GENETIC CONTROL OF METABOLISM

Question 1

2 ways in which wild strains of micro-organisms can be improved

Answer 1

mutagenesis and recombinant DNA technology

Question 2

mutagenesis

Answer 2

• exposing micro-organisms to UV light and other forms of radiation or mutagenic chemicals resulting in mutations,
• some of which may produce an improved strain of micro-organism.

Question 3

what is involved in Recombinant DNA technology

Answer 3

Recombinant DNA technology involves the use of recombinant plasmids and artificial chromosomes as vectors

Question 4

vector

Answer 4

• a DNA molecule used to carry foreign genetic information into another cell
• Artificial chromosomes and plasmids are examples of vectors used in recombinant DNA technology
• Artificial chromosomes are preferable to plasmids as vectors when larger fragments of foreign DNA are required to be inserted

Question 5

the role of restriction endonucleases and ligases in recombinant DNA technology

Answer 5

• Restriction endonucleases cut open plasmids and leave STICKY ENDS.
• Complementary specific ends (sticky ends) are produced when the same restriction endonuclease is used to cut open the plasmid and the gene from the chromosome.
• Ligase will seal the gene into the plasmid.

Question 6

components of a recombinant plasmid and artificial chromosomes: restriction sites

Answer 6

Restriction Sites - contain target sequences of DNA where specific restriction endonucleases cut.

Question 7

components of a recombinant plasmid and artificial chromosomes: regulatory sequences

Answer 7

Regulatory sequences - control gene expression and origin of replication allows self-replication of the plasmid/artificial chromosome

Question 8

components of a recombinant plasmid and artificial chromosomes: origin of replication

Answer 8

Origin of replication - allows for self-replication of the plasmid/artificial chromosome.

Question 9

components of a recombinant plasmid and artificial chromosomes: selectable markers

Answer 9

• Selectable markers - such as antibiotic resistance genes protect the micro-organism from a selective agent (antibiotic) that would normally kill it or prevent it from growing
• The selectable marker gene ensures that only the micro-organisms that have taken up the vector grow in the presence of the selective agent (antibiotic).

Question 10

the safety mechanism often used in recombinant DNA technology

Answer 10

Genes are often introduced that prevent the survival of the micro-organism in an external environment

Question 11

the use of recombinant yeast cells in recombinant DNA technology

Answer 11

• as plant or animal recombinant DNA expressed in bacteria may result in polypeptides being incorrectly folded.
• recombinant yeast cells can be used to produce active (functional) forms of the protein