Abraham Lincoln – Marfan SyndromeEmily Dickinson – Manic Depression

Vincent Van Gogh – EpilepsyAlbert Einstein – Dyslexia

John F. Kennedy – Addison’s DiseaseRita Hayworth – Alzheimer’s Disease

Ray Charles – Primary GlaucomaStephen Hawking – Amyotrophic Lateral

Sclerosis

Of course you may not have been born!

Chapter 13 – Genetic Engineering

Section 13-1: Changing the Living World

Humans have been able to control different species of organisms through several methods

Selective breeding = a method of breeding that allows only those individuals with desired characteristics to produce the next generation

Most domestic animals (dogs, cats, llamas, other farm animals) and crop plants have been produced through selective breeding

Selective breeding helped develop disease resistant crops to help food production

This technique was often used to develop those disease resistant crop strains

Hybrids are usually hardier than the parents and contain a mix of traits

Hybridization = crossing dissimilar individuals to bring together the best of both organisms

This technique is used to maintain desired characteristics in a line of organisms

Ex. Many dog breeds are maintained by inbreeding

Inbreeding = the continued breeding of individuals with similar characteristics

Inbreeding does have risks since the individuals are genetically similar, individuals could inherit recessive alleles resulting in defects (blindness, joint deformities)

While humans have worked to control some species, they

have also been able to increase variation as well

Breeders can increase the genetic variation in a population by introducing mutations, which are the ultimate source of genetic variability

Breeders can increase mutation rates by using radiation or chemicals

Scientists have produced many useful strains of bacteria using this method; ex. Bacteria that can digest oil could help to clean oil spills Scientists have also

been able to use this technique to create polyploidy plants (extra sets of chromosomes) which are usually larger and stronger

Section 13-2: Manipulating

DNA

Random mutations have a variety of results, both good and bad, but science has figured out how to methodically change DNA

Different techniques are used to extract DNA from cells, to cut DNA into smaller pieces, to identify the sequence of bases, and to make unlimited copies of DNA

Genetic engineering = making changes in the DNA code of a living organism

DNA extraction has become easy the cells are opened and the DNA is separated from the other cell parts

Restriction enzymes = enzymes that cut DNA at a specific sequence of nucleotides

Hundred of restriction enzymes are know and used as tiny scissors to cut DNA

In order to analyze DNA, it needs to be cut into smaller pieces

They are very precise and will only cut a DNA sequence if it matches exactly (like a lock and key)

Once DNA is cut into smaller pieces, it can be separated to be analyzed

Gel electrophoresis = a method of DNA separation in which a mixture of DNA fragments are placed at one end of a porous gel, and an electric voltage is applied

This method can be used to compare gene composition or even identify 1 particular gene

When the power is applied, the negatively charged DNA fragments start to move to the positive end of the gel (opposites attract)

Smaller pieces move faster and farther

Knowing the sequence of an organisms DNA allows scientists to study specific genes and figure out functions and specific gene combinations

In order to “read” DNA, scientists need a way to figure out the sequence of bases

They make many copies of the DNA – each one at a different length with a different dye on it

By separating the different length strands, they can determine the order of bases

They are able to use DNA polymerase to replicate an unknown strand

Enzymes that splice DNA together can be used to combine different pieces of DNA

Recombinant DNA = DNA that have been produced by combining DNA from different sources

Short pieces of DNA can be made by a lab machine (DNA synthesizer)

Scientists have determined a way to cut and paste DNA

Short segments are added to the beginning and end of DNA these are primers because they get the DNA ready to by copied by DNA polymerase

DNA is heated to separate the 2 strands then DNA polymerase and nucleotides are added and many copies get produced

A technique known as polymerase chain reaction (PCR) allows scientists to make many copies of DNA to be studiedPCR is like a copy machine for DNA

SECTION 13-3: CELL

TRANSFORMATION

What good would it do to modify DNA if it weren’t possible to put it back into a living cell and make it work?During transformation, a cell takes in DNA from outside the cell this external DNA becomes a component of the cell’s DNAGriffith was able to

demonstrate this with his pneumonia bacteria suggesting that bacteria can be transformed simply by placing them in a solution containing DNA

Plasmid = a small circular DNA molecules

Transforming bacteria

Plasmids are useful because they have DNA sequences that promote replication

Plasmids also have genetic markers that make it possible to tell if the bacteria has the plasmid (genes resistant to antibiotics are commonly used)

If the antibiotic resistance is used as a genetic marker, those cells that were transformed are the only ones that survive when treated with the antibiotic

Foreign DNA gets joined to the plasmid and the plasmids are added to cultures of bacteria

Bacteria cells take up the plasmids and get transformed

There are certain bacteria in nature that contain plasmids that infect plants and cause tumors

Scientists have figured out how to swap out the tumor causing DNA for foreign DNA

The plasmid can now be used to infect plants and transform them instead of cause tumors

Transforming plant cells

Many egg cells are large enough to inject DNA directly into the nucleus

Once in the nucleus, the enzyme that helps repair DNA may help insert the foreign DNA

Transforming animal cells

Section 13-4: Applications of Genetic

Engineering

Genetic engineering has spurred the growth of biotechnology, which is a new industry that is changing the way we interact with the living world

Transgenic organisms are organisms that contain genes from other species

Transgenic bacteria now produce many important substances useful for health and industry

Bacteria transformed with human genes can be used to make proteins such as insulin, growth hormone, and clotting factors

This makes it much easier and cheaper to treat certain diseases

Mice have been produced with human genes to make their immune systems similar to humans this allows scientists to study the effects of diseases on the human immune system

Livestock have been produced with extra growth hormone so that they can grow faster and produce leaner meat

Eventually, transgenic animals may be able to provide us with supplies of human proteins

Transgenic animals have been used to study genes and to improve food supply

Many plants have been transformed with a gene to produce a natural pesticide

Other plants have genes that make them resistant to weed killers

Eventually, transgenic plants may be able to produce human antibodies for fighting disease and other purposes

Transgenic plants are now an important part of the food supply

A clone = a member of a population of a genetically identical cells produced from a single cell

Scientists were able to prove they could clone multicellular organisms

Dolly (a sheep) was the first clone and was even able to reproduce

Cloning bacteria and other microorganisms has been easy to do

Researchers hope cloning will let us make copies of transgenic animals and help save endangered species

The technology is controversial because studies show that cloned animals may suffer from a number of genetic defects and health problems