B7 Variation And Evolution Flashcards
Environmental variation
Changes due to the environment Tattoos Scars Language Hair colour and length
Genetic variation
Differences from our genes Blood group Eye colour Shape of earlobe Natural hair colour
Genetic and environmental factors
A mixture of both Height Skin colour Weight Sporting abilities
Variation and survival
Variation is critical for survival and for evolution
Genetic variation
The product of 3 processes that lead to differences in genomes: mutations, sexual reproduction and meiosis
Most mutations have no effect and rarely change the phenotype
An early theory of evolution
French scientist Jean-Baptiste Lamarck in 1809
Organisms survived by adapting to their environment passed on this adaption to the next generation
Eg. Giraffes necks were stretched and then passed to next generation
How does evolution happen?
The environment does influence the phenotype but not in the way Lamarck suggested
Desired characteristics are passed to their offspring eg.resistant to antibiotics
Natural selection
When desired characteristics are passed to their offspring
Environmental changes
Geographical isolation, change in climate causes species to adapt differently
Overtime they will develop characteristics different to those or the original species
Darwin’s theory
He noticed that animal where the similar but not the same
This lead to the idea of natural selection and evolution
Natural selection
The most advantageous characteristics are passed on
Evolution
Species are changing and adapting through natural selection in order for survival
How are fossils formed?
By dead animal or plants being buried in mud,silt or sand
There is no oxygen so that organisms can not decay the body
Hard parts of animals like bones are fossilised
Can also be trapped in amber or volcanic ash
Evidence from fossil records
Older fossils are near the bottom
We can see which species have adapted, survived or died out
Radiometric dating
Allows us to identify the exact age of the fossil.
Incomplete fossil records
Geological activity has destroyed them
May be lost
Soft bodied organisms can not be fossilised
Missing links between species
Evolution of life
Some species have changed a lot whilst others have evolved very slowly
Some bacteria have changed very little as there is still chemical evidence of them in fossils
Warning colouration
To deter predators
Favoured by natural selection
Mimicry
Unrelated species develop similar warning colourations to help promote their survival
Isolation
Geographical isolation causes species to develop different advantageous characteristics
Eventually it will reach a point where the new species can no longer interbreed with the original species to form fertile offspring
Speciation
A species that evolves through natural selection to form a new species
Selection pressures
Pressures such as food, water, shelter creates competition to which only the best suited species survives and passes on its characteristics
Melanic moths
They changes colour from white/pale to a darkened colour in the industrial revolution to help it survive longer
Melanism
When a species changes its phenotype stop help survive longer
Genetic variation
Similar species breed together to provide a greater gene pool in which there is differences so that some species may survive longer than others
Gene theory
Genes work by controlling enzyme synthesis
Genes code for proteins
Antibiotic resistance
MRSA
This occurs through people not completing their course so the worse bacteria is exposed to the antibiotic. It can then develop resistance. The resistance gene can be passed to other bacteria through plasmids
Reducing AMR
People completing the course
No sharing prescription
Not skipping doses
Only prescribing when necessary
Solving the problem
Global governments working together
Encouraging pharmaceutical companies to develop a new drug
Economically challenging for pharmaceutical companies
New strains may not be the most effective over a long time
Advances in genes may be a solution to the problem
Selective breeding
Interbreeding species to get desired characteristics which will be more advantageous
Problems with interbreeding
Creates a small gene pool with little variation
Species can become accustomed to diseases which threaten their health and survival
Beneficial characteristics for crops
Grow and mature quickly
Distinctive taste, colour or aroma
Long shelf life
Can be frozen
Environmental change
genetically modified crops can be wiped out from a change due to little variation and resistance to new diseases
Traditional plant breeding
Using plants from a mixed selection to produce a plant then cross breeding with other plants till the desired phenotypes are produced
Producing a new variety
It takes a long time as it has to be grown and put through selection pressures to ensure it is different and is different form other similar species
Genetic engineering
Taking the desired characteristics of two species and putting them together
Insulin
We can genetically engineer bacteria to produce insulin
Genetically modified crops
They increase yields and produce better more desirable produce. It ensures crops are not lost to diseases
Genetic engineering technique
An enzyme is used to isolate to gene that codes for proteins.
The insulin gene is cut out and placed in a plasmid that is cut open by the same enzyme
The insulin gene is inserted into the plasmid
The plasmid is put back into the bacterial cell
The genetically modified bacteria are cultured
Feeding the world
GM crops can contain extra nutrients to help ensure people get the vitamins required
Eg. Golden rice contains beta carotene which helps code for vitamin A to help with eye sight
Herbicide and insecticide resistant crops
GM crops can produce toxins to kill insects without damaging the plant. This produces a greater yield
Ecological effects
Whilst there is concerns about pollen containing toxins that will damage other species (possibly through cross pollination), GM crops generally only kill pests that are eating the plant.
Gene markers
Helps identify GM species or antibiotic restraint genes.
It can be dangerous to the survival of species as it is easier for predators to identify them
GM safety
Some speculate that it may cause allergic reactions but it may be used to prevent people getting reactions
Like wise some people say it may cause cancer or autism
This has only been some what proven with the use of glyphosate
Which is described as harmless to us, animals and the environment
Ethics of GM
Not ethical as you are altering Gods creation
However it may be beneficial for the survival of mankind
Producing and marketing GM crops
Farmers can not sow seeds from GM crops as they wont breed true instead they have to buy new seeds.
Essentially exploiting poorer farmers
Have to label GM crops clearly so costumers can decide whether to buy them or not to.
Gene therapy
By using a vector we may be able to help treat genetic disorders however it poses many challenges
Many got sick from vectors in early trials
There is no guarantee that offspring will get the modified genes
Very technically and ethically difficult
GM cloning
Cloned in small groups (tissue cultures)
Can produce rare plants
Embryo transplants
Allow the cloning of animals to occur early on within a pregnancy
Adult cell cloning
Nucleus is combined with an egg cell An electric shock stimulates the cell to divide by mitosis Embryo has divided into a ball of cells Embryo implanted into an adult female Clone of sheep is born
Binomial system
Kingdom Phylum Class Order Family Genus Species
Evolutionary trees
Come from organisms alive today and from fossil records
Also look at base sequences of portions of DNA, or the structures of other chemicals such as proteins
Looks at bit like a family tree
Mass extinctions
Fossil records show there are 5 main extinctions
They are generally from a change in the environment
Causes of extinctions
New predators Compete with native organisms that are present for food Introduction of new species Change in the environment Invasive or new species
The sixth mass extinction may be occur because humans are
Transforming the landscape
Over exploitation of species
Pollution
Introduction of alien species
