Larry M. Frolich, Ph.D. Biology Department, Yavapai College Cell Structure and Function Cells as fundamental living unitCells as fundamental living unit Prokaryotic and Eukaryotic CellsProkaryotic and Eukaryotic Cells Cell MembranesCell Membranes Protein synthesis (quick overview)Protein synthesis (quick overview) Organelles and parts of a cellOrganelles and parts of a cell

Larry M. Frolich, Ph.D. Biology Department, Yavapai College What is Life? Life needs energy Life reproduces Life grows and develops Life maintains a stable condition— homeostasis Life responds to stimulus Life is organized because it has evolved

Larry M. Frolich, Ph.D. Biology Department, Yavapai College Life Evolves Life is organized hierarchically Evolution explains organization at every level of hierarchy All living organisms or species can be understood at every level of hierarchy All current living species (including humans) have evolved and are evolving

Larry M. Frolich, Ph.D. Biology Department, Yavapai College Cells are the basic and fundamental unit of life The first life was cellular life The Molecules of Life are what cells and all their internal parts are made up of Cells are fundamental unit of life

Larry M. Frolich, Ph.D. Biology Department, Yavapai College Two types of cells Prokaryotic cells –Relatively Simple –Relatively Small –No organelles with Molecules of Life distributed throughout cytoplasm –Bacteria are all prokaryotic cells Eukaryotic cells –More complex –Much bigger (100 x size of prokaryotic cells) –Internally organized with membrane-bound organelles –Multi-cellular organisms, like plants and animals, are all made up of eukaryotic cells

Larry M. Frolich, Ph.D. Biology Department, Yavapai College Eukaryotic cell

Larry M. Frolich, Ph.D. Biology Department, Yavapai College Endosymbiotic origin of mitochondria and chloroplasts Eukaryotic cells evolved from fusion or integration of prokaryotic cells Best evidence is in bacterial or prokaryotic appearance of mitochondria and chloroplasts These organelles are like little bacterial cells within our cells, now fully functionally integrated They perform fundamental cell functions. Mitochondria process sugars to produce energy; chloroplasts make sugars by photosynthesis But they maintain their own DNA and genetic control

Larry M. Frolich, Ph.D. Biology Department, Yavapai College Prokaryotic cells have: Cell membrane DNA molecule loose in cytoplasm Small Ribosomes where proteins are assembled from DNA information Microtubule structures like flagella and cilia Mitochondria and chloroplasts share most of these features, including their own independent DNA

Larry M. Frolich, Ph.D. Biology Department, Yavapai College WHAT EUKARYOTIC CELLS HAVE: Cell membrane Nucleus Mitochondria (and sometimes chloroplasts for photosynthesis) Larger ribosomes for protein assembly from DNA information Internal membranes that organize cellular spaces and distribution of Molecules of Life within cell (“cytoskeleton”) Eukaryotic cells (like our human cells) have:

Larry M. Frolich, Ph.D. Biology Department, Yavapai College WHAT CAN EUKARYOTIC CELLS DO? WHAT STRUCTURES ARE INVOLVED? Separate inside of cell from external environment and control what substances pass across membrane Cell Membrane Produce proteins/enzymes that catalyze chemical reactions or control movement across membrane Nucleus (DNA), Ribosomes on rough endoplasmic reticulum Break down sugars to form energy which is stored in phosphate bonds of ATP Mitochondria Organize distribution of Molecules of Life (macromolecules) and ions throughout cell Internal membrane system and “cytoskeleton” (ER, lysosomes, vessicles, microtubules) MoveFlagella, cilia, pseudopods

Larry M. Frolich, Ph.D. Biology Department, Yavapai College A cell membrane or plasma membrane separates cell from outside world—creates ability to regulate internal environment (homeostasis)

Larry M. Frolich, Ph.D. Biology Department, Yavapai College cell membrane

Larry M. Frolich, Ph.D. Biology Department, Yavapai College What are some characteristics of the plasma membrane? It is a phospholipid bilayer It is embedded with proteins that move in space It contains cholesterol for support It contains carbohydrates on proteins and lipids Selectively permeable cell membrane

Larry M. Frolich, Ph.D. Biology Department, Yavapai College What does selectively permeable mean? The membrane allows some things in while keeping other substances out cell membrane

Larry M. Frolich, Ph.D. Biology Department, Yavapai College How do things move across the plasma membrane? 1. Diffusion 2. Osmosis 3. Facilitated transport 4. Active transport 5. Endocytosis and exocytosis cell membrane

Larry M. Frolich, Ph.D. Biology Department, Yavapai College What are diffusion and osmosis? 1. Diffusion is the random movement of molecules from a higher concentration to a lower concentration 2. Osmosis is the diffusion of water molecules cell membrane

Larry M. Frolich, Ph.D. Biology Department, Yavapai College How does tonicity change a cell? Hypertonic solutions have more solute than the inside of the cell and lead to lysis (bursting) Hypotonic solutions have less solute than the inside of the cell and lead to crenation (shriveling) Isotonic solutions have equal amounts of solute inside and outside the cell and thus does not affect the cell cell membrane

Larry M. Frolich, Ph.D. Biology Department, Yavapai College What are facilitated diffusion and active transport? 3. Facilitated transport is the transport of molecules across the plasma membrane from higher concentration to lower concentration via a protein carrier 4. Active transport is the movement of molecules from a lower to higher concentration using ATP as energy; requires a protein carrier cell membrane

Larry M. Frolich, Ph.D. Biology Department, Yavapai College What are endocytosis and exocytosis? 5. Endocytosis transports molecules or cells into the cell via invagination of the plasma membrane to form a vesicle 6. Exocytosis transports molecules outside the cell via fusion of a vesicle with the plasma membrane cell membrane