Cell biology

Signal Transduction Mechanisms 4/12/16 Yeast Can be diploid or haploid If a cell can recognize the presence of another cell nearby it develops a schmoo which allows the cells to mate Cell communication is more complicated in multicellular organisms Multiple potentials before differentiation Communication is crucial Signal transduction moves information from the cell surface to the nucleus & other cellular targets Converts an outside message into a change in cell behavior Signal transduction Extracellular signal is converted to intracellular signals that direct cell behavior Cell communications depends on: Extracellular signal molecules Receptor proteins Intracellular signaling proteins Target proteins What type of molecules can be used as extracellular signals? Proteins

Protein Sorting 3/29/16 Organelles contain sets of proteins that are specific to their functions What is the function of the following organelles, and what types of proteins might be found in them? Nucleus? Transcription - RNA polymerase Transcription - transcription factor Replication - Mitochondria? ATP synthesis - ATP synthase Golgi? Synthesis of most proteins begins on ribosomes in the cytosol Cytosol - everything inside the cell that is not enclosed by membrane How are proteins delivered to the correct location? Signal sequences direct proteins to the correct compartment Short (15-60 aa) sequence in protein, specifies where it should go Inherent sequence coded for in the DNA information EX- NLS: nuclear localization signal Signal sequences function like zip codes!

LIPIDS & MEMBRANE STRUCTURE Lipids differ from the other macromolecules: not formed by linear polymerization however, they do have a high molecular weight they contribute to important cellular structures (membranes) What are they? Heterogeneous category of cellular components that are insoluble in water (hydrophobic) Lipids are typically rich in nonpolar hydrocarbon regions with relatively few polar groups Lipids have 3 main cellular functions: 1. Energy storage (fat to sugar) Lipids have about 6 times more energy than the same weight of a polysaccharide 2. Membrane structure 3. Transmission of chemical signals There are six main classes of lipids (FAMILIARIZE WITH THE FIRST 3) Fatty acids are the building blocks for several other kinds of lipids