organisation of parasitic eukarytoes of apicomplexa phylum

Answer 3

14 chromosomes, 1 apicoplast genome (similar to chloroplast), 1 mitochondrial genome

Question 4

describe genomic organisation of bacteria

Answer 4

usually single circular chromosome - but can also be two circular chromosomes, or linear chromosomes, or one linear + one circular.

Question 5

the smaller the genome, the more ______ in character an organism is

Answer 5

parasitic

Question 6

do chromosomes contain genes essential for all conditions?

Answer 6

yes

Question 7

do plasmids contain gens essential for all conditions? examples?

do plasmids replicate independently of host cell

Answer 7

no - however can regulate copy number, and resistance mechanisms etc

yes

Question 8

can plasmids be circular or linear?

can chromosomes be circular or linear?

Answer 8

ye

Ye

Question 9

what is copy number

Answer 9

average number of copies of a plasmid in a cell

Question 10

how is copy number regulated

Answer 10

plasmids have genes that encode proteins which regulate the copy number

Question 11

what are bacteriophages? describe their structure

Answer 11

viruses that infect bacteria

protein coat, genome, injecting apparatus

Question 12

what are transposable elements?

Answer 12

mobile DNA that can move in and out of chromosome - insertion sequences, composite transposons, some bacteriophages

Question 13

whats vartical transfer?

Answer 13

transfer of genetic material from parent to daughter - chromosomes, plasmid

Question 14

what is horizonal transfer

Answer 14

transfer of genetic material from cell to unrelated cell - via transformation, conjugation, transduction,

Question 15

describe transformation

Answer 15

competent bacteria take up DNA from environment

competency induced by chemicals/electroporation

Question 16

why is plasmid DNA optimal in transformation

Answer 16

replicates independently
doesnt need to be taken up by chromosome
not easily degraded

Question 17

describe conjucation process

Answer 17

pilus tip of F+ cell binds to receptor on surface of F- cell; pilus retracts to bring both cells together
conjugative bridge forms

plasmid nicked at origin of transfer, one strand goes to F- plasmid

DNA repairs itself

Question 18

describe F factor

describe F plasmid

describe F+/F-

Answer 18

F factor = DNA encoding: sex pilus, origin of transfer, proteins required for DNA transfer
F plasmid contains F factor

F+ cell contains DNA with F factor; is the donor
F- cell contains DNA without F factor; is recipient

Question 19

describe conjugation experiment

Answer 19

• E. coli require 5 amino acids to grow on a specific medium (doesn’t provide these aa’s). Strain A has genes encoding 2, strain B has 3. Therefore they can’t grow alone. Cultures of both strains combined, conjugation occurred, some growth occurred.
• When this experiment was replicated but strains A and B were separated by a filture, no growth occurred – hence via conjugation

Question 20

describe transduction

Answer 20

transfer viva bacteriophages

Question 21

two ways bacteriophages replicate?

Answer 21

lytic cycle

lysogenic cycle

Question 22

describe lytic cycle

Answer 22

bacteriophage injects DNA into cell
bacteriophage, and DNA within them, replicates
cell lyses, releasing bacteriophages iwth DNA

Question 23

describe lysogenic cycle

Answer 23

bacteriophage injects DNA
DNA integrates into chromosome
everything replicates

Question 24

what happened in transduction experiment?

Answer 24

occurred even when there was a filter - bacteriophages could pass the filter.

Question 25

describe transfection

Answer 25

foreign genes inserted into animal cells

Question 26

3 ways of transfection

Answer 26

modifying membrane via chemicals/electroporation
addition of DNA in liposomes
physical introduction using gene gun

Question 27

DNA transferred into a cell can only survive under what conditions?

Answer 27

DNA can replicate by itself

therefore be integrated into a plasmd or a chromosome

Question 28

how can DNA be integrated into a host chromosome

Answer 28

encoding proteins required for integration

being homologous to chromosome

Question 29

describe agrobacterium tumerfaciens and its relation to plants

Answer 29

has plasmid + linear chromosome

plasmid is tumour inducing; has T-DNA which is integrated into plant DNA, causing tumours to form.