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Natural selection and genetic modification B4, , , , go to photos, -…
Natural selection and genetic modification B4
evolution
charles darwins theory of evolution - all species have evolved form simple life forms which appeared on earth billions of years ago
process is
genetic variation - different individual animals in a different population have a different combination of genes
survival of the fittest - individuals adapted to the environment will have greater chance of survival
successful breeding - individuals with higher chance of survival more likely to breed successfully
better characteristics to survive - characteristics which are responsible for greater chance of survival are passed on to nect gen
resistance in bacteria
bacteria reproduce rapidly , mutations occur during reproduction this means bacteria can evolve rapidly
reducing antibiotic resistance strains
doctors should avoid providing antibiotics unnecessarily for example for treating non serious or viral infections
patience must finish a course of antibiotics to make sure all bacteria are killed
the use of antibiotics in agriculture eg cattle feed should be restricted
antibiotics
the development of antibiotics is a slow and costly process which struggles to keep up with the emergence of new strains
example of resistence strain in bacteria is MRSA
resistance strain of bacteria
if a mutated bacteria is reistant to antibiotics when a person is treated with antibiotics , the bacteria will survive and go on to reproduce
this bacteria is the original ancestor of a new resistance strain
The bacteria will spread as there will be no treatment for it and people will not be immune to it as they were previously treated with anti biotics
Charles Darwin developed his theory of evolution whilst aboard the HMS Beagle on an expedition to the Galapagos Islands. He built up evidence to support the theory of natural selection and in 1859 he published his ideas in "On the Origin of Species".
Lots of people didn't agree with Darwin's theory of evolution by natural selection.
People said he didn't have enough evidence and that his ideas went against religious beliefs that God created the world. Genes had not been discovered yet, so Darwin couldn't suggest a method of how characteristics were passed between parents and offspring.
What process gives rise to antibiotic-resistant bacteria?
natural selection
impacts of evolution and evidence
evolution - gradual change in inherited chracteristics of biological populations over time, usually driven by natural selection
the theory of evolution has greatly affected modern biology
many scientists have since studied how organisms have changed over time adn also how different species are related to eachother
genetics - scientists later discovered exactly how traits are inherited - through genes. Genetics is a huge area of biology
the evidence for evolution
the discovery of genes as a way to inherit characteristics and create variance supported theory of evolution
two main sources of evidence are...
fossils - fossils show gradual changes in organisms over vast periods of time
fossils are the remains or traces of ancient life. Fossils are found in rocks and have been preserved by natural process
three dif ways of forming fossils
3 more items...
Why is the fossil record incomplete?
a lot of early life forms were soft bodies so they didn't leave behind many noteworthy traces, geological activity has caused destruction of many traces of ancient life so because of this scientists cant be certain of the origins of life on earth
fossils can be dated so scientists have evidence for what organisms looked like at dif periods of time, comparing fossils indicated how humans have changed over time
oldest fossil human remains are of ardi - ardiphicous ramdius - dating back 4.4 million years ago
another fossil was found called lucy, which was dated at 3.2 million years old
there have been more discoveries by of human fossils by an archeologist - fossil hunter - called leakey, who discovered fossils from 1.6 million years ago
stone tools
2 more items...
antibiotic resistance in bacteria
bacteria reproduce rapidly, mutations occur during reproduction, if a mutated bacterium is resistance to antibiotics , itll survive exposure and go on to reproduce
this bacterium will represent ancestor of new resistance strain
classification
classification groups organisms by comparing their similarities and differences g
tradiitional - linnaen system - devised by carl linnaeus groups organisms based on thier structure and characteristics
He created 7 different groups
Kingdom, Phlyum, class, order, family, genus and species
carl woese proposed the 3 domain system which classifies organisms based on chemical analysis
3 domain system
archea - primitive bacteria
bacteria - true bacteria
eukaryota - organisms possssing complex subcellular structures - protists plants fungi and animals
To remember the order of the Linnaean classification (in descending size order): King Prawn Curry Or Fried Greasy Sausage.
Link Title
The ‘three-domain system’ was proposed by Carl Woese and classifies organisms based on chemical analysis:
archaea- primitive bacteria many of which live in extreme conditions
bacteria - true bacteria
eukaryota - organisms which posess complex sub cellular structures
evolutionary trees
evolutionary trees are used to show how scientists believe organisms are related
classification - current classification data is used for living organisms and fossil data is used for extinct organisms
dna sequencing
sequencing dna tells us how closely related dif species are because dna can change at a rate that is aprox constant over time and across different living organisms
working out how closely related organisms are using this method is called molecular phylogenetics
evolution - the start of a tree is a common ancestor and the branches show the species that have evolved from the common ancestor
genetic engineering
selective breeding
selective breeding or artificial modification happens when humans choose animals and crops to breed based on their genetic chracteristics
humans have done this in farming for thousands of years with both animals and crops to promote genetic characteristics which we see as desireable
organisms used in selective breeding
farm animals
crops
flowers
dogs
selective breeding
lots of steps for selective breeding process:
choose parents who display the strongest and most desired characteristics
breed the chosen parents
from the resultant off spring children choose the offspring which display the most desired chracteristics, breed these chosen offspring
repeat this process of breeding and reselection over many generations till all offspring show desired chracteristics
uses and dangers of selective breeding
usefulness and appearance are the two most common reasons for a characteristic to be desirable . Some useful examples are:
Animals - in farming, animals that produce milk or meat are also useful for yield related reasons
dogs - gentle natured domestic dogs are useful as they must coexist with humans
flowers - flowers can be selected based on visual criteria such as size or color
crops - disease resistence in food crops is a useful chracteristic because it improves yield - food production productivity
dangers of selective breeding
reduced variation - selective breeding can reduce variation - differences in characteristics within a population making it harder for a species to adapt to environmental change
inbreeding - selective breeding can lead to inbreeding, here some species become particularly suspectible to a disease or inherited defects, eg french bulldogs have been selectively bred to have flat faces but that causes them to hacve breathing problems
genetic modification
genetic engineering
genetic engineering involves modifying an organisms genome by introducing a gene from another organism to produce a desired characteristic
example of this include...
Vitamin A rice - a lack of vitamin A can lead to blindness
Alot of communities that were lacking vitamin A were found to use rice as the core of their diet
thus a gene that produced vitamin A was taken from bacteria and added to rice
insulin producing gene - a gene that produces insulin can be inserted into bacteria, those bacteria can then mass produce insulin to help treat people with diabetes
genetic engineering does not involve creating a new gene
process of genetic engineering
genetic engineering happens like this
cut the target gene out - enzymes known as restriction enzymes are used to cut a desired gene out of a chromosome
cut a vector - a restriction enzyme is used to cut a vector - both the target gene and the vector now have exposed sections of single stranded dna known as sticky ends
The vector is usually a bacterial plasmid or a virus
gene is inserted - an enzyme called ligase is then used to join up the sticky ends of the gene and the vector, so that the vector now carries the target gene
A marker gene - such as a antibiotic gene - is also added to the vector to make it easy to check that the vector has taken up the target gene
delivering gene - if the gene is delivered into cells by the vector before they have differentiated - at the egg or embryo stage- all cells in the developed organism will have the gene and show the characteristic
pros and cons of genetic modification
Genetic engineering is an exciting technology that has some potentially groundbreaking uses. These include:
Advantages of genetically modified crops
GM crops generally show increased yields
they could help provide nutrients that are often missing from the diets of those living in developing nations - eg golden rice for vitamin A
Gm crops are popular in some parts of the world and no complications have been experienced so far
improving food production efficiency
preventing inherited diseases
disadvantages of GM crops
some people expect GM crops to negatively impact wild flower and insect populations, thus reducing biodiversity
some people think that therell be long term effects of consumption on human health
if transplanted genes managed to espcape into the natural environment we could accidentally create a superweed which is resistant to herbicides
many people object to the use of genetic modification, some concerns are
because it is relatively recent to developments, is uncertain what the long term effects may be
some consider it unethical to create new life forms or move genes between species
exam qs
All birds have evolved from a single common ancestor.
Kingfishers and sparrows are two bird species that can be found in the UK, and can be seen in the following photos.
Kingfishers have large and broad beaks and feed on fish and crustaceans found in rivers.
Sparrows have short and cone-like beaks and feed on seeds
How have kingfishers and sparrows evolved over time to have different beak shapes?
Among birds, there is variation in beak shape. Some shapes are better for eating certain types of food.
2
A large, long beak is better for catching crustaceans and fish. A short, cone-shaped beak is good for cracking open seeds.
3
Beak shape is controlled by genes. Differences in beak shape arise due to random mutations.
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The individuals with the best beak shape for the food available will get more food and will be more likely to survive and reproduce to give offspring.
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The genes of the survivors that caused a particular beak shape will be inherited by their offspring.
link to www.google.co.uk
go to photos
