deck_6659373 Flashcards
Genetic engineering-
modifying the DNA of an organism to new genes w new traits
Biotechnology-
use of organisms to benefit humanity
Recombinant DNA technology-
researchers splice together DNAfrom different organisms
steps and info recombinant DNA tech
Scientists introduce foreign DNA into the cells of microorganisms; When cell divides, the foreign DNA is replicated and transmitted to daughter cells; DNA sequence is therefore cloned to provide millions of identical copiesgeneticists cut both foreign DNA and plasmid DNA with the same restriction enzyme. The two types ofDNA are mixed together and combined
Restriction enzymes
are used to cut DNA molecules only in specific places; Each enzyme recognizes and cuts the DNA at different site; Many cut at palindromic sequences; Cuts both strands, but in a staggered fashion- producessticky ends; If sticky ends of two molecules are put together, they are sealed by DNA ligase
origin of restriction enzymes
Derived from bacteria cells, which use these enzymes as defense against viral DNA
palindromic sequences-
base sequence of one strand reads the same as its complements when both are read in the 5’ to 3’ direction
sticky ends-
tails which can base pair with a complementarytail of any other DNA fragment or molecule cut by the same restriction enzyme
Plasmid-
very small circle of extra DNA found in bacterial cells that has a few genes and is replicated along w the other bacterial DNA.
Transformation
DNA (plasmids) from one cell can be taken up by other bacterial cells; Useful to bacteria because it can offer resistance to antibiotics
vector
carrier capable of transporting a DNA fragment into a cell. plasmids, viruses, etc.
vector capabilities
Vector can only carry a certain size of DNA fragment(smaller than 10 kb E. coli, up to 23 kb bacteriophage)
recombinant tech diagram
vector page
Genomic library-
collection of thousands of DNA fragments thatrepresent all the DNA in a genome
DNA cloning inside bacterial cells–Genome Library creation
Each fragment from genomic library is inserted into a plasmid, which alsocontains the gene forantibiotic resistance• Plasmid is then inserted intobacterial cell• Cells are incubated on a medium containing antibiotics, so those bacteria that do not contain the plasmid will die, while those that incorporated the plasmid will grow• Entire genome is therefore stored in collection ofrecombinant bacterial cells
DNA cloning inside bacterial cells diagram–genomic library
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Chromosome library-
containing all DNA fragments of a specific chromosome
cDNA library-
contains DNA derivedfrom mRNA after processing- does not contain introns
cDNA
complementary DNA
cDNA diagram
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genetic probe
To find a gene of interest in a library, a genetic probe is used- radioactively labeled segment of single-stranded DNA that can hybridize, or base-pair, to complementary sequences in the target gene
genetic probe diagram
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Polymerase Chain Reaction (PCR) purpose
Can amplify a tiny sample of DNA millions of times in a fewhours (discovered in 1985)
Polymerase Chain Reaction (PCR) process
done in a thermocyclerMix together sequence of DNA, primers, nucleotide bases, and a special polymerase called Taq polymerase which does not denature in heat• Heat and cool mixture over and over, allowing the DNA strands to separate and copy- DNA doubles with every cycle, so after only 20 cycles, over 1m copies are made
PCR diagram
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gel electrophoresis
method that separates different molecules usinga charged field
gel electrophoresis diagram
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gel electrophoresis process
DNA or RNA is loaded into a gelo An electric current is applied, making one endpositive and one end negative (- by the wells)o DNA and RNA have a slight negative charged due tonegatively charged phosphate groups- therefore theymigrate toward the positive pullo Different fragments travel at different speeds: Shorter fragments travel faster thru the gel Larger fragments travel slower thru the gelo If DNA of a known size is added, scientists can compare these to the fragments to figure out the molecular weight
DNA fingerprint-
a unique combination of DNA sequences that are inherited from parents.
tandem repeats-
some parts of DNA fingerprintsmany copies of the same short base sequences, one after another ex–four repeats of TTTC in one person as compared to 15 repeats in another person.
Restriction Fragment LengthPolymorphisms (RFLPs)
tandem repeats–Restriction enzymes that cut the DNA will produce different size fragments based on the number of repeats; these different size fragments will be visible in a gel electrophoresis. The banding pattern of DNA fragments (5 – 10 RFLP regions are used) is the DNA fingerprint. Can determinepaternity; Suspects from crime scene can be proven innocent.
Designer Plants:
application of DNA tech. Can hybridize plants with other varieties of plants in order to transfer desired genes.Use a plasmid to infect plants from the bacteria calledAgrobacterium tumefaciens- causes tumor (mass of cells) of recombinant DNA. New plants can then be regenerated from individual cells. Plasmid is therefore called Ti plasmid ex–insert a built-in insecticide gene into cotton plants so farmers don’t have to use so many insecticides,
designer plants diagram
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DNA fingerprint diagram
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Gene therapy-
In individuals with single gene disorder, a new functional gene can be inserted into the cells Must be cells that actively divide in the body so newgene will be replicated. Must be disease that can be cured by production of the normal protein. New gene can be inserted into cells using a harmless virus as a vector
Transgenic animals-
animals in which foreign genes have been introduced. Transgenic animals can often be engineered to produce foreign proteins of therapeutic or commercial importance. Often done in mice to study certain genes- ex- injected mouse embryo cells with gene for rat growth hormone.
Transgenic animals- creation
Produced by injecting DNA of a particular gene into the nucleus of a fertilized egg cell or nucleus of embryonic stem cells, Then the egg (or stem cells) is placed into the uterus of a femaleand allowed to develop.
Transgenic animals can often be engineered to produce foreign proteins of therapeutic or commercial importance–give example
Ex- foreign gene can be inserted into gene that codes for milk proteins. So foreign gene is activated only inmammary tissues involved in milk production- wheneverthe animal (cow, goat, sheep) is milked, that protein isproduced
Human Genome Project
Using all these techniques, scientists have been able to sequence all 3billion bases of the human genome- Completed in 2003- Estimated that there are about 20,000 genes, yet there are almost as many pseudogenes- inactivated, nonfunctional copies of genes- as there are genes- Discovered that protein-coding genes make up less than 2 percent ofour genome. Millions of transposable elements repeated over andover make up more than half of it.
Production of pharmaceutical products:
Insulin used to be derived from animals, but many diabetics were allergic to insulin from animal source. Using recombinant DNA, the gene for insulin can be spliced into E. coli–> e coli produces human insulin. Similarly, human growth hormone (only used to be available from cadavers) can also be manufactured in bacteria.
