Natural Selection And Genetic Modification Flashcards
Evolution
A gradual change in the characteristics of a species over time.
(Takes place over millions of years)…
Natural selection
The process allowing species to respond to particular selection pressures.
Stages of natural selection
Variation Overproduction of offspring Selection pressure Survival of the fittest Reproduction Adaptation
Why’s their genetic variation within a species?
Sexual reproduction and new alleles that arise due to mutations.
What’s overproduction of offspring?
Much offspring being produced to create a better chance of passing on genes.
What’s selection pressure?
Competition between individuals due to limited resources of natural factors (eg: light/food).
What’s survival of the fittest?
The organisms with more suitable characteristics having a better chance of survival so that they may reproduce.
What’s adaptation?
Organisms passing on their advantageous allleles, leading to gradual adaptation of a species to their surroundings. These changes only occur from generation to generation.
Industrial melanism
Change from light to dark forms in industrial areas.
Common ancestor
An organism that different species have descended from.
What’s the evidence proving evolution?
Antibiotic resistance
Fossils (hominids)
Development in complexity of stone tools
The pentadactyl limb
Hominids
Human beings and their ancestors.
ARDÍ (4.4 million yrs ago)
LUCY (3.2 million yrs ago)
TURKANA BOY (1.6 million years ago)
How does antibiotic resistance work?
When bacteria develops random mutations that work to a bacterium’s advantage (to resist particular antibiotics) which increases the likelihood of that bacterium’s survival and reproduction.
How do fossils prove evolution?
By arranging the fossils in chronological order, we can see changes over time. (Eg: we share a common ancestor w chimps 6 million years ago)
What species was ARDI? Where was she found and how old is she?
Ardipithecus Ramidus
Ardithipecus ramidus
She was found in Ethiopia, aged 4.4 million years old.
Characteristics of ardi
Apelike big toe for climbing trees Long arms and short legs Chimp size brain Leg structure suggesting she walked upright. Didn’t use hands to walk
What species was lucy? Where was she found? How old is she?
She is of species ASTRALOPITHECUS AFARENSIS and was found in Ethiopia.
She’s 3.2 million years old.
Characteristics of lucy
Arched feet (not climbing)
Longer arms and legs
Larger brain capacity than ardi
Walked more efficiently upright
What species is Turkana boy? Who discovered him and when? How old is he?
He’s of species HOMO ERECTUS. Was found by Richard Leakey in 1984.
He’s 1.6 million years old.
Characteristics of Turkana boy?
Short arms and legs
Similar brain size to that of humans.
Better adapted to walking upright than lucy.
Who came up with the theory of evolution by natural selection?
Charles Darwin
Alfred Russel Wallace
How long did Darwin sail the world and on which ship?
5 years on the HMS beagle.
How have Darwin and Wallace’s theories influenced modern biology?
We now all understand that we all came from a common ancestor.
We can now CLASSIFY organisms based on how closely related they are.
We now understand the risks of ANTIBIOTIC RESISTANCE and how to prevent this.
We now understand the need to CONSERVE as genetic diversity enables adaptations to changing environments.
Order of homo species
Homo habilis
Homo erectus
Homo Neanderthalis
Homo sapien
What type of tools did homo habilis produce?
Pebble tools often from hitting rocks together to produce sharp flakes. They were used for scraping meat off of bones and cracking bones open
What tools did homo erectus produce
Simple hand axes (sculpted) which were used to hunt, dig, chop and scrape meat off of bones
What tools did homo neanderthalis produce
Flint tools, pointed and wooden spears
What tools did Homo sapiens produce
50000 years ago, flint tools, buttons, needles and fishing hooks were discovered
How do scientists work out ho old a fossil is?
Looking at structural features
Stratigraphy
Carbon dating
Pentadactyl limb
Limb with five digits.
Many species have this which proves evolution as the similarity in bone structure must have came from one common ancestor.
Classification
Organising living organisms into groups
The five kingdoms`
Animals Plants Fungi Prokaryotes Protists
The five kingdom classification system is v out of date.
Acronym for classification
Korean Pandas Climb Over Fences Going South
Order of classification
Kingdom Phylum Class Order Family Genus South
What classification system do we use today? Why?
We use the three domain system as the five kingdom system is outdated due to advancements in technology and understanding of organisms. Carl woese proposed this after discovering differences within the prokaryotes kingdom.
Three domains
Eukarya
Archaea
Bacteria
Eukarya
Organisms with a nucleus and unused sections of genes.
Bacteria
Organism with no nucleus and no unused DNA.
Archaea
Organism with no nucleus and unused DNA.
Selective breeding
When humans artificially select which plants/animals are to breed so that genes for particular characteristics can remain in the population.
Process of selective breeding
1 select organisms with best characteristics
2 breed them
3 choose offspring w best characteristics and breed
4 repeat until all offspring have desired characteristics.
Benefits of selective breeding
Used in agriculture to increase yield.
Used in medicine to research.
Disadvantages of selective breeeding
Reduces gene pool.
Creates health problems.
Makes population more vulnerable due to lack of variation within species.
Tissue culture
Growing cells on an artificial growth medium, produces clones.
Why are plants grown this way?
Easy Useful Quick Takes up little space Can be grown all year.
Process of tissue culture
1 Choose plant you want to grow (based on characteristics).
2 Remove a small piece of tissue from the meristem of the parent plant.
3 grow tissue in a growth medium like agar jelly that contains nutrients and hormones under aseptic conditions (use bromine/chlorine)
4 can be moved to potting compost to carry on growth.
Use of animal tissue culture
Used in medical research to carry out experiments on cells in isolation.
Eg effect of glucose on pancreatic cells.
Why is animal tissue culture used in this way?
So that you can look at the effects of substance/environmental change on a single tissue without your results being affected by other processes from the whole organism.
Process of animal tissue culture
1 Extract a sample of tissue you want from the animal.
2 Separate the cells in the sample with enzymes.
3 Place the cells in a tissue vessel and bathe in a growth medium w nutrients so they can grow/multiply.
4 They can be stored for future use
Genetic engineering
Modification of an organism’s genome to introduce desirable characteristics via the use of enzymes/vectors.
Restriction enzymes
Recognise specific sequences of DNA and cut the DNA at these points. This leaves the DNA with sticky ends from where they have been cut.
Ligase
Enzymes used to join 2 pieces of DNA together at their sticky ends.
Recombinant DNA
Bits of DNA stuck together
Vector
Something used to transfer DNA into a cell. There are 2 sorts, plasmids and viruses.
Plasmid
Small, circular molecules of DNA that can be transferred between bacteria.
Virus
Insert DNA into the organisms they infect.
Process of genetic modification
1 Cut out the DNA you want to insert using restriction enzymes, also cut out the vector w the same.
2 stick the sticky ends of the vector and cut out DNA together by mixing them with ligase. This forms recombinant DNA.
3 insert the recombinant DNA into bacteria to multiply.
4 these can now be used to Markle the protein you want
Eg: bacteria is put in fermenter to produce insulin for those with diabetes
Uses of GM in agriculture and concerns
Can be used to genetically modify crops to increase yield/ be herbicide resistant.
Transplanted gene could spread to the environment, creating new super species. Also we are yet to know about the long term effects of GM food, could adversely affect food chain/human health.
Uses of GM in medicine and concerns
Can be used to produce useful proteins/ insulin from sheep/cows (eg via milk).
However is hard to predict effects it could have on the organism as many GM embryos die or have health problems.
How can GM be used for insect resistance?
Disadvantages?
Improves crop yield and reduces needs for chemical pesticides. Bacillus thuringiensis produces a toxin that kills insect larvae and is inserted into crop’s DNA so that it’s present in their stems/leaves. Specific to pests, harmless to rest.
Danger that the pests will develop resistance so farmers must use other insecticides too.
How does GM help us cope with overpopulation?
Help to increase food production while combatting deficiency diseases.
Some may argue that poverty is the real source of world hunger.
Countries may become dependent on GM companies.
Poor soil means no crop will survive.
Fertilisers
Disadvantages??
Improve soil and contain minerals like nitrates/phosphates to replace lost nutrients in the soil.
Excess fertilisers can cause eutrophication
Biological control
Disadvantages??
Using other organisms to reduce pest numbers, have longer effects and less impact on wildlife.
Can become pests themselves however…
