B14-Variation and evolution Flashcards
What is Variation ?
All the differences in the characteristics of individuals in a population .
Waht is the first cause of variation ?
-The alleles (characteristics) that individuals have inherited - geentic causes .
Example of genetic causes is eye and hair colour .
What is the second cause of variation ?
Environment , eg-language .
What is the third cause of Varition ?
-A combination of genes and the environment .
Example - height , some alelels which make you grow taller , BUT ALSO CAN BE AFFECTED by diet , calcium for bones to fully devlop .
In any population of a species there is a amssive amount of egentic variation .
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What causes genetic variation
Mutations
What are mutations
Random changes to DNA .
-Take place all the time and mosr have no effect at all on the phenotype .
What can some mutations do ?
-Some mutations may influence the phenotypes - alelles for tallness MAY lead to tallness if diet is suitable .
What is another thing mutations can do ?
-A small number of mutation can actually determine the phenotype - eye colour .
What is another thing mutations can do (black moths and white moths )
-Very rarely , a mutation can lead to a new phenotype .
-What can a new phenotype be beneficial for , what can it lead to ?
-A new phenotype can be beneficial if environment changes leading to rapid change in a species .
What is natural selection ?
-Organisms that can gain an advantage and therefore are more liekly to survive and breed .
What is the first stage of the survival of the fittest process ?
-Individual organsisms within a particular species may show a wide range of phenotype and genetic variation .
What is the second stage of the survival of the fittest process ?
-Individuals with characteristics msot suited to the environment are most likely to survive and breed sucessfully .
What is the third stage of the survial of the fittest process ?
-The alelles (variants) that have enabled these individuals to survive are then passed onto the next generation .
What happpens when two populations of one species become too different in phenotypes ?
- They can no longer interbreed to produce fertile offspring .
- these two populaitons have now become two separate species .
Humans realised wolves were useful how ?
- Wolves can protect you by alerting you
- Wolves can keep you warm and company .
Why have domestic dogs been selectievly bred ?
-They have been selectively bred to have a gentle nature .
Why have food crop have been selectively bred ?
-They have been selectiely bred to be resistant to disease .
Why have animals been selectively bred ?
-They have been selectively bred to produce more meat or milk .
Why have certain plants been selectively bred ?
-They have been slectively bred to produce large or unusal flowers .
What is the first stage of selective breeding ?
- Selec two individuals (male and femlae if animlas) from a mixed population who have best of that characteristcis .
- Breed parents together .
What is the second stage of selective breeding ?
-Reproduction produces variaition in offspring so some offspring will have the desired chat=racteristic but others won’t .
What is the third stage of selective breeding ?
- Select offspring with the ‘best’ characteristic and breed together .
- Continue doing this over many generations until all offspring have that characterstic .
What is the risk of selective breeding .
-If we breed otgetehr closely related animals and plants , we can get inbreeding .
-Inbreeding can cuase some breeds to be prone to disease or inherited diseases .
(dogs epilepsy )
What are clones ?
-Clones are genetically identical organisms through asexual reproduction .
Advantage of cloning plants
-As the clone is genetically identical to the original plant , we know exactly what the clones characteristics will be (colour of the flowers ).
What will the offspring be like if we use seeds ?
-As seeds re produced by sexual reporudction , all the offspring would be different .
What is a simple wy to clone a plant
-to take cuttings - gardeners have used this method for a long time .
How do you take cuttings ?
- A small piece of the plant is removed and the end is dipped in rooting powder .
How do you take cuttings (2) ?
- Rooting powder contains plant hormones and htis encourgaes plants to develop roots .
- By taking cuttings , we produce a genetically identitcal clone as a starter plant .
Disadvantage of taking cuttings ?
-Good for small amount of clones but cannot bedone for large amount ?
What do we do to clone large amounts of plants ?
-Tissue Culture
What is the first stage of tissue culture ?
-We take a palnt that we want to clone and we divide the plant into hundreds of tiny pieces .
What is the second stage of tissue culture ?
- Each of these pieces ocntains a small number of cells .
- These small groups of cells are then incubated with plant hormones .
What do plant hormones do ?
Plant hormones stimulate plant to grow and develop into fully-gorwn clones .
Why do conditons for tissue culture must be sterile ?
-As we don’t want to intorudce any microrganisms liek bacteria and fungi .
What is one reason why tissue culture is useful in commercial plant nuseries ?
-It allows growers to produce genetically identical plants , quickly and cheaply and as all the plnts are clones , gardeners can be certain what characteristics they want .
What is another reason why tissue culture is useful in commercial plant nurseries ?
It is also useful to preserve rare species .
What are the two ways to clone animals
- Embryo Transplants
- Animal Cell Cloning
What is the first stage of embryo transplants ?
-Giver fertility hormones to the female .
extract sperm and an egg cell from the naimals with the
characteristics we want .
What is the second stage of embryo transplants ?
Fertilisation produces a fertilised egg .
What is the third stage of embryo transplants ?
Allow the fertilised egg to develop into an early stage embryo .
-It is very important that the cells in thembryo must not have started to specialise .
What is the fourth stage of embryo transplants?
We now use a glass rod to split the embryo into two .
What is the fifth stage of embryo transplants
Finally we transplant the two mebryos into hsos t mothers womb .
-The embryos will then grow and develop . When these aniamals are born , you get two identical offsprings (clones)
What is the benefit of adult cell cloning rather than embryo transplants ?
When cloning from an adult , we know the characteristics the clone we wil have unlike embryo transplants .
What is the first stage of Adult Cell Cloning
.Start by removing a cell from the animal we want to clone .
What is the second stage of Adult Cell Cloning
We then remove the nucleus from this cell .
-This nucleues cotains the genetic information from the animal that we are cloning .
What is the third stage of Adult Cell Cloning
Take an unfertilised egg cell from the same species.
What is the foruth stage of Adult Cell Cloning
Then remove the nuecleus from the unefertilised egg and throw it away so it has no egentic material at all .
What is the fifth stage of Adult Cell Cloning
Insert the nucleus from the original audlt body cell into the epty egg cell .
-Now the egg cell only containts genetic information from the animal we are cloning .
What is the sixth stage of Adult Cell Cloning
Then give the egg cell an electric shock ,causing the egg cell to divide and form an embryo .
What is the seventh stage of Adult Cell Cloning
These embryo cells conntan the same genetic information as the adult skin cell we started with .
What is the eight stage of Adult Cell Cloning
When the embryo has developed into a ball of cells , it is then inserted into the wom of an adult female ,t o continue is development .
Host mother then gives brith to clone .
Why does the clone look nothing like the mother in Adult Cell Cloning ?
As the clone contains none of her genetic material .
