Kingdoms + domains (c) Flashcards
What are the 5 kingdoms?
- prokaryotae (bacteria)
- protoctista (unicellular eukaryotes)
- fungi
- plantae
- animalia
How were organisms originally classified?
Similarities in observable characteristics helped to originally classify
Describe prokaryotae e.g. bacteria
- unicellular + <5um
- no nucleus or other membrane-bound organelles (a ring of ‘naked’ DNA) and small ribosomes
- no visible feeding mechanism - nutrients absorbed through the cell wall or produced internally by photosynthesis
Describe protoctista e.g. algae, protozoa
- (mainly) unicellular
- eukaryotic
- some have chloroplasts
- usually live in water
- some are sessile (immobile), others move by cilia, flagella or amoeboid mechanisms
- nutrients acquired by photosynthesis (autrophic feeders), ingestion of other organisms (heterotrophic feeders) or both; some are parasitic
Describe fungi e.g. mushrooms, moulds, yeasts
- unicellular or multicellular
- eukaryotic (chitin cell wall)
- no chloroplasts or chlorophyll
- no mechanisms for locomotion
- most have a body or mycelium made of threads or hyphae
- nutrients acquired by absorptions - saprotrophic (absorb substances from dead of decaying material), some are parasitic
- most store their food as glycogen
Describe plantae
- multicellular
- eukaryotic (cellulose cell wall)
- contain chlorophyll
- most do not move
- nutrients acquired by photosynthesis - autotrophic feeds - organisms that made their own food
- store food as starch
Describe animalia
- multicellular
- eukaryotic (no cell walls)
- move with aid of cilia, flagella or contractile proteins, sometimes in the form of muscular organs
- nutrients acquired by ingestion - heterotrophic feeders
- food stored as glycogen
Why have there been recent changed to classification systems?
- originally based on observable characteristics but through the study of genetics, evolutionary links can be found
- DNA changes as organisms evolve, thus changing the characteristics or organisms
- comparing similarities in DNA + proteins of different species, evolutionary relationships can be discovered between them
What is the ‘Three Domain System’?
- 3 domains + 6 kingdoms
- groups organisms using differences in sequences of nucleotides in the cells’ rRNA as well as the cells’ membrane lipid structure + their sensitivity to antibiotics
What is the difference between the 3 domains?
Archaea, Bacteria, Eukarya - they all have unique rRNA + different ribosomes
Describe eukarya
80s ribosomes. RNA polymerase contains 12 proteins
Describe archaea
70s ribosomes. RNA polymerase of different organisms contain 8-10 proteins
Describe bacteria
70s ribosomes. RNA polymerase contains 5 proteins
What happens to the kingdoms in the domain system?
The Prokaryotae kingdom gets split into Archaebacteria and Eubacteria.
Why are the kingdoms separated?
Eubacteria are classified in their own kingdom because their chemical makeup is different from Archaebacteria.
