16.1  DNA Cloning

 Cloning is the production of identical copies of DNA

  1. Stems or root send up new shoots that are clones of the parent plant.
  2. Members of a bacterial colony on a petri dish are clones because they all came from division of   the same cell.
  3. Human identical twins are clones; the original single embryo separate to become two individuals. (Artificial Twinning)
  4. Somatic Cell Nuclear Transfer (SCNT) – adult cells used to create an embryo

Gene cloning is production of many identical copies of the same gene.

  1. If the inserted gene is replicated and expressed, we can recover the cloned gene or protein product.
  2. Cloned genes have many research purposes: determining the base sequence between normal and mutated genes, altering the phenotype, obtaining the protein coded by a specific gene, etc.
  3. Humans can be treated with gene therapy: alteration of the phenotype in a beneficial way.

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

recombinant DNA

The Polymerase Chain Reaction

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
target DNA.

Analyzing DNA Segments

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.

16.2  Biotechnology Products

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.

16.3  Genomics

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

  1. DNA microarrays identify a person’s complete genotype; this is called the genetic profile.
  2. DNA profiles can determine if a person has an increased risk for a particular disease
  3. The genetic profile can be used to determine if a particular drug therapy is appropriate in a specific clinical condition.


  1. Proteomics is the study of the structure, function, and interaction of cellular proteins.
  2. The information obtained from proteomic studies can be used in designing better drugs, and to correlate drug treatment to the particular genome of the individual.


  1. Bioinformatics is the application of computer technologics to the study of the genome.
  2. Information obtained from computer analysis of the genome can show relationships between genetic profiles and genetic disorders.

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.

Other Chapters: 13-1 (Genetic Material), 13-2 (DNA Structure), 13-3 (Replication), 14-1 (Function of Genes), 15 (Mutations), 16 (Biotechnology),