2.7 Genetic Control of Metabolism (Genetic Engineering)

Question 1

wild strains of useful micro-organisms are selected for and cultured in labs until a pure strain exhibit in the desired trait can be isolated, this creates a stock of microbes that produce the desired product, however, some may still lack some of the features useful to industrial growth of the organism

name some examples of the useful features used in industrial growth that the micro-organism might lack

Answer 1

• genetic stability
• ability to grow on low-cost nutrients
• ability to overproduce required metabolite
• ability to allow harvesting of desired metabolite

Question 2

what is mutagenesis?

Answer 2

the creation of mutations (and can be artificially increased by exposing organisms to mutagenic agents)

Question 3

name the two types of mutagenic agent

Answer 3

• radiation
• some chemicals

Question 4

describe ‘what Recombinant DNA Technology is and the steps involved within genetic engineering’

Answer 4

Recombinant DNA Technology allows the transfer of gene sequences from one organism to another, even across the species barrier. This makes situational possible to use artificially transformed micro-organisms to produce plant or animal proteins.

1. part of the human chromosome, containing insulin, gene is identified
2. the insulin gene is cut and removed from the human chromosome
3. a plasmid is removed from a bacterial cell
4. the plasmid is cut open and the insulin gene is inserted into the plasmid
5. the modified plasmid is placed into a bacterial cell
6. the modified plasmid multiplies inside the bacterial cell (insulin is produced by the cell)
7. the bacterial cell divides producing more bacteria with the human insulin gene
8. lots of insulin is produced — it is collected and purified from the bacteria

Question 5

what term is used to describe ‘the enzymes used to cut DNA into fragments and cut open plasmids’?

Answer 5

restriction endnuclease

Question 6

describe ‘the role of a vector writhing Recombinant DNA Technology’

Answer 6

In Recombinant DNA Technology, the restriction fragments are inserted into a vector to be carried from the genome of one organism to transform that of another.

Bacterial plasmids and artificial chromosomes are both used as vectors in Recombinant DNA Technology.

Question 7

what are bacterial plasmids and what do they need to contain to contain to be effective as a vector?

Answer 7

Bacterial plasmids are small rings of extra DNA that are found in bacteria.

They need to contain a restriction site, a marker gene and an origin of replication (ORI) to be effective as a vector.

Question 8

the restriction sites on the vector plasmid must be able to be cut open by the same restriction endonuclease used to extract the desired, why is this?

Answer 8

so that the sticky end of the vector and the inserted genes are complementary

Question 9

what are marker genes used for?

Answer 9

to determine whether a host cell has taken up the transformed plasmid or not

Question 10

what type of marker is antibiotic resistance?

Answer 10

a selectable marker

Question 11

what is the role of the origin of replication ‘ORI’ within a bacterial plasmid?

Answer 11

the ORI contains genes that control the self-replication of the plasmid DNA and regulatory sequences that allow the control of the expression of genes on the plasmid, including the inserted gene

Question 12

sometimes genes are introduced that stop the micro-organism from being able to survive in an external environment, why is this?

Answer 12

creating a micro-organism that is unable to survive in an external environment acts as a safety mechanism to prevent the spread of the mutant microbe

Question 13

wheat alternative host cells could be used to overcome the limitation of using prokaryotic cells?

Answer 13

yeast cells as they are eukaryotic but contain plasmids