Chapter 7 Notes Cell Structure & Function Section 7-1 ~ Life is Cellular A. The Discovery of the Cell (pg.169) 1. Early Microscopes: (Tell Who? What Discovered or Used? When?) a. b. In 1665, an Englishman Robert Hooke used an early compound microscope to look at a thin slice of cork. Used the term cell. In Holland about 1674, Anton van Leewenhoek used a single-lens microscope to observe pond water and found tiny living organisms even in the water he drank. 2. The Cell Theory (pg. 170) ~ a. b. The Cell Theory States: , German botanist Matthias Schleiden Concluded that all plants were made of cells. In 1839, German Theodor Schwann stated all animals were made of cells. In 1855, German Rudolf Virchow concluded that new cells could be produced only from existing cells. All living things are composed of cells. Cells are the basic units of structure & function In living things. New cells are produced from existing cells. B.Exploring the Cell pg (What is the main idea of this passage?) 1. Light Microscopy {How does this work? Advantages & Disadvantages?} Some light microscopes uses laser beams to scan cells for 3 dimensional pictures, produce movies of cells as they grow, divide & develop. Light has limitations with resolution. Microscopes are always improving. Light microscopes use light in order to magnify images. Light Microscopy / black widow spider Light Microscopy / black widow spider eyes Light Microscopy / diatom Light Microscopy / radiolaria x10 Kingdom: Protist Scientific Name: Amoeba proteus Image Courtesy of: Joanne Whallon Image Width: 30 microns Image Technology: Laser Scanning Confocal Kingdom: Fungus Scientific Name: Saccharomyces cereviceae Image Courtesy of: Whallon, Joanne Image Width: 24 microns Image Technology: Laser Scanning Confocal Microscopy Scanning Electron Microscopes (SEMs) {How does this work? Advantages & Disadvantages?} Electon microscopes use a pencil like beam of electrons to view the surface of specimens. Can view details of a specimen 1000 times smaller but the specimen must be in a vacuum and only non-living. Electron micrograph of a mitochondrion in a section from bat pancreas. The mosquito's head is mostly eye. The eyes of most insects are compound eyes, made up of many tiny lenses. Each lens sees a slightly different picture, making up a mosaic of the object it is looking at. This type of vision is very efficient at noticing very slight motions such as another insect trying to sneak up on it Flies use their feet for many purposes. The claws can grab to hold on. The small hairs will adhere to smooth surfaces through surface tension. Other hairs are sensory organs, allowing flies to taste with their feet. Many types of worms have become specialized to live as parasites inside other organisms. This spiny-headed worm uses the spines on its head to attach to the small intestine of a fish. Without a mouth, the worm absorbs nutrients from the fish through its body wall. Diatoms are tiny single celled plants that live inside a hard shell. They occur in great quantities both in salt and fresh water. When the plant dies, the shell sinks to the bottom. Over time, large quantities of these shells accumulate. They can be collected and used as diatomaceous earth in swimming pool filters. The shells allow water to pass through but trap any small dirt particles. This cross section of a fern leaf allows us a view of the inside of its cells. The electron microscope reveals many of the cells' structural details not noticeable with the light microscope. This beautiful vase-like structure is the skeleton of a single-celled organism called a radiolarian. Radiolarians live in large quantities as part of the ocean's plankton. When the radiolarian dies, it's shell sinks to the bottom. After millions of years of radiolarian shells "raining down" on the sea floor, they accumulate in great quantities. Much of the sea floor of the deep oceans are covered in this radiolarian "ooze". SEM ~ Insect antenna SEM ~ Bee head SEM ~ Bee Face SEM ~ dragonfly head SEM ~ plant pollen SEM ~ stem SEM~ wood SEM~ Leaf SEM ~ Tick (parasite) 3. Transmission Electron Microscopes (TEMs {How does this work? Advantages & Disadvantages?} Electrons are used to view objects. Scientists must first cut samples into ultra thin slices for electrons to pass through. Therefore only non-living specimens may be used. TEM images- Cells / cultured cells TEM images- Cells / freeze etch yeast TEM images- Cells / mitochondria TEM images- Cells / muscle l.s TEM images- Cells / nerve cell bundle TEM images- Plant cells / root cell Scanning Probe Microscopes In the 1990s a microscope that traces the surface of samples with a probe was perfected. Now we can observe single atoms. They can operate in ordinary air & in solutions. C. Prokaryotes & Eukaryotes pg OrganismDefinitionDescriptionActivities ProkaryoteGenetic material that is NOT contained in a nucleus. Smaller & less complex than eukaryotic cells. Grow, reproduce, respond & sometimes move EukaryoteContain a nucleus in which their genetic material is separated from the rest of the cell Larger & more complex with dozens of structures & membranes. Great Variety & carry out activities associated with living things. Difference between Prokayote & Eukaryotes is that Prokaryotes do NOT have a nucleus & Eukaryotes DO III. 7-3 Cell Boundaries pg. 182 ~All cells are surrounded by a thin, flexible barrier known as a cell membrane ~Many cells also produce a strong supporting layer around the membrane known as a cell wall. A. Cell Membrane 1. Regulates what enters & leaves the cell 2. Provides protection & support 3.Composed of a double-layered sheet called a lipid bilayer & contains protein molecules with carbohydrate molecules attached. 4. These proteins form channels and pumps that help to move material across the cell membrane. Many of the carbohydrates act like chemical identification cards that allows cells to identify one another. Why would cells need to identify each other? B. Cell Walls pg Present in many organisms, including plants, algae, fungi & many prokaryotes. 2. Lie outside the cell membrane & made of cellulose; a tough carbohydrate fiber 3. The main function is to provide support & protection for the cell 4. Made from fibers of carbohydrate & protein that are produced from within the cell. C. Diffusion Through Cell Boundaries One of the most important functions is to regulate the movement of dissolved molecules from the liquid on one side of the membrane to the liquid on the other side. 2. Diffusion is the process of particles moving from an area where they are more concentrated to an area where they are less concentrated. When the concentration of the solute is the same throughout a solution = equilibrium. (Because diffusion depends upon random particle movements, substances diffuse across membranes without requiring the cell to use energy. ) D. Osmosis is the diffusion of water through a selectively permeable membrane pg How Osmosis Works - Water will move from where it is more concentrated to where it is less concentrated until equilibrium is reached. When equilibrium = isotonic In the beginning, more concentration sugar side = hypertonic (above strength) The diluted or less sugar concentration side = hypotonic (below strength) 2. Osmotic Pressure is the pressure on the hypertonic side of a membrane What will happen? Why? What do you NOW know about the selectively permeable membrane? E. Facilitated Diffusion ( pg. 187) Facilitate = HELP 1. Happens when a cell membranes protein channel helps the diffusion of particles across. Occurs when a molecule that seems too large to pass through a cell membrane is able to get across. 2. Example: Red blood cells have an internal channel that allows glucose to pass through. 3. A net movement of molecules across a cell membrane will occur only if there is a higher concentration of that particular molecule on one side than on the other side. This movement does not require energy FROM THE CELL. F. Active Transport pg. 188 when a cell moves, materials against a concentration in the opposite direction & requires energy & carrier proteins within the membrane. 1. Molecular Transport is when small molecules and ions are carried across the membrane by protein pumps; used to move calcium, potassium & sodium ions. A considerable amount of our daily energy is devoted to this active transport. 2. Endocytosis & Exocytosis A. Endocytosis is the process of taking materials into the cell by means of infoldings or pockets of cell membrane which breaks loose and forms a vacuole. Phagocytosis is cell eating and when food is taken into a vacuole. Pinocytosis is cell drinking when liquids are taken into the cell within a vacuole B. Exocytosis is the release of large amounts of materials from the cell by vacuole fusing to the cell membrane and forcing the contents out of the cell. C. The removal of water by means of a contractile vacuole is one example of exocytosis. For example, this electron micrograph is showing the process of exocytosis.exocytosis The process begins by fusion of the membranes at the peripheral pole of the granule. Then an opening is created which widens to look like an omicron figure. This opening allows the granular material to be released. The membrane is now part of the plasma membrane and any proteins carried with it can be incorporated into the plasma membrane. Exocytosis Endocytosis IV.7-4 The Diversity of Cellular Life The diversity of life is so great that you might have to remind yourself that all living things are: ~composed of cells ~use the same basic chemistry ~follow the same genetic code ~contain the same kinds of organelles A. Unicellular Organisms pg Also called single celled 2. They grow, respond to the environment, transform energy & reproduce. 3. In terms of their numbers, unicellular organisms dominate life of Earth. Bacteria Cell Scanning electron micrograph of the common soil bacteria Pseudomonas aeruginosa. These bacteria are actively motile in aqueous environments. The one-celled organism amoeba proteus Volvox Algae B. Multicellular Organisms pg Multi Cellular means many celled and there is great variety among these organisms. 2. All depend on communication & cooperation among specialized cells cells created for a particular function 3.Specialized Animal Cells Red blood cells transport oxygen throughout the body Pancreatic cells produce compounds such as insulin that the body needs. Muscle cells - contract & relax to move parts of the body 4. Specialized Plant Cells Guard cells control the opening & closing of stomata on the underside of leaves. These cells come off the stratified squamous epithelial tissue on the inner surface of the cheek. These cells show the irregular, flat shape characteristic of typical "squamous cells." The nucleus (A) is centrally located, the cell membrane (C) is very thin, and the cell is filled with cytoplasm (B). A human red blood cell The villi of the small intestine are lined by a single layer of columnar cells (A) thus the name simple columnar epithelium. Note these cells are not as wide as they are tall with the darkly stained nuclei (B) located at the base of the cells. The cell membranes (C) are very thin but easily identified. Locations: lining most of the digestive tract Function: protection, secretion and absorption C. Levels of Organization are individual cells, tissues, organs, & organ systems. 1. Tissues Similar cells grouped into units & these cells perform a particular function. Ex: A collection of cells that produce digestive Enzymes in the pancreas make up one kind of tissue Most animals have 4 main types of tissue: muscle, epithelial, nervous & connective 2. Organs Many groups of tissues working together form an organ. Each muscle in your body is an individual organ because within your muscle there is much more than muscle tissuenerves tissues and connective tissues are there also. 3. Organ Systems A group of organs working together to perform a specific function Ex: Circulatory system, reproductive system, digestive system