Lecture 1

Question 1

cell signaling

Answer 1

• commuication that governs cell activity (coordinates cell fxn and interactions between cells)
• living cells continuously communicate through chemical cues
• cells send signals to others and interpret signals received from others and environment

Question 2

evolutionary relatedness

Answer 2

• same small set of signaling mechanisms found in diver species and processes

Question 3

evolution of cell signals

Answer 3

• eg: saccharomyces cerevisiae (yeast)
• mating factors: chemical messengers
  – exchange of mating factors (binding a-b and b-a)
  – mating (change shape, grow, fuse)
  – new ab cell (all genes of original, cell division)
• signal transduction pathways (series of steps which signal on cell’s surface converted to specific cellular response)

Question 4

last common ancestor

Answer 4

• 1 billion years ago
• same small set of signaling mechanisms found in diverse species
• inference: early versions of cell-signalling mechanisms evolved long before first mulitcellular organisms
• ancestral signalling mol. evolved in prokaryotes and single-celled eukaryotes (adopted for new uses in mulitcellular descendents)

Question 5

signalling in microbial worls

Answer 5

• critical among prokaryotes (facilitates various processes)
• bacteria secrete signaling molecules
• conc. of SM allow bacteria to sense population density (quorum sensing)
• signaling can coordinate activities of bacterial cells
• multicellular:
  – local signaling (between cells in direct contact)
  – local regulators (mol. travel short distances between cells

Question 6

forms of chemical signaling

Answer 6

• autocrine: cell targets itself
• across gap junctions: cell targets a cell connected by gap junction
• paracrine: cell targets nearby cell
• endocrine: cell targets distant cell through bloodstream

Question 7

long-distace signaling

Answer 7

• hormones (plants/animals)
  – plants mostly through air (gas), sometimes vessels
  – animals: endocrine signalling
• specialised cells release hormones traviling via circulatory system
• only specific receptor to signal can respond

Question 8

three stages of cell signalling

Answer 8

• reception
  – receptors bind to ligand
• transduction
  – receptor protein changes
  – activates intracellular molecules
• cell response
  – responds to signal