Untitled Deck Flashcards
What are prokaryotes?
Organisms lacking internal membrane-bound structures.
What is the size range of prokaryotic cells?
Cells with diameters ranging from 0.5-5 μm.
What are the three most common shapes of bacteria?
Sphere (cocci), rod (bacilli), and spiral (spiral, spirochete, helical, twisted rod).
Are prokaryotes unicellular or multicellular?
Unicellular, but may aggregate temporarily or permanently in colonies.
What is the function of cell walls in prokaryotes?
Maintain shape, provide protection, and are chemically different from eukaryotic cell walls.
What is peptidoglycan?
A component of prokaryotic cell walls, cross-linked by short polypeptides unique to each species.
What does the Gram stain indicate?
It is influenced by the amount of peptidoglycan in the cell wall.
What characterizes Gram-negative bacteria?
They have an outer membrane containing lipopolysaccharide (LPS) and a thin shell of peptidoglycan.
What characterizes Gram-positive bacteria?
They have a thick, homogenous sheath of peptidoglycan 20-80 nm thick.
What is a glycocalyx?
A gelatinous, sticky substance surrounding the cell, made of sugars and/or proteins.
What are the functions of glycocalyces?
Attachment, inhibits killing by white blood cells, and acts as a receptor.
What are the two types of glycocalyces?
Capsule (attached firmly for protection) and slime (water soluble for attachment).
What is the function of flagella?
A motile whiplike structure capable of rotating 360° extending beyond the cell surface.
What are the types of flagellar arrangements?
Monotrichous, amphitrichous, lophotrichous, and peritrichous.
What are fimbriae?
Non-motile, sticky proteinaceous extensions for adhesion to surfaces.
