Cloning is the production of identical copies of DNA
Gene cloning is production of many identical copies of the same gene.
Recombinant DNA Technology
1. Recombinant DNA (rDNA) contains DNA from two or more different sources.
2. To make rDNA, technician selects a vector.
3. A vector is a plasmid or a virus used to transfer foreign genetic material into a cell.
4. A plasmid is a small accessory ring of DNA in the cytoplasm of some bacteria.
5. Plasmids were discovered in research on reproduction of intestinal bacteria Escherichia coli.
6. Introduction of foreign DNA into vector DNA to produce rDNA requires two enzymes.
a. Restriction enzyme is a bacterial enzyme that cuts DNA, it creates fragments of DNA with “sticky ends”
b. DNA ligase joins fragments together
1. PCR can create millions of copies of a single gene or a specific piece of DNA in a test tube.
2. The polymerase chain reaction (PCR) uses the enzyme DNA polymerase to carry out multiple replications (a chain reaction) of
1. Mitochondria DNA sequences in modern living populations can decipher the evolutionary history of human populations.
2. DNA fingerprinting is the technique of using DNA fragment lengths, resulting from restriction enzyme cleavage and amplified by PCR, to identify particular individuals.
a. DNA is treated with restriction enzymes to cut it into different sized fragments.
b. During gel electrophoresis, fragments separate according to length, resulting in a pattern of bands.
c. DNA fingerprinting can identify deceased individuals or perpetrators of crimes
3. PCR amplification and DNA analysis is used to:
a. detect viral infections, genetic disorders, and cancer;
b. determine the nucleotide sequence of human genes: the Human Genome Project; and
c. associate samples with DNA of parents because it is inherited.
1. Genetically engineered organisms can produce biotechnology products.
2. Organisms that have had a foreign gene inserted into them are transgenic.
A. Transgenic Bacteria
1. Bacteria are grown in large vats where they can make products such as insulin and human growth hormone, and vaccines
2. Transgenic bacteria have been produced to improve the health of plants and degrade substances, such as oil
3. Transgenic bacteria can produce chemical products, such as phenylalanine (artificial sweeteners)
B. Transgenic Plants
1. Foreign genes now give cotton, corn, and potato strains the ability to produce insect toxin s
2. Plants are being engineered to produce human proteins including hormones, clotting factors, and antibodies
C. Transgenic Animals
Animal use requires methods to insert genes into eggs of animals (early in development). Using this technique, many types of animal eggs have been injected with bovine growth hormone (bGH) to produce larger fishes, cows, pigs, rabbits, and sheep.
“Gene pharming” is the use of transgenic farm animals to produce pharmaceuticals; the product is obtainable from the milk of females.
D. Cloning Transgenic Animals
1. The cloning of Dolly in 1997 showed that mammals could be cloned.
2. Cloning of mammals involves injecting the nucleus of an adult cell into an enucleated egg.
3. The cloned eggs begin development in vitro and are then returned to host mothers until the clones are born.
Scenario 1: A well-loved horse named Barbero breaks his leg in a race. Many people were praying for his well being and thousands of dollars were spent trying to get him to recover. Mail and flowers poured into the animal hospital and stable where Barbero lived. Alas, after a year of poor recovery, the decision was made to euthanize Barbero. The owners save sample of his DNA so that Barbero can be cloned. Do you think they should clone him? Why or why not.
Scenario 2: Melissa is a happy 5 year old who is loved by her family. She becomes ill and is diagnosed with childhood leukemia. A desperate search ensues to find a bone marrow donor whose type matches Melissa. After a year of searching, Melissa’s outlook is grim. Her family decides to clone Melissa so that her clone could be the bone marrow donor. Do you think this is a god idea? Why or why not.
Genetics in the 21st century concerns genomics: the study of genomes of humans and other organisms.
A. Sequencing the Bases
The HapMap Project -- catalogs sequence differences, called haplotypes, in humans.
The Genetic Profile
16.4 Gene Therapy
1. Gene therapy involves procedures to give patients healthy genes to make up for a faulty gene.
2. Gene therapy also includes the use of genes to treat genetic disorders and various human illnesses.
3. There are ex vivo (outside body) and in vivo (inside body) methods of gene therapy.