B14 Flashcards
Two types of variation
Genrtic variation and environmental variation
Variation
Its how organisms can vary in appearance, size, eye colour……….
Our characteristics are determined by
Our genes inherited by parents
The combining of genes from two parents causes
Genetic variation - no two of the soecies are genetically identical (other than identical twins)
Environmental variation
The envrionment including the conditions that organisms live and grow in, causes difference brtween members of the same species.
- it covers a range of sifferences from losing toes, getting a tan, to yellow leaves and dark leaves
Mutations
Changes to the sequence of bases in DNA. Mutations lead to changes in protein that a gene codes for.
- most mutations have no effect on the protein genes code for, so phenotype is barely affected.
- some very slightly influence characterisitics
- if environment changes, and the new phenotype makes an individual more suited to the new environment.
Theory of Evolution
All of today’s species have evolved from simple life froms that fursf started to develop over three billion years
Evolution
How species have developed over millions of years
The species on earth today have
Evolved over millions of years
The process of evolution started with _____ organisms which lived in ______, over time these evolved to become ________. This eventually produced the animals of the ____ and _____ we observe today. Most of the evidence for evolution comes from ________
Unicellular, water, multicellular. Air, land, fossils
Survival of the fittest
Organisms with the most suitable characteristics for the environment would be more successful competitors and would be more likely to survive
Natural selection
Organisms with the most suitable characteristics for the environment would be more successful competitors and would be more likely to survive
Selective breeding
When humans artificially select the plants/animaks that are giing to breed si that the genes for particular characteristics remain in the population
Organisms are selectively bred to develop certain features…..
- animals that produce meat/milk
- crops with disease resistance
- dogs with good/gentle temperament
- decorative plants with big/unsusual flowers
Selective breeding process:
- from exisiting stock, select ones sith desriable characteristics
- breed them together
- select best offspring, breed them together
- do this over several generations, and desirable traits gets stronger and stronger
- eventually all will have the characterisitics.
Drawbacks of SELECTIVE BREEDING
- reduces the gene pool (num of different alleles in a populatio)
- this is because farmers breed the best animals togehter which are usually always closely related (inbreeding)
- causes health problems as more chance of organisms inhering harmful genetic defects as gene pool is limited
- serious problems if new disease appears, as not much variation in the population.
- as they are all closely related, if one dies to it, the others are also likely to succumb it.
Advantages of Selective breeding:
- Higher economic gains
- eliminating disease
- create new varieties of crops
- does not involve genetic modification
- ## produces fitter, stronger animals
Disadvantages of selective breeding
- animal discomfort
- loss of variety and variation (inbreeding)
- no control of genetic mutations
- can lead to loss of traits
- it can change the evolution of a species
Genetic engineering is a process which involves
modifying the genome of an organism by introducing a gene from another organism to give a desired characte
Plant crops have been genetically engineered to be
resistant to diseases or to produce bigger better fruits.
Bacterial cells have been genetically engineered to produce
useful substances such as human insulin to treat diabetes.
In genetic engineering, genes from the chromosomes of humans and other organisms can be
‘cut out’ and transferred to cells of other organisms.
The main steps in genetic engineering:
• enzymes are used to isolate the required gene; this gene is inserted into a vector, usually a bacterial plasmid or a virus
• the vector is used to insert the gene into the required cells
• genes are transferred to the cells of animals, plants or microorganisms at an early stage in their development so that they develop with desired characteristics.
Genetic modification (bacteria, crops, sheep, inherited disease
- Bacteria have been GM to produce human insulin thst can be used to treat diabetes
- GM crops have had their genes modified to improve suze/auality of their fruit, make them resistant to disease/insects/herbicides.
- sheep have been genetically engineered to produce substances, like drugs, in their milk that csn be used to treat human diseases.
- scientists are researching GM treatmentsfor inherited diseases caused by faulty genes. (By inserting working genes into people with the disease (gene therapy).
Pros of GM crops:
- the characteristics chosen for GM crops can increase the yield, making more food.
- in developing nations = often lack of nutrients in their diets = GM crops can be engineered to contain missing nutrients
- GM crops are being grown in places, often no problems
Cons of GM CROPS:
- Growing GM crops affect the number of wikd flowers that kune in/around crops - reducing BIODIVERSITY
- not all people convinced that GM crops are safe and concerned that we don’t fully understand the affects of eating them on human health
- A big concern is that transplanted genes may get out into the natural environment.
Concerns about genetic engineering
• Genetic engineering is a very new science-no one can be sure about the long term effects.
• Insects may become pesticide-resistant if they eat a constant diet of pesticide-forming plants.
• Genes from GM plants and animals might spread into the wildlife countryside. This might affect wild flowers and insects.
Three advantages of GE in agriculture
- improved plant growth rates of plants
- increased crop food value
- ability to grow crops in adverse conditions
Genetic engineering may one day be used to dure human genetic disorders. How
- ‘healthy’ genes could be inserted into affected cells.
• the affected cells could then begin to work properly
• advances in science may mean we can alter peoples genes
• Scientists would then be able to change the affected gene so they no longer have the disorder
Plants can be cloned by tissue culture and from cuttings
Tissue Culture:
- Where a few plant cells are put in a growth medium with hormones, they grow into new plants - clones of the parent plant
- some plants can be made very quickly, in little space grown all year.
-Tissue culture preserves rare plants that are hard to reproduce naturally and by plants nurseries to produce lots of stock quickly.
Cuttings:
- Gardeners take cuttings from good parent plants, then plant them to produce genetically identical copies of the parent plant.
- These plants can be produced quickly and cheaply. Older, simpler method thsn tissue culture.
A species is a group of similar
Organisms that can reproduce to give fertile offspring.
Speciation is
The development of a new species
Speciation occurs when
Populations of the same species become so different thst they csn no longer successfully interbreed to produce fertile offspring.
Animal clones using Embryo Transplants:
- sperm cells taken from a bull and egg cekls are from cow.
- the sperm are used to artificially fertilise an egg cell. The embryo that develops then splits manu times before any cells become slecialised.
- cloned embryos can then be implanted into lots of other cows where they grow into baby calves.
Adult cell cloning is another way to make a clone….
