Microbial structure Flashcards
What is the difference in the structure of eukaryotic cells and prokaryotic cells?
eukaryotic - cytoplasm filled with organelles
prokaryotic - no organelles independent of plasma membrane
What are the structural features of bacteria?
capsule pili flagellae spores slime cell wall
What is the function of the cell wall in bacteria?
differentiates bacterial species into gram positive and gram negative
What is used to distinguish between gram positive and gram negative bacteria?
gram staining
What is the 4 steps of gram staining?
- primary stain - crystal violet dye - stains all bacterial cells purple
- trapping agent - Gram’s iodine - forms CVI complexes in the cell wall
- decolourisation - alcohol - interacts with lipids in wall
- counterstain - safranin - gram negative becomes pink and gram positive purple
What are the 3 components of a bacterial cell wall?
PGN - peptidoglycan
LPS - lipopolysaccharide
LTA - lipoteichoic
What is the structure of a gram positive cell wall?
2 layers with a thick PGN layer and LTA
What is the structure of a gram negative cell wall?
3 layers with a thin PGN layer, outer membrane and LPS
What are the structural features of viruses?
nucleic acid
capsid
envelope
spikes
What are protozoa?
single-celled eukaryotes
What are fungi?
multicellular eukaryotic cells with thick carbohydrate walls
How do bacteria replicate?
binary fission
What are the 4 stages of bacterial growth?
lag
log
stationary
death
How can bacteria be classified?
- gram stain
- cell shape
- atmospheric preference
- key enzymes
What are the 6 steps of viral replication?
adsorption penetration replication assembly maturation release of naked viruses
