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Points to Ponder. A natural disaster strikes. Families are separated. How can they be reunited? If a body is found and the person cannot be identified by looks, how can we identify them? What types of identifiers do we have?.
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Points to Ponder A natural disaster strikes. Families are separated. How can they be reunited? If a body is found and the person cannot be identified by looks, how can we identify them? What types of identifiers do we have?
A natural disaster strikes. Families are separated. How can they be reunited? • If a body is found and the person cannot be identified by looks, how can we identify them? • What types of identifiers do we have? • DNA- skin, sperm, saliva, blood • Fingerprinting • Teeth
Sydney Leslie Goodwin 1910-1912 • Died in the sinking of the RMS Titanic • Known as “The Unknown Child” • The Goodwins and their 6 children were third class passengers and all perished • Finally identified in 2007 using DNA
KEY CONCEPT Biotechnology relies on cutting DNA at specific places. Baby 81 was rescued after the 2004 Indian Ocean tsunami. He was reunited with his parents by using DNA fingerprinting technology
Biotechnology allows us to • Produce transgenic organisms • Clone • Study diseases and evolution • Produce medical treatments for people with illnesses
DNA cannot be picked up and rearranged by hand • Therefore, scientists must be able to work with DNA without being able to see it, or handle it directly
Scientists use several techniques to manipulate DNA. • Chemicals, computers, and bacteria are used to work with DNA. • Scientists use these tools in genetics research and biotechnology.
Restriction enzymes act as “scissors” by cutting DNA • allow scientists to more easily study and manipulate genes • cut DNA at a specific nucleotide sequence called a restriction site Restriction enzyme DNA
Different restriction enzymes cut DNA in different ways. • each enzyme has a different restriction site
some cut straight across and leave “blunt ends” • some make staggered cuts and leave “sticky ends” Sticky ends
Between what nucleotides does this restriction enzyme cut between? T and C or C and T
Restriction enzyme: cuts between T and A ATTACGACCTAGGACG How many fragments are produced? Are all the fragments the same length? Please organize the fragments from biggest to smallest. How many nucleotides in each segment when organized?
Restriction enzyme: cuts between T and A ATTACGACCTAGGACG How many fragments are produced? 3 Are all the fragments the same length? No Please organize the fragments from biggest to smallest. ACGACCT/AGGACG/ATT How many nucleotides in each segment when organized? 7, 6, 3
After DNA has been cut, several different things can be done with it • The gene can be studied • The gene can be placed in another organism • But first, the DNA fragments have to be separated from one another • Sorted according to their size
Gel electrophoresis is used to separate DNA fragments by size. • A DNA sample is cut with restriction enzymes. • Electrical current pulls DNA fragments through a gel.
Smaller fragments move faster and travel farther than larger fragments. • Fragments of different sizes appear as bands on the gel.
A restriction map shows the lengths of DNA fragments between restriction sites. • only indicate size, not DNA sequence • useful in genetic engineering • used to study mutations
Restriction enzyme: cuts between T and A ATTACGACCTAGGACG Please organize the fragments from biggest to smallest. ACGACCT (7) AGGACG (6) ATT (3)
- Please organize the fragments from biggest to smallest. ACGACCT (7) AGGACG (6) ATT (3) 10 9 8 7 6 5 4 3 2 1 0 - - - +