B3 - Selective Breeding , GM and Cloning Flashcards
What varieties of crop do we need?
• give a high yield
• are resistant to diseases that may cause health problems within the species
• do not bend over and break their stalks in the wind
• depending on where they are grown, are resistant to
drought/flooding/frost
• taste good
• have a long shelf life
• contain desired amounts of particular nutrients.
How is selective breeding done in plants?
• Parent plants with the desired characteristics are
selected.
• These are cross bred – pollen from one parent plant is placed on the female parts of the other parent plant.
• The seeds are collected and grown.
• The offspring that have inherited both characteristics are selected and cross bred again.
• Their seeds are collected and grown.
The process is repeated over many generations, until a new variety is produced with all the desired characteristics.
What breeds of animals do we want?
- have more muscle and less fat for lean meat
• produce higher milk yields
• lay more eggs - reach maturity quicker
• have better/more wool
• can run faster (such as racehorses and greyhound dogs).
What are the disadvantages of selective breeding?
Inbreeding may reduce the gene pool. This could lead to
• an accumulation of harmful recessive characteristics
• reduction in variation.
How are organisms genetically modified?
Enzymes are used to cut DNA, to obtain a gene for a desired characteristic, and to insert that gene into another organism’s DNA. This can produce organisms with different characteristics.
What are the advantages of making human insulin?
• Enough insulin can be made to treat all the people with diabetes.
• There is no risk of transferring diseases from pigs to humans.
• People with diabetes who are vegetarian will not object.
How is human insulin made?
the human gene for making insulin is inserted into a bacterium. The bacteria make insulin (a protein). Scientists can collect it.
What is gene therapy?
Changing a person’s genes in an attempt to cure disorders
How is gene therapy done?
Gene therapy does not change an organism’s genes permanently. Copies of a functioning (normal) gene or allele may be inserted into certain body cells of a person who has a recessive genetic disease, such as cystic fibrosis.
What are the main principles of genetic engineering?
• selection of desired characteristics
• isolation of genes responsible
• insertion of the genes into other organisms
• replication of these organisms.
Why is Golden rice a GM crop?
Genes that control the production of beta-carotene have been taken from daffodils and put into rice. The GM rice plants make beta-carotene in the rice grains. When humans eat this rice they turn beta-carotene into vitamin A. Each year in the world many children go blind or die due to lack of vitamin A. Golden rice will be a good way of providing enough vitamin A to children in developing countries at no extra cost.
Why is cotton a GM crop?
GM cotton is resistant to caterpillar pests. GM cotton has a gene from a bacterium. The gene codes for a toxin that kills the caterpillars. This Bt toxin has been used for decades by extracting it from bacteria. Now the GM cotton plants themselves make the toxin and kill the caterpillars even when they are inside the boll.
Why should USA not be worried about GM crops?
• No superweeds have developed that are resistant to
weedkillers.
• There is no reported reduction in biodiversity where GM
crops are grown, compared with where they are not grown. Fears that the Monarch butterfly would become extinct have not proved true so far.
• No one has reported a health problem from eating GM food.
What are the arguments for GM crops?
- More people can be fed, as GM crops produce higher yields.
- Many people have no problem with the idea of eating GM produce.
- GM farms may have increased productivity while using fewer inputs, so food costs may fall.
- Most GM crops have been safe so far.
What are the arguments against GM crops?
- Poor farmers that would benefit from the high-yield GM crops may not be able to afford the seeds.
- Those who have a problem with the idea of eating GM produce won’t buy it, meaning that farmers lose money and markets.
- GM crops may change the ecosystem in ways that cannot be reversed.
- GM crops could cross-pollinate with wild plants, making it impossible to control genetic modification.
