m4.3 Classification and evolution

Taxonomy

• study of heirarchy

• placing organisms in taxonomic hierarchy

Classification

• basis of classification is phylogeny

• to sort living organisms into groups

• organisms in each group share similar features

  1. identify species

  2. predict characteristics

  3. make evolutionary links

Linnaean Classification system

• hierarchical

• kingdom (kevin)

• phylum (please)

• class (come)

• order (over)

• family (for)

• genus (great)

• species (sex)

Binomial naming

• always italics

• Genus species

• universal: address species in same language

• genus in name: shows relation

5 kingdom

• prokaryote

• protoctista

• fungi

• plantae

• animalia

Prokaryote

• unicellular

• no nucleus

• no membrane bound organelles

• eg bacteria

protoctista

• unicellular

• nucleus

• membrane bound organelles

• some chloroplast

• amoeba: spreading

• antotrophic: nutrients required by photo

• heterotrophic: ingest other organisms

• algae

Fungi

• uni/ multi

• nucleus

• membrane bound organelles

• chitin cell wall

• no chloroplast

• saprophytes: squire nutritions through absorption

• mould

Plantae

• second largest kingdom

• multi

• membrane bound organelles

• chloroplast

• cell wall

• autotrophic: make own food

• flowers

Animalia

• largest kingdom

• multi

• nucleus

• membrane bound organelles

• no cell wall

• no chloroplast

• mammals

3 domain system

• groups organisms using difference in rRNA and cell m lipid structure and sensitivity to antibiotics

• bacteria- eubacteria- prokaryotae

• archea- archaebacteria- prokaryotae

• eukaryotic: protoctista, fungi, plantae, animalia

Phylogeny

evolutionary relationship between organisms

• classify organisms

• shows how closely related organisms are

phylogenetic tree

• oldest org branch away at bottom

• tips: rep speeches

• nodes: rep common ancestor

• sister groups: split from same node

• can be done without red to L.C

• L.C uses phylogeny to check class groups correct

• produces continuous trees

• L.C assume all animals within same rank

Types of variation

• interspecific: variation between different species

• intraspecific: variation within a species

Causes of variation

• genetic

• environment

Genetic variation

• eye

• blood type

• bacterial resistance

• leaf shape

• gender

Environmental variation

• plants affected more by environment than animals

• language

• scars

• piercing

Both genetic and environmental

• height

• weight

• hair colour

• non communicable diseases

• behaviour

• muscle mass

Where does genetic variation come from

• alleles

• mutations: change in organelles DNA and gene and protein

• mutations in body class are relatively isolated

• mutation in gamete passed on to off spring

• sexual reproduction: independent assortment and crossing over causes indv to be genetically different from parents

Continuous variation

• number

• no distinct category

• vary in range

• influenced by gene and env

• shown in line graph and histograms

Discontinuous

• word

• distinct category

• controlled by gene

• shown in bar chart

Normal distribution curve

most data lie in middle of curve

Standard deviation

measure of how spread out the data is

• higher the sd higher the spread

• if high sd,we’ve variation

T test

compare mean values of two sets of data

• shows significant difference between means

• degrees of freedom (n1+n2)-2

P value

how likely result due to chance

Null hypothesis

suggest no statistical significance exists in observation

Spearman’s rank

measures correlations between 2 variables

• correlation doesn’t equal causation

• degrees of freedom= n

Prove natural selection

• palaeontology

• anatomical similarities

• biochem similarities

• observing evolution in lower life forms

Palaeontology (fossil)

• impressions: imprints left in ground

• gradual replacement: hard parts replaced by materials

• preservations: dead animals sealed in amber= no decay

• hard parts: bones and shells

• fossil records: fossils which has been arranged chronologically and in taxonomic order

Divergent evolution

one species split up into other species

• pentadactyl limb

• shows divergent of one common ancestor

• all have same lineages but changes shape = we all have common ancestor

Convergent evolution

organisms evolving same traits even if they have different lineages

• may mislead understanding of evolution

• to avoid misunderstanding with competitive biochem (study proteins)

Neutral evolution

variability in structure of molecule doesn’t affect function (most variability occurring outside molecules active region)

Comparative biochem

• compare molecular sequester of particular molecule like rRNA to see how closely related they are

• can estimate when two species last shared common ancestor