Download New Genes for Old – Revision Pack (B3)

New Genes for Old – Revision Pack (B3)
Selective Breeding:
There are many problems with selective breeding; sometimes SB can lead to the
inbreeding, where two closely related individuals mate. This can cause health
problems for the species.
Inbreeding can lead to a reduction in the variety of alleles in the population (this is
also known as the gene pool). This can lead to:
-
An increased risk of harmful recessive characteristics showing up in offspring
A reduction in the ability to change easily; lack of variation
Genetic Engineering:
Key examples of genetically engineered organisms include:
-
Beta-carotene being put in rice to increase vitamin A content for countries
where there is little vitamin A and a reliance on rice
Bacteria that have been made to contain human insulin
Crop plants have been engineered so that they are frost or damage resistant
There are advantages and disadvantages to genetic engineering:
Advantage
Organisms with the desired
characteristics can be created quickly
and efficiently
Disadvantage
There is a risk that the inserted genes
may have unprecedented and harmful
side effects
There are also quite a lot of ethical issues surrounding genetic engineering:
-
Some people think it is just morally wrong
Others think that there may be long-term side effects like a damage to
ecosystems by GE animals / plants
There are four steps to genetic engineering:
STEP 1: Identify the desired characteristic
STEP 2: The desired genes are identified and removed from an organism (isolation)
STEP 3: These genes are then inserted into another organism
STEP 4: These organisms then reproduce and replicate
(This is shown on the following page in a diagram as an example)
New Genes for Old – Revision Pack (B3)
Gene therapy:
The use of genetic engineering to change a person’s genes and cure certain
disorders is called gene therapy.
Gene therapy could involve gametes or body cells. The changing of gametes is the
most controversial because it could lead to ‘designer babies’.
New Genes for Old – Revision Pack (B3)
Past Papers:
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New Genes for Old – Revision Pack (B3)
New Genes for Old – Revision Pack (B3)
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New Genes for Old – Revision Pack (B3)
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New Genes for Old – Revision Pack (B3)
Mark Schemes:
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New Genes for Old – Revision Pack (B3)
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