B15 Variation Flashcards
What is variation?
Differences in characteristics of individuals in a population
What can cause variation?
Genetic causes
Environmental
How do new phenotype variants occur?
Mutations
What is selective breeding?
Breeding plants and animals for particular characteristics
Describe the process of selective breeding
1. Choose parents with the desired characteristics
2.Breed them together
3.Choose offspring with desired traits and breed again
4. Continue over many generations until all offspring show this characteristic
What are the consequences of inbreeding?
Inherited defects and disease
What is genetic engineering?
Modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic
How have bacteria been genetically engineered?
To produce useful substances
e.g human insulin to treat diabetes
How have plant crops been genetically engineered?
To be resistant to disease/herbicides/pesticides
To produce bigger fruits
To produce higher yields
What are enzymes used for in genetic engineering?
To cut out the required gene
What is used to transfer the required gene in to the new cell in genetic engineering?
Vectors
(such as bacterial plasmids or a virus)
Describe the steps involved in adult cell cloning
- Nucleus removed from unfertilised egg cell
- Nucleus from adult body inserted in to egg cell
- Electric shock stimulates egg cell to divide to form an embryo
- Embryo develops and is inserted in to the womb
What is tissue culture cloning?
Using small groups of cells from plants to grow new identical plants
Why is tissue culture cloning of plants important?
to preserve rare species and for growing plants commercially in nurseries
What is ‘cutting’ as a cloning method?
Simple method used by gardeners to produce many identical plants from a parent plant
Describe cloning through using embryo transplants
Cells split apart from a developing animal embryo before they are specialised, then identical embryos are transplanted in to host mother
What is selective breeding used for?
(examples)
Disease resistance in crops
Animals that produce more meat or milk
Larger or unusual flowers
BENEFITS of cloning
Large number of identical offspring produced
Quick and economical
Desired traits guaranteed
RISKS of Cloning
Limits variation and causes reduction in gene pool
May be more vulnerable to diseases and changes in the environment
Ethical considerations around cloning living organisms
BENEFITS to Genetic engineering
Potential to overcome some inherited human diseases
Crops can be resistant to herbicides and make their own pesticides
Higher crop yields
RISKS of Genetic engineering
Genes from GM plants may spread to other wildlife which could have a bad effect on ecosystems
Negative impact on population size of wild flowers and insects
Ethical concerns
We do not know the long term effect of eating GM crops
What is a clone?
An individual that has been produced asexually and is genetically identical to its parent
