7. genetic control of metabolism

Question 1

wild strains of microbes can be improved by…

Answer 1

mutagenesis and recombiant DNA technology

Question 2

how can wild strains of microorganisms be improved by mutagenesis

Answer 2

Exposure to UV light and other forms of radiation or mutagenic chemicals results in mutations, some of which may produce an improved strain of micro-organism

Question 3

describe recombiant DNA technology

Answer 3

(genetic engineering) involves the use of recombinant plasmids (plasmid with new gene from another species) and artificial chromosomes as vectors.

Question 4

what are vectors

Answer 4

A vector is a DNA molecule used to carry foreign genetic information into another cell

both plasmids and artificial chromosomes are used as vectors during recombinant DNA technology.

Question 5

why are artificial chromosomes preferable to plasmids as vectors

Answer 5

they are more useful when larger fragments of foreign DNA are required to be inserted.

Question 6

how are sticky ends produced

Answer 6

when the same restriction endonuclease (which recognises a specific short sequence of DNA bases) is used to cut open the plasmid and the gene from the chromosome.

Question 7

what enzyme cuts open plasmids and specific genes out of chromosomes, leaving sticky ends

Answer 7

Restriction endonuclease

Question 8

what does restriction endonuclease do

Answer 8

it is an ezyme that cuts open plasmids and specific genes out of chromosomes, leaving sticky ends

Question 9

Recombinant plasmids and artificial chromosomes contain…

Answer 9

-restriction sites
-regulatory sequences
-origin of replications
-selectable markers

Question 10

Explain why scientists use antibiotics when carrying out the recombinant DNA technology to improve existing microorganism strains

Answer 10

to eliminate/kill any bacteria that have not taken up a plasmid

Question 11

describe a restriction site

Answer 11

contain target sequences of DNA where specific restriction endonucleases cut

Question 12

describe a regulatory sequence

Answer 12

control gene expression

Question 13

describe origin of replication

Answer 13

allows self-replication of the plasmid

Question 14

describe selectable marker gene (e.g. antibiotic resistance)

Answer 14

protect the micro-organism from a selective agent (antibiotic) that would normally kill it or prevent it growing

Question 15

why is it important that safety mechanism are often introduced

Answer 15

so that no other organisms get the genes that have been put in the bacterium.

any microorganism that did take up an ‘escaped’ microorganisms plasmid would not survive.

Question 16

why are recombinant yeast cells sometimes used

Answer 16

because some plant or animal recombinant DNA expressed in bacteria may result in polypeptides being incorrectly folded.

Use of recombinant yeast cells to produce active forms of the protein which are inactive in bacteria.