BIOTECHNOLOGY AND GENETIC ENGINEERING
Stem cell researchGMO & Cloning, Views for and against genetic engineeringDihybrid crossingsMutations in mitochondrial DNA – tracing female ancestry
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BIOTECHNOLOGY - DEFINITION
(Technological application) is the use of living systems and organisms to develop or make useful products, or to make or modify products or processes for specific use
GENETIC ENGINEERING
Also called genetic modification, is the direct manipulation of an organism's genome using biotechnology.
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An organism that is generated through genetic engineering is considered to be a genetically modified organism (GMO).
New DNA may be inserted in the host genome by first isolating and copying the genetic material of interest and then inserting this construct into the host organism.
Genes may be removed or deleted.
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WHAT IS GENETIC ENGINEERING?
Genetic engineering is the process of modifying an organism’s genetic composition by adding foreign genes to produce desired traits or evaluate function
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GENETIC ENGINEERING TECHNIQUES
applied in numerous fields including research, agriculture, industrial biotechnology, and medicine
Examples The first GMOs were bacteria in 1973; GM mice were generated in 1974. Insulin-producing bacteria were commercialized
in 1982 Genetically modified food has been sold since
1994. Glofish, the first GMO designed as a pet, was first
sold in the United States December in 2003.
GENETIC ENGINEERING TECHNIQUES
Enzymes used in laundry detergentMedicines such as insulin and human
growth hormone are now manufactured in GM cells,
Food crops include resistance to certain pests, diseases, or environmental conditions, reduction of spoilage, or resistance to chemical treatments (e.g. resistance to a herbicide), or improving the nutrient profile of the crop.
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GENETIC ENIGINEERINGDISADVANTAGES Expensive May be difficult for poor people to
access Interfere with nature Immoral/ we cannot play
God/unethical Domination of the world food products
by only a few companies
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Disadvantages……..continued
Loss of biodiversity NOT REDUCES VARIATION
Potential health impacts Violation of natural organism’s
intrinsic value(right to independent existence)
Unsure of long term effects Genes from transgenic organisms
could escapeand be transferred to wild organisms
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GENETIC ENIGINEERING
ADVANTAGES Production of medication Production of resources cheaply Control pests with specific genes inserted into
the crop Selecting the best genes to produce better
resistant crops Using specific genes to increase crop yields /
food security Selecting genes to increase shelf life of plant
products
ADVANTAGES….Continued Selecting genes that may increase maturation
times to meet the demand Selecting genes that may decrease maturation
times to meet the demand Using specific genes to improve nutritional valueof
food for better health Improve the taste of food DNA and proteins of transgenic organisms unlikely
to cause problems / transgenic organisms do not survive easily in wild
Produce organisms that can clean up pollution Endangered species can be saved Increases genetic variation
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WHAT ARE STEM CELLS?
Undifferentiated biological cells that can differentiate into specialized cells and can divide (through mitosis) to produce more stem cells. They are found in multicellular organisms.
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In mammals, there are two broad types of stem cells:
embryonic stem cells, which are isolated from the inner cell mass of blastocysts, and
adult stem cells, which are found in various tissues. In adult organisms, stem cells act as a repair system for the body, replenishing adult tissues.
In a developing embryo, stem cells can differentiate into all the specialised cells —ectoderm, endoderm and mesoderm — but also maintain the normal turnover of regenerative organs, such as blood, skin, or intestinal tissues.16
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REGENERATIVE SKIN
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SOURCES OF STEM CELLS
1.Bone marrow, which requires extraction by harvesting, that is, drilling into bone (femur and pelvis),
2.Adipose tissue (lipid cells), which requires extraction by liposuction, and
3.Blood, which requires extraction from the donor (similar to a blood donation), and passed through a machine that extracts the stem cells and returns other portions of the blood to the donor.
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SOURCES OF STEM CELLS……
Stem cells can also be taken from umbilical cord blood just after birth.
Of all stem cell types, adult harvesting involves THE LEAST RISK.
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USES OF STEM CELLS
Adult stem cells are frequently used in medical therapies, for example in bone marrow transplantation.
Stem cells can now be artificially grown and transformed (differentiated) into specialized cell types with characteristics consistent with cells of various tissues such as muscles or nerves.
Embryonic cell lines and adult stem cells generated through therapeutic cloning have also been proposed as promising candidates for future therapies.
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STEM CELL THERAPY
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ETHICS
Cloning
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Roslin Institute, Edinburgh
Dolly and first born lamb, Bonnie.
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WHAT IS CLONING?
The term, “cloning,” describes several different processes of making identical copies of biological material.
Why is cloning important? Because it has the potential to treat a wide range of diseases by generating “self ” tissues.
CLONING
In biology, cloning is the process of producing similar populations of genetically identical individuals that occurs in nature when organisms such as bacteria, insects or plants reproduce asexually.
Cloning in biotechnology refers to processes used to create copies of DNA fragments (molecular cloning), cells (cell cloning), or organisms. 28
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THE CLONING OF DOLLY
Somatic Cell Nuclear Transfer (SCNT):Dolly—The First True Clone (1997)
Breast Cell (udder) (six-year-old Sheep)
Get the nucleus
Empty Egg Cell
+
Cloned Sheep!
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Number of successfully
reconstructed eggs
Number of reconstructed eggs that were able to be implanted in
pseudo-pregnant sheep
Number of cloned sheep
actually born
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SIGNIFICANCE OF DOLLY
The effort showed that genetic material from a specific adult cell, programmed to express only a distinct subset of its genes, can be reprogrammed to grow an entirely new organism.
Before this demonstration, it had been shown by John Gurdon that nuclei from differentiated cells could give rise to an entire organism after transplantation into an enucleated egg. However, this concept was not yet demonstrated in a mammalian system.
ETHICAL ISSUES
Who will take responsibility for the new (cloned) individual?
Outcome on humans still unknown – ethically unacceptable
Stem cells are removed from a fertilized egg (embryo) – thereafter it is destroyed – Is this ethical? 32
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INDEPENDENT ASSORTMENT
allele pairs separate independently during the formation of gametes. This means that traits are transmitted to offspring independently of one another.
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Mendel could only formulate this after performing dihybrid crosses
DIHYBRID CROSS: A Genetic cross that
differs in TWO TRAITS e.g. Height in Plants and Seed colour
Mendel formulated this principle after performing dihybrid crosses between plants that differed in two traits, such as seed colour and seed shape. After these plants were allowed to self-pollinate, he noticed that the same ratio of 9:3:3:1 appeared among the offspring. Mendel concluded that traits are transmitted to offspring independently
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DIHYBRID CROSSING
Alleles for different traits are distributed to sex cells (& offspring) independently of one another.
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GENOTYPES
GENOTYPES: 2 CHARACTERISTICS (TRAITS) crossed e.g. Height of plants and colour of seeds.
Tall plants (L) and short plants (l) Green seeds (G) and yellow seeds (g)
Genotypes of parents: LlGg and LlGg (both heterozygous)
Phenotypes of parents: both tall plants with green seeds
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GENOTYPES AND GAMETES
Genotypes of parents:LlGg x LlGg GAMETES: write as follows: 1 and 3,
1 and 4; then 2 and 3, 2 and 4: LG Lg lG lg (both parents)
Then do crossing in PUNNETT
WORK STEP BY STEP AND SYSTEMATICALLY
LG Lg lG lgLG LLGG LLGg LlGG LlGgLg LLGg LLgg LlGg LlgglG LlGG LlGg llGG llGglg LlGg Llgg llGg llgg
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WORK STEP BY STEP AND SYSTEMATICALLY
LG Lg lG lgLG LLGG LLGg LlGG LlGgLg LLGg LLgg LlGg LlgglG LlGG LlGg llGG llGglg LlGg Llgg llGg llgg
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WORK STEP BY STEP AND SYSTEMATICALLY
LG Lg lG lgLG LLGG LLGg LlGG LlGgLg LLGg LLgg LlGg LlgglG LlGG LlGg llGG llGglg LlGg Llgg llGg llgg
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Check genotypes and phenotypes
LG Lg lG lgLG LLGG LLGg LlGG LlGgLg LLGg LLgg LlGg LlgglG LlGG LlGg llGG llGglg LlGg Llgg llGg llgg
GENOTYPES: LLGG (1) LLGg (2) LlGG (2) LlGg (4) LLgg (1) Llgg (2) llGG (1) llGg (2) llgg (1) = 9 types
PHENOTYPES:
GENOTYPES PHENOTYPES LLGG (1) tall, green (1) LLGg (2) tall, green (2) LlGG (2) tall, green (2) LlGg (4) tall, green (4) LLgg (1) tall, yellow (1) Llgg (2) tall, yellow (2) llGG (1) short, green (1) llGg (2) short, green (2) llgg (1) short, yellow (1)
9
3
3
1
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MUTATIONS IN MITOCHONDRIAL DNA USEFUL: Trace genetic linkages Sperms + Ova contain also
MITOCHONDRIA WITH DNA AND GENES
mtDNA of sperm cell does NOT fuse with that of the egg cell
mtDNA is handed down from mother to child
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MUTATIONS IN MITOCHONDRIAL DNA
By following mutant nucleotides in mtDNA, we follow our female line of descent
Mutations take place at faster rate – making it easier to trace female lineage
mtDNA is handed down from mother to child By following mutant nucleotides in mtDNA,
we follow our female line of descent Mutations take place at faster rate – making
it easier to trace female lineage