Fichas
Evidence for Evolution
Fichas del conjunto (16)
- 1comparative DNA - genomics- all living things made of DNA, same DNA code --> common ancestor
- sequence of DNA varies between organisms
- new genes can be gained by mutations
- genes lost by natural selection or genetic drift
- when speciation occurs, the new species would have similar DNA to ancestral species - 2RELATION SENTENCES - genomics- species that are distantly related, have more differences in their DNA sequence
- closely related species have more similarities in their DNA sequence
- the more difference in the DNA sequence between two species, the more time has passed since a common ancestor - 3endogenous retroviruses- an ERV is a viral sequence that has become part of an organisms genome
- store genetic info as DNA and upon entering a cell the retrovirus will copy its RNA into DNA --> reverse translocation
- offspring of infected individual will contain the ERV - 4RELATION SENTENCES - ERV- species distantly related have less shared ERV
- closely related species have more shared ERV
- the more shared ERV between two species the less time has passed since a common ancestor - 5Mitochondrial DNA (MtDNA)- circular ring of DNA
- 37 genes --> 16 500 base pairs
- only inherited from mother
- higher mutation rate than nuclear DNA
- human MtDNA has been slowly diverging from the MtDNA of our original female ancestor
- the amount of mutations is proportional to time passed
- best used for comparing individuals within a species --> track migration routes - 6RELATION SENTENCES -MtDNA- the degree of similarity between the MtDNA of any two individuals provides an estimate of the closeness of the relationship through maternal ancestors
- 7Comparative protein studies- comparison of amino acids sequence in particular proteins
- ubiquitous proteins appear to be in all species and carry out basic but essential tasks that are required for life - 8comparative protein studies examplecytochrome C - required for cellular respiration and appears to have remained the same over millions of years of evolution
- 9bioinformatics- use of computers to describe the molecular components of living things
- look at evolution by analysing DNA changes in large number of organisms - 10comparative genomics- comparing genomes of species to look at similarities and differences in organisms as well as genes
- comparative genomics has revealed a high degree of similarity between closely related organisms such as humans and chimpanzees - 11comparative embryology- vertebrates show a degree of similarity of early embryonic stages
- features at some point in their development --> dorsal brain and spinal cord, skeleton, post anal tail, gill slits, aortic arches - 12comparative embryology- involves looking at structural features of related organism to ascertain a degree of similarity between them
- similarities suggest a common ancestor
- common development pathway depends on closeness of relationship
- these provide evidence of common ancestory - 13homologous structures- features of organisms that have a fundamental similarity of structure
e.g forelimbs, pentadactyl limb (hand)
- evidence of common ancestry
- similar structures but different functions - 14vestigial organs- structures of reduced size that appear to have no functions but may have been important in previous ancestors
e.g pink membrane on inner eye, transparent third eyelid, muscles to move ears, wisdom teeth, pointed canine, appendix, coccyx bone - 15why we don't have these organs anymore- reduced in size to conserve energy
- organs will probably disappear altogether as there is no selection pressure to retain them
- provide evidence of change over time - 16phylogenetic tree- show evolution over time
- how closely related organisms are
Información
- Descripción
- Year 12 Sciences Fichas sobre Evidence for Evolution, creado por Savannah Kerr el 05/09/2017.
- Creado por
- Savannah Kerr
- Visitas
- 1
- Valoración