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BIO - 4.2.2 Classification and Evolution > Evolution of Classification Systems > Flashcards

Flashcards in Evolution of Classification Systems Deck (3)
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Three Domain System

- This is the current classification system used by scientists.
- Prokaryotae kingdom becomes divided into 2: Archaebacteria & Eubacteria
- Three domains: Archaea. Bacteria, and Eukarya.
- The organisms in the different domains contain unique form of rRNA and different ribosomes:
- Eukarya have 80s ribosomes; RNA polymerase has 12 proteins.
- Archaea have 70s ribosomes; RNA polymerase of different organisms contains between 8-10 proteins
- Bacteria have 70s ribosomes; RNA polymerase contains 5 proteins


Archaebacteria and Eubacteria

- Archaebacteria are ancient bacteria that can live in extreme environments like hot thermal vents.
- Eubacteria, also known as true bacteria, are found in all environments; most bacteria are from Eubacteria kingdom.


Changes to classification systems

- Early classification systems only used observable features to place organisms into groups.
- Through the study of genetics and other biological molecules, scientists can now study the evolutionary relationships between organisms. These links can be used to classify.
- When organisms evolve, their internal and external features change, as does their DNA as DNA codes for these characteristics.
- More closely related organisms will have more similar molecules and DNA.
- Example of a protein that has changed is haemoglobin which has 4 polypeptide chains but this haemoglobin differs from chimpanzees' by only one amino acid and by gorillas in 3. This indicates a common ancestry between the various primate groups.