Biotechnology Flashcards
What is Morden biotechnology ?
Morden biotechnology refers to the processes and techniques that involved in the manipulation of DNA, cells, tissues, or biological processes to attain knowledge, produce goods and products.
Using the production of human insulin as an example, describe the major steps in recombinant DNA technology.
- Obtain DNA fragments containing the DNA encoding human insulin (the gene of interest).
- Obtain vectors (e.g. plasmids).
- Cut the DNA fragments and the plasmids using the same restriction enzyme.
- Join the DNA fragments and the open plasmids together using a DNA ligase.
What is plasmids ?
Plasmids are small rings of double-stranded extrachromosomal DNA
What is the function of plasmid ?
As vectors for transferring gene of interests into host cells
Name the enzyme used in the recombinant DNA technology
Restriction enzyme
What is the function of restriction enzyme ?
~ recognises a specific base sequence and cuts the doubled-stranded DNA
~cut open the plasmids
Why same restriction enzyme is used to cut both plasmids and DNA sample ?
~ restriction enzyme recognizes a specific base sequence and cuts the double-stranded DNA.
~some restriction enzyme leave short lengths of single-stranded DNA at cut ends. These cut ends are called /sticker ends
~the unpaired base in sticky ends of DNA fragments are complementary to those in the sticker ends of the plasmids
Why same restriction enzyme is used to cut DNA samples?
~ cut the DNA with the same base sequence
How do DNA fragments and plasmid blind together?
With the help of the DNA ligase, the DNA fragment and the plasmids joined together by hydrogen bond.
What is the function of the DNA ligase ?
~ catalyses the joint of the DNA fragment and the plasmids by covalent bond (hydrogen bond)
what is the purpose of introducing the recombinant plasmid into the hosts cells?
replication and expression of the DNA encoding the gene of interest
what bacteria is usually used for the introdcing of ploasmids?
E.coli
Why plasmids need to carry a selective marker ?
To enable selection of transformed bacteria
how to select the traansformed plasmids?
~plasmids carrying a selective marker such as an antibiotic resistance gene are often used as vectors
~ when the bacteria that have been mixed with the recombinant plasmids are cultured on an agar plate containing the antibiotic, only the transformed bacteria which carrying the antibiotic resistance gene survive and divide to form colonies
describe the process of the gene cloning
~ after the selection of the transformed plasmids, they are clutured in the steel tanks caklled fermenters.
~in each bacterium, ther recombinant plasmids replicates independently of the bacterial chromosome
~the plasmids is also copied into the daughter cells when bacterium divides
~ as a resuklts, many copies of the DNA encoding the gene of interest may formed
how is the human inslulin produced using recominant plasmids?
~ the recombinant plasmids anre introduced to the bacteria (host cell)
~the transformed bacteria is then selected by culturing the bacteria ojn the agar plant containg the antibiotic
~the transormed bacteria are cultured in fermeters
~DNA encoding human insulin is expressed ande polypeptides are produced
~ the polypeptide is extracted from bacteria and processed into the functional human insulin
what is the advantages using recombinant DNA technology in human insulin production
~insulin produced is same as the insulin produced in human body —> no rejection by the immune system
~the insulin produced is pure
~the production yield is high:
* many copies of the DNA encoding the human insulin are present in the bacterial culture.
* the growth rate is high
* the bacterial culture continuously produced insulin whereas each animal pancreas can only provide a limited amount of insulin
~ extraction cost is low
Why do people not using pig insulin?
~may cause tissue rejection
~may cause disease