Chapter 13 Section 1 DNA Technology

DNA Identification Only.10% of the human genome varies from person to person 98% of our genetic makeup does not code for any protein. Called noncoding DNA

Steps in DNA Identification 4 main steps Isolate the DNA in a sample and, if needed, make copies Cut the DNA into shorter fragments that contain repeating sequences Sort the DNA by size Compare the size fragments in the unknown sample of DNA to those of known samples of DNA If a match occurs, a person’s identity is known

Copying DNA:PCR Often the DNA samples collected are too small Polymerase Chain Reaction (PCR) is a technique that quickly produces many copies of a DNA fragment Use primers, artificially made pieces of single stranded DNA polymerase to initiate replication

Cutting DNA Restricting Enzymes Restriction enzymes-bacterial proteins used to cut long DNA molecules into shorter pieces These 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 size Gel Electrophoresis Gel electrophoresis separates nucleic acids or proteins according to their size and charge The resulting pattern of bands is called a DNA fingerprint

Comparing 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 strands 13 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 DNA The 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 substance Recombinant DNA results when DNA from two different organisms are joined

Plasmids Plasmids 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 DNA

Probe A probe is a strand of RNA or single-stranded DNA that is labeled with a radioactive element or florescent dye To determine which of the colonies contain the desired strand of DNA, researches will view them under ultraviolet lights or exposed to photographic film.

Medical Uses In 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 technology Types of uses Clotting factors Human growth hormone for people with growth defects Factors to treat immune-system deficiencies and anemia

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