1 2 Vitamin A deficiency can result in night blindness and weakened immunity. It affects over 250...

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Vitamin A deficiency can result in night blindness and weakened immunity. It affects over 250 million people each year.

I can’t see in dim light.

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Our body can synthesize vitamin A from beta-carotene.

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Scientists have successfully transferred the genes for producing beta-carotene from maize and bacteria to rice plants.

genes

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The resultant Golden Rice can produce high levels of beta-carotene in its grains.

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A Swiss scientist developed transgenic golden rice rich in iron and vitamin A, two major nutrient deficiencies in developing countries where the major staple food is rice. This involved genetically engineering 3 proteins and the vitamin precursor β-carotene from 4 different species.

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What are the advantages of geneticengineering over traditional breeding in crop improvement

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2.1 Biotechnology in medicine

• human insulin

Production of pharmaceutical products

• human growth hormone• vaccines• monoclonal antibodies (單克隆抗體 )

similar processes

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1 Human growth hormone (HGH)• secreted from the pituitary gland


• important in development of bones and muscles

• deficiency:

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• HGH was extracted from the pituitary gland of dead people


limited supply

1 Human growth hormone (HGH)

contaminated with pathogens

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1 Human growth hormone (HGH)• recombinant HGH

unlimited amount

pure

low cost

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1 Human growth hormone (HGH)• bacteria are commonly used

- provide plasmids that act as vectors

- serve as host cells

- can be transformed easily

- can grow rapidly

- can grow in inexpensive culture media

- relatively stable culture

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2 Vaccines• antigenic proteins can be produced by

recombinant DNA technology


e.g. vaccines against hepatitis B

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Prepare a recombinant plasmid


2 Vaccines

gene for viral surface protein

plasmid

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Introduce the recombinant plasmid into a yeast cell


2 Vaccines

yeast cell

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Culture GM yeast on a large scale


2 Vaccines

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According to the genetic information of the viral gene, the GM yeast produces the viral surface protein


2 Vaccines

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The viral surface protein is collected and purified for use


2 Vaccines

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2 Vaccines• traditional hepatitis B vaccines contain

the whole viruses


viruses may become active and infectious

• recombinant hepatitis B vaccines contain only a viral surface protein

safer to use

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Principle of EdibleEdible vaccine

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3 Monoclonal antibodies• antibodies produced by the cell clones

derived from a single parent B cell


• highly specific

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"magic bullet" monoclonal antibody1. myeloma cells –

keeing dividing--immortal

2. fuse with healthy antibody-producing B-cells

3. Hybridomas produced

4. select hybridomas cells with specific antibodies

5. Grow in culture

6. Harvest monoclonal antibodies

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3 Monoclonal antibodiesi) For diagnosis of diseases


• recognize the surface proteins of cancer cells in tissue samples

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3 Monoclonal antibodiesii) For developing sensitive tests


• home pregnancy tests• bind to human chorionic gonadotrophin

(HCG) in urine

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Application of monoclonal antibodies:

Pregnancy testing kit

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3 Monoclonal antibodiesiii) For isolating and purifying

important biological molecules


• specific to the molecule of interest

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3 Monoclonal antibodies• Drawback of

monoclonal antibodies produced using B cells from mice


could stimulate an immune response in humans Results in their rapid removal from the blood, inflammatory effects, and the production of human anti-mouse antibodies

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In vitro / Recombinant Monoclonal antibodies:


less likely to be destroyed in the human body

a human antibody with a small part of a mouse monoclonal antibody

Made by merging mouse DNA encoding the binding portion of a monoclonal antibody with human antibody-producing DNA in living cells, and the expression of this hybrid DNA through cell culture yielded partially mouse, partially human monoclonal antibody.

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3 Monoclonal antibodies• recombinant monoclonal antibodies


• used in the treatment of some forms of cancer- linked with a toxic drug

or a radioactive substance –magic bulletmagic bullet

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Gene therapy• to treat a disease by supplementing the

defective gene with a normal gene


• vectors for transferring a normal gene into a target celle.g. harmless viruses

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Diagram of the human chromosome set, showing the location of some genes whose mutant forms can cause hereditary diseases. Conditions that can be diagnosed using DNA analysis are indicated by a red dot.

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Gene therapy• ex vivo (先體外後體內 ) gene therapy:


cells are genetically modified outside the body and then put back into the patient

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Gene therapy with a retrovirus

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Gene therapy• in vivo (體內 ) gene

therapy:


cells are genetically modified inside the body

vectors with normal genes

direct transfer of normal genes into cells

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Cystic fibrosis (CF), the most common lethal, single-gene disorder affecting Northern Europeans and North Americans, is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene.

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Gene therapy• germ line gene therapy (種系基因治療 ) :


corrects the genetic material of gametes or zygotes

• genetic correction is inheritable• done on animals only

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Gene therapy• somatic cell gene therapy (體細胞基因治療 ) :


corrects the genetic material of somatic cells

• genetic correction is not inheritable• all human trials are of this type

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Gene therapy

• treat genetic diseases, cancer and infectious diseases


• as a preventive measure against diseases• correct a disease before it develops and help remove all the defective genes in the human population

Potential benefitsPotential benefits

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Gene therapy

• viral vectors cause diseases


• viral vectors cause severe immune reactions

• insertion of new genes affects the expression of existing genes

Potential hazardsPotential hazards

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Gene therapy

• new genes wrongly transported into non-target cells, produce too much of the missing protein or produce the protein at the wrong time


Potential hazardsPotential hazards

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Risks involved in gene therapy• in an attempt experiment to treat

Ornithine transcarbamylase deficiency by gene therapy, a patient died in 1999.

• The patient was injected with adenoviruses carrying a corrected gene in the hope that it would manufacture the needed enzyme.

• He died four days later, apparently having suffered a massive immune response triggered by the use of the viral vector used to transport the gene into his cells.

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Risks involved in gene therapy• in an attempt experiment to treat

Ornithine transcarbamylase deficiency by gene therapy, a patient died in 1999.

• The patient was injected with adenoviruses carrying a corrected gene in the hope that it would manufacture the needed enzyme.

• He died four days later, apparently having suffered a massive immune response triggered by the use of the viral vector used to transport the gene into his cells.

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.

• tampering with human genes might lead to the practice of eugenics, a deliberate effort to control the genetic makeup of human populations.

• The most difficult ethical question is whether we should treat human germ-line cells to correct the defect in future generations.

• we will have to face the question of whether it is advisable, under any circumstances, to alter the genomes of human germ lines or embryos. Should we interfere with human evolution in this way?

Gene therapy poses many ethical and social questions

Gene therapy poses many ethical and social questions

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Stem cell therapy2.1 Biotechnology in medicine

• unspecialized cells

• unlimited mitotic cell division

• can differentiate into different kinds of cells

• Embryonic stem cells /Adult stem cells

• Differs in their “potency”

• unspecialized cells

• unlimited mitotic cell division

• can differentiate into different kinds of cells

• Embryonic stem cells /Adult stem cells

• Differs in their “potency”

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totipotent, pluripotent, multipotent?

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totipotent, pluripotent, multipotent?

• TotipotentTotipotent cells can form all the cell types in a body, plus the extraembryonic, or placental, cells. Embryonic cells within the first couple of cell divisions (8-cell stage) after fertilization are the only cells that are totipotent.

• PluripotentPluripotent cells can give rise to all of the cell types that make up the body. e.g. embryonic stem cells (16-cell stage).

• MultipotentMultipotent cells can develop into more than one cell type, but are more limited than pluripotent cells; adult stem cells and cord blood stem cells, peripheral blood stem cells are considered multipotent.

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embryonic stem cells

• from blastocysts

• can differentiate into almost any cell types

(Pluripotent)

embryonic stem cells

• from blastocysts

• can differentiate into almost any cell types

(Pluripotent)

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After fertilization, the zygote undergoes cleavage:the first few mitotic divisions multiply the total number of cells without increasing total mass.The ball of cells that implants in the uterus is a blastocyst, and contains the inner cell mass, where embryonic stem cells can be harvested.

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adult stem cells

• from childhood or adult tissues like bone marrow, blood, skeletal muscles

• can only differentiate into a limited range of cell types “Multipotent” or unipotent

adult stem cells

• from childhood or adult tissues like bone marrow, blood, skeletal muscles

• can only differentiate into a limited range of cell types “Multipotent” or unipotent

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• stem cells may be used to replace damaged or abnormal cells in the treatment of diseasese.g. blood stem cells in bone marrow and in

peripheral blood, cord blood (臍帶血 ) containing blood stem cells are used in the treatment of blood diseases (multipotent)

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e.g. human embryonic stem cells

human blastocyst

isolate embryonic stem cells

cultured embryonic stem cells

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induce the cells to differentiate into specific cell types

insulin-producing cells• for treating type 1 diabetes

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cardiac muscle cells• for treating heart disease

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neurones• for treating spinal cord injuries,

Parkinson’s disease

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• Since the regrown cells originate from the patient, there should be no immune rejection of the transplanted tissue.

Stem cell therapy / stem cell cloning

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• isolation of embryonic stem cells involves destruction of human embryos

controversial• adult stem cells occur in low number,

are difficult to isolate and can only differentiate into a limited range of cell types

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• human skin cells were successfully re-programmed to become unspecialized cells in 2007 – IPS cells

Nobel Prize in physiology or

medicine (2012)

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may act as a limitless source of immune-compatible cells for transplantation

• human skin cells were successfully re-programmed to become unspecialized

cells in 2007 –IPS cells

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Sources of stem cells (1) human embryos

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Sources of stem cells (2) IPS – induced pluripotent stem cells

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Sources of stem cells (2) IPS – induced pluripotent stem cells

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Applications of IPS cells

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• questions to be answered

How can we induce embryonic stem cells to differentiate into

each of the desired cell types?

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• questions to be answered

Are re-programmed cells safe to use in therapy?

How long can the transplanted cells last in the body?

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1 Some examples of pharmaceutical products using biotechnology include human insulin, human growth hormone, and vaccines

.monoclonal antibodies


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2 Monoclonal antibodies are antibodies produced by theclones

derived from a single parent B cell.


cell

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3 is to treat a disease by supplementing the defective gene with a normal gene.


Gene therapy

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gene therapy

gene therapy

Affects gametes and zygotes

Affects somatic cells

Genetic correction is inheritable

Genetic correction is not inheritable

Germ line Somatic cell

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a It may treat genetic diseases, cancer and infectious diseases.

5 Potential benefits of gene therapy:

preventive


b It may be used as a measure against diseases.

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c It may correct a disease before the disease develops in the individuals and help remove all the in the human population.

5 Potential benefits of gene therapy:

defective genes


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a Viral vectors may gain the ability to cause diseases during modification.

6 Potential hazards of gene therapy:

immune reactions


b Viral vectors may cause severe.

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c The insertion of new genes may affect the of existing genes.



expression

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d The new genes may be wrongly transported into cells. They may also produce too much of the missing protein or produce the protein at the wrong time. This results in other health problems.



non-target

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e The patient is repeatedly exposed to possible hazards when



repeated gene therapy is required.

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7 Stem cells may be used in the treatment of type diabetes, heart disease, muscular dystrophy,


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spinal cord injuries, Parkinson’s disease, etc.

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2.2 Biotechnology in agriculture

• organisms whose genetic material has been altered through genetic engineering

What are transgenic organisms?

Golden Rice

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• transgenic organisms are useful in scientific research

for the study of gene functions


as disease models

for toxicity tests for new products

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Transgenic plants in agriculture and the food industry• many transgenic plants are major crops


soya bean (52%)

maize (31%)

cotton (12%)

canola (5%)

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Transgenic plants in agriculture and the food industry

• introduce genes for improving the yields or nutritional value of crops


• many transgenic plants are major crops

for food use and as parents in traditional breeding

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1 Herbicide resistant soya beans and maize

• weeds can be killed by herbicide

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2 Pest resistant maize and cotton

• toxin is pest-specific• reduces the use of chemical pesticides

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3 Disease resistant papayas

• prevents crops from being damaged by diseases

• reduces the use of chemical pesticides

viral resistant non-transgenic

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• crops can be grown in winter, dry climates and on saline lands


4 Rice, wheat and tomatoes tolerant to cold, drought or high salinity of soil

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5 Tomatoes with a longer shelf life

• reduces the loss of fruits• fruits of better quality

non-transgenic

transgenic

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6 Soya beans, canola and rice with improved nutritional value

• higher levels of ‘good’ lipids help prevent heart disease

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• higher levels of beta-carotene, vitamin E, iron, zinc or lysine prevent dietary deficiencies

6 Soya beans, canola and rice with improved nutritional value Animation

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Transgenic animals in agriculture and the food industry• introduce genes for improving the

productivity and quality of farm animals


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1 Fast-growing salmon

• decreases overfishing of wild salmon

non-transgenic transgenic

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2 Cold resistant salmon• expands the area for fish farming

3 Transgenic pigs that produce more lean tissue and less fat

• improves human health

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4 Transgenic goats that produce milk with improved composition and production

• produces lactose-free milk suitable for people who cannot tolerate lactose

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• produces milk with a lower level of ‘bad’ lipids which is healthier for the heart

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• increases milk production

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5 Transgenic sheep that produce more wool of better quality

• improves the quality of wool• increases wool production

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6 Transgenic pigs that produce 60% less phosphorus in their manure

• reduces pollution caused by manure

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1 are organisms whose genetic material has been altered through genetic engineering.

Transgenic organisms


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a They are used for the study of

2 Uses of transgenic plants and animals in scientific research:

gene

b They act as models.


functions.

disease

c They are used for tests for new products.

toxicity

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• resistance to herbicides,

3 Examples of desirable characteristics built into transgenic plants:

diseases


andcold drought

pests

• tolerance to , or high salinity of soil

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• delayed or

3 Examples of desirable characteristics built into transgenic plants:


nutritional value

softening• improved

ripening

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• improved meat or milk

• resistance

• faster growth

4 Examples of desirable characteristics built into transgenic animals:

cold


andcomposition production

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• manure with low levels of

• improved wool quality and production

4 Examples of desirable characteristics built into transgenic animals:

phosphorus


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a Transgenic plants and animals with improved productivity and quality are produced. They may provide a more reliable

5 Uses of transgenic plants and animals in agriculture:


foodsupply for all people.

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b They can be used as in traditional breeding.



parents

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c They can help protect the environment by reducing the use of chemical or producing less polluting .



pesticidesmanure

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In addition to beta-carotene, whatother useful products can be produced from genetic engineering?

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Human insulin, human growth factor, vaccines and monoclonal antibodies can be produced from genetic engineering.

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What are the advantages of geneticengineering over traditional breeding in crop improvement?

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Genetic engineering provides a quicker and more precise method to modify the genetic make-up and hence the characteristics of crops.

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What are the advantages of geneticengineering over traditional breeding in crop improvement?

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It also allows the transfer of new characteristics from completely non-related species.

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applications in medicine include

Biotechnology

production of pharmaceutical

products

gene therapy

stem cell therapy

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examples

production of pharmaceutical products

human insulin

human growth hormone

vaccinesmonoclonal antibodies

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gene therapy

divided into

germ line gene therapy

somatic cell gene therapy

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used to produce Biotechnology

productivity quality

transgenic plants and animals

used in agriculture to improve

1 2 Vitamin A deficiency can result in night blindness and weakened immunity. It affects over 250...

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Transcript of 1 2 Vitamin A deficiency can result in night blindness and weakened immunity. It affects over 250...