Frontiers of Biotechnology

Chapter 9Mr. Scott

Manipulating DNA• How can

scientists manipulate the code?

• Scientists use their knowledge of the structure of DNA and its chemical properties to study and change DNA molecules.

Manipulating DNA• Tools of Molecular

Biology– Genetic

Engineering• Making changes in

the DNA code of a living organism

– DNA Extraction• Open a cell

(mechanical and chemical methods)

• Use a chemical to separate the DNA from the rest of the cell parts (an alcohol)

Manipulating DNA–Cutting DNA

• DNA molecules are very long

• Restriction enzymes

– Enzymes that cuts DNA at a specific sequence of nucleotides

• Restriction Site– Site where

restriction enzyme cuts DNA

• Hundreds of different restriction sites from enzymes

Manipulating DNA• Sticky ends

– these are the cut ends of the DNA–Pieces can stick to corresponding nucleotides

–Used in biotechnology

Manipulating DNA– Separating DNA

• Gel electrophoresis– A mixture of

DNA fragments is placed at one end of a porous gel (negative end), and an electric voltage is applied to the gel

–The molecules will move from negative to positive

Manipulating DNA• Restriction Maps–A pattern of bands showing lengths of cut DNA

–Can be used to study mutations

Manipulating DNA

Copying DNA• PCR or Polymerase chain reaction

• Photocopying DNA over and over

• Use strands of DNA that are called primers

Copying DNA• 3 – Step

Process– Need DNA to

be copied, 4 bases, and two primers

• Primers – short segment of used for starting point

• Steps1. Separating2. Binding3. Copying

DNA Fingerprinting• DNA

Fingerprinting–DNA that can

be used for identification

–Cut with enzyme and run through gel electrophoresis

DNA Fingerprinting• Greatest differences in DNA are found in regions not used for genes–Each person has differing numbers of repeating units in similar regions

–Differences are found by gel electrophoresis

DNA Fingerprinting• Indentification and Probability–Identification depends on probability

DNA Fingerprinting• Uses of

Fingerprinting–Criminal cases–Family

relations• Paternity• Kinship for

immigration purposes

• Species studies

• Agriculture

Genetic Engineering• Cloning

– Clone – a genetically identical model• Gene or organism

–Transfer DNA between cells

–Dolly – The cloned sheep from 1997

–Controversial

Genetic Engineering• Cloning has potential

benefits.–organs for transplant into humans

–save endangered species• Cloning raises concerns.

–low success rate–clones “imperfect” and less healthy than original animal

–decreased biodiversity

Genetic Engineering• Genetic Engineering–Changing DNA to give it new traits

–Can insert healthy genes or cloned genes

Manipulating DNA–Cutting and

Pasting• Recombinant DNA

• Enzymes join genes from one strand of DNA with genes from another strand of DNA

• DNA synthesizers

– Enzymes join artificial pieces of DNA with natural pieces

Genetic Engineering• Transforming

Bacteria–Foreign DNA is

joined to plasmid• Plasmid – small,

circular DNA molecule

• Genetic marker – a gene that makes it possible see which bacteria are carrying the plasmid (that is marked) and which bacteria are not.

Genetic Engineering• Transformation–When a cell takes in foreign DNA and joins it with the existing DNA

–This external DNA becomes part of the cells DNA

Genetic Engineering• New genes can

be added to an organism’s DNA.– Genetic

engineering involves changing an organism’s DNA to give it new traits.

– Genetic engineering is based on the use of recombinant DNA.

– Recombinant DNA contains genes from more than one organism.

(bacterial DNA)

Genetic Engineering• Transgenic

Organisms–Organisms that contain genes from other species

–Firefly and tobacco plant

–Genetic engineering has increased the growth of biotechnology

Genetic Engineering• Transforming Plant

Cells– Using bacterium

that normally infect plant cells and cause tumors

– Taking away the cell wall some plant cells will take up DNA on their own

– If successful recombinant DNA will be found in a chromosome of the cell

Genetic Engineering• Transforming

Animal Cells– DNA can be

injected directly into the nucleus of an egg

– Enzymes help insert the new DNA into the eggs existing DNA

– New DNA contains markers that tell which cells picked up the DNA

Genetic Engineering

–Transgenic microorganisms• Bacteria reproduce quickly

• Uses:–Can grow human

proteins• Insulin, growth

hormone, and clotting factor

Genetic Engineering

–Transgenic Animals• Mimic human body for testing

• Faster growing animals

• No more food poisoning

• Grow human proteins

Genetic Engineering• Transgenic

animals are used to study diseases and gene functions.– Transgenic mice

used to study development and disease

– Gene knockout mice used to study gene function• Leptin – helps

control food intake – common for the obese

Genetic Engineering

Genetic Engineering–Transgenic Plants

• Natural insecticide

• Resist weed killing chemicals

• Food resistant to spoiling

• Weather resistant plants

• Grow vitamins or proteins

Genomics and Bioinformatics

• Genomics is the study of genomes.–Can include the sequencing of the genome

–Comparisons of genomes within and across species

Genomics and Bioinformatics

• DNA Sequencing–Determining

the order of DNA nucleotides in genes or in genomes.

–Genomes of several different organisms have been sequenced

Genomics and Bioinformatics

• The Human Genome Project– Has sequenced

all of the DNA base pairs of human chromosomes.

– Analyzed DNA from a few people

– Still working to identify and map human genes

Genomics and Bioinformatics

• Technology and Genes– Bioinformatics

• The use of computer databases to organize and analyze biological data.

– DNA microarrays • Used to study

the expression of many genes at once.

– Proteomics – The study and

comparison of proteins.

Genetic Screening and Therapy

• Genetic screening can detect genetic disorders.– Determines risk of having

or passing on a geneticdisorder

– Used to detect specificgenes or proteins

– Can detect some genesrelated to an increasedrisk of cancer

– Can detect some genesknown to cause geneticdisorders

DMD N

Genetic Screening and Therapy

• Gene therapy is the replacement of faulty genes.

• Several experimental techniques are used for gene therapy.–Genetically engineered viruses

used to “infect” a patient’s cells– Insert gene to stimulate

immune system to attack cancer cells

– Insert “suicide” genes into cancer cells that activate a drug

Genetic Screening and Therapy

• Gene therapy has many technical challenges.–Inserting gene into correct cells

–Controlling gene expression–Determining effect on other genes