Term
| Outline three outcomes of the sequencing of the complete human genome. |
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Definition
. medical benefits:
- diagnosis of disease, or predisposition to disease
- identification of disease carriers
- better drugs design using knowledge of protein structure
- greater success of gene therapy
. number of human genes = about 25,000
. huge improvements in sequencing technology
. new insights into the role of non-coding DNA |
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Term
Outline a basic technique used for gene transfer, involving:
Plasmids |
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Definition
. plasmids = vector = medium by which genes of interest are transferred to host
- small (2-30 genes) loops of bacterial DNA which bacteria can:
. capture from environment by transformation
. replicate and transfer to other bacteria |
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Term
Outline a basic technique used for gene transfer, involving:
A host cell (bacterium) |
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Definition
- receives a gene of interest via a vector (=gene transfer)
- replicates repeatedly, passing on gene of interest to offspring (= cloning) |
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Term
Outline a basic technique used for gene transfer, involving:
Restriction enzymes (endonucleases) |
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Definition
- produced naturally by bacteria as defense against viruses
- used to cut the desired section of the DNA
- recognises unique sequences of DNA in plasmid and in gene of interest
- cuts DNA, producing "sticky ends"
. complementary sticky ends in gene of interest and plasmid
. allow incorporation of gene of interest into plasmid
. producing recombinant DNA |
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Term
Outline a basic technique used for gene transfer, involving:
DNA ligase |
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Definition
- creates covalent bonds
- joining together gene of interest within plasmid
- producing recombinant DNA |
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Term
| State two examples of the current uses of genetically modified crops or animals. |
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Definition
- genetically modified cows
. contain human genes for making medically important proteins (insulin, growth hormones)
. human proteins are extracted from cow's milk and sold as pharmaceuticals
- genetically modified tomatoes contain genes to ripen without becoming soft |
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Term
| Discuss the potential benefits and possible harmful effects of one example of genetic modification. |
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Definition
- potential escape of genetically engineering plants from cultivation
- out-competing naturally occurring varieties, thus becoming super weeds
- altering ecosystem interactions |
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Term
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Definition
- a group of organisms of identical genotype
- a group of cells descended from a single parent cell |
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Term
| Outline a technique for cloning using differentiated cells |
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Definition
- cloning farm animals
. differentiated mammary cells extracted from parent sheep; growth in nutrient-deficient solution to stop the cell cycle
. undifferentiated egg cells extracted from egg donor; nucleus removed and discarded
. mammary cell placed next to enucleated egg cell
. electric shock causes two cell membranes to fuse, and mitosis to trigger
. mitotic division continues, producing embryo
. embryo implanted into surrogate mother
. after 5-month gestation, Dolly the lamb born with identical genotype to parent donating nucleus from mammary cell |
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Term
| Discuss the ethical issues of cloning in humans. |
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Definition
- opposition to human cloning is very strong, based on a variety of arguments most of which invoke a violation of "the sanctity of life"
- arguments for human cloning involve at least two different cloning techniques
. cloning fetal tissue (stem cells) to produce organs and other tissues (but not entire individuals) for medical purposes (curing disease)
. cloning individuals
- for parents carrying genetic disease alleles, producing normal children has reduced probability
- among embryos produced normally, identify diseased embryos and discard, separate and clone healthy embryos, saving frozen embryos for later pregnancies |
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