T4- Changing Genes Flashcards
What is selective breeding
The process by which humans artificially select orgainsms with desirable characteristics and breed them to produce offspring with similar phenotypes
Outline the main steps involved in selective breeding
- Identify a desired characteristic e.g disease resistance
- Selective parent organisms that show the desired traits and breed them together
- Select offspring with the desired traits and breed them together
- Process repeated until all offspring have the desired traits
What is the main advantage of selective breeding
Creates organisms with desirable features:
- crops produce a higher yield of grain
- cows produce a greater supply of milk
- plants produce larger fruit
- domesticated animals
Other han agriculture , where else is selective breeding useful
- in medical research
- in sports e.g horse racing
Outline 4 disadvantages of selective breeding
- Reduction in the variation (which becomes especially harmful in sudden enviromental change)
- inbreeding results in genetic disorders
- development of other physical problams e.g respiratory problems in bulldogs
- potential to unknowingly selective harmul recessive alleles
How can plants be cloned (2)
- taking plant cuttings
- tissue culture
What is tissue culture
A method of growing living tissue in a suitable medium
4 steps to how plants are grown using tissue culture
- Select a plant that shows desired characteristics
- Cut simple small sample pieces from meristem tissue
- Grow in a petri dish containing growth medium
- transfer to compost for further growth
What must be ensured when preparing tissue cultures
Ensure aseptic conditions to prevent contamination by microorganisms
What does the growth medium contain
Nutrients and growth hormones
4 advantages of growing plants by tissue culture
- fast and simple process
- requires little space
- enables the growth of many plant clones with the same desirable characteristics
- useful in the preservation of endangred plant species
What are the disadvantages of growing plants by tissue culture (2)
- Reduction in the gene pool (variation)
- plant clones often have a low survival rate
- could unknowingly increase the presence of harmful recessive alleles
Why is animal tissue culturing useful
- Useful in the preparation of tissue samples for medical research
- enables the investiagton of how different factors may affect a specific animal tissue
Describe how animal tissue cultures are prepared
- Extract a sample of tissue from an animal
- Use enzymes to seperate cells within the sample
- Grow in a culture vessel containing growth medium
- Once grown, store the sample
What is genetic engineering
The modification of the genome of an organism by the insertion of a desired gene from another organism
Enables the formation of an organism with beneficial characteristics
Descibe process of genetic engineering
- DNA is cut at specific base sequences by restriction enzymes to create sticky ends
- Vector dna cut using using the same restirction enzymes to create complementary sticky ends
- Ligase enzymes join the sticky ends of the DNA and vector dna forming recombinant dn
- Recombinant dna mixed with and taken up by target cells
What is a vector
A structure that delivers the desired gene into the recipient cell e.g plasmids, viruses
Describe the benefits of genetic engineering (3)
- increased crop yields for growing population e.g herbicide-resistance, disease-resistance
- useful in medicine e.g insulin-producing bacteria
- GM crops produce scarce resources - e.g source if vitamin A
Describe 4 risks of genetically engineering
- Long term effects of consumption of GM crops unkown
- negative envirmental impacts e.g reduction on biodiversity - impact on food chain
- Late onset health problems in GM animals
- GM seeds are expensive
What is Bacillus thuringiensis
Insect larvae harmful to crops
Bt is a bacterium which seperates a toxin that kills insect larvae
How is genetic engineering used to protect crops against insects
The gene for toxin production in bt can be isolated and inserted into the dna of crops
- bt crops nowsecrete the toxin which kills any insect larvae that feed on it
Benefits of bt crops (3)
- Increased crop yield (fewer crops damaged)
- lessens the need for artificial insecticides
- bt toxin is specific to certain insect larvae so so is not harmful to other organsims that ingest it
Risks of bt crops (3)
- long term effects of consumption of Bt crops unknown
- insect larvae may become resistant to the Bt toxin
- killing insext larvae reduces biodiversity
Outline the agricultural methods of increasing food production (2)
- intensive farming methods e.g. use of fertilisers and pesticides
- biological control
Main advantag of intensive farming
Increases crop yields
3 disadvantages of intensive farming methods
- fertilisers can wash into nearby water sources and cause eutrophication
- the use of herbicides and insecticides reduces biodiversity
What is biological control
When a new organism (often a predator) is introduced into an ecosystem to control a pest or pathogen
Advantages of using biological control to increase food production
- the results of biological control generally last for a long period of time
- the effects on wildlife are less severe
Risk of using biological control
Risk of the control organism becoming a pest itself
