15.1 Biotechnology = Genetic Engineering

• Agriculture

• Human health

• Criminal justice

Adding, deleting, or transplanting genes from one organism to another, to alter the organisms in as a means of meeting societal needs.

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15.2 Transgenic Biotechnology

• Transgenic organism: an organism whose genome has stably incorporated one or more genes from another species.• DNA from one organism put into another • Example: Human gene in a bacterial cell

• Human insulin is produced within a bacterium

Insulin from cows and pigs until…

1982 –biotech revolution

Chop out human DNA sequence for production of insulin

Insert into E. coli

Grow cells that make human insulin

Produced efficiently - huge quantities

1st genetically engineered drug approved by the Food and Drug Administration

Other important examples

1. Human growth hormone (HGH)-dwarfism

- Weight loss in AIDS pts

2. Erythropoietin (EPO)-Production of red blood cells-Illnesses & treatments that lead to anemia

Prevent diseases

Cure diseases

Treating diseases

• The treatment of diabetes

Biotechnology – Human Health: The treatment of diseases and production of medicines are improved with biotechnology

Gene Therapy for SCID (severe combined immunodeficiency disease)

Immune system can’t properly make a type of white blood cell - caused by a bad gene

Vulnerable to most infections

Usually leads to death within the first year of life

“Bubble Boy”

Gene Therapy for SCID

- Remove cells from bone marrow (stem cells - ability to develop into any cell type)

- Infect stem cells with transgenic virus carrying a working copy of the gene

- Put cells back in patient

- Pt cells should produce normal white blood cells, permanently curing disease.

- Worked in 14 out of 16 cases

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Restriction Enzymes: proteins derived from bacteria that can cut DNA in specific places.

Figure 15.3

1. A portion of a DNA strand, highlighted here, has the recognition sequence GGATCC.

2. A restriction enzyme moves along the DNA strand until it reaches the recognition sequence and makes a cut between adjacent G nucleotides.

3. A second restriction enzyme makes another cut in the strand at the same recognition sequence, resulting in a DNA fragment.

“sticky ends”

DNA fragment

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bacterium

plasmidbacterialchromosome

Plasmids

Figure 15.4

• small, extra-chromosomal rings of bacterial DNA that can exist outside of bacterial cells and that can move into these cells through the process of transformation

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human cell containinggene of interest

proteinsynthesis

human proteinof interest

1. Use restriction enzymes to snip gene of interest from the isolated human genome.

2. Insert gene into plasmid (complementary sticky ends will fit together).

3. Transfer the plasmid back into bacterial cell.

DNA bacterialchromosome

Use same restrictionenzyme to snip plasmid.

bacterium

recombinant DNA

transformation

bacterialclones

replication4. Let bacterial cells replicate. Harvest and purify the human protein produced by the plasmids inside the bacterial cells.

plasmid

Figure 15.5

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Getting Human Genes into Plasmids

• Recombinant DNA: 2 or more segments of DNA that have been combined by humans into a sequence that does not exist in nature.

• Cloning vector: self-replicating agent that functions in the transfer of genetic material. • Viruses known as bacteriophages are another

common cloning vector.• Yeast, hamster cells, & mammals

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Real-World Transgenic Biology

• Transgenic food crops are planted in abundance today in the United States.• GMOs

• Genetically modified organisms

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Selective Breeding

• Used for thousands of years

• Taking the crops with best traits and breeding with other optimal traits

• Can take years

• Now, genes can be taken and put into the crops

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More Nutritious Crops

• Low Vit A = blindness

• Beta Carotene helps make Vit A

• Rice is grown with a gene for beta carotene

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Resistance

• Crops can be given genes that help them resist pest-killing treatments

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Faster Growing and Money Saving Organisms

• Salmon that can grow in half the time

• Chickens without feathers were grown to save time and money

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Fears and risks: Are genetically modified foods safe?

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#1: Organisms that we want to kill may become invincible.

#2: Organisms that we don’t want to kill may be killed inadvertently.

#3: Genetically modified crops are not tested or regulated adequately.

#4: Eating genetically modified foods is dangerous.

#5: Loss of genetic diversity among crop plants is risky.

#6: Hidden costs may reduce the financial advantages of genetically modified crops.

GMO Fears

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Almost everyone in the United States consumes genetically modified foods regularly without knowing it.

What foods are responsible for this?

15.3 Reproductive Cloning

• “Dolly” the sheep

• Somatic Cell Nuclear Transfer

• Controversial

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What is a clone?

• A genetically identical copy of a biological entity• Genes, cells, plants

• Reproductive cloning is the process of making adult clones of mammals of a defined genotype.

• Dolly the sheep was a reproductive clone.• Other mammals have been cloned since then

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Somatic Cell Nuclear Transfer (SCNT)

• Egg cell has nucleus removed and is fused with an adult cell containing a nucleus and, therefore, DNA.

• The fused cell then starts to develop as an embryo and is implanted in a surrogate mother.

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whitesheep

black-facedsheep

uddercells

egg cell(nucleusremoved)

Dollysurrogatemother

embryo

DNA

1. A cell was taken from the udder of a six-year-old white sheep and then allowed to divide many times in the laboratory. Meanwhile an egg was taken from a black-faced sheep.

2. One of the resulting udder cells was selected to be the “donor” cell for the cloning. Meanwhile, using a slender tube called a micropipette, researchers sucked the DNA out of the egg.

3. The donor cell and egg were put next to each other, and an electric current was applied to the egg cell.

4. This caused the two cells to fuse and prompted an activation that reprogrammed the donor-cell DNA. This caused the fused cell to start developing as an embryo.

5. After some incubation, the embryo was implanted in a third sheep, which served as the surrogate mother.

6. This mother gave birth to Dolly the sheep, which grew into an adult.

Figure 15.8

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Reproductive Cloning

• Reproductive cloning can work in tandem with various recombinant DNA processes to produce adult mammals possessing special traits.

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Human Cloning

• Human clone - genetic replica of the person who provided the donor-DNA cell• genetically identical in the same way that

identical twins are

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15.4 Cell Reprogramming

• Two promising methods exist for generating human cells that are needed to treat victims of accident or disease:• Production through embryonic stem cells• Production through induced pluripotent stem

cells

• Both methods use the reprogramming of cells to yield desired cell types.

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Cell Fates: Committed or Not?

• Most cells in the adult human body have undergone commitment• a developmental process that results in cells

whose roles are completely determined• Most muscle cells have undergone commitment

• Can give rise to nothing but muscle cells

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What is a Stem Cell?

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Embryonic Stem Cells

Figure 15.9

fertilization days 1–3 day 5

blastocyst

innercell mass

Cells from the blastocyst’s inner cell mass, known as embryonic stem cells (ESCs), can give rise to all the different cell types in the adult human body.

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Adult Stem Cells

• Not the same as ESC

• Demonstrated some ability to differentiate into various types of cells

• Do not have the differentiation potential of ESCs, nor the same ability to replicate

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Obtaining ASCs is difficult

• Where they exist

• All of the 60+ distinct organs of the human body

Where we can obtain them

Bone Marrow

Umbilical Cord Blood

Placental Tissue

Adipose (fat) Tissue

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Induced Pluripotent Stem Cells

• 2007 – researchers developed a type of human stem cell not derived from an embryo: the iPSC

• Appear to have all the developmental power of ESC

• Potentially fewer issues with tissue rejection in medical transplantation procedures

• Widely used as a means of studying human disease

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Induced Pluripotent Stem Cells (iPSCs)

• Induced Pluripotent Stem Cells – adult cells that are “reset” to behave like an ESC

• From almost any tissue – biopsy

http://learn.genetics.utah.edu/content/stemcells/quickref/

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Potential uses of stem cells

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15.5 Forensic Biotechnology

• Forensic DNA typing: use of DNA to establish identities in connection with legal matters• Identities of criminals, biological fathers, and

disaster victims

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The Use of PCR

• Polymerase chain reaction (PCR): technique for quickly producing many copies of a segment of DNA

• Useful in situations, such as crime investigations, in which a large amount of DNA is needed for analysis, yet the starting quantity of DNA is small.

https://youtu.be/q-40l8nmsis

© 2011 Pearson Education, Inc. Figure 15.11

double-strandedDNA

single-strandedDNA

double-strandedDNA

primers

1. A researcher selects a DNA region of interest.

2. The DNA is heated, causing the two strands of the double helix to separate.

3. As the mixture cools, short DNA sequences called primers form base pairs with complementary DNA sequences on their respective strands.

4. DNA polymerase goes down the line, synthesizing complementary DNA strands. The end result is a doubling of the original DNA.

5. The process is repeated many times, doubling the amount of DNA each time.

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15.6 Controversies in Biotechnology

• Biotech progress also comes slowly because so many of the processes it is developing are not just new, but controversial.

• A notable biotech controversy concerns genetically modified (GM) crops or GMOs.

• Opponents of genetically modified crops are concerned about their effect on human health and the environment.

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Controversies in Biotechnology

• There is no evidence so far that GM crops have had detrimental effects in either area.

• But, consumer resistance to the crops has sharply limited both the types being planted and the types being put into development.

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Controversies in Biotechnology

• Some biotech controversies are essentially ethical in nature.

• Among these are the controversies concerning embryonic stem cells and therapeutic cloning.

• A more general controversy has to do with the question of what level of constraint society ought to impose on the modification of living things.

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What’s everyone so afraid of?

Designer babies

- select for eye color

- select for height

- select for gender

What are the limits?

HW

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Three Parent IVF

- What is it?

-Who would use it?

-Why is it controversial?

HW

https://youtu.be/jQxsW_H5qr4