6.1.3 - Manipulating Genomes (set B - Genetic Engineering)

Question 1

What is genetic engineering?

Answer 1

Manipulation of the genome - involves isolation a gene for a desirable characteristic in one organism and placing it into another organism, though the use of a suitable vector

Question 2

Outline and explain how the desired gene is isolated - give 2 ways?

Answer 2

• restriction endonuclease enzymes cut required gene from DNA of an organism (cut the 2 strands unevenly - leaving one strand of DNA fragments a few bases longer than the other) sticky ends make it easier to insert desired gene into DNA of different organism
• isolating the mRNA for the desired gene and using the enzyme reverse transcriptase to produce a single strand of complementary DNA (easier to identify the desired gene)

Question 3

Explain the role of vectors within genetic engineering?

Answer 3

• most common are bacterial plasmids - can combined with host DNA to form recombinant DNA
• plasmids often chosen because they contain a marker gene - allows scientists to identify cell that have successfully taken up the plasmid

Question 4

Explain how DNA fragments are inserted into plasmids?

Answer 4

Plasmid cut open (restriction endonuclease is used - same one used to isolate DNA fragments)

Plasmid has complementary sticky ends to the sticky ends of the DNA fragment - complementary bases of the sticky ends are lined up - enzyme DNA ligase forms phosphodiester bonds between sugar and phosphate groups of 2 strands of DNA - joining them

Question 5

explain the role of marker genes in plasmid vectors?

Answer 5

Marker genes are essential in plasmids because they help identify which cells have successfully taken up the plasmid

• second marker gene used to show recombinant gene - will not function if DNA fragment is inserted successfully
• often gene producing a fluorescent or enzyme that triggers colour change

Question 6

Transferring vector