Biology: Natural Selection And Genetic Modification Flashcards
What is evolution?
The slow and continuous change of organisms from one generation to the next
Name three things that effect an organisms chance of surviving in its natural environment . What is the fancy science word for these things?
Predation (predator/prey complexes), competition for resources and disease
‘Selection pressures’
Explain natural selection and how it affects a population
Individuals with characteristics better adapted to the selection pressure in their environment are more likely to breed as they have a higher chance of survival. This means the alleles responsible for this useful characteristics are more likely to be passed on or the next generation. Those not adapted to the environment are less likely to survive and reproduce, so over time beneficial characteristics will become more common in the population.
Explain how bacteria provides evidence for evolution
Antibiotic resistance shows evidence for evolution because it makes a bacteria better adapted to its environment in which antibiotics (a selection pressure) is present
Explain how antibiotic resistance came about
Bacteria sometimes developed random mutations in their DNA, which can create new alleles, changing the bacterias characteristic: they can become resistant to certain drugs. A host being treated to get rid of an infection will take the drug, but the bacteria is resistant. All the non resistant bacteria die, but the resistant bacteria live and reproduce, passing on the resistant allele.
Name four pieces of evidence of evolution
Bacteria resistant to antibiotics, rats resistant to poison, fossils developing and changing over time periods, stone tools
How do fossils show evidence for evolution?
By arranging fossils in chronological order, gradual changes in the organisms can be observed, showing species have changed and developed over billions of years
How can scientists estimate the brain size of a fossil?
Working out Cranial capacity - the space taken up by the brain in the skull
How old is Ardipithecus ramidus (Ardi?) what are its 4 notable features?
4.4 million years old, big ape like feet Long arms short legs Brain size or a chimpanzee Walked upright like a human
How old is Australopithecus afarensis (Lucy?) what are its 4 notable features?
3.2 million years old Arched feet for walking Arms and legs between ape and human size Brain slightly larger to chimpanzees brain Walked upright
How old is homoerectus (Turkana Boy) what are its 3 notable features?
1.6 million years old
Short arms and long legs
Brain similar to human size
Walked upright
What are the three ways scientists can date stone tools?
Structural features: simpler tools are older
Stratigraphy: rock layers. Deeper tools in Older layers are older
Carbon dating: study carbon-containing material to date it
How did stone tools change over time?
Grew more complex, had more purpose, got pointier
What are the five kingdoms of organism classification?
Animals: fish, mammals etc
Plants: grass, trees
Fungi: mushrooms, mould
Prokaryotes: singled cell organisms with no nucleus
Protests: eukaryotic single felled organisms e.g. Algae
What are the 8 sub groups for classifying organisms? (EG, kingdom)
Domains Kingdom Phylum Class Order Family Genus Species
What can we say about genes and relations between organisms?
The more similar the genome, the more closely related the organisms
What are the three domains? Explain them.
Archaea: look similar to bacteria but are genetically very different
Bacteria: true bacteria
Eukarya: broad range of organisms including fungi, animals and protists
What is selective breeding?
When humans artificially select plants or animals that are going to breed so genes for that particular characteristic remain in the population
Give the four basic steps of selective breeding
1: from existing stock select the organism which have characteristics you desire
2: bred them with each other
3: select best of the offspring, breed them together
4: continue this for several generations, ad desirable trait gets stronger and stronger. Eventually, all offspring will have the characteristic
Give an example of selective breeding is useful in terms of bulls on farms
Some cattle will be larger, and produce more meat. To improve meat yields, farmer will select cows and bulls with these characteristics and breed them together. Continue for several generations, and eventually he’ll always get a high meat yield
How has selective breeding helped medical research?
Studies in Investigating reasoning behind alcoholism, rats have been bread that like and dislike alcohol. This allows researches to compare the differences between their brains, to try and work out how to stop alcoholics.
What are the three disadvantages of selective breeding?
Reduces gene pool: ‘best’ animals or plants will be closely related, so there will be less variation of genes
2: inbreeding causes health problems as more chance of organisms inheriting harmful genetic defects
3: new disease appear and there’s not much variation in the population, so less chance of resistant alleles being present
What do restriction enzymes do?
Recognise specific sequences of DNA and cut the DNA at these points, leaving the DNA with sticky ends where they’ve ben cut
What do ligase enzymes do?
Join two pieces of DNA together at their sticky ends
What are two different pieces of DNA stuck together called?
Recombinant DNA
What is a vector?
Something used to transfer DNA into a cell
What are the two types of vectors?
Plasmids and viruses
Give the five steps of genetic engineering
1: DNA you want to insert (e.g. Gene for human insulin) is cut out with a restriction enzyme. Vector DNA is cut open, with same restriction enzyme
2: vector DNA and DNA you’re inserting are left with sticky ends. They are mixed together with ligase enzymes
3: ligase join the pieces of DNA together to make recombinant DNA
4: recombinant DNA (vector containing new DNA) is inserted into other cells, e.g. Bacteria
5: these cells now use the gene you inserted to make the protein you want. Bacteria containing gene for human insulin can be grown in huge numbers to produce insulin for those with diabetes
How can genetic modification be used in agriculture?
Crops can be made resistant to herbicides, and increase crop yield
How is genetic modification useful in Medicine?
Make bacteria produce human insulin, put human genes that make useful proteins into livestock
What are the drawbacks of generic modification?
Hard to predict how modifying the genome will predict an organism. Many genetically modified embryos don’t survive long, or habe health issues.
Transplanted genes may get into the environment, doing things we don’t want,making weeds resistant to herbicide for example
