Topic 4 - Natural selection and genetic modification Flashcards
What is natural selection?
– process where organisms better adapted to their environment survive and produce more offspring.
Bacterial resistance in antibodies
-Bacteria reproduce at a fast rate.
- Mutations result in new genes e.g.a gene for antibiotic resistance.
- Exposure to antibiotics– those w/ antibiotic resistant
genes survive and those without die.
- w/ antibiotic resistance can reproduce and pass on gene to offspring.
- population of antibiotic resistant bacteria increases.
- Bacterial diseases spread because people aren’t immune to new resistant bacteria and there’s no treatment for it.
e.g. MRSA
Describe Ardi
ardipithecus ramidus
- 4.4 mil. yrs old – found in Ethiopia
- structure of feet – climbed trees w/ ape like big toe
- long arms & short legs
- brain the size of a chimp
- walked upright – didn’t use hands to walk
Describe Lucy
Austalopithecus afarensis
- 3.2 mil. yrs old – found in Ethiopia
- more human-like than Ardi
- arched feet- more adapted to walking
- arms and legs between ape and human
- brain slightly larger than Ardi, but similar to chimp
- walked upright more efficiently than Ardi
Describe Turkana Boy
Homo erectus
- 1.6 mil. yrs ago – found in Kenya
- more human-like than Lucy
- short arms & long legs– more like human than ape
- brain size larger than Lucy - similar to human
- better adapted to walking upright
Describe homo habilis
- 2.5-1.5 mil yrs ago
- simple stone tools (pebble tools) – hit rocks together to make sharp flakes – used to scrape meat from bones or crack bones open
Describe homo erectus
- 2-0.3 mil. yrs ago
- sculpted rocks to make more complex tools e.g. hand axes
- used this to hunt, dig, chop and scrape meat from bones
Describe homo neanderthalis
- 300,000- 25,000 yrs ago
- more complex tools
- flint and pointed tools and wooden spears
Describe homo sapiens
- 200,000 yrs ago - present
- flit tools used
- pointed tools e.g. arrowheads, fish hooks, buttons and needles appeared circa 50,000 yrs ago
What is a pentadactyl limb?
- limb w/ 5 digits
- many organisms have this implying they have a common ancestor, but not always e.g. cats and bats
What is carbon dating?
- looking at natural radioactive decay of an
isotope of Carbon (Carbon-14) to estimate how long ago an organism lived
How can we date tools by stratifying rock layers?
- Each layer of sediment must have been formed at the same time.
- can date the fossils in this layer and use this to estimate when the tools were formed.
Animal kingdom classification and order
- kingdom Kinky
- phloem Police
- class Constables
- order Only
- Family Fancy
- Genus Gay
- Species Sergeants ………lol
Animal five kingdoms system (what they’re split into)
- animals
- plant
- fungi
- prokaryotes e.g. bacteria
- protist
Differences between archea, bacteria and Eukaryota
Archaea - primitive bacteria that live in extreme environments e.g. hot springs
- Bacteria - true bacteria– but are similar to archaea
- Eukaryota- organisms that have a nucleus enclosed in membranes e.g. protists, fungi, plants and animals
What is selective breeding?
- when humans choose which organisms to breed to produce offspring w/ a certain desirable characteristic
Describe selective breeding?
- Parents w/ desired characteristics are chosen.
They’re bred together. - From offspring those w/ desired characteristics are bred together.
- process repeated many times until all the offspring have the desired characteristic.
Dangers of selective breeding
- lead to inbreeding.
- Breeding those w/ similar desirable characteristics means you’re breeding closely related individuals.
- so they mostly have the same alleles
- if environment changes or there’s a new disease, species could become extinct-they all have the same genetic make-up
- important in selective breeding of plants
- also cause genetic defects
What is tissue culture?
- a method of culturing living tissue– making it grow outside the organism, within growth medium
Describe culturing tissue
- Take organism you want to clone
- Using tweezers, remove piece of tissue from a fast-growing region of organism
- maintain sterile conditions and place tissue on
special growth medium– contains hormones and nutrients - when tissue has developed enough can be
transferred to compost for further growth
What is genetic engineering ?
- Modifying genome of an organism by using gene from another organism to give it a desired characteristic.
e. g. Plant cells have been engineered for disease resistance or to have larger fruits
Describe genetic engineering
- Genes from chromosomes are ‘cut out’ using restriction enzymes.
- same restriction enzymes used to cut vector into where genes will be placed.
- Ligase enzyme used to attach sticky ends of gene and vector together, to produce a recombinant gene product.
- vector is placed in another organism at early stage in development so desired gene moves into its cells and organism can grow w/ desired characteristics.
- in plants vector is put into unspecialised cells– so can produce identical copies of modified plant.
Benefit and disadvantage of genetic engineering
benefit
-In agriculture used to improve yields by modifying crops to grow in different conditions, e.g. hotter or drier climates
disadvantage
- People worried we don’t completely understand effects of GM crops on human
health.
What are fertilisers?
provide nutrients to plants, makes them more resistant to environmental conditions and able to grow faster and
larger -increase crop yields
What is biological control?
- use of certain species to control population of other species.
Advantages and disadvantages of genetic engineering
advantage
- useful in medicine produce certain hormones in
microorganisms
disadvantage
- herbicides and pesticides can kill insects and other plants, reduces biodiversity
Advantages and disadvantages of selective breeding
advantage - plants or animals can be bred to be resistant to a particular disease disadvantage - Lack of genetic variation if one susceptible to disease then all are
Stages of genetic engineering
- gene from chromosome is cut by restriction enzyme and creates sticky ends
- same restriction enzyme is used to cut vector (virus or bacterial plasmid)
- ligase enzyme used to attach sticky ends of the gene and vector together to produce recombinant DNA
- vector then placed in another organism etc.
