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Cells: The Basic Unit of Life The Diversity of Cells section 1 Cell: basic building block of life I. Cells and Cell Theory A. Robert Hooke first person to describe cells in 1665, built a microscope discovered box like structures in cork named them cells- "little rooms" these cells were the outer layer of dead cork cells B. Discovered differences between cells Hooke looked at slices of live plants saw 'juicy' cells Hooke also looked at feathers, fish scales and eyes of houseflies Also continued looking at live plants and fungus Discovered plants and fungus have cell walls made them easy to see Animal cells do not have a cell wall C. Finding Cells in Other Organisms Anton van Leeuwenhoek Dutch merchant In 1673, made his own microscope and looked at pond scum saw small organisms in the water named them animalcules -"little animals" Today we call them protists single celled organisms Leuwenhoek also looked at animal blood fish, birds and frogs= oval blood cells humans and dogs = round blood cells first to look at bacteria discovered yeast is a single cell organism D. Cell Theory almost 200 years passed before scientists concluded all living things have cells Matthias Schleiden plants- said they are made of cells Theodore Schwann studied animals- said they are made of cells Schwann wrote the first two parts of the Cell Theory 1. All organisms are made of cells 2. The cell is the basic unit of life In 1858, Rudolf Virchow, a doctor stated cells could form only from other cells This was added to the cell theory 3. All cells come from existing cells II. Cell Size A. Most cells are too small to see without a microscope 50 cells B. A few large cells largest cell is an yolk of an egg can be this size because it doesn't have to take in more nutrients C. Many small cells There is a physical reason why cells are small Cells take in food and get rid of waste through their outer surface (cell membrane) As a cell grows it needs more food and produces more waste If a cell becomes to big, it cannot take in enough food or pump out enough The area of the cell's surface and its volume limit the size of the cell called the surface area to volume ratio ratio = Surface Area ( outside covering) volume ( whole inside) III. Parts of a cell A. Common parts cells have different shapes and sizes do different functions have parts in common B. Cell Membrane and Cytoplasm all cells are surrounded by a cell membrane protective layer/ acts as barrier separates cell from environment controls materials moving in and out of cell cells also have a fluid fluid and contents are called cytoplasm C. Organelles are structures that perform specific functions within the cell carry out life processes different cells have different organelles most have membranes some float in the cytoplasm; others are attached to the membrane or other organelles D. Genetic Material All cells contain DNA at some point of their life the RBC's ( red blood cells )lose DNA when leaving bone for the blood stream genetic material that carries information needed to make new cells and organisms is passed from parent cells to new cells controls cell activities In some cells DNA is enclosed in an organelle called a nucleus IV. Two Kinds of Cells A. All cells have cell membranes, cytoplasm and DNA B. Two Basic Types of Cells Prokaryotic Cells prokaryotes single cell no nucleus 2 types Eukaryotic Cells eukaryotes V. Prokaryotes: Eubacteria and Archaebacteria A. Eubacteria ( or just bacteria) most common world's smallest cell doesn't have a nucleus DNA is in a long chain No membrane covered organelles does have ribosomes ( tiny organelles made of protein) strong web-like outer wall ( cell wall) protects, give shape, allows nutrients to pass in and out live in soil, water and other organisms B. Archaebacteria not as common similar in many ways single cell have ribosomes have cell membranes has circular DNA lack memebrane covered organelles differences ribosomes look different cell wall and membrane are 3 types of archaebacteria Heat loving Salt loving Methane making Extremeophiles heat loving, salt loving live where conditions are extreme hot springs, very salty water VI. Eukaryotic Cells/ Eukaryotes A. Eukaryote an organism with a nucleus and membrane covered organelles largest cell ( 10x bigger than bacteria) have nucleus with DNA membrane covered organells each has a specific job B. All living things that are not bacteria or achaebacteria are made of eukaryotic cells C. Types of eukaryotes animals plants fungus yeast mushrooms protists algae amoebas D. Multicellular "many cells"