CHAPTER CHAPTER 13 & 1413 & 14

Genetic EngineeringGenetic Engineeringandand

The Human GenomeThe Human Genome

13-2 Manipulating DNA13-2 Manipulating DNA

A. Tools of Molecular BiologyA. Tools of Molecular BiologyScientists use their knowledge to transfer Scientists use their knowledge to transfer

genes, rewrite DNA codes, and eliminate genes, rewrite DNA codes, and eliminate mutations to create the best possible mutations to create the best possible genetic outcome. This new science is genetic outcome. This new science is called called Genetic EngineeringGenetic Engineering..

Genetic engineering - Genetic engineering - making changes in making changes in the DNA code of a living organismthe DNA code of a living organism..

Techniques of Genetic EngineeringTechniques of Genetic Engineering

1. DNA Extraction = 1. DNA Extraction = DNADNA is extracted is extracted from cells by a simple chemical procedure.from cells by a simple chemical procedure.

2. Cutting DNA - Scientists use 2. Cutting DNA - Scientists use restrictionrestriction enzymes to reduce DNA into fragments enzymes to reduce DNA into fragments that can be easily analyzed.that can be easily analyzed.

restriction enzymes – restriction enzymes – an enzyme that cuts an enzyme that cuts DNA at a specific sequence of nucleotidesDNA at a specific sequence of nucleotides..

Recognition sequences

DNA sequence

Restriction enzyme EcoRI cuts the DNA into fragments.

Sticky end

Restriction Enzymes

3.3. Separating DNA - DNA fragments can be Separating DNA - DNA fragments can be separated by a process called separated by a process called gel gel electrophoresis.electrophoresis.An electric voltage is applied to a gel plate An electric voltage is applied to a gel plate containing DNA fragments. The DNA containing DNA fragments. The DNA moves toward the positive end of the gel. moves toward the positive end of the gel. The smaller The smaller the DNA fragments the the DNA fragments the faster they move. As the DNA fragments faster they move. As the DNA fragments move, they create a pattern of bands in move, they create a pattern of bands in the gel. The bands are compared with the gel. The bands are compared with other samples of other samples of DNADNA. Gel . Gel electrophoresis can electrophoresis can be used to compare be used to compare gene composition of different individuals.gene composition of different individuals.

DNA plus restriction enzyme

Mixture of DNA fragments

Gel

Power source

Longer fragments

Shorter fragments

Figure 13-6 Gel Electrophoresis

B. Using the DNA Sequence B. Using the DNA Sequence With the DNA fragments separated, With the DNA fragments separated,

DNA molecules can now be read, DNA molecules can now be read, studied and changed.studied and changed.

1. Reading the sequence - The 1. Reading the sequence - The fragmentsfragments that are separated in gel that are separated in gel electrophoresis can be tagged with electrophoresis can be tagged with different dyes. The fragments are different dyes. The fragments are placed in a test tube with DNA placed in a test tube with DNA polymerase, four nucleotide bases, polymerase, four nucleotide bases, and a small number of bases that and a small number of bases that have a chemical dye attached.have a chemical dye attached.

Section 13-2

Figure 13-7 DNA Sequencing

2. Cutting and Pasting - It is possible to 2. Cutting and Pasting - It is possible to make make syntheticsynthetic sequences of DNA to be sequences of DNA to be spliced with natural occurring sequence spliced with natural occurring sequence using enzymes. These same enzymes using enzymes. These same enzymes make it possible to take a gene from one make it possible to take a gene from one organism and attach it to the DNA of organism and attach it to the DNA of another chromosome. This DNA is another chromosome. This DNA is sometimes called sometimes called recombinantrecombinant DNA. DNA.

Recombinant DNA – Recombinant DNA – DNA produced by DNA produced by combining DNA from different sourcescombining DNA from different sources..

13-4 Genetic Engineering13-4 Genetic Engineering A.A. Genetic engineering has spurred the Genetic engineering has spurred the

growth of biotechnology. With this new growth of biotechnology. With this new science, researchers are able to science, researchers are able to construct organisms that are transgenic.construct organisms that are transgenic.

Transgenic Organisms - Transgenic Organisms - A species that A species that contains genes from other species. contains genes from other species.

13-4 Genetic Engineering13-4 Genetic Engineering A gene from one organism can be A gene from one organism can be inserted into cells of another organism. inserted into cells of another organism. Transgenic microorganisms are now used Transgenic microorganisms are now used to produce a wide variety of substances to produce a wide variety of substances useful for health and industry. useful for health and industry.

Examples: Examples: insulin insulin production and production and human human growth hormones.growth hormones.

22. Transgenic Plants and Animals. Transgenic Plants and Animals

The major concept is that these The major concept is that these organisms are being widely used to organisms are being widely used to improve our food supply. This improve our food supply. This generation of plants and animals generation of plants and animals are now a major percentage of our are now a major percentage of our total food supply and are known as total food supply and are known as genetically modified foodsgenetically modified foods (GM (GM foods).foods).

3. Cloning 3. Cloning

A clone is a member of a population of A clone is a member of a population of identical cells produced from a single cell. identical cells produced from a single cell. The use of cloning technology is The use of cloning technology is controversial because it raises ethical and controversial because it raises ethical and moral issues.moral issues.

1997: Dolly, the lamb, was the first 1997: Dolly, the lamb, was the first mammalmammal cloned from an adult cell. cloned from an adult cell.

Cloning

Flowchart

A body cell is taken from a donor animal.

An egg cell is taken from a donor animal.

The fused cell begins dividing, becoming an embryo.

The nucleus is removed from the egg.

The body cell and egg are fused by electric shock.

The embryo is implanted into the uterus of a foster mother.

The embryo develops into a cloned animal.

A donor cell is taken from a sheep’s udder. Donor

NucleusThese two cells are fused using an electric shock.

Fused Cell

The fused cell begins dividing normally.

EmbryoThe embryo is placed in the uterus of a foster mother.Foster

Mother

The embryo develops normally into a lamb—Dolly

Cloned Lamb

Egg Cell

An egg cell is taken from an adult female sheep.

The nucleus of the egg cell is removed.

Figure 13-13 Cloning of the First Mammal

14-3 Human Molecular Genetics14-3 Human Molecular Genetics

A. DNA fingerprintingA. DNA fingerprinting

Molecular biologists have used the Molecular biologists have used the biological fact that no individual is biological fact that no individual is exactly like the other genetically. exactly like the other genetically.

1. DNA fingerprinting – 1. DNA fingerprinting – analyzes analyzes sections of DNA that have little or no sections of DNA that have little or no known function but vary widely from known function but vary widely from one individual to another.one individual to another.

Restriction enzyme

Chromosomes contain large amounts of DNA called repeats that do not code for proteins. This DNA varies from person to person. Here, one sample has 12 repeats between genes A and B, while the second sample has 9 repeats.

Restriction enzymes are used to cut the DNA into fragments containing genes and repeats. Note that the repeat fragments from these two samples are of different lengths.

The DNA fragments are separated according to size using gel electrophoresis. The fragments containing repeats are then labeled using radioactive probes. This produces a series of bands—the DNA fingerprint.

DNA Fingerprinting

14-3 Human Molecular Genetics14-3 Human Molecular Genetics

E. Gene Therapy - E. Gene Therapy - the process of the process of changing the gene that causes a changing the gene that causes a genetic disorder.genetic disorder.

In gene therapy an abnormal or faulty In gene therapy an abnormal or faulty gene is replaced by a normal gene is replaced by a normal working gene. This way the body working gene. This way the body can make the correct can make the correct proteinprotein or or enzymeenzyme to eliminate the disorder. to eliminate the disorder.

Normal hemoglobin gene

Bone marrow cell

Chromosomes

Genetically engineered virus

Nucleus

Bone marrow

Gene Therapy