Chapter 13+14- Variationa and Evolution Flashcards
Variation
Differences in the characteristics of individuals
Variation may be due to
The genes they have inherited
The condition in which they have developed
A combination of genetic and environmental causes
Mutations in the DNA over generations, these are continuous but rarely change the phenotype
Evolution
Change in inherited characteristics of a population over time through a process of natural selection which may result in the formation of a new species
Species def
A group of similar organisms capable of interbreeding to procuce fertile offspring
Speciation def
The formation of a new species due to evolution which may result in the extinction of previous species
Natural selection
Charles Darwins theory that individuals within a population who have characteristics most suited to their surrounding environments have the best chance of success of survival and reproduction. The genes that allow these individuals to be successful will then be passed on to their offspring
Selective breeding
The process by which humans breed plants and animals for particular genetic and aesthetic characteristics
Stages of selective breeding
- Choose two parents with desired characteristics from a mixed population
- Breed these two parents together
- From the offspring, choose those with the desired characteristics and breed them together
- Repeat this process over many generations until all the offspring dhow desired characteristics
Pros of selective breeding
- Desired characteristics
- Can create new varieties
- Disease resistance in crops
- Can produce domesticated animals with a gentle nature
- Increased milk/meat yield from cattle
- These could increase profits for farmers or breeders
Cons of selective breeding
- Possibility of inbreeding which can cause genetic mutations
- Negative health affects, more susceptible to diseases, lower life spans, bad quality of life for animals
- Ethical issues, unnatural
- Reduces variation
Genetic engineering
A process where a an organisms gens are modified
Stages of genetic engineering
- Enzymes are used to isolate the required gene
- This gene is inserted into a vector (usually a bacterial plasmid or a virus
- The vector is used to insert the gene into the required (host) cells
- Genes are transferred to the cells of animals of plants of microorganisms at an early stage in their development so they develop with the desired characteristics
Pros of genetic engineering
Improve crop yield
Improve resistance ro pesticides
Extend shelf life of products
Manufacture a certain chemical eg.Insulin
Cons of GE
Unnatural
Inserted genes may have unwanted side affects
