Week 1: i. Microbial Classification & Taxonomy; Bacterial structure + The Prokaryotic Cell Cycle; Bacterial Growth, Physiology and Metabolism Flashcards
What is cyanobacteria?
- Cyanobacteria is the first unicellular form of life identified ≈ 3.6 billion years ago.
What is the molecular phylogeny tool? (3)
- Molecular Phylogeny is the tool that enables us to understand the complexity of life and the relationships between living forms.
- This is done by comparing the ribosomal RNA (rRNA) genes.
- rRNA is well conserved so helps identify relationships between organisms. In prokaryotes,
get 16SrRNA & in eukaryotes, get 18SrRNA.
- Based on rRNA analysis, life has evolved into 3 main lineages:
o Prokaryotes (unicellular; bacteria)
o Archae (unicellular microbes, not of clinical significance) &
o Eukaryotes (multicellular, more complex organisms like fungi, protozoa)
What are the differences between prokaryotes vs eukaryotes? (8)
What are the types of microbes? (4)
- Viruses
- Bacteria
- Fungi
- Parasites
What are the characteristics of viruses? (5)
What are the characteristics of bacteria? (5)
What are the characteristics of fungi? (3)
What are the characteristics of parasites? (4)
Bacterial Classification:
- STAINING REACTIONS:
- Gram staining: (2)
= Gram-positive (Dark blue/purple – Due to thick cell wall, peptidoglycan layer)
= Gram-negative (Pink – Due to thin cell wall)
What is acid-fast?
Used with organisms that stain poorly with Gram stain e.g. Mycobacterium tuberculosis
Ziehl Neelsen stain (End TB); Kinyoun stain (Nocardia)
- SIZE:
- Measured in ______ (micrometres)
microns
What are the shapes of bacterial classification? (3)
- Cocci, Bacilli, Spiral
- Bacilli can be cocco-bacillary (bacilli shaped but rounder), pleomorphic (different bacillary
sizes and shapes) or club shaped/chinese-lettering - Spiral shape can be tight or loose coils
Bacterial Classification:
- ARRANGEMENT =
- Cocci in chains (streptococci) or in clusters (staphylococci)
Bacterial Classification:
- CULTURABLE OR NON-CULTURABLE (ABILITY TO GROW) =
(2)
- Culturable: Dilute bacterial suspension in a solution, plate out on solid agar medium and
observe colonies to determine organism type (perform further tests for definitive result) - Unculturable: Bacteria that cannot be grown on any artificial non-living conditions (identify
using PCR, Polymerase chain reaction)
Bacterial Classification:
- GROWTH REQUIREMENTS (FOR CULTURABLE) =
Aero-tolerance (tolerance for O2) v/s Anaerobe (intolerance for O2) AND Fast v/s Slow growers
What is flagella?
Locomotion; antigen; immune evasion
What is fimbriae?
Adherence
What are pili?
Join adjacent bacteria cell for partial DNA transfer (conjugation)
What is the capsule (most polysaccharide) ?
Protects the cell from dehydration and nutrient loss; antiphagocytic; antigenic/immunogenic; biofilm formation
What is the cell wall (cytoskeleton = peptidoglycan) ?
Rigidity & shape; protection against osmotic pressure - prevention of lysis; antigenic
What is the cytoplasmic membrane (phospholipid bilayer) ?
Cell respiration; cell precursor synthesis; selectively permeable
What is cytoplasm?
Solvent for materials used in all cell functions
What is intracytoplasmic inclusions?
Intracellular storage bodies