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
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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
what are the six major groups of fungi*
- Chytridiomycota
- Zygomycota
- Glomeromycota
- Ascomycota
- Basidiomycota
- Microsporidia
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Fungi
Other unicellular or multicellular
eukaryotic microbes are in the group
Distribution of Fungi
- Primarily terrestrial, many pathogenic, some symbiotic
Nutrition of fungi
- Heterotrophic saprophytes (gain energy from dead organic material)
Fungi taxonomy
Moulds, mushrooms, unicellular yeasts
Structure of Fungi
- Moulds have hyphae, yeasts are unicellular, chitin cell wall
Distribution of Algae
Most are aquatic e.g. seaweeds
Some are symbiotic e.g. with corals; with fungi to
form lichens
Algae Taxonomy
Algae is an informal term for a large, diverse
group of photosynthetic eukaryotes that are not
necessarily closely related
Groups include: Green algae, Euglenoids, Golden algae, Yellow-Green algae, Diatoms, Brown algae, Red Algae, Dinoflagellates
5 groups of algae
Green algae, Red algae, Brown algae, Diatoms, Dinoflagellates
Algae nutrition
Photoautotrophic (mostly) i.e. photosynthetic
Structure of algae
Highly variable size/shape, unicellular or multicellular
Contain chloroplasts for photosynthesis
Groups of protozoa
Flagellates, amoebae, sporozoans, ciliates
FACS
Structure of Protozoa
Motile using psuedopodia, flagella or cilia
Unicellular, highly variable size/shape
Taxonomy of protozoa
Protozoa (also protozoan) is an informal term
for unicellular eukaryotes which feed on
organic matter, “animal-like” as are often
motile predators
Distribution of Protozoa
Aquatic/terrestrial
Some are animal pathogens
Nutrition of protozoa
Chemoheterotrophic (use organic compounds
to gain C and energy)
Distribution of Slime moulds
Terrestrial or aquatic environments
Taxonomic groups of Slime moulds
Two main groups
- Acellular slime moulds, Cellular slime
moulds
Nutrition of Slime moulds
Heterotrophic saprophyte, feed on microorganisms
Structure of Slime moulds
Cellular
- Amobea-like cells which feed by phagocytosis
- cells aggregate to form motile multicellular slug
- Produce spores with cellulose cell walls from fruiting bodies
Acellular
- Streaming masses of colorful protoplasm, produces
fruiting bodies and spores
Viruses
- Acellular microorganisms that do not appear on the Universal Phylogenetic tree (dont have rRNA)
Distribution of Viruses
- Obligate intracellular parasites of living cells
Taxonomy of viruses based on
Host
Virion structure and composition
Mode of reproduction
Nature of disease
Structure of Viruses
10-300nm diameter
Nucleocapsid core composed of DNA or RNA surrounded by a protein Caspid
Four morphological types: Icosahedral, Helical, Enveloped, Complex
1um - 1 micrometer
