BIO 182 Lecture Notes - Lecture 6: Microorganism, Competitive Advantage, Motility
Document Summary
Multicellular life: about one billion years ago, eukaryotic protists, colonies specialization reproductive cells open evolutionary doors . Cambrian explosion: eukaryotes failed to separate during cambrian explosion. Becoming multicellular requirements: cells stick together, communication between cells, specialization. Pectins adhere plant cells to adjacent cells. Communication in animal cells connections between cells made up of a ring of proteins. Communication in plant cells plasmodesmata are connections lined by extensions of the cell membrane. More complex organisms have more complex communication. Stem cell undifferentiated cell that has the potential to be specialized into anything. Specialization occurs because some genes are activated and some are silenced. Major origins of multicellularity: red algae cell walls didn"t separate, brown algae rigid cell walls didn"t separate, fungi (happened twice) hyphae stuck together and get nutrients from environment, green plants/algae. Cells get stuck together with stuff like jelly: animals. Diffusion molecules move from high concentration to low concentration because of kinetic energy.
