Ch 7 Inside the Cell 01 31 2012 Plasma membrane structure common to every cell creates internal environment that differs from conditions outside the cell Prokaryotic Bacteria and Archaea 10x smaller than eukaryotes Chromosome o Most prominent structure o Single circular consists of large DNA molecule associated with a small number of proteins contains genes o DNA is in super coiled structure o Nucleoid found in center of cell genetic material is not seperated o Plasmids super coiled DNA outside chromosome contains genes Ribosomes o Cell interior o Consists of RNA molecules and proteins Extensive Internal Membranes o Preform photosynthesis Organelles o Membrane bound compartment o Contain enzymes and pigment molecules required for photosynthesis to occur o Contains enzymes or structures specialized for a specific function o Long thin fibers that serve a structural role in the cell o Research still occurring as to whether they play a role in the cell or not Cytoskeleton Plasma Membrane one side o Consists of phospholipid bilayer and proteins that span the bilayer or attach to o Cytoplasm contents of the cell o Creates internal environment that is distinct from the outside nonliving o Allows the passage of compounds required for life prohibit entry of dangerous environment material Flagella flagellum o Rotation allows aquatic cells to swim through the water o Located on the surface of the cell o Over 40 different proteins involved in building and controlling Cell wall o Tough fibrous layer that surrounds the plasma membrane o Resists pressure from cell expansion o Protects organism and gives it shape rigidity Eukaryotic Have membrane bound nucleus Eukarya Many are unicellular Larger than prokaryotes compartment organelle o 2 key advantages Specific chemicals required for specific chemical reactions are located within a given incompatible chemical reactions can be separated chemical reactions become more efficient Nucleus shape o Contains chromosomes and functions an info storage and processing center o Enclosed by nuclear envelope complex double membrane o Nuclear lamina pore like openings stiffens the structure and maintains its o Nucleolus where RNA molecules found in ribosomes are manufactured and the large and small ribosomal subunits are assembled Rough Endoplasmic Reticulum o Knobby looking structures are ribosomes that attach to the membrane o Lumen the interior of the rough ER o Protein manufacturing center Smooth Endoplasmic Reticulum o Parts of ER that are free of ribosomes o Contains enzymes that catalyze reactions involving lipids o Manufacturing site for phospholipids used in plasma membranes Golgi apparatus o Products of rough ER pass through Golgi apparatus before they reach final o Consists of flattened membranous sacs called cisternae which are stacked on destination top of one another o Cis side is closed to rough ER receives products from rough ER o Trans side is oriented toward plasma membrane ships them out toward cells structure Ribosomes o Cytosol fluid portion of cytoplasm o Complex molecular machines that manufacture proteins o Not surrounded by a membrane Peroxisomes o Globular organelles o Single membrane o Originate as buds from the ER o Centers for oxidation reactions energy for the cell reactions possible Lysosome o Function as digestive centers o Glyoxysomes in plant leaves oxidize fat to form a compound that can store o The enzymes found in the peroxisome make a specialized set of oxidation o Interior lumen is acidic because proton pumps in the lysosome membrane import enough hydrogen ions to maintain a pH of 5 0 o Autophagy damaged organelles are surrounded by a membrane and delivered into a lysosome o Phagocytosis plasma membrane of a cell surrounds a smaller cell or food particle and engulfs it forming a structure called a phagosome o Receptor mediated endocytosis macromolecules outside cell bind to membrane proteins that act as receptors o Endocytosis refers to any pinching off the plasma membrane that results in the uptake of material from outside the cell o Pinocytosis brings fluid into the cytoplasm via tiny vesicles that form from in foldings of the plasma membrane Vacuoles o Large 80 of the cells volume o most act as storage deposit o stored material is water or K and Cl Mitochondria o Produces ATP o Cristae inner membrane is connected to these sac like structures o Mitochondrial matrix solution inside the inner membrane o Manufacture their own ribosomes Chloroplasts o Plant cells o Where sunlight is converted to chemical energy during photosynthesis o Double membrane around exterior o Thylakoids membrane bound flattened vesicles o Grana thylakoids stacked like pancakes into piles o Stroma outside thylakoids in the region certain critical enzymes and substrates are here The cell wall o Plants fungi algae o Outside the plasma membrane o Furnishes the stiff outer layer that provides structural support for the cell o Lignin some plants have secondary cell wall Cytoskeleton o Extensive system of protein fibers o Gives the cell its shape and structural stability o Cytoskeleton proteins are involved in moving materials within the cell 01 31 2012 01 31 2012