Variation and Evolution Flashcards
Phenotype
Observable characteristics of an individual due to the interaction with their genes and their environment.
Variation
Differences in the characteristics of individuals within a population
Why is there so much genetic variation?
Mutation
How can mutation be beneficial?
The organism is more likely to survive and reproduce and pass their genes (survival of the fittest)
Natural selection
fittest individuals selected to survive
Evolution
Inheritance of certain characteristics in a population, over multiple generations, could lead to a change in the whole species.
Theory of evolution
All of today’s species have evolved from simple life forms that first started to develop over three billion years ago.
Why did some people disagree against Darwin’s theory?
- Went against religious beliefs on how life on
Earth developed - Darwin couldn’t prove how useful
characteristics were passed on; did not know
anything about genes or mutations - Wasn’t enough evidence to convince scientists
as there weren’t a lot of other studies on
evolution
How has Darwin theory been proven?
- Fossil records
- Antibiotic Resistance
Speciation
Over a long period, the phenotype of organism can change so much (natural selection) that a completely new species is formed.
What are some reasons for extinction?
- Environment changes too quickly
(deforestation) - New predator kills them all (humans hunting)
- New disease kills them all
- Cannot compete with another species for food
- Catastrophic event that kills them all (collision
with asteroid)
Selective breeding
Humans artificially select organisms to breed together to develop features that are useful or attractive.
What are examples of offspring from selective breeding
- Animals that produce more meat or milk
- Crops with disease resistance
- Dogs with a good, gentle temperament
- Decorative plants with big or unusual flowers
Selective Breeding process
- From existing stock, select ones with
characteristics of your choice - Breed them together
- Select best offspring and breed together
- Continue this process over many generations
for all the offspring to have the characteristics
What is the main drawback of selective breeding?
It reduces the gene pool meaning inbreeding takes place
Gene pool
The number of different alleles in a population
inbreeding
- Can cause health problems because there’s
more chance of organisms inheriting harmful
genetic defects when the gene pool is limited. - If new disease appear it would very serious as
there is not variation in the population as all
the stocks are closely related.
Genetic Engineering
Transferring a gene thatcontains the desirable characteristics from one organism’s genome to another (modifying genome).
Examples of genetic engineering
- Bacteria being genetic modified to produce
human insulin to treat diabetes - Sheep has been genetically engineered to
produce drugs in their milk to treat human
diseases - gene therapy
- GM crops has improved size and quality of
fruits or resistant to diseases
Gene therapy
inserting working genes into people with the disease.
How is Genetic Engineering carried out
- A useful gene is isolated from one organism’s
genome using enzymes and is inserted into a
vector - Vector usually a virus or a bacterial plasmid
- When the vector is introduced to the target
organism, the useful gene is inserted into its
cells.
Genetic engineering drawbacks
- Small risk that GM could negatively affect our
health - if crops breed with wild plants they could
spread their new genes and affect the gene
pool
What are the 2 methods that clones plants
- Tissue culture
- Cutting
Tissue culture
A few plants are put in a growth medium with hormones and grow into new plants- clones of parent
- can be made very quickly in little space and all
year round
