Biotechnology Principles And Processes Class 12 Biology Revision Notes
Class 12 Biology students should refer to the following concepts and notes for Biotechnology Principles And Processes in standard 12. These exam notes for Grade 12 Biology will be very useful for upcoming class tests and examinations and help you to score good marks
Biotechnology Principles And Processes Notes Class 12 Biology
Biotechnology is a broad area of science involving multiple disciplines designed to use living organisms or their products to perform valuable industrial or manufacturing processes or applications pertaining to human benefit.
Recombinant DNA technology:
An organism's genome contains virtually all the information necessary for its growth and development
Steps in producing recombinant DNA
1. The required gene is cut from a DNA molecule using a restriction enzyme.
2. A bacterial plasmid is isolated and cut with the same restriction enzyme. This ensures cut ends are complementary (same base sequence) to the ends of the required gene.
3. The required gene is joined to the plasmid using the enzyme DNA ligase in a process called ligation.
How do we obtain DNA and how do we manipulate DNA?
Quite straightforward to isolate DNA
For instance, to isolate genomic DNA
1. Remove tissue from organism
2. Homogenise in lysis buffer containing guanidine thiocyanate (denatures proteins)
3. Mix with phenol/chloroform - removes proteins
4. Keep aqueous phase (contains DNA)
5. Add alcohol (ethanol or isopropanol) to precipitate DNA from solution
6. Collect DNA pellet by centrifugation
7. Dry DNA pellet and resuspend in buffer
8. Store at 4°C
Each cell (with a few exceptions) carries a copy of the DNA sequences which make up the organism's genome.
How do we manipulate DNA?
It used to be difficult to isolate enough of a particular DNA sequence to carry out further manipulation and/or characterisation of its molecular sequence
Recombinant DNA Technology
- Purification of the TARGET fragment
- Cloning into vectors
- Transformation of host cell and selection
Introduction of recombinant DNA into host cells:
Some commonly used procedures:
5. Agrobacterium mediated gene transfer
DNA is manipulated using various enzymes that modify and/or synthesise it Until 1970 there were no convenient methods available for cutting DNA into discrete, manageable fragments.
1970 - The Beginning of the Revolution
Discovery of a restriction enzyme in the bacterium Haemophilus influenzae
. Restriction enzymes are endonucleases
• Bacterial enzymes .
• Different bacterial strains express different restriction enzymes.
• The names of restriction enzymes are derived from the name of the bacterial strain they are isolated from.
• Cut (hydrolyse) DNA into defined and REPRODUCIBLE fragments.
• Basic tools of gene cloning .
Names of restriction endonucleases
Titles of restriction enzymes are derived from the first letter of the genus + the first two letters of the species of organism from which they were isolated.
The product of each reaction is two double stranded DNA fragments
Restriction enzymes do not discriminate between DNA from different organisms
Restriction endonucleases are a natural part of the bacterial defence system
• Part of the restriction/modification system found in many bacteria
• These enzymes RESTRICT the ability of foreign DNA (such as bacteriophage DNA) to infect/invade the host bacterial cell by cutting it up (degrading it)
• The host DNA is MODIFIED by METHYLATION of the sequences these enzymes recognise
o Methyl groups are added to C or A nucleotides in order to protect the bacterial host DNA from degradation by its own enzymes
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