OCR - A-Level - Biology - Evidence used in Classification

OCR - A-Level - Biology - Evidence used in Classification

1. Biological Molecules

   • More similar molecules, more closely related
     • Determines closeness of relation as well as spp group

2. Cytochrome C

   • A protein used in respiration which differs between species
   • Compare amino acid sequences to determine drift of closeness of relation
     • More similar sequence, more closely related.
   • Can take you to a certain point
     • E.g. Humans are identical to chimpanzees
     • Other methods are needed to classify further

3. DNA

   • Genetic code is a sequence of base pairs
     • Differences in base pairs between species originated from mutation, to evolution
       • Comparing DNA identifies similarities and differences
         • More different, less related

4. RNA

   • Sequences of base pairs

5. Convergent evolution

   • Organisms that aren't closely related develop similar traits due to environmental factors

6. 3 Domain Classification

   • Eukaryote
     • Similar enzymes for synthesising RNA
       • Similar mechanisms DNA replication and RNA synthesising
         • Production of some proteins that bind to their DNA
   • Prokaryote
     • Bacteria (Eubacteria)
       • Different cell membrane structure
         • Flagella with a different internal structure
           • Different enzymes for synthesising RNA
             • Different mechanisms for DNA replication and RNA synthesising
               • No proteins bound to genetic material
     • Archaebacteria (Archaea)