Variation and evolution Flashcards
What is a mutation?
A random change in a gene
Explain how the peppered moth is an example of natural selection: (5)
Mutations in the peppered moth have caused some to develop black wings, these black moths originally were more threatened by the predation of birds than white versions. during the Industrial Revolution when smoke was abundant, black moths became better camouflaged in the environment and were preyed on less, this means that they were able to reproduce and pass this trait onto their offspring through the gene in their alleles. over generations, black alleles became more common within the population.
Describe the process of selective breeding: (4) give disadvantages and advantages
- choose parents with desired characteristics from a mixed population
- breed them together
- from the offspring, select the ones who express the desired characteristics most.
- breed offspring with other competent traits.
- this continues over generations until the characteristic is expressed by all of the offspring.
advantages:
* we can produce organisms with desired characteristics benefitting their appearance of usefulness which may help us to economically grow.
disadvantages:
* inbreeding can cause growth abnormalities (resulting in many being put down), ethical
* limited variation in the population make them prone to extinction.
* takes a long time
* characteristic has to be present in the population already
Discuss selective breeding and genetic engineering:
Selective breeding involves deliberately breeding two parents who express desired products to create offspring that inherit them and repeating it over generations until all of the offspring inherit the desired characteristics. This can take years to do and can remove certain characteristics as it makes a population with little variation, it also relies on the characteristic being found within the population.
Genetic engineering involves extracting a gene that codes for a specific characteristic in another organism and implanting it to be expressed in another. The gene is cut from the organism with the trait using restrictive enzymes and inserted into a cut vector using ligase enzymes. The vector (a bacterial plasmid for example) now contains the desired gene and is used to transfer the gene into a cell of another organism at early stages of its development. As the organism grows, it grows with the trait in its genome, and it expresses it. This process is much faster than selective breeding, therefore takes up less resources and money, it also introduces traits into a population which may not have had it present and can result in crop yields increasing and being resistant to certain disease such as TMV. However, this leads to ethical issues with the potential of us engineering our babies to have certain traits, it’s also said that GM foods have not been proved to be safe to eat long term due to its new discovery. additionally, genetic pollution can cause some attempts of genetic engineering to be be useless and cause more problems.
Explain how bacteria are genetically engineered to produce a human protein (insulin):
- Using restriction enzymes we remove the insulin gene from the nucleus of a human cell.
- using another restriction gene, we remove a plasmid from a bacteria cell and cut it open.
- Using ligase enzymes we fuse the gene into the plasmid creating one loop.
- the plasmid is then inserted into another bacterium so that it can asexually reproduce through binary fission, producing identical daughters with the insulin gene.
- insulin gene is switched on and harvested.
What are the two types of adult cell cloning?
-therapeutic cloning
-reproductive cloning
Define selective breeding:
Purposefully selecting individuals from a mixed population with the most desired characteristics to breed together and produce offspring who express the characteristics.
Define genetic engineering:
Modifying the genetical material of an organism
Describe the process of genetic engineering: (4) give disadvantages and advantages
- The gene is cut from the organism with the trait using restrictive enzymes and inserted into a cut vector using ligase enzymes.
- The vector (a bacterial plasmid for example) now contains the desired gene and is used to transfer the gene into a cell of another organism at early stages of its development.
- As the organism grows, it grows with the trait in its genome, and it expresses it.
What are the three techniques of modern cloning:
- Tissue cultures
- Embryo transplants
- Adult cell cloning
Describe the process of using tissue cultures to clone from an endangered plant: Include advantages and disadvantages
Take a small sample from the plant you want to clone.
Add the sample to an agar plate which contains nutrients and plant hormones to create a large mass of the sample.
Use other hormones to stimulate the sample cells to form new plants.
+ this can help scientists revive endangered plants or maintain rare species.
+ this helps farmers to produce large crop yields of the same high quality
- expensive
Describe the process of using embryo transplants to clone high quality cows: Include advantages and disadvantages
- Give fertility hormones to a high quality female cow so she produces many mature egg cells.
- Fertilise these eggs using the sperm of a high quality male cow.
- Extract embryo, which has divided into a ball of cells, from the cow.
- At this early stage, we divide the individual cells from the embryo, as they all can still grow into multiple embryos.
- Insert the cell into the uterus of multiple surrogate mothers to conceive the cows.
+ this means that multiple high quality embryos can be made
+ high quality embryos can be shipped off to other poor quality farms to breed into their population.
Describe the process of using adult cell cloning to clone a cow: Include advantages and disadvantages
- Extract the nucleus out of a cell from the organism you want to clone.
- Insert it into an enucleated egg cell
- Give the egg cell (that now contains the genetic information of the desired organism) an electrical shock to stimulate mitosis and form an embryo
- Implant the embryo into a surrogate to conceive.
+ this helps us to clone an organism exactly so we can replace pets
