Chapter 17 - DNA Technology Flashcards
“Recombinant DNA”
- Use enzymes + lab techniques to isolate segments of interest
- Combine/splice DNA from diff species
- Create genes w/ new functions
- Typ. involves propogation of recombinant DNA in bact/yeast cell
“Genetic engineering”
- Use lab-based tech to alter DNA
- Changing single base pair
- Deleting regions DNA
- Adding new segment
- May involve production of desired trait
- Cancer therapies, brewing yeasts, gen-mod plants/livestock
T/F: Plasmids are extrachromosomal DNA in bact, archaea, and euk
FALSE: Bact, arch and some fungi
T/F: Genes on plasmids NOT essential to host, but may confer selective advantage
TRUE
Desc method of “Restriction enzymes”
- Bind to spec sequences (recognition sites)
- Cleave doub-tranded DNA at this site or defined distance from it
What is the difference between Type I/III and Type II restrict. enzy?
Type I/III: ID rec site THEN cleave DNA a dist from it
Type II (most pop): cut DNA directly @ rec site
List two restriction enzymes, their microbial source, their recognition sequence and the ends that are produced.
- BamHI
Source: Bacillus amyloliquefaciens H
Rec seq: 5’ GGATCC ‘3 + reverse seq
Ends produced: 5’ G GATCC 3’ / 3’ CCTAG G 5’ - EcoRI
Source: Escherichia coli
Rec seq: 5’ GAATC 3’ + reverse seq
Ends produced: 5’ G AATTC 3’ / 3’ CTTAA G 5’
What is challenge w/ cloning euk DNA into bacteria?
Pre-mRNA (hnRNA) requires removal of introns, add. of poly A tail, 5’ cap (need to use version that can be made in bact)
What is solution to cloning euk DNA into bact?
Construction of complementary DNA (cDNA) involving role of key enzyme: reverse-transcriptase (uses euk mRNA as a template for cDNA, w/ primer TTTTTT…)
T/F: Positively-charged DNA moves towards the negative pole of the gel during gel electrophoresis.
FALSE: NEGATIVELY-charged DNA moves towards the POSITIVE pole.
Describe the mechanism by which gel electrophoresis is used to separate DNA.
- Restriction endonucleases selectively cleave DNA segments
- Restriction fragments are produced
- Processed DNA samples are loaded with dye and placed in the wells of the gel
- An electric current is induced in the gel
- As the current flows towards the positive pole, the negative DNA fragments travel through the gel. Smaller fragments travel farther than bigger ones.
- Fragments are separated based on size and compared to a ladder
Describe the southern blotting technique to ID strands of DNA.
- Separate DNA molecules
- Transfer-separated DNA molecules (buffer passes upwards through layers to transfer fragments on to filter)
- Filter placed on X-ray film to produce image of DNA bands (hybridize to radioactive spec DNA probe)
T/F: The radioactive probe present in the Western Blotting Technique is important for for IDing DNA sequences of interest and trying to prove with certainty that a band found on the cell is a spec gene seq.
FALSE: This is important for Southern blotting. Western Blotting concerns proteins.
What does the rxn mixture for PCR contain?
- Primers
- Target DNA (including gene of interest)
- Thermostable DNA polymerase (Taq)
- Each of 4 deoxyribonucleotide triphosphates (dNTPs)
“Primers” for PCR?
Synthesized DNA oligonucleotides 15-30 nucleotides long which provide the 3’ OH needed for DNA synthesis during PCR