2.7 - Genetic Control of Metabolism

Question 1

Wild Strain Definition

Answer 1

A wild strain is the most common variety of microorganisms that can be found.

Question 2

Qualities Desired in Wild Strains

Answer 2

Qualities desired in wild strains of microorganisms include:
* Genetic stability (doesn’t mutate often)
* Grow on low-cost media
* Produce lots of product
* Easy to obtain products

If a wild strain doesn’t have the desired qualities then they can be improved through mutagenesis and recombinant DNA technology.

Question 3

Mutagenesis

Answer 3

Mutagenesis is the production of mutations.

Exposing a microorganis to UV light and other forms of radiation or mutagenic chemicals result in mutations. Some of these will produce an improved strain of microorganism.

Question 4

Recombinant DNA Technology

Answer 4

Recombinant DNA technology is the transfer of gene sequences from one organism to another. This involves vectors.

Question 5

Vector

Answer 5

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

Question 6

Recombinant DNA Technology and Vectors

Answer 6

Both plasmids and artifical chromosomes are used as vectora during recombinant DNA technology.

Artificial chromosomes are preferred as vectors when larger fragments of forgein DNA are required to be inserted.

Question 7

Process of Recombinant DNA Technology

Answer 7

1. Restriction endonucleases cut open plasmids and specific genes out of chromosomes, leaving sticky ends.
2. Ligase seasl the gene into the plasmid

Question 8

Complementary Sticky Ends

Answer 8

Complementary sticky ends are produced when the same restriction endonuclease is used to cut open the plasmid and the gene from the chromosome.

Question 9

Requirements for Recombinant DNA Technology

Answer 9

1. Restriction endonuclease - an enzyme used to cut target sites of DNA and open plasmids
2. Restriction site - contains target sequences of DNA where specific restriciton endonucleases cut
3. Selectable marker genes - (e.g antibiotic resistence genes) protect the microorganism from a selective agent (antibiotics) which helps the microorganism to survive whilst other microorganisms which weren’t successful in recombinant DNA tech would die.
4. Origin of replication - allows self-replication of the plasmid/artifical chromosome
5. Regulatory sequences - control gene expression
6. Ligase - seals the gene into the plasmid

Question 10

Safety Mechanism

Answer 10

Genes are often introduced that prevent the survival of the microorganism in an external environment.

Question 11

Recombinant Yeast Cells

Answer 11

Recombinant yeast cells may be used,as plant or animal recombinant DNA expressed in the bacteria may result in polypeptides being folded incorrectly.