Mechanisms Of Evolution Flashcards

Question

cons of selective breeding

Answer 1

loss of genes in a population - by not allowing some animals to breed, their genes could be lost forever in a population animal discomfort - may cause physical problems such as animals bred for rapid weight gain may develop muscular/skeletal problems - farmers breed cows to have large udders, so now since cows have difficulty walking and have health problems - some chickens are too heavy to stand, so they have to lay down all the time can lead to interbreeding - in order to create a certain type of animal through selective breeding, sometimes brothers and sisters of a population will mate to pass on favourable traits, and this can lead to health problems

Answer 2

- natural selection acts on alleles, which are inheritable - the total collection of alleles that exists within a population is called its gene pool

Answer 3

is a group of individuals of the same species, which live in the same geographic area and readily interbreed to produce fertile offspring

Answer 4

- unless there is an evolutionary process acting on a population, the allele frequency in the population's gene pool should remain the same from generation to generation - although the proportions of phenotypes in the population may change, the proportions of alleles in the gene pool should not - but real populations do not change over time and microevolutionary change does happen These processes that lead to change in a population - mutations of an allele, introducing a new allele to the gene pool - gene flow - immigration into the population and emigration out of the population - genetic drift - natural selection

Answer 5

- mutations of an existing allele can produce a new allele - alleles introduced this way are often recessive and stay hidden, unless individuals breed with related individuals - recessive alleles are often deleterious, but are also an important source of biological variation - mutation create variation within the gene pool or genetic diversity. Genetic diversity is what allows evolution to occur - this is because genetically diverse populations have a greater range of phenotypes which increases the chance that at least some individuals will survive in the face of environmental change

Answer 6

- migration is the movement of individuals between populations - when individuals move from one population to another and then breed with the residents of the new population, 'Gene flow' can change frequency of alleles in the new population - immigration - movement of individuals INTO a population - emigration - movement of individuals OUT OF a population migration does NOT create new genetic variation, it moves around already existing variation

Answer 7

- allele frequency is simply how common an allele is in a population - consider a gene that has 2 alleles: A and a, the frequency can be worked out using the following: the frequency of allele A = number of A alleles in the population / total number of alleles in the population

Answer 8

- genetic drift occurs because alleles are inherited randomly from parents - it describes changes to the gene pool that occurs by chance and are not driven by selection pressures. These changes can occur: - because allele frequencies are not the same from generation to generation. for example, an allele may not be passes on to the next generation and, in small populations, this may mean that it is soon lost from the gene pool entirely - because a change event may kill individuals non-selectively, altering the allele frequencies in the gene pool - the effect of genetic drift are much easier to see in small populations - whereas the effects of genetic drift on large populations are minor compared to the entire gene pool and are often overshadowed by natural selection, genetic drift working in small populations can result in big changes

Answer 9

- founder effect - bottleneck effect

Answer 10

- this occurs when a small number of individuals found a new population (they colonise a new isolated area such as an island) - the alleles present in the founding members of the new population may not be representative of the original population - due to the small population there is a greater chance for genetic drift to occur and there to be a lower range and frequency of alleles - as a result evolution is likely to occur faster in founder populations when compared to the original population

Answer 11

- it occurs when a population is drastically reduced in size, for example by a natural disaster. The alleles present in the surviving members of the population may not be representative of the original population. The range of alleles will be reduced and the frequency of the alleles will change. If the population increases again, it will have a reduced genetic biodiversity - this makes the surviving population more at risk of extinction

Answer 12

natural selection produces changes in the allele frequencies of gene pools when the changes become so great the populations are so different that they can no longer reproduce with one another - speciation has occured - natural selection causes microevolution within a gene pool - eventually a population accumulates enough changes that a new species can be identified and speciation has occurred - sometimes several speciation events occur and lead to a collection of new species or even higher classification groups. this is macroevolution - microevolutionary changes build up over time to produce macroevolution this occurs when populations are reproductively isolated. Because of this they are subjected to different selection pressures - these differing selection pressures mean that the population changes significantly from the original population to form a new species

Answer 13

1. variation - original population - one population, one species - within a population a range of variety of characteristics exist. this population shares a common gene pool 2. isolation - initial step of speciation - two populations, one species - a barrier has formes which prevents interbreeding between the two populations. the two populations now have separate gene pools 3. selection - evolution of reproductive isolation - two subspecies, one species - in each population, over a number of generations, different selection pressures will act to bring about a change in the gene frequencies of each gene pool. such a changing population is evolving into separate subspecies 4. speciation - new distinct species after equilibrium of new ranges - two species - if isolation and selection continue over a long period of time, the changes in the gene frequencies can become great enough to prevent population from ever interbreeding successfully. When this happens the populations have evolved into separate species the key in speciation is there must be isolation - gene flow must be inhibited between the two groups so natural selection can happen independently of each other

Answer 14

- isolating mechanisms separate two subgroups of a population and prevent them from producing fertile, viable offspring - these mechanisms can operate before reproduction has occurred or after reproduction - the organisms become so genetically diverse that they form two new species - they are then no longer able to interbreed, even if the populations come back together

Answer 15

pre-reproductive isolating mechanisms are biological or ecological mechanisms that prevent organisms from being able to interact to reproduce: - geological from physical barriers: such as rivers, mountain ranges, oceans - temporal (time) mechanisms: individuals breed during different seasons of the year of times of the day - behavioural mechanisms: individuals have different seasons of the year of times of the day - morphological mechanisms: individuals have different reproductive structures

Answer 16

three mechanisms don't prevent mating but prevent formation of viable, fertile offspring - gametes mortality (gametes do not survive after mating) - zygote mortality (zygote forms but does not survive) - hybrid sterility (adult offspring develop but cannot produce viable gametes) - hybrid sterility is not often a reproductive isolating mechanism in plants, where polyploidy is common

Answer 17

in allopatric speciation from the ancient Greek 'allos' = other and 'patro' = homeland, gene flow is disrupted when populations become physically separated through geographical isolation. The populations diverge. This may be become of different selection pressures acting on the two populations, or it may be due to other random processes such as genetic drift - allopatric speciation occurs as populations are geographically isolated

Answer 18

- water, for terrestrial organisms - land, for aquatic organisms - mountains

Answer 19

- continental drift - rising sea levels - climate change

Answer 20

- subpopulations - isolated by physical barrier - no gene flow - different selection pressures - natural selection - two different species - genetic drift will occur independently in subpopulations

Answer 21

- before the grand canyon was carved out by the Colorado river, only one species of squirrel inhabited the area - as the canyon got deeper over time, it became increasingly difficult for squirrels to travel between the north and south sides - eventually it was too deep for the squirrels to cross, they became isolated on each side resulting in two sub-populations that were reproductively isolated from each other - eventually these populations became two species

Answer 22

selection pressures can become so great that species become extinct

Answer 23

genetics and demographics - small populations = increased risk - mutations -- causes a flux in natural selection -- beneficial genetic traits are overruled - loss of genetic diversity -- shallow gene pools promote massive inbreeding - habitat destruction - natural causes (asteroids, acid rain, disease)

Answer 24

extinction occurs quite rarely but there have been periods when the rate of extinction has been quite high. These are mass extinction we appear to be in the midst of the sixth mass extinction, which began around 50,000 years ago, when modern humans spread out of Africa this coincided with the extinction of several species of megafauna

Answer 25

more than 1 billion animals were killed in the 2019/2020 Australia bushfire season. Endangered species, including the long-footed potoroo, Kangaroo Islands gloss black cockatoo and Batman Bay's Spring midge orchid were pushed towards extinction the devastating wildfires undid decades of careful conservation work on Kangaroo Island and have threatened to wipe out some of the islands unique fauna altogether - preservation of genetic diversity is key to preventing extinction - having a large gene pool means having more alleles to draw upon to face the pressures of natural selection

Answer 26

- biogeography - involves maintaining population distributions and allowing populations to remain connected -- conservation areas -- wildlife corridors - reproductive behaviour - that maintains diversity and random mating practices - population dynamics - maintaining population size and density

Answer 27

populations with reduced diversity face increased risk of extinction, so conservation projects usually focus on maintaining genetic diversity rapid extinction events can lead to greater loss of large organisms than of small ones. A large distribution area is generally a big advantage, because it may allow some pockets of habitat to survive large population size can also be some protection, because the population is likely to have a more diverse gene pool and thus a greater variety of alleles and phenotype options as the pressures from natural selection change

Answer 28

- human/medicinal - agriculture - conservation - forensics

Answer 29

- genetic testing (e.g. BRCA1 and BRCA2 genes) - pharmaceutical production via cloning (e.g. growth hormone, insulin) - gene therapy - correcting "defective" gene with healthy version (e.g. Cystic fibrosis, CRISPR) - cell therapy - using whole cells - paternity testing, ancestry

Answer 30

- improving nutrition in food - pesticide resistance - herbicide resistance - disease resistance - drought tolerance - other GMOs

Answer 31

- genetic engineering involves changing the genetic sequences of an organism using modern biotechnological techniques, like recombinant DNA technology - genetically engineered organisms are also called genetically modified organisms (GMOs) or transgenic organisms - a genetically modified organisms has had its genome changed at the molecular level in a laboratory to express certain traits that are desirable. These organisms then grow and pass the trait onto their offspring - a transgenic organism is a genetically modified organism that has has a gene from a completely different species added to their genome.

Answer 32

- you must be able to make enough copies of DNA to work with -- or else there are not enough to work with, and you'll run out - you must be able to extract and purify DNA -- or else parts of cells will interfere with the process - you must be able to cut DNA exactly where you want -- or else you can't have specific engineering of DNA sequences - you must be able to insert a piece of DNA exactly where you want into another piece of DNA (this is called recombination) -- or else the inserted DNA or the receiving DNA may not work properly - you must be able to identify successful recombinant events -- or else you may waste a lot of effort and money - you must be able to read the sequence of DNA -- so that you can check the right modifications have been made

Answer 33

recombinant DNA is simply DNA made from two or more different sources, who may be of the same or different species. You could think of it a bit like an organ transplant, but with genes

Answer 34

- isolate the gene of interest and cut it out using enzymes - make a cut in an isolated bacterial plasmid, a DNA molecule that will transport the gene - use enzymes to bond the gene and the plasmid together - insert the plasmid into a bacterial colony, which will express the gene and produce the product of interest

Answer 35

we always use the same sticky-end restriction enzyme to cut the gene of interest and the bacterial plasmid this ensures that the two cut ends have the same overhanging segments, which will be complementary. They can easily join together using base pairing rules. Not all plasmids take up the restriction fragments, simply due to chance. The plasmids that do not take up the restriction fragments form weak hydrogen bonds across the strands, but these aren't strong and stable enough. There are still gaps in the backbone of each DNA strand To properly join the two DNA strands together, we use the "glue" ligase, where restriction enzymes break phosphodiester bonds, ligases create phosphodiester bonds between bases. this creates a more stable joint. The reason this works because the structure of DNA is consistent across all organisms. Restriction enzymes and ligases work consistently across DNA molecules

Answer 36

plasmids make good DNA copiers because: - plasmids can incorporate foreign DNA - plasmids have a variety of recognition sites, so scientists can mix and match restriction enzymes to produce the most suitable cut - plasmids DNA sequence are separate from the main body of the bacteria's DNA - their small, circular nature gives them stability and they are easy to manipulate - plasmids can be copied within bacteria, which are easily grown in the lab - plasmids can replicate even when they contain foreign DNA - genes on plasmids can be expressed in bacteria

Answer 37

for recombinant plasmids to be useful, they need to enter a host cell so that the gene can be expressed. Scientists can simply add the recombinant plasmid to a bacterial colony, as bacteria are capable of undergoing bacterial transformation, where they simple absorb genetic material from their environment. Some bacteria take up the recombinant plasmid, while others don't. Inside the ones that do, the recombinant plasmid replicated, to that the host cell contains multiple copies of the plasmid. when the host undergoes cell division, the plasmids do too. these two methods amplify one another, so we see many plasmids and many copied of the gene of interest. the host expresses the gene and produces large quantities of the desired product.

Answer 38

scientists go back to the drawing board and make sure that the plasmid - before doing any kind of cutting and pasting - contains a marker gene for identification and a marker gene for isolation. For identification, scientists use screening genes such as lacZ. When expresses, this gene produces an enzyme that in turn produces a blue substrate. some restriction enzymes cut in the middle of this gene, so recombinant colonies cannot produce this enzyme. They remain white, instead of turning blue. Other screening genes produce florescent proteins, which light up in florescent microscopy. For isolation, scientists use antibiotic resistance genes, such as amp. Although typically undesirable, antibiotic resistance keeps the recombinant colony alive while others die off. scientists simply apply an antibiotic (for amp, this is ampicillin) to isolate the recombinant colonies

Answer 39

1. a gene of interest (DNA fragment) is isolated from human tissue cells 2. an appropriate plasmid vector is isolated from a bacterial cell 3. human DNA and plasmid are treated with the same restriction enzyme to produce identical sticky ends 4. restriction enzymes cuts the plasmid DNA at its single recognition sequence, disrupting the tetracycline resistance gene 5. mix the DNAs together and add the enzyme DNA ligase to bond the sticky ends 6. recombinant plasmid is introduced into a bacterial cell by simply adding the DNA to a bacterial culture where some bacteria take up the plasmid from solution

Answer 40

plasmids are accessory chromosomes occurring naturally in bacteria - in nature, plasmids are usually transferred between closely related microbes by cell-to-cell contact (a process called conjugation) - simple chemical treatments can make mammalian cells, yeast cells and some bacterial cells that do not naturally transfer DNA, able to take up external DNA - the bacterium Agrobacterium tumefaciens (opposite) can insert part of its plasmid directly into plant cells

Answer 41

the Ti plasmid is form a soil bacteria that causes tumors (galls) in plants - it can be successfully transferred to plant cells where a segment of its DNA can be integrated into the plant's chromosome

Answer 42

- important stable in human and livestock diets - worlds most widely cultivated crop - significant threat of disease by Leaf rust and yellow rust - able to isolate the rust-resistance gene L6 from a rust-resistance falx plant - introduce it into a wheat plant - also other elements such as increasing yield, tolerance to abiotic stress etc

Answer 43

- bioengineered transgenic rice crop - first produced in 1999 - contains B-carotene (provitamin A) from daffodils and bacteria (genes inserted rice embryos using a plasmid) - converted int vitamin A in consumers - tackling childhood blindness in 3rd world countries, also skin and immune health - GR2 contains 25x more B-carotene

Answer 44

- feeds livestock, pets, fertiliser, produces oil - herbicides used to kill weeds growing throughout the crop - develop canola crops that are resistant to herbicide - these contain a protein to break down glyphosate from a soil bacteria - can spray broad-spectrum herbicide and crop will be unaffected

Answer 45

- Bt cotton contains genes from the soil bacterium, which are toxic to the common cotton pathogen, the Heliothis caterpillar

Answer 46

- 2015 - 1st approved transgenic animal consumption, first harvests in 2020 - genes from: -- Pacific Chinook Salmon - growth hormone -- Ocean pout - promoter sequence - capable of growing at twice the rate of conventional Atlantic salmon without affecting any other qualities - growth time hales from 3 years to 18 months - eggs sterile, so unable to breed if escaped

Answer 47

- can improve health, nutritional value, growth capacity of agricultural species, help contribute to global food crisis and public health - strict guidelines ensure food is safe, DNA is common to all organisms

Answer 48

- selective breeding has/can be used to improve agricultural species - long term effects of GMOs unknown

Answer 49

- transgenic crop is a single line or strain (monoculture) - only the transgenic crop may be farmed or unmodified crop may not be farmed - may limit ability to crop to adapt to other aspects of the environment/pests - could reduce potential to develop desirable crop lines in the future

Answer 50

- the factors limiting growth of transgenic plant are removed - therefore transgenic plant becomes a weed of difficult to control - transgenic plant may monopolise other resources - they outcompete other plants or change food web

Answer 51

- transgenic species may exchange genes to other species - resulting in the engineered trait in another species - these species may become a superweed/pest because they can no longer be controlled

Answer 52

- if the plant was engineered for herbicide resistance, farmers may overuse herbicides (to kill weeds) - the overuse will pollute the environment or cause evolution of resistant weeds by natural selection

Answer 53

- herbicide resistant weeds often called "super weeds" are nuisance plants that have developed resistance to one of more herbicides - weed resistance to herbicides can develop in GMO and non-GMO crops - gene transfer or gene flow can occur between GMO crops and organic or other related plants crops via cross pollination. E.g. Canola crop in Kojonup - resulting in the transgenic trait being transferred - these plants may now become "super weeds" because they are no longer controlled by the herbicide

Answer 54

- genetic engineering has existed for year e.g. farmers breed specific cattle to achieve desired traits - biotechnology is simply an extension of this

Answer 55

- not natural - selective breeding only involves individuals from the same species, biotechnology can mean transferring genes across species - rarely happens naturally

Answer 56

- crops can be made resistant to low impact herbicides, enable farmers to use less toxic herbicides - little transfer of genes between species

Answer 57

- herbicide-resistant crops may encourage farmers to use more herbicide, potentially more damaging for environment - may be some gene transfer, weeds become resistant to herbicides

Answer 58

- conservation biology - the integrated study of ecology, physiology, evolution, molecular biology and genetics with a view of sustaining biological diversity at all levels - biotechnology can be used for: -- monitoring endangered species -- assessing gene pools for breeding programs -- quarantine - biodiversity levels - genetic, species and ecosystem, all interconnected - biotechnology - used to maintain viable gene pools - gene pool - a collection of alleles for all the genes in the reproducing members of a population at a given time - it is a genetic reservoir of traits - large gene pool = large genetic variation - viable gene pool - contains sufficient alleles/genes to give enough genetic diversity for survival in a changing environment - to maintain a viable gene pool must consider -- biogeography -- reproductive behaviours -- population dynamics

Answer 59

- behaviours related to the production and care of offspring, courtship, sexual behaviour, parental care - needs to be considered to prevent inbreeding and loss of advantageous genes - keep advantageous alleles, genetic diversity and reproductive fitness high

Answer 60

- study of the number, gender, age and relatedness of individuals - affected by births, deaths, immigration and emigration - factors affecting dynamics are both density-dependent and density-independent -- availability of resources -- bushfire, logging

Answer 61

- identifies species threatened with extinction - provides evidence of effective strategies - eDNA (environmental DNA) is DNA left behind in an environment by an organism (hair, scats, skin, scales) -- platypus, northern quolls, gouldian finch

Answer 62

- use of a probe that monitors DNA in water bodies used by the finch - able to use data to estimate population size, population diversity, reproduction

Answer 63

- enviroDNA using eDNA to monitor the platypus - platypus difficult to observe in the wild, very elusive, nocturnal, widespread and sparse population - collecting data about the changing distribution, able to list them on endangered list - monitor the threats to populations

Answer 64

- northern populations have declined significantly due to land clearing, increase in human population, can toads and feral cats - populations are disconnected - now listed an endangered - use scats for analysis - sequencing and profiling, diversity of population - knowing the boundaries of populations, barriers to gene flow can assist in developing effective conservation plans

Answer 65

- small populations at risk of loss of genetic diversity, inbreeding depression -- increased risk of deleterious recessive alleles becoming homozygous --> increase in genetic diversity - PCR, DNA sequencing, genome mapping can be used to selectively breed individuals that are not related/show great genetic diversity - managed in zoos by studbooks - create "insurance populations" by translocation - e.g. mountain pygmy possum, Tasmanian devil

Answer 66

- the isolation of organisms that have arrived from elsewhere or possibly been exposed to disease - Khapra beetle - stored grains (wheat, rice, dried food) -- often confused with another less detrimental pest -- DNA fingerprinting to accurately identify

Answer 67

- using genetically microorganisms for bioremediation - bioremediation - consumption and breakdown of environmental pollutants by introduced or naturally occuring micro-organisms - used to remove heavy metals and toxic substances from contaminated sites

Answer 68

- crime scenes - identification of disaster/terrorism victims - tracking illegal animal trade

Answer 69

moral principles concerning right and wrong that govern behaviour

Answer 70

the study of ethical issues arising from advances in biology and medicine

Answer 71

- cloning - cloning a gene - recombinant DNA - biological cloning - cloning an organism -- embyo splitting - egg fertilised in vitro, two cells of zygote split then develop individually -- nuclear transfer - nucleus from donor inserted into a hollow ovum, divides and then develops

Mechanisms Of Evolution Flashcards

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