BISC 1112 Lecture Notes - Lecture 1: Euglenozoa, Rhizaria, Vacuole
Document Summary
Carry out all of their functions using eukaryote cell organelles. As body increases in size, the ratio of surface area to volume increases. Volume increases by body length x3 and surface area increases by body length x2: as volume increases, diffusion of waste, gases, and mrna from the center of the cell to the surface becomes more difficult. Contractile vacuoles: osmotic regulation: vacuoles periodically fill with water that is then expelled, function primarily in osmoregulation. Nutrition: 1) photoautotrophs- contain chloroplasts, 2) heterotrophs- absorb organic molecules or ingest larger food particles. Food vacuoles are formed through specialized structure called a cytosome: 3) mixotrophs- combine photosynthesis and heterotrophic nutrition. Digestion: enzymes secreted into food vacuole, food is digested and nutrients transported into cytoplasm, undigested material is secreted out of the cell. Sensation: photosynthetic protists typically show positive taxis to low or moderate light intensities. Secretion- cysts walls: protect against harsh conditions. Reproduction: asexual- through cell division (mitosis)
