7.5 - Genetic modification (genetic engineering)
Manipulating genes
● ***Genome: (total) genetic information carried on chromosomes inside EACH cell
○ This information carried in DNA, in form of sequences of bases making up
each gene
● ***Genetic modification (GM): making changes to DNA molecule, e.g.:
○ Moving gene from one species into different species - species then
becomes transgenic, given new characteristic
■ ***Transgenic (轉基因): transfer of genetic material from one
species to a different species
○ Changing base sequence of gene → altering protein structure for which
it codes
○ Deleting gene by removing it from chromosome
Using restriction enzymes (限制酶) and ligase enzymes
(連接酶) to make recombinant DNA
● Restriction enzymes - collected from different species of bacteria
○ Each type recognizes a particular sequence of bases in a DNA molecule
(restriction site), THEN completely cuts the DNA double helix at this site
■ Usually cut DNA double helix in staggered way, leaving overhanging
single-stranded lengths of DNA (sticky ends)
● When different species of DNA, with matching “sticky ends”, mixed together in
solution, sticky ends of one piece pair up with the other → creating single
recombinant DNA molecule (hybrid [雜交種])
○ Temporary join between 2 pieces in recombinant DNA can be made
permanent, with use of DNA ligase (ALSO found in bacteria) - makes
strong bond in region of (temporary) joining point
1
, ●
Plasmids and viruses as vectors
● ***Vector (載體): carry genes into cells, creating transgenic organisms
○ E.g.: piece of DNA (e.g.: plasmid)/DNA from inside of virus can move into
cells under certain conditions & act as vector
● Using recombinant plasmids as vectors
○ ***Plasmid (質粒): small circle of DNA present in bacteria; usually
carry just a few genes, much smaller than main DNA chromosomes
of bacteria (with 100+ genes)
■ Naturally exchanged/swapped between bacteria
○ Way of introducing foreign genes (i.e.: genes from other species) into
bacteria
2
Manipulating genes
● ***Genome: (total) genetic information carried on chromosomes inside EACH cell
○ This information carried in DNA, in form of sequences of bases making up
each gene
● ***Genetic modification (GM): making changes to DNA molecule, e.g.:
○ Moving gene from one species into different species - species then
becomes transgenic, given new characteristic
■ ***Transgenic (轉基因): transfer of genetic material from one
species to a different species
○ Changing base sequence of gene → altering protein structure for which
it codes
○ Deleting gene by removing it from chromosome
Using restriction enzymes (限制酶) and ligase enzymes
(連接酶) to make recombinant DNA
● Restriction enzymes - collected from different species of bacteria
○ Each type recognizes a particular sequence of bases in a DNA molecule
(restriction site), THEN completely cuts the DNA double helix at this site
■ Usually cut DNA double helix in staggered way, leaving overhanging
single-stranded lengths of DNA (sticky ends)
● When different species of DNA, with matching “sticky ends”, mixed together in
solution, sticky ends of one piece pair up with the other → creating single
recombinant DNA molecule (hybrid [雜交種])
○ Temporary join between 2 pieces in recombinant DNA can be made
permanent, with use of DNA ligase (ALSO found in bacteria) - makes
strong bond in region of (temporary) joining point
1
, ●
Plasmids and viruses as vectors
● ***Vector (載體): carry genes into cells, creating transgenic organisms
○ E.g.: piece of DNA (e.g.: plasmid)/DNA from inside of virus can move into
cells under certain conditions & act as vector
● Using recombinant plasmids as vectors
○ ***Plasmid (質粒): small circle of DNA present in bacteria; usually
carry just a few genes, much smaller than main DNA chromosomes
of bacteria (with 100+ genes)
■ Naturally exchanged/swapped between bacteria
○ Way of introducing foreign genes (i.e.: genes from other species) into
bacteria
2
