Topic 4: Natural Selection and Genetic Modification Flashcards
What is selective breeding?
The process by which humans artificially select organisms with desirable characteristics and breed them to produce offspring with similar phenotypes
What are the main steps involved in selective breeding?
Identify a desired characteristic, select parent organisms that show the desired traits and breed them together, select offspring with the desired traits and breed them together and the process repeated unto all offspring have the desired traits
What is the main advantage of selective breeding?
Creates organisms with desirable features
Where else is selective breeding useful?
In medical research and in sports
What are the disadvantages of selective breeding?
Reduction in the gene pool, inbreeding results in genetic disorders, development of other physical problems and potential to unknowingly select harmful recessive alleles
How can plants be cloned?
Taking plant cutting and tissue culture
What is tissue culture?
A method of growing living tissue in a suitable medium
How are plant are grown using tissue culture?
Select a plant that shows desired characteristics, cut multiple small sample pieces from meristem tissue, grow in a Petri dish containing growth medium and transfer to compost for further growth
What must be ensured when preparing tissue cultures?
Ensure aseptic conditions to prevent contamination by microorganisms
What does the growth medium contain?
Nutrients and growth hormones
What are the advantages of growing plants by tissue culture?
Fast and simple process, requires little space, enables the growths of many plant clones with sales desirable characteristics and useful in the preservation of endangered plant species
What are the disadvantages of growing plants by tissue culture?
Reduction in the gene pool, plant clones often have low survival rate and could unknowingly increase the presence of harmful recessive alleles
Why is animal tissue culturing useful?
Useful in the preparation of tissue samples for medical research and enables the investigation of how different factors may affect a specific animal tissue, without harming the animal itself
How does animal tissue culture are prepared?
Extract a sample of tissue from an animal, use enzymes to separate cells within the sample, grow in a culture vessel containing growth medium and once grown, store the sample
What is genetic engineering?
The modification of the genome of an organism by the insertion of a desired gene from another organism and enables the formation of an organism with beneficial characteristics
What happens in the process if genetic engineering?
DNA is cut at specific base sequence by restriction enzymes to create sticky ends, vector DNA cut using the same restriction enzymes to create complementary sticky ends, ligaments enzymes join the sticky ends of the DNA and vector DNA forming recombination DNA and recombination DNA mixed with and ‘taken up’ by target cells
What is a vector?
A structure that delivers the desired gene into the recipient cell
What are the benefits of genetic engineering?
Increased crop yields for growing population, using in medicine and GM crops produce scarce resources
What are the risks of genetic engineering?
Long-term effects of consumption of GM crops unknown, negative environmental impacts, late-onset health problems in GM animals and GM seeds are expensive
What is Bacillus thuringiensis (Bt)?
Insect larvae are harmful to crops and Bt is a bacterium which secretes a toxin that kills insect larvae
How is genetic engineering used to protect crops against insects?
The gene for toxin production in Bt can be isolated and inserted into the DNA of crops and Bt crop now secrete the toxin which kills any insect larvae that feed on it
What are the benefits of Bt crops?
Increased crop yields, lessens the need for artificial insecticide and Bt toxin is specific to certain insect larvae so is not harmful to other organisms that ingest it
What are the risks of Bt crops?
Long term effects of consumption of Bt crops unknown, insect larvae may become resistant to the Bt toxin and killing insect larvae reduces biodiversity
What agricultural methods of increasing food production?
Intensive farming methods and biological control
What is the main advantage of intensive farming?
Increases crop yields
What are the disadvantages of intensive farming methods?
Fertilisers can wash into nearby water sources and cause eutrophication, the use of herbicides and insecticides reduces biodiversity and ‘battery’ farming is often seen as unethical
What is biological control?
When a new organism is introduced into an ecosystem to control a pest or pathogen
What are the advantages of using biological control to increase food production?
The results of biological control generally last for a long period of time and effects on wildlife are less severe
What is the risk of using biological control?
Risk of control organism becoming the pest itself
What is classification?
The organisation of organisms into groups
What is taxonomy?
The classification of organisms into taxa: kingdom, phylum, class, order, family, genus and species
What are the five kingdoms?
Animals, plants, fungi, protists and prokaryotes
What happens to the number organisms in each taxi as you move down the hierarchy?
The number of organisms in each taxon group decreases
Organisms were grouped based on similarities and differences in their anatomy and behaviour. What is the problem with this?
Organisms that are not closely related may look alike and behave similarly if they live in the same environment and some closely related species may look very different if they live in different habitats
What advancements in science have led scientists to reconsider the five kingdoms classification system?
Microscopes, biochemistry and DNA and RNA analysis
What are the three domains system of classification like?
Organisms are initially divide into an extra three groups: Archaea, Bacteria and Eukarya.
What domains do eukaryotic organisms belong to?
Eukarya
Which domain do prokaryotic organisms belong to?
Archaea and Bacteria
What is the domain Bacteria?
Consists of true bacteria
What is the domain Archaea?
Consists of primitive organisms and contains extremophiles (adapted to live in extreme conditions)
What is evolution?
A gradual change in the inherited traces within a population over time and occurs due to natural selection
What happens in natural selection?
Genetic variation exists due to spontaneous mutations, selective pressures exist, random mutations givens an organism a selective advantage, organism is better adapted to the environment and survival, organism reproduces passing on it’s beneficial alleles and frequency of advantageous alleles increase
Why does competition between organisms in a habitat exist?
The resources within a habitat required for survival are limited
How can antibiotic resistance in bacteria can be used as an example to illustrate the process of evolution?
Genetic variation exists due to spontaneous mutations, antibiotics act as a selection pressure, mutations gives a bacterium antibiotic-resistant, if an antibiotic is administered, the bacterium is better adapted and survived, whilst other bacteria are killed, bacterium reproduces, passing on it’s resistant variants and frequency of antibiotic-resistant allele increases
Why is the development of antibiotic resistance in bacteria a good study for evolution?
Bacteria reproduce very rapidly, allowing the first-hand observation of evolution
How can the observation of fossils provide evidence for evolution?
Older fossils contain simpler organisms, newer fossils contain more complex organisms, comparison of fossils show that simple organisms evolved into more complex life forms and foodies can be organisms into chronological order, allowing the changes in organisms over time to be observed
What role did Darwin play in the development of the theory of evolution by natural selection?
Studied a variety of organisms whilst travelling around the world, noted the traits can be passed from parents to offspring, proposed the idea of ‘survival of the fittest’ and established the theory of natural selection
What role did Wallace play in the development of the theory of evolution by natural selection?
He proposed a theory of natural selection that was similar to Darwin’s, although the mechanisms were different and he gathered greater evidence to support the theory
How has the theory of evolution by nature selection impacted modern biology and society?
Enables the classification of organisms into taxa, influences modern medicine by emphasising the importance of finishing antibiotic treatment and the need for the constant production of new antibiotics and highlights the importance of high genetic diversity in habitats which aid conservation projects
What fossils have provided evidence for human evolution?
Ardi, Lucy and Leakey
How has the development of stone tools provided evidence for evolution?
Correlation between the development of more complex tools and an increase in brain size and primitive tools are older than more complex tools
What methods are used by scientists to date tools?
Carbon-14 dating - estimating the age of carbon-containing material that is found in tools
Stratigraphy - using the age of layers of sediment surrounding the tools as an indication of the age of the tool
What is a pentadactyl limb?
A limb with five digits present in animals, bird, reptiles and amphibians
How does the pentadactyl limb provide evidence for evolution?
The presence of the pentadactyl limb suggest that all species that posses it have a common ancestor
