BISC 303 Lecture Notes - Lecture 15: Commensalism, Lysozyme, Peptidoglycan

• School: Simon Fraser University
• Department: Department of Humanities Biological Sciences
• Course: BISC 303
• Professor: Julian Guttman

Document Summary

Positive: mutualism, both species benefit, depend on each other to survive, cooperation, both benefit but don"t depend, commensalism, one benefits and one is unaffected. Negative: predation, one preys on another, parasitism, one benefits one is harmed, some co-existence btwn host and parasite. Usually grows inside host: amensalism, one species kills the other, competition, one outcompetes other for resources commensalism eating at the same table. Organisms live on all surfaces of an organism exposed to environment lots of skin commensals commensals. How does intestinal mucosa avoid constant attachment/invasion: peristalsis contents move by smooth muscle action, mucous secretion/flow decreases the probability of attachment (goblet cells, epithelial cell sloughing (desquamation) Animals without commensals are still viable, called gnotobiotic animals. One grows at expense of host, host is harmed. By convention, parasite refers to: 1) protozoans (eg. plasmodium > malaria, 2) worms (eg. tapeworms/flukes) Eg rhinovirus affect upper respiratory tract and nowhere else.