bacterial cell structures and functions Flashcards
What are the two domains of prokaryotic microorganisms?
Bacteria and Archaea.
What is a key difference between prokaryotic and eukaryotic cells?
Prokaryotic cells lack a membrane-bound nucleus and organelles.
What is the typical size range of bacteria?
0.1 to 5 micrometres.
Name the three main bacterial shapes.
Cocci (spherical), Bacilli (rod-shaped), Spirilla (spiral-shaped).
What are Vibrio and Pleomorphic bacteria?
Vibrio: comma-shaped; Pleomorphic: variable shape.
What are the three components of the bacterial cell envelope?
Cell membrane, cell wall, and outer membrane (Gram-negative only).
What is the bacterial plasma membrane made of?
Phospholipid bilayer with embedded proteins.
What type of linkage do bacterial membrane lipids have?
Ester linkage between glycerophosphate and fatty acids
How do archaeal membranes differ chemically from bacterial ones?
Archaea have ether linkages and isoprene units, not fatty acids.
What is the fluid mosaic model?
Describes the flexible, dynamic nature of the plasma membrane.
What are the two types of membrane proteins?
Integral (transmembrane) and Peripheral proteins.
List three major functions of the plasma membrane.
Selective barrier, structural integrity, energy generation.
Where does ATP synthesis occur in bacteria?
At the plasma membrane via the electron transport chain.
What drives active transport and motility in bacteria?
Proton motive force (PMF).
Name the three bacterial transport systems.
Simple transport, Group translocation, ABC transport systems.
Define uniport, antiport, and symport.
Uniport: single molecule; Antiport: two molecules, opposite; Symport: two molecules, same direction.
What is the bacterial cell wall made of?
Peptidoglycan (murein).
What sugars are in peptidoglycan?
N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM).
What forms the crosslinks in peptidoglycan?
Peptide chains between NAM subunits.
How does Gram-positive crosslinking differ from Gram-negative?
Gram-positive: peptide interbridge; Gram-negative: direct crosslink.
What are teichoic acids?
Polymers in Gram-positive cell walls, for structure and ion transport.
What layers make up the Gram-negative cell envelope?
Outer membrane, thin peptidoglycan wall, cytoplasmic membrane.
What is the LPS layer?
Lipopolysaccharide layer; forms the outer membrane of Gram-negative bacteria.
Why is LPS significant medically?
It acts as an endotoxin, toxic to humans.
