key area 2.7 - genetic control of metabolism

Question 1

artificial chromosomes

Answer 1

• type of vector used in recombinant DNA technology which can carry larger fragments of forgein DNA that are required to be inserted into a host cell

Question 2

DNA ligase - recombinant DNA tech

Answer 2

• enzyme which seals the DNA fragment into the plasmid to form a recombinant plasmid

Question 3

properties that make an effective vector

Answer 3

• restriction sites for inserting DNA
• selectable marker genes
• origin of replication
• regulatory sequences to control gene expression

Question 4

selectable marker genes

Answer 4

• these protect the microorganism from a selective agent that would normally kill or prevent growth
• enables scientists to determine whether the plasmid vector has been taken up by the host cell or not

Question 5

restriction sites for inserting DNA

Answer 5

• the restriction site will contain target sequences of DNA where restriction endonuclease cuts
• the same enzyme will be used to cut the gene from the chromosome to ensure that the sticky ends are complimentary, allowing ligase to seal the strands together

Question 6

origin if replication

Answer 6

• this is where DNA replication begins, and is essential for the generation of many copies of the recombinant plasmid
• this means more copies of the gene are expressed producing more product per cell

Question 7

mutagenesis

Answer 7

• the creation of mutants by inducing mutations
• the rate of mutagenesis can be increased by exposing organisms to mutagenic agents eg UV light, radiation, mutagenic chemicals

Question 8

mutagenic agent

Answer 8

• agent which increases mutation rate when an organism is exposed to it

Question 9

recombinant DNA technology

Answer 9

• the process of gene sequences being transferred from one organism to another

Question 10

restriction endonuclease

Answer 10

• enzyme which is used to cut specific genes out of the donor organism and cut open the bacterial plasmids that receive the genetic information

Question 11

restriction site

Answer 11

• the location which restriction endonuclease cuts the DNA in such a way that it leaves sticky ends
• the target sequence is found if both DNA strands but running in opposite directions

Question 12

sticky ends

Answer 12

• these are produced by cutting nucleotides on each stand apart to leave a short single stranded fragment

Question 13

vector

Answer 13

• DNA molecule used to carry foreign genetic information into another cell

Question 14

strain improvement - wild strains need to be improved to?

Answer 14

• produce larger quantities of target compound
• improve generic stability
• improve ability to grow on low cost nutrients
• allow easy harvesting of the target compound

Question 15

strain improvement

Answer 15

• amplify a specific metabolic step in a pathway to increase the yield of target compound
• remove inhibitory controls
• cause cells to secrete product into surroundings for ease of harvesting
• for safety, gene that prevent survival of microorganisms on the wild/external environment

Question 16

why can yeast cells be used

Answer 16

• recombinant DNA expressed in bacteria can result in the production of polypeptides that are folded incorrectly are are non functional
• these proteins can be more successful in recombinant yeast cells, which are eukaryotic and so have enzymes that can produce active, functional forms of the protein