Classification & Structure of Micro-organisms Flashcards
What does the Three-Domain system of classification include?
Bacteria
Archaea
Eukaryota
Give 5 facts about bacteria
- Bacteria are Prokaryotes
- Consist of membranes that are made up of unbranched fatty acid chains & are attached to glycerol by ester linkages.
- Bacteria cell walls contain peptidoglycan.
- Bacteria are found almost everywhere, such as the gut microbiome & antibiotic producers.
- Most bacteria are not clinically important.
Give 5 facts about Archaea
- Archaea are prokaryotes.
- Consist on membranes that are made up of hydrocarbon chains & are attached to glycerol by ether linkages.
- Cell walls do not contain peptidoglycan.
- Archaea are able to live in extreme environments.
- No clinical significance.
Give an example of Archaea that can live in extreme environments.
Thermus aqauticus- TAQ Polymerase, used in PCR. This version of TAQ polymerase can survive going up to 72 degrees for the denaturing step in PCR.
Give 4 facts about Eukarya.
- Eukarya are prokaryotic cells.
- Consist of membranes that are made up of unbranched fatty acid chains & attached to glycerol by ester linkages.
- Eukarya do not have a cell wall.
- The eukarya that do have a cell wall do not contain peptidoglycan.
What domain are protista in?
Eukarya
They are unicellular, and examples are protozoa/algae.
What domain are Fungi in?
Eukarya
They can be unicellular or multicellular, and examples are yeasts/moulds.
Give 9 comparisons of Prokaryotes & Eukaryotes.
-Similarities: Cytoplasmic membrane, cytoplasm, ribosomes, DNA/RNA, ATP.
-Differences: DNA does not contain histones in prokaryotes, but does in Eukaryotes.
DNA is circular in prokaryotes but linear in eukaryotes.
Genes do not contain introns in Prokaryotes, but could in eukaryotes.
DNA is found in the cytoplasm in a nucleoid region in prokaryotes, however is bound in a nucleus in Eukaryotes.
Prokaryotes do not contain membrane bound organelles, but Eukaryotes do.
Prokaryotes have 70S ribosomes, however Eukaryotes have 80S ribosomes.
Prokaryotes replicate Asexually via binary fission, and Eukaryotes Asexually replicate via mitosis, or Sexually replicate via meiosis.
DNA is haploid in prokaryotes, but diploid in Eukaryotes.
The average size of a prokaryote is 1-5micrometers, but for Eukaryotes it is 10-100micrometers.
Name the 6 kingdoms of Life
Plantae Animalia Fungi Protista Eubacteria Archaebacteria
What are the approaches to Classification?
-Classical Characteristics:
Morphology-cell shape/size is genetically stable.
Physiology/Metabolism -directly related to nature & activity of microbial proteins.
Biochemistry- proteomics, phenotypes (MALDI-TOF).
-Molecular Characteristics:
compare to microbial genomes to estimate taxonomic similarity.
Ribosomal RNAs (rRNAs) from small ribosomal subunits, i.e.
16S- bacteria & archaeal cells
18S-eukaryotes.
Name the taxonomic ranks for Eukaryotes
Domain Kingdom Phylum Class Order Family Genus Species
Name the taxonomic ranks for Bacteria
Domain Phylum Class Order Family Genus Species
What is Colitis?
Bacterial Disease resulting in plaque in large intestine.
- Caused by clostridium difficile
- Gram positive bacterium
- Phylum: Firmicutes
- Class: Clostridia
- 15micrometers long & 1.5micrometers wide.
- Spores persist in the environment
- Colonises the colon before causing diarrhoea/colitis.
What is Bubonic Plague?
Bacterial Disease
- Caused by Yersinia Pestis
- Gram negative bacterium
- Phylum: Proteobacteria
- Class: Gamma proteobacteria
- 1.5micrometers long & 1micrometer wide.
- Transmitted by rodent fleas.
What is Lyme Disease?
Bacterial Disease
- Caused by Borrelia burgdorferi
- Phylum: Spirochaetia
- 15micrometers long & 0.2micrometers wide.
- Transmitted by a tick bite.
