Bacterial Physiology Basics Flashcards
What is the difference between Prokaryotic cells and Eukaryotic cells
Prokaryotic cells have no membrane bound organelles or nucleus e.g bacteria. Eukaryotic cells have complex organelles with a nucleus
Describe the structure of gram positive cells
- Thick cell wall consisting of several peptidoglycan layers.
- Teichtoic acids also present which sense the external environment.
- Pseudoperiplasm between inner membrane and peptidoglycan layer
- Retain crystal violet dye
Describe the structure of gram negative cells
- Single thin later of peptidoglycan located between other membranes.
- Outer membrane contains LPS (endotoxin).
- Periplasm filled with gel like material comprising, proteins small metabolites, olligosaccharides.
- The cell wall has pores which enable transport of nutrients.
- Lose crystal violet dye
Define: Glycolysis
Conversion of glucose into pyruvate.
What determines cell shape?
Peptidoglycan in the cell wall
What is the Gram-staining process?
- Stain with crystal violet
- Apply iodine (acts as a mordant forming a complex with the crystal violet)
- Decolourise
- Counterstain
What is the most important role of the bacterial cell wall?
A) Maintain the shape of the cell
B) Protect the cell from osmotic pressures
C) Prevent ions from diffusing away from the cell
B) They help bacteria resist phagocytosis by macrophages.
B) Protect the cell from osmotic pressures
The third amino acid in the peptidoglycan crosslinking chain is either diaminopimilic acid or lysine because this amino acid must
A) Be positively charged for a salt bridge to form.
B) Be hydrophillic.
C) Have a free amino group for peptide bond formation.
D) Have a large R-side chain to fill space in the cell wall.
C) Have a free amino group for peptide bond formation
The presence of D-amino acids in the crosslinks of the peptidoglycan layer is most likely because
A) Most peptidases can only cleave L-amino acids.
B) D-amino acids fit the structural constrains of the cell wall better than L-amino acids.
C) Most L-amino acids have already been used for protein synthesis.
D) D-amino acids are easier to crosslink in the absence of ribosomes.
A) Most peptidases can only cleave L-amino acids.
Define: Plasmid
Self-replicating segment of double stranded DNA
The significance of the plasma membrane is that
A) It selectively allows some molecules to pass into the organism
B) It prevents movement of molecules out of the organism
C) It is the site of protein synthesis
D) All of the above
D) All of the above
What is the function of ribosomes in cell metabolism
Site of protein synthesis