SB4 Natural Selection and Genetic Modification Flashcards
Individuals inherit characteristics…
randomly.
When individuals inherit random characteristics providing a survival advantage is called?
Natural selections.
When humans choose organisms with useful characteristics and breed them together is?
Artificial selection.
What does selective breeding produce?
New animal breeds and plant varieties.
What is an example of selective breeding?
Humans breeding only the hairier sheep to have very hairy offsprings.
What was the first plant that was selectively bred?
Wheat.
What are desired characteristics for food plants?
~Disease resistant (less likely to be killed or suffer from disease symptoms)
~Yield (useful product)
~Ability to cope with environmental change (drought etc)
~Fast growth
~Good flavour
What is genetic engineering?
Changing the DNA of one organism by inserting genes from another organism.
What does genetic engineering create?
Genetically modified organisms (GMOs)
What is a advantage and disadvantage of genetic engineering?
Advantage - It is faster then artificial selection
Disadvantage - More expensive
What are some modern day uses of Genetic engineering?
~GM pigs can develop organs for human transplant
~GM bacteria can produce antibiotics
~GM crops can produce a greater greater yield or grow faster
~GM crops resistant to disease
Scientists have created a goat that produces spider silk in its milk. Explain how they have done this.
They would have take the gene for silk production from a spider and inserted it into the genome of the goat so the goat was able to create the protein needed for silk production.
How is tissue culture carried out?
Growing cells or tissues in a liquid containing nutrients.
These cells are then treated to become differentiated (specialised)
Advantages of tissue culture in medicine.
~Cells are easy to grow
~Use patients own stem cells
~No chance of rejection by body
~Allows us to see how cells respond to different medicines.
Advantages of tissue culture in plants?
~Produces new plants of rare species on the brink of extinction.
~Used to grow species that cannot grow easily from seed e.g. orchids.
~Produces clones of GM plants.
Advantages of selective breeding.
~Disease resistance can be increased.
~Increased yield e.g. in milk, meat or grain.
~Advantageous alleles can be selected and passed on to offspring.
Disadvantages of selective breeding.
~Poor animal welfare.
~Diseases may affect organisms as they are bred in huge numbers.
~Some allele become rare or disappear and may be useful in the future.
Advantages of Genetic Engineering.
~Resistance to pests and diseases.
~Less reliance on the use of insecticides and herbicides.
~Desired characteristics can be selected and produced quickly, in large numbers.
~Produce useful substances e.g. insulin, cheaply. GM insulin is suitable for vegans.
Disadvantages of Genetic Engineering.
~Seeds for GM crops are extremely expensive.
~GM crops may cross breed with wild varieties, passing on resistance genes.
~Genes may have unknown consequences on health (no evidence for this however)
~Slightly different to human insulin, may not be suitable to all humans.
What are the main steps of Genetic engineering?
- DNA taken from a human cell.
- Use a restriction enzyme to cut out the gene for insulin from the DNA. This leaves sticky ends.
- Use a restriction enzyme to cut the plasmid out of a bacterial cell.
- Use the same restriction enzyme to cut a section of DNA from the plasmid.
- Insert the gene for insulin into the plasmid.
- Use a ligase enzyme to join the ends of the DNA. The sticky ends will match and join up.
- Put the plasmid with the insulin gene back into a bacterial cell. The bacteria is know as a vector.
- Leave the bacteria to divide.
- Insulin is removed and purified.
- Ready for use in humans.
What is the process of cutting out a gene from the DNA of one organism and inserting it into the DNA of another called?
Gene splicing.
How can we control pests the eat our crops?
Insecticides or biological control.
How to use insecticides?
Spraying it onto the crop which kills different insects.
What are the advantages of using GM crops in agriculture? (5)
- Bt toxin only affects insects that eat the plant - does not harm pollinators.
- Less reliance on insecticide.
- Insect predators e.g. ladybirds are not harmed.
- GM crops usually have higher yield which means more profit for farmer.
- GM crops can be resistant to pests and herbicides.
What are the disadvantages of using GM crops in agriculture? (5)
- Insects that suck sap e.g. aphids are not killed by the toxin so the farmer may still need to use insecticides.
- Insects can become resistant to the toxin.
-GM crops are more expensive than non - GM - Concerns that eating GM has unknown health risks.
- Concerns that resistance genes could pass to weeds during cross breeding.
