PowerPoint Presentation

1So you are studying for your exam: Genetic EngineeringDisclaimer: This is a REVIEW of key points and Learning Target concepts of the unit and is based on the premise of prior learning of the unit. It is not meant as a stand-alone teaching lesson.On each slide CLICK the audio icon for slide narrated explanation, otherwise refer to associated slide notes.Each slide has its own audio file associated with it .

Welcome to this episode of the So you are studying for your exam video series.

This episode deals with Genetic Engineering

As with all the episodes in this series, the standard disclaimer applies

Look for the Audio Icon for narration explanation of each slide.1

Genetic Engineering:Changing and adding genes to an organisms DNA to give it new traitsClone genes not whole organisms How and why can we do this?DNA is UNIVERSAL!DNA 4 common nucleotides (A,T,G,& C)DNA Common double helix structureRNA Common 4 nucleotides (A, U, G, & C)Codons code for 20 common amino acids the make proteins2

Genetic Engineering uses the principles of genetics along with cellular chemistry to alter an organisms genome and produce new transgenic organisms. Transgenic, literally translated means across the genes. This technology can be used to produce new foods and medicines.

Genetic engineering involves cloning. Cloning can be that of an entire organism or can be making an exact copy of a single gene.

New genes can be added to an organisms DNA which will give the organism new traits that can be expressed.

Viruses have always been genetic engineers. They insert a gene into a host cells DNA (either directly or indirectly through RNA transcriptase) and give the host cell the ability to produce and assemble new viruses. We take advantage of this and sometimes use viruses as a delivery system for a gene in genetic engineering.

The how and the why that makes genetic engineering possible is because of the universality of DNA and protein synthesis. All organisms on Earth are based on the same four nucleotides (A, T, G, & C) arranged in sequences that code for proteins. Those proteins are synthesized using RNA which has common nucleotides among organisms and mRNA codons that are universal. The same 20 amino acids that the codons code for in one organism are also used to make proteins in other organisms. The most basic metabolic functions are based on genes shared across all organisms (further evidence of a common ancestor for all life on Earth).

If you take a gene sequence from one organism, you can insert it into another organisms DNA easily using base pair rules. Once the gene is inserted, mRNA can be made by transcription and bring the reading frame of codons to the ribosome. The tRNA will bring the correct amino acid for each codon to the ribosome because of the pairing rules between the tRNA anticodon and the mRNA codon. The ribosome will assemble the amino acids into a polypeptide chain for the specific protein. All the steps of protein synthesis are essentially the same no matter what organism is performing the task.

2

Clone:genetically identical copy of a gene or an organismCloning occurs in nature:

3

Genetic engineering in the form of cloning of organisms also occurs in nature.

Examples of cloning in nature include:Plants which clone themselves from roots, stems and leaves.Plant tissue contains stem cells that can develop into many types of cells through determination and differentiation. This means a root, leaf, or stem can give rise to an entire new plant that is genetically identical to the original plant that the root, leaf or stem came from.

Bacteria reproduce asexually by binary fission. This produces genetic clones. Bacteria reproduce very quickly, sometimes at a rate of every 20 minutes. The increased rate of reproduction and multiple generations in a short period of time leads to an increase in mutation rate which contributes to genetic variation in a population of bacteria.

Simple Animals clone themselves during asexual reproduction through budding e.g. Hydra. A small mass of cells grows and separates from the original hydra. This mass of cells develops into an entire new hydra organism genetically identical to the hydra the mass developed from and separated from. Cloning may also occur during regeneration of portions of an organism such as in sea stars.

As we can see, nature has been using cloning as a form of asexual reproduction in many different organisms for a very long time.

3

Cloning mammals more difficultSomatic Cell Nuclear Transfer (SCNT)Haploid nucleus removed from unfertilized egg gamete cellDiploid nucleus from somatic cell inserted into the egg cellStimulated (chemicals and electricity) to go through mitosis and start dividingEmbryonic bastocyst (mass of cells) implanted in uterusDevelops into cloned offspring23464

Simple animals are one thing in regards to cloning, but cloning mammals is a much more difficult procedure. Scientists have had success. The most famous and first mammal to be cloned using an adult somatic cell was Dolly the Sheep who lived from July 5, 1996 to February 14, 2003.

Scientists feel that the possibility of cloned animals in livestock for food and breeding may someday be a reality. If a cow has the genetics to be an excellent producer of milk, why chance genetics of sexually produced offspring having the same ability. Cloning, though it doesnt ensure the exact same abilities, does increase the odds. This is a very controversial application and has people concerned about long-term outcomes for the animal clones and people who ingest the products of these animals.

Somatic Cell Nuclear Transfer (SCNT) places a diploid adult somatic cell nucleus inside an enucleated egg cell (meaning the nucleus of the egg cell has been removed). The new cell is stimulated with chemicals and electricity and tricked into thinking it was just fertilized. The zygote cell then starts to go through mitosis and forms a blastocyst just as it would if the egg had been fertilized by a sperm cell. The blastocyst can then be implanted into a females uterus of the same species. If the blastocyst successfully implants and develops, the new organism will be a genetically identical organism to that organism from which the somatic cell nucleus was obtained.

Some genetic engineering companies have opened a market for cloning beloved pets such as dogs and cats for very rich people who can not bear to part with their precious fluffy.

4

Rainbow Somatic cell DNACC Cloned/Carbon CatAllie Surrogate momEgg donor AnonymousMany Factors affect gene expression Epistasis, Inactivation, Methylation, Epigenetics5

Scientists have found that genetic clones do not always turn out phenotypically exactly like the organism they were cloned from.

Case in point CC the cat. Rainbow a female calico cat (this should start to sound familiar and make sense now) was the cat that the adult somatic cell was obtained from. Rainbows somatic cells nucleus was placed in the enucleated egg of another female cat donor. The resulting blastocyst was implanted into Allie who acted as a surrogate and carried and gave birth to CC. Allie and CC are not genetically related at all. CC has the exact same genetics as Rainbow, but does not look like Rainbow. Hmmm..

Remember X chromosome inactivation and the patchwork fur pattern that resulted in female cats producing calico coats?

Many things can effect how the actual genes present in the DNA are expressed. Epistasis, inactivation, methylation all affect how genes are expressed beyond just the alleles present. The study of how other factors affect genetic expression is called Epigenetics. Epi- means upon, so literally upon the genes.

Many scientists are studying the epigenetics of identical twins and are finding that methylation patterns of the DNA are very similar at birth, but become much different as the twins age. This could explain why one twin may develop cancer and the other twin does not. 5

Genetic engineering is based on:Recombinant DNA6

Genetic engineering can also clone a single gene and not an entire organism. This is based on using recombinant DNA or DNA that contains genes from more than one organism.

Restriction enzymes cut the gene out of a strand of DNA leaving offset or staggered ends to the gene. These offset ends are called sticky ends because the nucleotides are exposed and not hydrogen bonded to an opposite nucleotide. A plasmid is a circular DNA molecule in a bacteria that is separate from the bacteriums chromosome. The plasmid will be replicated along with the chromosome when the bacteria reproduces. The plasmid is cut at specific sites in the nucleotide sequence that have nucleotides that will hydrogen bond with the sticky ends of the gene to be inserted. This uses the base pair rules to insert the gene into a plasmid of a bacteria.

This procedure of gene insertion can be used to:Engineer crops to be resistant to cold or insects. Engineer crops to produce vitamins or medicinesEngineer bacteria to produce medicines or enzymes

6

7

Gene insertion creates a transgenic organism defined as an organism that has one or more genes from another organism inserted into its genome.Transgenic bacteria used to make human insulin for diabetics:The human gene for making insulin is inserted into a plasmidThe plasmid inserted into bacteriaBacteria expresses gene and makes inulin which can be processed for diabetics.When the bacteria goes through asexual binary fission, the plasmid will be replicated and the new bacterial cells will also contain plasmids with genetic instructions for making insulin.

This single application of genetic engineering has saved countless human lives.7

Transgenic plants are common in agriculture:

8http://webertube.com/mediadetails.php?mid=8468&

Transgenic plants are very common in agriculture.

The Bacillus thuringiensis or Bt gene is used to give plants resistance to insects. Bt is a bacteria found in the soil and produces a protein that has insecticidal properties for insects who consume it.

The Bt gene is introduced into the genome of a plant and now the plant is able to make the protein coded for by the gene. This gives the plants naturally defense against insects without use of chemical insecticides.

Many crops are now genetically modified (GM / GMO -organism)

There are benefits of creating genetically modified crops:Less chemical fertilizer and insecticides.Higher crop yields.Increased growing seasons or locations.

But, and remember the world is full of big buts

Scientists have concerns about some uses of genetic engineering:Possible long-term health effects of eating GM foods includeAllergiesDiseasesPossible effects of GM plants on ecosystem and biodiversity such asKeystone species cascade effectNew vulnerabilities of engineered organism not yet determined.Selective resistance to the genetic engineering by the insects such as is seen in antibiotic resistant bacteria.

Overall, genetic engineering has a lot of potential benefits, but also the technology could be misused or the effects of altering genomes may not be fully understood in the long-term.

Cloning, whether a single gene or an entire organism, is highly controversial and should be explored with caution and diligence.

82015-06-09T17:09:56-0400com.apple.VoiceMemos (iPhone OS 8.3)2015-06-09T17:16:13-0400com.apple.VoiceMemos (iPhone OS 8.3)2015-06-09T17:25:38-0400com.apple.VoiceMemos (iPhone OS 8.3)2015-06-09T17:33:04-0400com.apple.VoiceMemos (iPhone OS 8.3)2015-06-09T17:38:56-0400com.apple.VoiceMemos (iPhone OS 8.3)2015-06-09T17:41:51-0400com.apple.VoiceMemos (iPhone OS 8.3)2015-06-09T17:43:41-0400com.apple.VoiceMemos (iPhone OS 8.3)2015-06-09T17:49:22-0400com.apple.VoiceMemos (iPhone OS 8.3)