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 / Disadvantage
Organisms with the desired characteristics can be created quickly and efficiently / 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)

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’.

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