The five kingdoms + phylogeny

the five kingdoms - why?

• more species were discovered

• more was being discovered about organisms

• it became increasingly difficult to divide living organisms into just two kingdoms

• development of microscopes meant better observation of cellular structures, identifying the significant cellular differences in bacteria from other organisms

What are the 5 kingdoms?

• Prokaryotae

• Protoctista

• Fungi

• Plantae

• Animalia

Prokaryotae - features

1. unicellular

2. no nucleus

3. no membrane bound organelles

4. small ribosomes

5. ring of naked dna

6. no visible feeding mechanisms - nutrients are absorbed through the cell wall or produced internally by photosynthesis

e.g E.coli

protoctista - features

1. mainly unicellular

2. nucleus and other membrane bound organelles

3. some have chloroplasts

4. some are sessile or move using cilia, flagella or amoebic mechanisms

5. nutrients are acquired through photosynthesis ( autotrophic feeders ) or ingest other organisms (heterotrophic feeders) - some are parasitic

e.g amoeba

fungi - features

1. unicellular or multicellular

2. nucleus, other membrane-bound organelles, and a cell wall mainly composed of chitin

3. no chloroplasts

4. no mechanisms for locomotion

5. most have a body or mycellium made of threads or hyphae

6. nutrients are acquired through absorption - mainly decaying material (saphotrophic feeders) - some are parasitic

7. most store their food as glycogen

plantae - general features

1. multicellular

2. other membrane-bound organelles, including chloroplasts, and a cell wall mainly composed of cellulose

3. all contain chlorophyll

4. most are immobile but some gametes travel using cilia or flagella

5. nutrients are acquired by photosynthesis - autotrophic

6. store food as starch

animalia - features

1. multicellular

2. no chloroplasts

3. nucleus and other membrane-bound organelles

4. move with aid of cilia, flagella, and contractile proteins, sometimes in the form of muscular organs

5. nutrients are acquired by ingestion - heterotrophic

6. food stored as glycogen

Scientists are now able to study the evolutionary links between organisms due to…

• study of genetics and biological molecules

• also comparing the similarities in DNA and proteins of different species so that they can discover evolutionary relationships between them

Woese’s system groups organisms using…

differences in the sequence of nucleotides in the cells’ ribosomal RNA (rRNA) as well as the cells’ membrane lipid structure and their sensitivity to antibiotics

Eukarya - ribosomes and form of rRNA

• 80s ribosomes

• RNA polymerase

• contains 12 proteins

Archaea - ribosomes and form of rRNA

• 70s ribosomes

• RNA polymerase of different organisms contain 8 - 10 proteins

• very similar to eukaryotic ribosomes

Bacteria - ribosomes and form of rRNA

• 70s ribosomes

• RNA polymerase contains five proteins

Archaebacteria

can live in extreme temperatures

• hot thermal vents

• anaerobic conditions

• highly acidic conditions

e.g methanogens live in anaerobic sewage treatment plants and make methane

Eubacteria

found in all environments - most bacteria in the eubacteria kingdom

Eubacteria and Archaebacteria are classified as their own kingdoms because…

they have different chemical makeup for e.g peptydoglycan is in the cell wall of eaubacteria whereas in archaebacteria it is not

Woese’s six kingdom system

1. Eubacteria

2. Archaebacteria

3. Protoctista

4. Fungi

5. Plantae

6. Animalia

phylogeny

evolutionary relationships between organisms

Advantages of phylogeny

• Shows evolutionary relationships

• Shows evolutionary timeline

• Is continuous whereas classification requires discrete taxonomical groups so it doesn’t force any organisms into specific unfit groups

• Hierachal nature of linnaean classification implies that different groups within the same ranks are equivalent e.g orchids and cats are in the same family but orchids have existed over 100 million years whereas cats are 30 million which implies that they are the same

• certain groups could have longer histories or different levels of diversity

explain phylogeny tree