CHAPTER 19 : GENETIC TECHNOLOGY 👩🔬
GENETIC ENGINEERING
Aim : remove a gene from one organism and transfer it into another so that the gene is
expressed in it new host
Recombinant DNA (rDNA) - DNA made by joining pieces from two or more different sources
Genetically modified organism (GMO) - the organisms that expresses new gene(s)
GENE TECHNOLOGY
The change in genetic material in the cell which therefore changes the product of the cell
during protein synthesis
ENZYMES FOR GENE TECHNOLOGIST
1)RESTRICTION ENZYMES (ENDONUCLEASE)
- enzyme that cuts DNA at or near specific recognition nucleotide sequences known as
restriction sites
-cut straight across the sugar-phosphate backbone to give blunt ends or they cut in a
staggered fashion to give sticky ends
-sticky ends= short lengths of unpaired bases that can easily form hydrogen bonds with
complementary sequences of bases on other pieces of DNA cut with the same restriction
enzyme
2)REVERSE TRANSCRIPTASE
-enzyme used to generate complementary DNA (cDNA) from an RNA template. This creates
single-stranded DNA from an RNA
-mainly associated with retroviruses
3)DNA POLYMERASE
-convert single-stranded DNA molecule into double-stranded DNA ,by adding free nucleotide
to the exposed bases on the strand by complementary base pairing
-now, the DNA can be inserted into a suitable vector, such as a plasmid
4)DNA LIGASE
-join together the sugar-phosphate backbones of the DNA molecule and plasmid, producing
a closed circle of double-stranded DNA containing the new gene.
STEPS IN RECOMBINANT DNA TECHNOLOGY
, 1)Identification & isolation of gene of interest or DNA fragment to be cloned
i)The gene donor is the human pancreas.
iii)The isolated gene insulin gene. It is then cut by restriction enzymes to leave sticky ends.
Plasmid as a vector is extracted from E.coli bacteria. It is also cut with the same restriction
enzymes to produce sticky ends.
2)Insertion of this isolated gene in a suitable vector
-Vector - a DNA molecule containing the foreign integrated gene that can multiply within the
living host cell
PLASMIDS
-small, circular, double-stranded DNA
-often carry genes that may benefit the survival of the organism, eg antibiotic resistance
Properties
1)small so that it can easily enter cells
2)circular so it is not damages by host cell enzymes
3)self-replicate in cell so it can multiply to make many copies of gene
4)have restriction site so new gene can be added
5)have antibiotic resistance/ fluorescence genes so recombinants/ cells that took up
plasmid can be recognised
6)have promoter so gene can be expressed
GENETIC ENGINEERING
Aim : remove a gene from one organism and transfer it into another so that the gene is
expressed in it new host
Recombinant DNA (rDNA) - DNA made by joining pieces from two or more different sources
Genetically modified organism (GMO) - the organisms that expresses new gene(s)
GENE TECHNOLOGY
The change in genetic material in the cell which therefore changes the product of the cell
during protein synthesis
ENZYMES FOR GENE TECHNOLOGIST
1)RESTRICTION ENZYMES (ENDONUCLEASE)
- enzyme that cuts DNA at or near specific recognition nucleotide sequences known as
restriction sites
-cut straight across the sugar-phosphate backbone to give blunt ends or they cut in a
staggered fashion to give sticky ends
-sticky ends= short lengths of unpaired bases that can easily form hydrogen bonds with
complementary sequences of bases on other pieces of DNA cut with the same restriction
enzyme
2)REVERSE TRANSCRIPTASE
-enzyme used to generate complementary DNA (cDNA) from an RNA template. This creates
single-stranded DNA from an RNA
-mainly associated with retroviruses
3)DNA POLYMERASE
-convert single-stranded DNA molecule into double-stranded DNA ,by adding free nucleotide
to the exposed bases on the strand by complementary base pairing
-now, the DNA can be inserted into a suitable vector, such as a plasmid
4)DNA LIGASE
-join together the sugar-phosphate backbones of the DNA molecule and plasmid, producing
a closed circle of double-stranded DNA containing the new gene.
STEPS IN RECOMBINANT DNA TECHNOLOGY
, 1)Identification & isolation of gene of interest or DNA fragment to be cloned
i)The gene donor is the human pancreas.
iii)The isolated gene insulin gene. It is then cut by restriction enzymes to leave sticky ends.
Plasmid as a vector is extracted from E.coli bacteria. It is also cut with the same restriction
enzymes to produce sticky ends.
2)Insertion of this isolated gene in a suitable vector
-Vector - a DNA molecule containing the foreign integrated gene that can multiply within the
living host cell
PLASMIDS
-small, circular, double-stranded DNA
-often carry genes that may benefit the survival of the organism, eg antibiotic resistance
Properties
1)small so that it can easily enter cells
2)circular so it is not damages by host cell enzymes
3)self-replicate in cell so it can multiply to make many copies of gene
4)have restriction site so new gene can be added
5)have antibiotic resistance/ fluorescence genes so recombinants/ cells that took up
plasmid can be recognised
6)have promoter so gene can be expressed
