Cell Signaling Part 2 Concept Review

Figure 9.18 Cell-cell communication enables these (a) Staphylococcus aureus bacteria to work together to

form a biofilm inside a hospital patient’s catheter, seen here via scanning electron microscopy. S. aureus is the

main cause of hospital-acquired infections. (b) Hawaiian bobtail squid have a symbiotic relationship with the

bioluminescent bacteria Vibrio fischeri. The luminescence makes it difficult to see the squid from below because it

effectively eliminates its shadow. In return for camouflage, the squid provides food for the bacteria. Free-living V.

fischeri do not produce luciferase, the enzyme responsible for luminescence, but V. fischeri living in a symbiotic

relationship with the squid do. Quorum sensing determines whether the bacteria should produce the luciferase

enzyme. (credit a: modifications of work by CDC/Janice Carr; credit b: modifications of work by Cliff1066/Flickr)