What is Biotechnology? 15.1 What is Biotechnology? Transgenic Biotechnology Transgenic Biotechnology. Biotechnology. Transgenic organism

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1 What is Biotechnology? 15.1 What is Biotechnology? Biotechnology the use of technology to control biological processes as a means of meeting societal needs Gene therapy Genetic engineering Bioremediation Industrial processes Bioinformatics Many others Transgenic Biotechnology 15.2 Transgenic Biotechnology Transgenic organism An organism whose genome has stably incorporated one or more genes from another species Many biotechnology products are produced within transgenic organisms 1

2 Transgenic Biotechnology Restriction Enzymes Human growth hormone (HGH) produced within a bacterium that has been made transgenic by means of incorporating a human gene Restriction enzymes proteins derived from bacteria that can cut DNA in specific places Restriction Enzymes Plasmids sticky ends DNA fragment 1. A portion of a DNA strand has the highlighted 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. Plasmids 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 Transformation Uptake and incorporation of foreign DNA Figure

3 Plasmids bacterium Getting Human Genes into Plasmids bacterial chomosome plasmid Figure 15.4 Recombinant DNA two or more segments of DNA that have been combined by humans into a sequence that does not exist in nature Human DNA can be inserted into plasmid rings The same restriction enzyme is used on both the human DNA of interest and the plasmids Complementary sticky ends of the fragmented human and plasmid DNA will bond together, splicing the human DNA into the plasmid. Getting Human Genes into Plasmids Turning out Protein Once plasmids have had human DNA spliced into them, the plasmids can then be taken up into bacterial cells through transformation 3

4 Turning out Protein Turning out Protein As these cells replicate, producing many cells, the plasmid DNA inside them replicates as well. These plasmids produce the protein coded for by the human DNA that has been spliced into them. The result is a quantity of the human protein of interest. Turning out Protein human cell containing bacterium gene of interest bacterial plasmid DNA chromosome protein synthesis Use same human protein restriction of interest enzyme to 1. Use restriction snip plasmid enzymes to snip gene of interest from the isolated human genome. recombinant DNA 2. Insert gene into plasmid (complementary sticky ends will fit together). transformation Plasmids are One Type of Cloning Vector Cloning vector self-replicating agent that functions in the transfer of genetic material Viruses known as bacteriophages are a common cloning vector 3. Transfer the plasmid back into bacterial cell. replication 4. Let bacterial cells replicate. Harvest and purify the human protein produced by the plasmids inside the bacterial cells. bacterial clones Figure

5 Plasmids are One Type of Cloning Vector Real-World Transgenic Biology A large number of medicines and vaccines are produced today through transgenic biotechnology. Real-world Transgenic Biology Real-world Transgenic Biology Other Transgenic organisms Bacteria Yeast hamster cells mammals such as goats. GM foods Genetically modified crops Transgenic food crops modified for Disease resistance Pest resistance Vitamin content Drought resistance Planted in abundance today 5

6 Real-world Transgenic Biology Real-world Transgenic Biology Figure 15.6 Reproductive Cloning 15.3 Reproductive Cloning A clone is a genetically identical copy of a biological entity Genes can be cloned, as can cells and plants 6

7 Reproductive Cloning Reproductive Cloning Reproductive cloning is the process of making adult clones of mammals of a defined genotype. Dolly the sheep was a reproductive clone Somatic cell nuclear transfer (SCNT). variants of the process that was used with Dolly reproductive cloning of mammals is carried out through this process Somatic Cell Nuclear Transfer (SCNT) Egg cell (ovum) has its nucleus (haploid) removed and is fused with an adult cell containing a nucleus (diploid) and, therefore, DNA. The fused cell then starts to develop as an embryo and is implanted in a surrogate mother Somatic Cell Nuclear Transfer (SCNT) white sheep udder cells 1. A cell was taken from the 2. 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 second black-faced sheep. black-faced sheep egg cell 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. DNA embryo The donor cell and egg were put next to each other, and an electric current was applied to the egg cell. 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. After some incubation, the embryo was implanted in a third sheep, which served as the surrogate mother. surrogate mother Dolly 6. This mother gave birth to Dolly the sheep, which grew into an adult. Figure

8 Reproductive Cloning Human Cloning Reproductive cloning can work in tandem with various recombinant DNA processes to produce adult mammals possessing special traits A cell can be made transgenic for such a trait then used as the starting cell (the donor-dna cell) in producing an adult mammal with the trait Human cloning Now technically possible Anyone attempting to undertake the process would face technical, legal, and ethical obstacles Human Cloning Human clone would be a genetic replica of the person who provided the donor-dna cell The donor and his or her clone would be genetically identical in the same way as identical twins 15.4 Forensic Biotechnology 8

9 Forensic Biotechnology Forensic Biotechnology Today DNA is used to identify Criminals Biological fathers or other family members Disaster victims Unknown organisms Forensic DNA use of DNA to establish identities in connection with legal matters, such as crimes The Use of PCR The Use of PCR Polymerase chain reaction (PCR) Technique for quickly producing many copies of a segment of DNA Hundreds to millions Through thermocycling Regimen of heating and cooling of a DNA template in the presence of DNA polymerase, primers, and free nucleotides double-stranded DNA single-stranded DNA primers double-stranded DNA 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. Figure

10 The Use of PCR Finding Individual Patterns PCR is 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. Forensic DNA typing usually works through comparisons of short tandem repeat (STR) patterns that are found in all human genomes. Finding Individual Patterns Copying DNA Through PCR Police will compare the STR pattern in a suspect s DNA with the STR pattern in DNA that has been extracted from a crime scene. PLAY Animation 15.3: Copying DNA through PCR 10

11 Cell Fates: Committed or Not? 15.5 Stem Cells Commitment developmental process that results in cells whose roles are completely determined Also called differentiation Cell Fates: Committed or Not? Stem Cells Most muscle cells have undergone commitment, for example, and hence can be nothing but muscle cells and give rise to nothing but muscle cells. Stem cells Cells in the early embryo that have not yet undergone commitment and can give rise to various kinds of cells undifferentiated A relatively small number of cells in the adult body have a similar capability. 11

12 Stem Cells Embryonic Stem Cells Stem cells have a continuing capacity to produce more cells of their own type, along with at least one type of specialized daughter cell Blastocyst An early embryonic stage One source of stem cells fertilization days 1 3 day 5 blastocyst inner cell mass Figure Embryonic Stem Cells Adult Stem Cells Embryonic stem cells (ESCs) Cells from the blastocyst s inner cell mass can give rise to all the different cell types in the adult human body ESCs Differ from adult stem cells, which are found, in small numbers, in various types of tissues in the adult body 12

13 Adult Stem Cells Adult Stem Cells Adult stem cells have demonstrated some ability to differentiate into various types of specialized cells subject of continued research interest Adult stem cells do not have the differentiation potential of ESCs nor the ESC s ability to continue to produce specialized cells generation after generation ESC s Pluripotent (or even totipotent) ASC s multipotent The Fight Over Embyonic Stem Cells ESC s Involved in controversy There is an ethical issue connected to the use of ESCs for research purposes Harvesting ESCs originally researchers had to destroy the embryos the cells are a part of, something many people regard as a destruction of human life The Fight Over Embyonic Stem Cells Others hold that embryos are potential human life, and that society has a greater responsibility toward impaired children and adults than it does toward embryos. 13

14 The Fight Over Embyonic Stem Cells New research in 2007 showed that human ESCs could be produced without the need to use embryos Adult cells may be induced back to a an undifferentiated state This should help to resolve this ethical controversy The Fight Over Embyonic Stem Cells Federal funding of embryonic stem cell research was sharply limited by order of President Bush. In consequence, an increasing portion of this research was/is being funded by states and by private sources. President Obama has now reversed that position Embryos may not be created for ESC s The Potential of Embryonic Stem Cells Most experts believe embryonic stem cells hold out great potential, but this potential has yet to be realized in human beings. Most human trials involving embryonic stem cells are likely to be 5 to 10 years away. Therapeutic Cloning Cells derived from ESCs and then introduced into a human body may set off an immune system attack. Such an attack could be avoided if individuals could produce their own stem cells either adult or embryonic which could then be used to derive the therapeutic cells introduced into the body. 14

15 Therapeutic Cloning Therapeutic Cloning Therapeutic cloning The use of cloning to produce human embryonic stem cells that can be used to treat disease and injury a standard cell from an adult s body would be used as the donor-dna cell in the SCNT cloning process The resulting embryo would then be allowed to divide to the blastocyst stage at which point ESCs from the embryo would be harvested and coaxed into specialization Those specialized cells would then be used to repair the body of the individual who provided the donor-dna cell Therapeutic Cloning Therapeutic cloning suffered a setback in 2005 when it was revealed that a leading researcher in the field, Woo Suk Hwang of South Korea, had faked many of his results Biotechnology in the Real World 15

16 Biotechnology in the Real World Controversies in Biotechnology Advances in biotechnology tend to be costly and to come slowly. This is so partly because the biotech processes being developed are fundamentally new and hence require considerable regulatory scrutiny. 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. Controversies in Biotechnology Controversies in Biotechnology Opponents of genetically modified crops are concerned about their effect on human health and the environment. 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. 16

17 Controversies in Biotechnology Controversies in Biotechnology Some biotech controversies are essentially ethical in nature. Among these are the controversies concerning embryonic stem cells and therapeutic cloning. Figure Controversies in Biotechnology 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. 17