Cell Structure and Function There are two types of cells: Prokaryotes and Eukaryotes Typically cells ranges from 5 to 50 micrometers in diameter, the smallest Mycoplasma bacteria are only 0.2 micrometers across, and even the best light microscopes can barely see so small them. The biggest cell, a giant amoeba Chaos chaos may be 1000 micrometers in diameter, which is large enough to be seen unaided as a tiny speck in pond water. Despite the differences in sizes, ALL cells contain the molecule that carries biological information – DNA. In addition, a thin flexible barrier called a cell membrane surrounds all cells. Cells fall into two broad categories. It all depends on whether they contain a nucleus. The nucleus is a large membrane-enclosed structure that contains the cell’s genetic material in the form of DNA. The nucleus controls many of the cell’s activities. Eukaryotes: Cells that enclose their DNA in nuclei. Generally larger and more complex than prokaryotic cells. Contains dozens of structures and internal membranes. Contains MEMBRANE BOUND ORGANELLES Many are highly specialized. Eukaryotes: o Plants o Animals o Fungi o Protists Cell Organization o What is the role of the cell nucleus? Contains nearly all of the cell’s DNA and, with it, the coded instructions for making proteins and other important molecules. o Can be divided into two major parts: the nucleus and the cytoplasm. Cytoplasm is the fluid portion of the cell outside the nucleus o Contains organelle, “little organs” that perform specialized functions within the cell itself. Living version of a modern factory o Specialized machines and assembly lines of the factory are analogues to the difference organelles of the cell. o Follow instructions and produce products Prokaryotes Cells that do not enclose DNA in nuclei Generally smaller and simpler than eukaryotic cells Prokaryotes grow, reproduce, and respond to their environment, or even swim despite how simple they are! Bacteria are prokaryotes!! DO NOT CONTAIN A NUCLEUS!!!!! Have cytoplasm as well, even though they have no nucleus. Contains organelles just like eukaryotic cells, some are the same; some are different. More to come on that! Contains NO MEMBRANE BOUND ORGANELLES Little known facts about cells: 1) Cells have varying life spans a. Based off of the type and function of the cell b. Anywhere from a few days to a year. Digestive tract cells live only a few days, while the immune system can live up to 6 week. Pancreatic cells can live for as long as a year. 2) Cell commit suicide a. A cell become damaged or undergoes some type of infection, it will self-destruct by a process called apoptosis. It is used to ensure proper development and to keep the body’s natural process of cell division in check. 3) There are more bacterial cells in the body than human cells. a. 95% of all cells are bacteria cells, with the vast majority being in the digestive tract. Use the textbook to work with your lab groups to complete the sketches and question in the Cell Parts Study Guide! Cell Story Project: Create a story with the cell parts and functions. See rubric for details!