CB4- Natural Selection And Genetic Modification Flashcards

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1
Q

What is variation within species?

A
  • variation is when organisms have different phenotypes (observable characteristics) due to their differing genotypes and environmental factors that they have lived with
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2
Q

How does genetic variation occur?

A
  • your genome is all the genes that make up your body. Genes code for specific amino acids which in turn codes for particular proteins that will have specific functions
  • genetic variation occurs due to mutations, the change in the DNA code can change the amino acids, therefore changing the protein it codes for
  • everyone in the world will have a different, unique genome (apart from identical twins) meaning they will have a different combination of proteins, making them look physically different, environment can also affect the phenotype.
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3
Q

What effects do mutations have on organisms?

A
  • most mutations within genes do not have a large effect on phenotype, but sometimes it can alter a characteristic
  • while some mutations have undesirable effects like diseases and illnesses, some can actually be beneficial and give an organism desirable traits that can help them survive selection pressures (things like predation, change in climate, lack of food etc.)
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4
Q

What are selection pressures?

A
  • factors that affect an organisms chance of surviving and reproductive
  • these are things like predation, competition for resources and diseases
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5
Q

Describe natural selection/ survival of the fittest

A
  • due to mutations arising within a population, there will be genetic variation amongst its members, some will have specific characteristics that make them better adapted to selection pressures. For example if there was a lack of food, taller giraffes would be able to reach higher trees while the shorter ones would starve.
  • when these changes in environment/ environmental pressures are introduced, the better adapted organisms whose genetic variation that gives them desirable characteristics will survive while the disadvantaged ones will die and not be able to pass on the disadvantageous trait.
  • the surviving organisms would then survive and be able to reproduce successfully, the alleles that are responsible for the beneficial characteristics will then most likely be passed on to offspring and this trait would become more common overtime
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6
Q

Who theorised natural selection and evolution

A

Charles Darwin

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7
Q

Why is genetic variation so important?

A
  • genetic variation is extremely important in a population
  • this is because if all member of the same population had the exact same genome, selection processes like a disease would immediately wipe them all out leaving no surviving organisms
  • because of genetic variation, if a selection pressure were to be brought to a population those with the beneficial traits that allow them to survive this pressure will live and be able to reproduce, allowing the species to continue existing.
  • this will also allow offspring to carry the desirable allele making sure that if the environmental change were to occur again, the whole population would be able to survive
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8
Q

What is evolution?

A
  • when natural selection occurs over and over again, causing a slow and continuous change in the organism’s characteristics over time, giving them phenotypes that are best suited for the environment
  • eventually a new species will evolve with the individuals having better adapepyed characteristics
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9
Q

Explain the GENIE acronym for evolution.

A
  • G- genetic variation - the characteristics of organisms within a population are different due to mutations and overall differences in genomes
  • E- environmental pressure - conditions will change and selection pressures will be introduced, increasing competition between organisms
  • N- natural selection - natural selection will run its course and the better adapted species with the beneficial characteristics will survive the environmental pressure while the disadvantageous ones will die
  • I- inheritance - the better adapted survivors will pass on their beneficial alleles to their offspring who will gain the adaptations and also survive the selection pressure
  • E- evolution - if the environmental conditions remain, natural selection will continue to occur over and over again and a new species will eventually evolve with all its members having beneficial characteristics
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10
Q

Describe the evolution of woolly mammoths and elephants.

A
  • woolly mammoths and elephants evolved from the same animal (they share a common ancestor)
  • an area where this ancestor lived began to get colder
  • due to genetic variation, some animals had hairier skin and were more likely to withstand the cold temperatures and survive especially when food was scarce
  • the organism with less hair would ultimately freeze to death, especially with a lack of food because there would be no way to generate body heat
  • the surviving hairy animals would then survive and breed, giving them beneficial characteristic to offspring
  • over time the organism would become more hairy forming a new specie
  • this is an example of evolution that takes place over a long course of time.
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11
Q

Describe the evolution of rats and warfarin rat poison.

A
  • in the 1940s and 50s a substance called warfarin was used to poison rats
  • upon its introduction many rats died but in 10 years most of the rats became immune to the warfarin
  • this was due to genetic variation, there were some rats that had alleles that made them resistant to the poison
  • these rats then underwent survival of the fittest where the warfarin resistant rats survived and were left to reproduce offspring that also carried these alleles for poison resistance, eventually creating a resistant rat population
  • this is an example of faster evolution.
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12
Q

Describe the evolution of antibiotic resistant bacteria.

A
  • bacteria are able to develop random mutations in their DNA creating new alleles which can affect the bacteria’s characteristics eg. An allele for antibiotic resistance
  • in a population of bacteria, some may be more resistant to antibiotics and take longer to kill
  • upon taking antibiotics, most bacteria will die, however those with the resistant genes will continue to survive, living for longer and then reproducing, creating a population of antibiotic resistant bacteria which becomes more common over time.
  • this is known as an antibiotic resistant strain
  • this is an example of longer evolution
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13
Q

What are antibiotics?

A
  • antibiotics are drugs designed to kill bacteria or stop it from reproducing
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14
Q

What was the first ever antibiotic?

A
  • penicillin
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15
Q

Why is it so important to take antibiotics for their full course?

A
  • often, people stop taking antibiotics once they feel better, however this leaves the resistant bacteria that takes longer to kill alive, and able to reproduce new resistant bacteria that cannot be treated with the same antibiotic
  • this is dangerous because if someone were to still carry this infection caused by antibiotic resistant bacteria, they could spread this into others, who also would now have antibiotic resistant bacteria that could not be treated with antibiotics
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16
Q

Why is anti biotic resistance becoming more common?

A
  • Doctors often prescribe antibiotics in cases where they aren’t necessary. For example, mild or viral infections
  • Many people don’t take the full course of antibiotics, so not all the bacteria are killed
  • Huge amounts of antibiotics are given to farm animals in order to make them grow faster
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17
Q

What are fossils?

A
  • the preserved remains of organisms that died millions of years ago
  • can be found as skeletons in rock, hardbody parts like bones and shells which do not decay easily or are replaces by minerals as they decay
  • imprints/impressions in the ground
  • entire organisms that have not yet decayed
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18
Q

How do fossils provide evidence of how organisms have changed overtime?

A
  • fossils found in rocks can show this change because the deeper the rock, the older it is
  • by arranging fossils in chronological order, gradual changes in organisms can be observed, this shows evidence for evolution because it shows how species have changed and developed
  • rocks that are deeper in soil are often older whereas those that are in a higher level are more recent
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19
Q

What are some drawbacks to using fossils as evidence for human evolution?

A
  • fossils don’t always show smooth changes in organisms over time because some fossils have still not been discovered.
  • some soft bodied life forms may have also decayed faster creating a gap that remains undiscovered
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20
Q

What are hominids?

A
  • this is the name given to human beings and their ancestors
  • hominid species that have been found often have a mix of characteristics between human and ape like
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21
Q

Describe ardi.

A
  • alive 4.4 million years ago
  • ardipithecus ramidus
  • feet structure suggests she climbs trees as she had big ape like toes
  • long arms and short legs (more ape like)
  • her brain was the size of a chimpanzee but her leg structure suggest she was able to walk upright
  • structure of her hand bones shows that she did not use them to assist with walking
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22
Q

Describe Lucy.

A
  • 3.2 million years ago
  • Australopithecus afarensis
  • more human like than ardi
  • had arched feet more adapted to walking then climbing, no ape like toes, more human like, the structure of her leg bones also suggests she walked upright
  • brain was slightly larger than ardi
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23
Q

Describe the homo habilis.

A
  • 2.4 - 1.4 million years old
  • quite short with long arms but still walked upright
  • discovered by Mary and Louis leaky
24
Q

Describe the homo erectus.

A
  • 1.6 million years old
  • mixture of human and ape like features but is more human like than Lucy
  • shorter arms and longer legs, very human like
  • large brain
  • structure of legs and feet suggest he was well adapted to walk upright, even more than Lucy
  • discovered by Mary and Louis leaky
25
Q

Describe Homo sapiens.

A
  • 195,000 years ago
  • modern humans
26
Q

What is the difference between the ardipithecus and Australopithecus compared to the homo species

A
  • homo species are a lot more human like with characteristics closer to modern humans
27
Q

What do stone tools indicate about the evolution of the homo species?

A
  • it is evident that the homo species continued to evolve because of their stone tools usage which continued to evolve and grow more complex- this is because evolution allowed for their brains to get larger)
  • they started off very simple and could of been used to skin animals or cut up meat
  • they eventually became more complex being sculpted into axes, tools and weapons like spears as the brain got larger
28
Q

What are some ways that scientists can can work out how old a stone tool is?

A
  • looking at the structural features- simple tools are likely to be older than more complex ones
  • stratigraphy- the study of rock layers- older rock layers are found below younger layers so tools and fossils found in deeper layers are usually older
  • carbon-14 can be used to estimate the age of certain objects, stone tools and fossils often absorbed atmospheric carbon of its time and this can be dated using carbon-14
29
Q

how do antibiotics work?

A
  • Antibiotics damage the bacterial cells by inhibiting their cellular processes, but do not damage the host cells
  • they can target cell walls as bacteria have cell walls but animal cells do not
30
Q

What was karl Linnaeus’ way of classifying organisms?

A
  • in the 1700’s karl linnaeus proposed a new type of classification, according to characteristics which divides organisms into groups based on what they look like
  • he founded the Linnaean system in which species would first be classified into 5 kingdoms. These include: animals, plants, fungi, prokaryotes(no nucleus), protists(eukaryotes)
  • then they would be subdivided into smaller and smaller groups with more common features
  • the process was: kingdom, phylum, class, order, family, genus, species
31
Q

What are the 5 kingdoms?

A
  • animals- fish, mammals, reptiles
  • plants- trees, flowers
  • fungi- mushrooms
  • prokaryotes- single called organisms without a nucleus (bacteria)
  • protists- single celled organism that are eukaryotic
32
Q

Upon the 5 kingdoms which are eukaryotic and which are prokaryotic?

A
  • animals, plants, fungi, and protists were all eukaryotic cells, they have DNA in the form of chromosomes in their nucleus.
  • prokaryotes on the other hand are different because they no not have a nucleus and their DNA is rather lying free
    Eg. In Bacteria(a prokaryote) dna lies within plasmid DNA and chromosomal DNA not in a nucleaus
33
Q

Recount all the steps of classification in the Linnaeus system.

A
  • kingdom (king)
  • phylum (prawn)
  • class (curry)
  • order (or)
  • family (fried)
  • genus (greasy)
  • species (sausage)
34
Q

What is the organisms binomial name?

A
  • Linnaeus used the two last groups of his classification system (genus and specie) to give the organism its binomial name
  • the binomial name of a species must be written in italics and with a capital letter at the start of the genus.
35
Q

When classifying an organism, going down the Linnaeus steps for classification, what is notable?

A
  • as you go through the process of classification, the characteristics of the organisms in a group get more and more similar while the groups get smaller
  • eventually when reaching the species, all the organism are one type.
36
Q

Are there any issues with Linnaeus system of classification?

A
  • since Linnaeus proposed this in the 1700’s we can argue that it is quite outdated and now a days we can see the genomes of species and their internal structures in greater details using microscopes
  • this system of classification also causes issues for organisms that have evolved with similar characteristics, but do not share a common ancestor. To be in the smaller groups like genus and species, the organisms would have to be closely related with a common ancestor
  • due to improved technology we can analyse the sequence of DNA bases to see how closely related organisms are (the more similar their sequences, the closer they are related and have evolved from a common ancestor), we no longer have to only use phenotype as a grounds for classification.
37
Q

What did Carl Woese propose?

A
  • Carl woese in the 1990’s found that classification could be more specific if prior to the Linnaeus system of kingdom, phylum, class, order, family, genus and specie, organisms could first be divided in three DOMAINS: archea, bacteria and eukarya, then go on to undergo the Linnaeus system
  • he proposed this because using genetic analysis he found that member of the prokaryotes kingdom were not that closely related
  • he therefore split the prokaryotes into archea and bacteria
38
Q

What are Carl Woese’s 3 domains?

A
  • archea- cells with no nucleus, but the genes contain unused sections of DNA (a type of prokaryote)
  • bacteria- cells with no nucleus and no unused sections of DNA in genes (a type of prokaryote)
  • eukarya- cells with a nucleus that contain unused sections of DNA in genes, basically eukaryotic cells like animals, plants, fungi and protists
39
Q

What is selective breeding?

A
  • selective breeding is when humans artificially select the plants or animals that are going to breed because they may have desirable characteristics, this allows the desirable characteristics to remain in the population
  • for example selective breeding may be done to sheep which have more wool, animals which provide more meat or milk, crops with disease resistance, more domesticated animals or organisms that can survive environmental pressure
  • by carrying out selective breading over and over again, new breeds of animal species and new varieties of plants can be produced.
40
Q

Describe the basic process for selective breeding.

A
  1. From existing stick, select the ones that have the characteristic you want to be prominent in the population
  2. Breed them together
  3. Select the best of the offspring and breed them together
  4. Continue this process over and over again over several generations until the desirable trait becomes stronger and more prominent
41
Q

How is selective breeding useful in agriculture?

A
  • selective breeding is useful in agriculture because it allows farmers to increase their yields
  • with animals they are able to breed those with the best traits like lots of meat and milk production and thick wool on sheep’s which will provide more produce
  • with plants they are also able to get desirable traits like bigger fruits and disease resistance
42
Q

What are some risks behind selective breeding.

A
  • what causes variation in the first place is the alleles within an organism which creates various characteristics
  • when only some favourable characteristics are targeted and bred for, the gene pool becomes reduced
  • this means that other characteristics can be ignored which could cause them to be reduced or completely vanish when it could be a beneficial allele in the future
  • this also means that a lot of inbreeding occurs and all the organism are closely related which can cause numerous health defects
  • since a lot of the population will have similar genomes there will be little to no genetic variation. This is very bad because if a disease or change in environment were to arise, since everyone has the same genetic makeup no one would be better suited to survive leaving most organisms dead. There may not even be surviving organisms that could reproduce, continuing the population
  • animal welfare is also a huge ethical concern because for example when chickens are constantly selectively bred for their breasts, they could eventually become so large that the chicken is unable to breathe
43
Q

What are some issues involved with inbreeding?

A
  • can cause health problems since the organisms can inherit harmful genetic defects
  • animal welfare is a huge ethical concern as some animals like pigs are so inbred that they have breathing problems and can be deformed
44
Q

What is genetic engineering?

A
  • genetic engineering is modifying an organisms genome to quickly introduce a desirable characteristic
  • this is done by finding one organism with a desirable characteristic eg. A plant with large fruits and then taking the gene that is responsible for the production of large fruits and inserting it to another organism so that it can develop the same traits
  • this creates a GMO- a genetically modified organism
45
Q

What are some similarities and differences between genetic engineering and selective breeding?

A

Differences
- selective breeding does not cause any altercations in the genetic material and aims to enhance a desirable trait by selecting two mates whereas genetic engineering changes the genetic material at its DNA and also does not involve mates but rather recombinant DNA
- selective breeding does not introduce foreign DNA into the genome, genetic engineering does
- genetic engineering is much faster compared to selective breeding which has to be done over time
- selective breeding is a lot cheaper

Similarities
- both are looking for a desired characteristic

46
Q

What are some pros of genetic engineering?

A
  • in agriculture, crops can be genetically modified in order to increase yield
    Eg. They can be modified to produce more fruits, be resistant to diseases, resistant to herbicides
  • in medicine they are able to genetically engineer bacteria into producing human insulin, researchers can transfer human genes that produce insulin into animals, these animals will then produce these specific proteins which can then be extracted and used by humans. This same process can also happen with organs where GM pigs are developed with human like organs for transplants.
47
Q

Why is herbicide resistance beneficial to farmers?

A
  • herbicides are chemicals that kill plants like weeds
  • if a plant is herbicide resistant, farmers are able to spray them with the herbicides to kill surrounding weeds but not the plants.
48
Q

What are some cons to genetic engineering?

A
  • we are not fully aware of how GM plants will affect our health, although there is not direct evidence proving they are unhealthy, we are still unsure
  • modified organisms like herbicide resistant plants may reproduce with wild plants and get out into the environment, this may affect the ecosystem negatively
  • genetic modification may have bad effects on on the organisms, for example genetically modified embryos often do not survive and other genetically modified animals can have health problems later on in life
49
Q

What is golden rice?

A
  • golden rice is a GMO with two genes inserted into its genome, one from a daffodil and another from a bacterium
  • they allow the rice to produce beta carotene which helps humans make vitamin A
  • golden rice is a helpful GMO which can be used in poorer parts of the world where vitamin A deficiency is a problem
  • a lack of vitamin a can cause blindness
50
Q

How does genetic engineering and GM bacteria help diabetes?

A
  • GM bacteria can be created to produce insulin by using a human gene that produces insulin and a plasmid DNA from bacteria and joining them together
  • insulin was once extracted from dead pigs and cows, but insulin from GM bacteria is cheaper and more suitable for vegans aswell as those who do not consume pork or beef due to religious reasons
  • however GM bacteria insulin is slightly different to insulin from mammals so not all diabetics can use it.
51
Q

Describe the steps of genetic engineering.

A
  1. From human DNA find a gene that carries the desirable trait you are looking for and cut this section out using restriction enzymes.
  2. This will leave sticky ends on each end of the cut section. Sticky ends are basically unpaired bases
  3. Then the vector DNA (either plasmids or viruses) will be cut open using the same restriction enzymes as was used to cut the human DNA in order to get the same sticky ends
  4. The sections of DNA that are being inserted are then mixed with the cut vector DNA using the enzyme ligase which will join the sticky ends together by connecting their unpaired bases
  5. This forms recombinant DNA.
  6. The recombinant DNA can then be inserted into other cells and these cells can now produce what ever desirable trait you wanted.
52
Q

What are restriction enzymes?

A
  • enzymes that recognise specific sequences of DNA and cut the DNA at these points, leaving behind sticky ends
53
Q

What is a vector?

A
  • a vector is something that is used to transfer DNA into a cell, the desirable trait from the human DNA will be inserted into this vector DNA and then inserted into other organisms so it can have this desirable trait
  • vectors can either be in the form of plasmids (small circular molecules of DNA that contains genes and can be transferred between bacteria) or viruses (they insert DNA into the organisms that they infect)
54
Q

What is ligase?

A
  • an enzyme that is used to join two pieces of DNA together at their sticky ends
55
Q

What is recombinant DNA?

A
  • DNA that has been combined (the vector which now contains the new DNA from the human gene that has been inserted)
56
Q

Describe the process of bacteria being genetically engineered to produce insulin.

A
  1. The DNA for human insulin production is cut open using restriction enzymes
  2. The vector DNA (in this case plasmids) will be cut open using the same restriction enzymes used to cut the human DNA to produce the same sticky ends.
  3. The plasmid DNA and human DNA will now be mixed together with ligase enzymes to join together at the sticky ends
  4. This recombinant DNA is then inserted into the bacteria
  5. The bacteria will now be able to use the insulin producing gene and be grown in huge numbers to produce insulin for people with diabetes.