2 - Taxonomy of Microorganisms Flashcards
What does binomial nomenclature consist of
- Genus: Noun, Capital first letter, italicised (Homo)
- Species: Descriptive, Lower case, Italicised (sapiens)
What are the taxonomic ranks
- Domain/Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species
Phenetic system
Groups organisms based on similarity of observable characteristics
Five kingdom system
Monera, Protista, Fungi, Plantae, Animalia
Member of Parliament For Plants and Animals?*
Why is five kingdom system no longer accepted
As not all organisms that appear similar should be grouped together. Did not differentiate between prokaryotes and eukaryotes.
Define Prokaryotic cell
Simple cells, lack membrane bound nucleus
Define Eukaryotic cell
Complex cells, have a nucleus and other membrane bound organelles
Features of prokaryotic cells (Size, Cell wall, Genetic material, Mitosis and meiosis, ribsomes, membrane bound organelles, plasma membrane, site of respiration and photosynthesis, locomotion)
- Size: Smaller than eukaryotic
- Cell wall: Contain peptidoglycan
- Genetic material: One circular DNA molecule, no nucleus
- Mitosis and meiosis: Absent
- Ribosomes: 70S, free in cytoplasm
- Membrane bound organelles: Absent
- Plasma membrane: Sterols absent
- Site of respiration: Plasma membrane
- Site of photosynthesis: Internal membranes
- Locomotion: Flagella that rotate
Features of eukaryotic cells (Size, Cell wall, Genetic material, Mitosis and meiosis, ribsomes, membrane bound organelles, plasma membrane, site of respiration and photosynthesis, locomotion)
- Size: Larger
- Cell wall: No peptidoglycan
- Genetic material: arranged in chromosomes. Nucleus present
- Mitosis and meiosis: Present
- Ribosomes: 80S, on ER
- Membrane bound organelles: Present
- Plasma membrane: Sterols present
- Site of respiration: mitochondria
- Site of photosynthesis: chloroplasts
- Locomotion: Flagella and cilia that undulate or amoeboid movements
Universal phylogenetic tree
Based on sequence of rRNA, good indicator of evolutionary relatedness as all cells contain rRNA.
Divided into 3 domains: Bacteria and Archaea (prokaryotes), Eukarya (eukaryotes)
List three differences between Bacteria, Archaea and Eukarya*
- Membrane lipids: Archaea have ether linked branched aliphatic hydrocarbon chains. Bacteria and Eurkaya are ester linked straight hydrocarbon chains
- Amino acid carried by tRNA: Bacteria is N-Formylmethionine, others are Methionine
- RNA Polymerase: Bacteria (one type with simple subunit pattern - 6 subunits), Archaea (one type, complex subunit pattern - 8 to 12 subunits), Eukarya (Three types, complex subunit pattern - 12 to 14 subunits)
what are the similarities between mitochondria, chloroplasts and bacteria
Size, single circular choromosme, 70S ribosomes, Use formyl methionine, Undergo bonary fission
First cells
Root of the phylogenetic tree is in teh bacterial branch
Considered the last universal common ancestor (LUCA)
It is thought that then archaea and eukraya developed from bacteria
however fossilized prokaryotes are difficult to find
First prokaryotes were anaerobes
Endosymbiotic hypothesis
- Ancestral eukaryotic cell lost cell wall and developed ability to engulf prey
- Engulfment of bacterium providing ATP energy, evolved into mitochondria
- Engulfment of cyanobacterium providing photosynthetic ability, evolved into chloroplasts
Diatom evolution
- Example of evidence for endosymbiotic hypothesis through Diatom genome sequencing
- Led to new hypothesis that secondary endosymbiosis had occurred to form diatoms (green alga engulfed red alga that had engulfed a cyanobacterium)
Protists
- Term to cover unicellular and sometimes multicellular eukaryotic microbes which lack differentiated tissues
- EG, algae, protozoa, slime moulds
