Chapter 13
Chapter 13Section 1 DNA TechnologyDNA Identification Only .10%
of the human genome varies from person to person98% of our genetic
makeup does not code for any protein.Called noncoding DNA
Steps in DNA Identification4 main stepsIsolate the DNA in a
sample and, if needed, make copiesCut the DNA into shorter
fragments that contain repeating sequencesSort the DNA by
sizeCompare the size fragments in the unknown sample of DNA to
those of known samples of DNA
If a match occurs, a persons identity is knownCopying
DNA:PCROften the DNA samples collected are too smallPolymerase
Chain Reaction (PCR) is a technique that quickly produces many
copies of a DNA fragmentUse primers, artificially made pieces of
single stranded DNA polymerase to initiate replication
Cutting DNA Restricting EnzymesRestriction enzymes-bacterial
proteins used to cut long DNA molecules into shorter piecesThese
enzymes are called endonuclease Will recognize specific short DNA
sequences and cut the DNA at, or near the targeted
sequence.Sometimes will leave sticky ends to aid complementary
sequences in binding.
Sorting DNA by sizeGel ElectrophoresisGel electrophoresis
separates nucleic acids or proteins according to their size and
charge
The resulting pattern of bands is called a DNA
fingerprintComparing DNA:DNA Fingerprints
A technician will permanently preserve DNA by placing a
positively charged nylon membrane over the gel
The DNA molecules in the gel are negatively charged, and
therefore stick to the membrane
Scientists will compare this membrane to the membrane of the
targeted DNA of interest.Is this accurate?DNA fingerprinting
typically compares 5-13 repeating strands of nucleotides.Crime labs
compare 13 strands13 strands will produce the odds that 2 people
will share the DNA profile at around 1 in 100 billion.There are
roughly 7 billion people in the world
I would say pretty good odds!Recombinant DNAThe previous
techniques are used to modify the genome of a living cell or
organism.Genetic engineering-the process of altering the genetic
material of cells or organisms to allow them to make a new
substanceRecombinant DNA results when DNA from two different
organisms are joined
PlasmidsPlasmids are small rings of DNA found naturally in some
bacterial cells in addition to the main bacterial chromosomes.
Steps of transferring insulin genes
Bacterial and targeted DNA
DNA is cut with restriction Enzymes
DNA segments are joined at sticky ends, using DNA ligase
Recombinant DNA is then inserted into host bacterium
After bacterium have been allowed to grown into colonies, a
probe will be used to identify targeted DNAProbeA probe is a strand
of RNA or single-stranded DNA that is labeled with a radioactive
element or florescent dyeTo determine which of the colonies contain
the desired strand of DNA, researches will view them under
ultraviolet lights or exposed to photographic film.
Medical UsesIn 1982, recombinant DNA was made by inserting human
gene for insulin into a bacterial plasmid Since 1982 more than 30
products have been made using DNA technologyTypes of usesClotting
factorsHuman growth hormone for people with growth defectsFactors
to treat immune-system deficiencies and anemia
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