Chapter 13 Genetics and Biotechnology 13.1 Applied Genetics

Selective Breeding The process by which desired traits of certain plants and animals are selected and passed on to their future generations is called selective breeding.

Selective Breeding Hybridization is crossing parent organisms with different forms of a trait to produce offspring with specific traits. Hybrid organisms can be bred to be more disease-resistant, to produce more offspring, or to grow faster. A disadvantage of hybridization is that it is time consuming and expensive.

Selective Breeding Specific traits in breeds can be maintained by inbreeding (breeding two closely related organisms) Clydesdale horses have been inbred to retain the desired traits: strength, agility, and obedient nature

Selective Breeding Disadvantages of inbreeding is that harmful recessive traits can also be passed to future generations German Shepherd hip dysplasia

Test Cross A test cross involves breeding an organism that has the unknown genotype (PP or Pp) with one that is homozygous recessive (pp) for the desired trait

Chapter 13 Genetics and Biotechnology 13.2 DNA Technology

Genetic Engineering Technology that involves manipulating the DNA of one organism in order to insert the DNA of another organism, called exogenous DNA.

Genetic Engineering Production of human insulin by bacteria was one of the first commercially successful uses genetic engineering technology.

Genetic Engineering Genetically engineered organisms are used: to study the expression of a particular gene. to investigate cellular processes. to study the development of a certain disease. to select traits that might be beneficial to humans.

Genetic Engineering Many bizarre and interesting uses for genetic engineering technologies have been reported.

DNA Tools An organism’s genome is the total DNA in the nucleus of each cell. DNA tools can be used to manipulate DNA and to isolate genes from the rest of the genome.

DNA Tools Restriction Enzymes are proteins used to cut DNA at specific sequences in specific ways. Restriction enzymes are naturally present in bacteria to cut and thus restrict foreign DNA from interfering with the bacterial DNA

Restriction Enzymes EcoRI specifically cuts DNA containing the sequence GAATTC. The ends of the DNA fragments, called sticky ends, contain single-stranded DNA that is complementary.

Restriction Enzymes

Gel Electrophoresis An electric current is used to separate DNA fragments according to the size of the fragments in a process called gel electrophoresis. When an electric current is applied, the DNA fragments move toward the positive end of the gel. The smaller fragments move farther faster than the larger ones.

Gel Electrophoresis The unique pattern created based on the size of the DNA fragment can be compared to known DNA fragments for identification.

Recombinant DNA Technology Recombinant DNA is DNA combined from two (or more) sources.

Recombinant DNA Technology A gene of interest from one organism’s DNA is cut out with a restriction enzyme. Another organism's DNA is cut open with the same restriction enzyme. The gene that was cut out is inserted in the open DNA of the second organism. Result is a transgenic organism Easy to insert genes into bacteria; more difficult with other organisms

Recombinant DNA Technology To make a large quantity of recombinant plasmid DNA, bacterial cells are mixed with recombinant plasmid DNA. Some of the bacterial cells take up the recombinant plasmid DNA through a process called transformation. Large numbers of identical bacteria, each containing the inserted DNA molecules, can be produced through a process called cloning.

Recombinant DNA Technology To understand how DNA is sequenced, scientists mix an unknown DNA fragment, DNA polymerase, and the four nucleotides—A, C, G, T in a tube.

Recombinant DNA Technology Each nucleotide is tagged with a different color of fluorescent dye. Every time a modified fluorescent-tagged nucleotide is incorporated into the newly synthesized strand, the reaction stops.

Recombinant DNA Technology The sequencing reaction is complete when the tagged DNA fragments are separated by gel electrophoresis.

Recombinant DNA Technology A technique called the polymerase chain reaction (PCR) can be used to make millions of copies of a specific region of a DNA fragment.

Recombinant DNA Technology

Uses of Recombinant DNA

Biotechnology Organisms genetically engineered by inserting a gene from another organism are called transgenic organisms.

Biotechnology Transgenic animals are produced for biological research.

Biotechnology Transgenic plants are produced to solve food or nutritional problems Rice plants with increased iron and vitamins could decrease malnutrition. Genetically engineered cotton resists insect infestation of the bolls.

Biotechnology Insulin, human growth hormone and substances that dissolve blood clots are made by transgenic bacteria. Transgenic bacteria slow the formation of ice crystals on crops to protect them from frost, clean up oil spills, and decompose garbage.

Chapter 13 Genetics and Biotechnology 13.3 The Human Genome

The Human Genome Project International Project to sequence the entire approximately three billion nucleotides that make up the human genome. Began in 1990 and completed in 2003; ahead of schedule and under budget. Found that less than 2% of all the nucleotides in the body code for all of the approximately 100,000 proteins in the body.

DNA Fingerprinting Using noncoding sequences that are unique to each individual (except identical twins), scientists can identify individuals by their DNA. Any cell of the body can be used since all cells have the same DNA (except red blood cells that do not have a nucleus). The amount of DNA is magnifed by PCR, then cut with restriction enzymes and separated by gel electrophoresis.

DNA Fingerprinting Banding patterns are unique to each person Used to identify suspects and victims in a crime, determine paternity, and identify soldiers killed in war. Also used to determine evolutionary relationships

Identifying Genes After sequencing the DNA the next step is identifying genes. Originally thought that humans had 100,000 genes because we have 100,000 proteins (one gene-one protein) Now know that we have 20,000-25,000 genes. Complicated analysis that uses information from other genomes DNA sequences along with computer algorithms

Bioinformatics and DNA Microarrays Bioinformatics is a field of study creates and maintains databases of biological information. DNA microarrays are tiny microscope slides or silicon chips which contain the genes of an organism (a few genes or the whole genome).

The Genome and Genetics Disorders More than 99% of an individuals DNA sequence is the same as any other individual. Some of the differences that exist are a result of a mutation to cause a genetic disorder. HapMap project seeks to identify common genetic variation that occur in humans.

The Genome and Genetics Disorders Pharmacogenomics is the study of how genetic inheritance affects the body’s response to drugs. Gene therapy is a technique used to correct mutated genes. Viruses are used as a vector to insert the “good” gene into the patients cells All gene therapy trials stopped in 2003 due to a death caused by a reaction to virus

Genomics and Proteomics Studying the genome is genomics. Genes are storage units Proteomics is the study of the structure and function of human proteins. Proteins are machines of the cell