Topic 4 Natural selection: Natural selection, selective breeding, resistant organisms, Human evolution & Tools. genetic moderfication Flashcards
What was Darwins theory of evolution?
He proposed that individual organisms within a particular species show a wide range of variation for a characteristic. Individuals with characteristics most suited to the environment are more likely so survive and to breed successfully. The characteristics that have enabled these individuals to survive are then passed on to the next generation; this is called natural selection.
How do bacteria become resistant and how is this evidence for evolution?
Bacteria can evolve wuickly because they reproduce at a fast rate. Mutations of bacteria produce new strains. some bacteria might become resistant to certain antibiotics. The evolution of the bacteria is an example of natural selection supporting dawins theory.
What are the main steps in the development of resistance?
1) Random mutations occur in the genes of individual bacteria cells
2) some mutations protect the bacteria cell from the effects of the antibiotic
3) bacteria without the mutation die or cannot reproduce when the antibiotic is present
what is MRSA?
MRSA is very dangerous because its resistant to most antibiotics, the number of them has increased partly due to the overuse and misuse of antibiotics. In order to reduce the rate of development of antiobiotic resistant strains: antibiotics should not be prescirbed innapropraitely and patients should always complete the full course of antibiotics to ensure resistant strains.
How are fossils evidence for evolution?
fossils are preserved remains of a dead organism from millions of years ago, they are found in rocks and can be formed from hard body parts such as bones and shells which do not decay easily or be replaced by minerals as they decay. Preserved traced of organsisms such as footprints become covered in layers of sediment which eventually become rock - fossils of simplest organissms found in oldest rocks and fossils of more complex organsisms found in newer rocks; supporting dawins theory stating that simple life forms gradually evolved into more complex ones.
What is Ardi?
Ardi is a female human-like fossilised skeleton that dates 4.4million years ago. her bones show she was probably able to walk upright but she had very long arms and long toes. the bones that made up her feet suggest that humans and chimpanzees evolved separately.
What is Lucy?
Lucy is also a female human-like fossilised skeleton and dates from 3.2 million years ago. Lucy’s bones suggest she walked in an upright position like a human but possessed a relatively small, ape-like skull. Lucy’s foot bones show that she had similar feet to modern humans but with much more curved toes.
what is Leaky?
The skeleton looks much more like that of a modern human than either Ardi or Lucy, this most recent skeleton suggests that humans may have evolved from Africa.
how can tools be used as evidence for human evolution?
Primitive tools (flint hand axes) have been found in remains from palaeolithic age (10,000 to 2.5million years ago). More advanced tools (arrowheads) have been found in the neolithic Age (4000 to 6000 years ago).
How can u do dating of tools?
Dating can be done by radiocarbon dating or other techniques which looks at the amounts of elements like iron or potassium. It is assumed that the tool is approximately as old as the rock which surrounds it.
What is genetic modification?
GM involves taking a gene from one species and putting it into another species. It involves the selection of the desired characteristic, isolation of the gene responsible for the characteristic, insertion of the gene into another organism, and the replication of the transgenic organism
What are uses of Genetic modification in medicine?
Natural insulin can be taken from the pancreases of pigs or cattle. However this insulin causes adverse reactions in some people and its supply is limited. Nowadays most insulin is made using gentically modified bacteria that have had the human gene for insulin inserted into them. This GM insulin has some advantages over insulin taken from pigs or cattle: It can be made in very large amounts from bacteria grown in a fermenter, it is less likely to cause adverse reactions, and it overcomes ethical concerns from vegetarians and some religious groups.
What does genetic modification need to work?
genetic modification needs a DNA vector and certain enzymes. Vectors take pieces of DNA and insert them into other cells. Viruses and plasmids can act as vectors.
What are restriction enzymes?
Restriction enzymes cut DNA at specific sites, rather than just in random places along the DNA molecule. Similarly, Ligase enzymes join pieces of DNA together at specific sites.
How is GM insulin made?
1) The gene for making insulin is cut from a length of human DNA using restriction enzymes.
2) It is inserted into a plasmid using ligase enzymes
3) The plasmid goes into a bacteria cell
4) the transgenic bacterium reproduces, resulting in millions of identical bacterica that produce human insulin
