BiotechnologyPacket #26

Chapter #9

Introduction

Since the 1970’s, humans have been attempted to manipulate and modify genes in a way that was somewhat predictable.

Biotechnology merges biological information with computer technology to advance research.

Biotechnology involves techniques that are used to make or modify the products of living organisms in order to improve plants or animals, or to develop useful microorganisms.

Key Terms & The Making of a Transgenic Organism

Transgenic Organism

A transgenic organism has had a gene(s), from another organism, inserted into its genome.

The inserted genes are then expressed to display a specific phenotype.

Necessities for Making a Transgenic Organism

In order to make a transgenic organism the following pieces are necessary to be used/produced: - Donor DNA Restriction Enzymes Fragments Vector DNA Recombinant DNA

The Process in a Nutshell I—Prokaryotic Transgenic Organism

There are variations, depending on what a scientist is trying to accomplish, in the making of a transgenic organism.

Scientists select a gene, from a donor, to be inserted into a different organism.

The gene of choice, found within/on the DNA molecule, would be cut out, using restriction enzymes, to produce a fragment.

The Process in a Nutshell II—Prokaryotic Transgenic Organism

The fragments are spliced into vector DNA—producing recombinant DNA. DNA ligase is used to join

the DNA fragment together with the vector’s genome.

Vector DNA is normally a plasmid.

The plasmid, now in the form of recombinant ,is inserted into bacterial cell.

The bacterial cell is replicated producing a transgenic organism.

The Process in a Nutshell III—Eukaryotic Transgenic Organisms

One way of producing a transgenic eukaryote would involve: - Inserting bacteria, or

viral, organism, containing the recombinant DNA, into the organism into eukaryote.

Waiting until the eukaryotes genome has been changed by the invading bacteria/virus.

The Process in a Nutshell IV—Eukaryotic Transgenic Organisms

A second technique for producing a transgenic eukaryote would involve: - Isolating a gene Inserting the gene into a

totipotent stem cell. Placing the stem cell(s)

into a blastocyst. Blastocyst = ball of cells

during early stages of embryonic development

Placing the blastocyst, with embryonic stem cell containing inserted DNA fragment, into uterus.

Purpose of Recombinant DNA

Recombinant DNA technology isolates and amplifies specific sequences.

Amplification can be accomplished by making more of the transgenic organisms. Accomplished via

organism reproduction Cloning.

The Importance of Transgenic Organisms

The Importance of Transgenic Organisms

Transgenic organisms allow gene targeting and mutagenesis screening that help identify the function of a gene and its protein product.

Cloning

Cloning

Cloning is the generation of genetically identical organisms

Genomics & Genetic Libraries

Genomic Library & cDNA Library

Genomic Library DNA library containing an

organism’s complete genome In the form of thousands

of DNA fragments

cDNA Library DNA library made up of

“DNA clones” reconstructed using reverse transcriptase Must be made from mRNA

Genomics Sub-discipline in genetics of

characterizing the entire genomes of organisms.

Homework Assignment

What are some of the advantages, and disadvantages, of having a cDNA library?

Genetic Probes

Genetic Probes

Genetic probes are radioactively labeled DNA or RNA sequence that enables geneticists to identify complementary nucleic acid sequences. If used to identify a DNA

strand, the DNA molecule will have to be separated into into two strands via artificial denaturation—heat.

The Making of Genetic ProbesSouthern Blot Technique

DNA fragments, produced using restriction enzymes, are separated via gel electrophoresis. Fragments are blotted

onto a nitrocellulose or nylon membrane.

The membrane is bathed in a labeled probe for a specific DNA fragment.

The selected DNA fragments are cut out of the gel

Homework Assignment

Define Northern Blot.

Define Western Blot.

Making Copies of DNA in a Lab Setting

Introduction

Once a sequence of DNA (DNA fragment) has been isolated, it is sometimes necessary to make large amounts of that sequence for study.

Polymerase Chain Reaction

Allows rapid, efficient amplification of DNA sequences of interest. In vitro technique

Researchers target a particular DNA sequence, by specific primers, and then clone the DNA sequence by heat resistant DNA polymerase.

Used to help amplify DNA from crime scenes and archaeological remains

Gene Therapy

Gene Therapy

Simple idea—hard to practice

The use of sequencing, cloning and vector insertion techniques to Deliver working

versions of genes to individuals who are born with deleterious mutant versions of the gene. Germ Line Therapy Somatic Gene

Therapy

Genetic Engineering & Food

Genetic Engineering of Agricultural Species

Foreign genes, under study, for insertion into commercial plant species. Helps provide Selective herbicide resistance Increased yield Plant-grown vaccines and

pharmaceuticals Improved nutrient balance

Problems? Human allergic reactions to

foreign proteins Increased use of herbicides “jumping” of plasmids from

commercial crops to weed species.

Eco-mayhem!

Review