Classification and evolution

Chapter 10 - Page 29 of spec

Why do scientists classify organisms

predict characteristics, identify species, find evolutionary links

species

group of individuals that are able to reproduce to produce fertile offspring

taxonomic hierarchy/groups

domain, kingdom, phylum, class, order, family, genus, species

how are species biologically classified

taxonomic hierarchy of kingdom

binomial system of naming species

first word is genus uppercase, second word is species lowercase, italics or underlined

advantages of binomial nomenclature

universal name for organisms (no confusion), provide info about relationships bw organisms (same genus=common ancestor)

the 5 kingdoms

Protoctista, prokaryotae , fungi, plantae, animalia

another name for prokaryote

monera

Prokaryote features

single celled. no nucleus/membrane bound organelles. plasmids. peptidoglycan cell wall. 70s ribosomes

Protoctista features

single celled. eukaryotic. heterotroph/autotroph. flagella/cilia. organism not found in any other kingdoms. some have chloroplasts.

Fungi features

multicellular/unicellular. saprotrophic. no chloroplast/cilia/flagella. chitin cell walls. store food as glycogen. mycelium made of hyphae. reproduce via spores (no locomotion).

Plantae features

multicellular. autotrophic. have chloropasts (some might have cilia/flagella). cellulose cell wall. store food as starch.

Animalia features

multicellular. heterotrophic. have cilia/flagella/contractile proteins. no cell walls/chloroplast. store food as glycogen. can form tissues.

autotroph

organism that sysnthesises complex organic molecules from inorganic molcules via photosynthesis

Heterotroph

organism that acquires nutrients by the ingestion of other organisms

Saprotroph

organism that releases extra-cellular enzymes and absorbs nutrients

classification systems

DNA, physiology, morphology, biochemistry, cytochrome c, similarities in observable features of organisms (early classification method), similarities in behaviour (early classification method)

how DNA is used to classify organisms

the more similarities bw DNA or aa sequences or proteins means the organisms are more closely related

how cytochrome c is used to classify organisms

protein found in mitochondria of all eukaryotic cells used for respiration, there are different versions of cytochrome c in different species, the more similar versions the more closely related organisms are

evidence for 3 domain system

Eukarya - 80s ribosomes, 12 proteins in RNA polymerase. Archaea - 80s ribosomes, 8 to 10 proteins in RNA polymerase. Bacteria - 70s ribosomes, 5 proteins in RNA polymerase. Concluded they were too different to be classed in the same kingdom.

who created 3 domain system

Woese

what are the 3 domains

eukarya, archaea, bacteria

archaebacteria

can live in extreme conditions (hot thermal vents, anaerobic conditions, highly acidic environments), example methanogens live in sewage plant treatments making methane

Eubacteria

found in all environments, most common, chemically different to archaebacteria

bacteria

70s ribosomes. RNA polymerase contains 5 proteins. has 1 kingdom in its domain: Eubacteria

archaea

70s ribosomes, RNA polymerase contains 8 - 10 proteins. has 1 kingdom in its domain: Archaeba

eukarya

80s ribosomes. RNA polymerases contains 12 proteins, has 4 kingdoms in its domain (plantae, Protoctista, fungi,animalia)

what are the 6 kingdoms in the 3 domain system

Protoctista, Fungi, Plantae, Animalia, Archaebacteria, Eubacteria (prokaryote has been split into 2)

compare the kingdom and domain classification systems

both systems use observational evidence,but domain also uses molecular evidence. both have the 5 kingdoms. eukaryotic organisation: domain have 1 domain, kingdom have 4 kingdoms. prokaryotic organisation: domain has 2 domains, kingdom has 1 kingdom

explain the difference between classification and phylogeny

Classification is simply sorting organisms into groups. Phylogeny investigates the evolutionary relationships between organisms.

Process of natural selection

1. mutation 2. variation within population 3. selection pressure 4. best suited to environment survive 5. reproduction to pass on advantageous allele/mutated gene 6. frequency of gene increases over generations 7. allele increases in population

Scientists developing evolution in order

Hutton > Lyell > Wallace > Darwin

How did Darwin and Wallace contribute to the theory of evolution?

observed that birds have different beak shapes. concluded that birds with beak shapes most suited to the food they eat are more likely to survive and pass on their genes to their offspring.

give other evidence for the theory of evolution

palaeontology/fossils, comparative biochemistry (genes/DNA), comparative anatomy, sequence of aa, sequence of bases

types of variation

intRAspecific (same species), intERspecific (different species)

Difference between continuous and discontinuous variation

Continuous - gradual changes over a range, polygenetic, large environmental effect i.e. height, mass. Discontinuous - distinct categories, monogenetic, little environmental effect i.e. blood group, bacteria shape, gender, eye colour.

genetic causes of variation

different alleles, crossing over at the chiasmata, independent assortment, independent segregation, mutations, random fusion of gametes, chance

environmental causes for variation

light intensity, scars, diet, disease, UV index

pentadactyl limbs

a limb with 5 parts, all mammals have this, suggest evolution from a common ancestor

3 types of adaptations

anatomical, physiological, behavioural

meaning of anatomical

physical features, changes to body structure, i.e. camouflage, teeth, mimicry, body coverings

meaning of physiological

changes to bodily processes, i.e. venom production, water holding, antibiotic production

meaning of behvioural

changes organism’s behaviour, i.e. courtship, migration, hibernation, survival behaviour, innate/learnt, seasonal

taxonomic groups

why might organisms from different taxonomic groups show similar features (with example)

Marsupial moles and placental moles live in different continents but share similar anatomy because they have adapted to similar environments (convergent evolution)

implications of evolution for humans

pesticide resistance means entire crops destroyed by insects. bacterial antibiotic resistance means infections or harder to treat

homologous structure

same underlying structure in different organisms but have different functions. exist in organisms that HAVE a common ancestor

advantage of phyolgeny

produces a continuous evolutionary history of an organism

convergent evolution

unrelated species evolve similar traits due to similar environmental pressures, despite having different ancestral origins.

analogous structures

structures that look the same but have different functions. exist in organisms that do NOT have a common ancestor

sheep blowflies

parasitic fly that lay their eggs in the wool of sheep. can be fatal for sheep. they are resistant to pesticides

peppered moths

industrial revolution caused trees to be covered in soot, pale peppered moths died but dark peppered moths survived because they were better camouflaged/adapted. went back to pale colour after industrial revolution

Darwin’s conculsion

characteristics are passed onto the next generation

reproductive isolation

prevents transfer of genes creating 2 sub-populations meaning eventually a species becomes genetically isolated

why would albino frogs be used for cloning

show offspring are clones, identify parents of clones

advantage of using clones to test treatments

genetically identical so all react the same to a drug

disadvantage of using clones to test treatments

no genetic variation so don’t see varied response like in real populations, clone may have unknown health issue affecting results, expensive

applications of cloning

preserve endangered animals, produce stem cells/tissues/organs, xenotransplantation, produce best animals

why might lack of genetic variation contribute to the rapid spread of disease

if one organism is susceptible to a disease its clone is also likely

how can you use selective breeding to improve disease resistance of a crop

cross breed with disease resistant variety, select most resistant offspring, breed again, continue for many generations