Ch.13 Modern Applications of Microbial Genetics Flashcards
Molecular Cloning using Transformation Protocol
1) bacterial cells plated onto antibiotic-containing medium (inhibits cells that were not transferred by plasmid)
2) blue-white screening technique is used for lac Z encoding plasmid vectors (pUC19)
3) White colonies resulting from blue-white screening contain plasmids with an insert and can be further screened to characterize the foreign DNA
4) to ensure the correct DNA was incorporated into the plasmid, the DNA insert can then be sequenced
Blue colonies
have a functional beta-galactosidase enzyme because the lacZ gene is uninterrupted (no DNA inserted to polylinker site)
-result from digested, linearized plasmid religating to itself
White colonies
lack a functional beta-galactosidase enzyme indicating the insertion of foreign DNA within the polylinker site of the plasmid vector
- disrupts the lacZ gene
transfection
the introduction of recombinant DNA molecules into eukaryotic hosts
What laid the foundation for recombinant DNA technology?
use of bacterial hosts – particularly eukaryotic
what are transgenic plants & provide example
genetically engineered plants
- bacterial strain that produces human insulin
Flavr Savr plant
first transgenic plant sold commercially
- delayed ripening tomato in 1944
blue-white screening
allows selection of bacterial transformants that contain recombinant plasmids using the phenotype of a reporter gene that is disabled by insertion of the DNA fragment
biotechnology
the science of using living systems to benefit humankind
genetic engineering
involves the use of recombinant DNA technology, the process by which a DNA sequence is manipulated in vitro, thus creating recombinant DNA molecules that have new combinations of genetic material – the recombinant DNA is then introduced into a host organism
genetic engineering
involves the use of recombinant DNA technology, the process by which a DNA sequence is manipulated in vitro, thus creating recombinant DNA molecules that have new combinations of genetic material – the recombinant DNA is then introduced into a host organism
When is an organism considered transgenic?
if the DNA that is introduced comes from a different species
How do prokaryotes acquire foreign DNA and incorporate functional genes into their own genome?
Horizontal Gene Transfer processes…
- Conjugation: mating with other cells
- Transduction: viral infection
- Transformation: taking up DNA from environment
molecular cloning
a set of methods used to construct recombinant DNA and incorporate it into a host organism
-Herbert Boyer and Stanley Cohen first demonstrated cloning process with African clawed frog
How are DNA molecules manipulated in recombinant DNA technology?
using naturally occurring enzymes derived from bacteria and viruses
What makes the creation of recombinant DNA molecules possible?
endonucleases (restriction enzymes)
- bacterial enzymes produces as a protection mechanism to cut and destroy foreign DNA that is most commonly a result of bacteriophage infection
restriction enzyme role in forming recombinant molecules
cutting DNA fragments that can then be spliced into another DNA molecule
-cuts at a recognition site (usually palindromic sequence)
Palindrome
a sequence of letter that reads the same forward as backward
-contain same base pair sequences in 5-3 direction as the 5-3 direction on complementary sequence
How does a restriction enzyme cut the Palindrome?
it recognizes the palindrome and cuts each backbone at identical positions
-their cut reveals sticky or blunt ends
Do blunt ends or sticky ends of the palindrome better attach?
sticky ends: form hydrogen bonds b/w complementary bases
hybridization
refers to the joining together of two complementary single strands of DNA
What process rejoins the two single strands of DNA together in recombination?
ligation by DNA ligase
Plasmid
small pieces of circular, double stranded DNA that replicate independently of the bacterial chromosome