Microbial Structure Flashcards
What is the difference in the genetic material of eukaryotes vs prokaryotes concerning nuclei?
Eukaryotes:
- has true nucleus; bound by double membrane
Prokaryotes:
- no nucleus; has a nucleoid; no physical boundary
What is the difference in the genetic material of eukaryotes vs prokaryotes concerning DNA?
Eukaryotes:
- linear DNA
- organised into chromosomes; complexes with proteins
Prokaryotes:
- circular DNA
- DNA “naked”; plasmids present
What is the difference in the genetic material of eukaryotes vs prokaryotes concerning ribosomes?
Eukaryotes:
- large complex ribosomes with many types of rRNA & proteins
Prokaryotes:
-70S ribosomes
What is the difference in structure between eukaryotes and prokaryotes concerning membrane bound organelles?
Eukaryotes:
+ Cytoplasm filled with large complex collection of membrane bound organelles
Prokaryotes:
+ No membrane bound organelles independent of plasma membrane
Which type of cells have mitochondria and what are they?
Eukaryotes - mitochondria with cristae are “energy centres”
Which type of cells have mesomes and what are they?
Prokaryotes - mesomes are used in aerobic respiration, cell division, DNA replication
What are the structural components of bacteria?
\+ Capsule \+ Pili (fimbriae) \+ Flagellae \+ Spores \+ Slime \+ Cell wall
What are features/properties of the bacteria capsule?
+ Loose polysaccharide structure
+ Protects cell from phagocytosis
+ Protects cells from dessication
What are features/properties of pili?
+ Singular = pilus “hair”
+ Composed of oligomeric pilin proteins
+ Appendage used for bacterial conjugation
+ Forms tube/bridge to enable transfer of plasmids between bacteria
+ Highly antigenic
+ Plays role in attachment
What are the features/properties of fimbriae?
+ Singular = fimbria “thread”
+ Not on all bacteria
+ May contain lectins which recognise oligosaccharide units on host cells
+ Facilitates bacterial attachment to host surfaces
What are the features/properties of flagellae?
+ Singular = flagellum “whip”
+ Organs of locomotion
+ Single/multiple
+ Composed of flagellin protein
+ 20nm-thick helical hollow tube
+ Driven by rotary engine at anchor point on inner cell membrane
What are the features/properties of spores?
+ Metabolically inert form triggered by adverse environmental conditions
+ Adapted for long-term survival allowing regrowth under suitable conditions
+ Hard, multi-layered coats making spore difficult to kill
What are some common diseases caused by sporing bacteria?
\+ Botulism \+ Gas gangrene \+ Tetanus \+ Food poisoning \+ Anthrax
What sporing bacteria causes botulism?
Clostridium botulinum
What sporing bacteria causes gas gangrene?
Clostridium perfringens
What sporing bacteria causes tetanus?
Clostridium tetani
What sporing bacteria causes food poisoning?
Clostridium perfringens
What sporing bacteria causes anthrax?
Bacillus anthracis
What are the features/properties of slime?
+ Polysaccharide material
+ Secreted by some growing bacteria in biofilms
+ Protects against immune attack
+ Protects against eradications by antibiotics
What is Gram staining?
+ Based on chemical and physical properties of the cell walls
+ Differentiates bacterial species into 2 groups:
- Gram positive (+)
- Gram negative (-)
What are the 4 steps involved in Gram staining?
- Primary stain
- Trapping agent
- Decolourisation
- Counterstain
What is involved in step 1: Primary stain?
Cresyl violet dye stains all the bacterial cells purple
What is involved in step 2: Trapping agent?
+ Gram’s iodine is used
+ Forms CVI complexes in cell wall (larger than CV so not to be easily washed out of the PGN layer)
What is involved in step 3: Decolourisation?
+ Alcohol/acetone is utilised
+ Interacts with lipids in cell wall