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Transcript
Cells Light Microscopes Lenses bend light, magnifying and focusing the image. Anton Van Leeuwenhoek Simple Microscope: has one lens Example: magnifying glass Compound Microscope: has more than one lens Example: modern microscope can magnify 400X Microscopes Electron microscopes Electron microscopes use a beam of electrons to create the image. The beam of electrons is focused by a magnetic field. Magnification is up to one million times and the specimen is usually dead. Scanning Electron Microscope (SEM) -electron beam scans surface -gives a picture of the outside Transmission Electron Microscopes (TEM) -electron beams pass through the specimen -gives a cross section view Types of Microscopy Light Microscopy Human Cheek Cell Electron Microscopy Plant Root Cell Scanning Electron Microscopy White Blood Cell With fluorescent dyes. SEM Nerve Cell SEM Skin Cell http://learn.genetics.utah.edu/content/begin/ cells/scale/ http://www.cellsalive.com/howbig_js.htm Cell Size 0.2 micrometers Mycoplasma bacteria Average 5-50 micrometers 10 centimeters Ostrich Egg Cells are either simple prokaryotes or complex eukaryotes. Prokaryote or Eukaryote? Prokaryote Small Simple No nucleus, no organelles Eukaryote Large Complex internal structures (organelles) Nucleus Who is a prokaryote? Who is a eukaryote? BACTERIA Protists Fungi Plants Animals (humans too!) Types of Eukaryotic Cells Plant Cell Animal Cell Protozoa Cell (paramecium) The Discovery of the Microscope Lead To the Discovery of Cells History *Anton von Leewenhoek discovered the microscope *Robert Hooke discovered cells and named them Further Discoveries: Matthias Schleiden- All plants are made of cells. Theodor Schwann- All animals are made of cells. Rudolf Virchow- All cells come from existing cells. Cell Theory 1) All living things are made up of cells. 2) Cells are the basic unit of structure and function in living things. 3) New cells are produced from existing cells. Structures Found in All Cells Cell membrane Genetic material Cytoplasm Ribosomes Cell Membrane Made of phospholipids and proteins. Functions : 1. Regulates what enters and leaves the cell. selectively permeable 2. Support 3. Protection Phospholipid Attracted To Water Repelled By Water Phospholipid Bilayer Phosphate “heads” are attracted to water (hydrophilic). They are oriented to the OUTSIDE of the cell membrane bilayer. Fatty acid “tails” are repelled by water (hydrophobic). They move to the INSIDE of the cell membrane bilayer. Cell membrane: -all cells have this structure -made of lipid bilayer -embedded proteins (act as channels & pumps) The Fluid Mosaic Model Various macromolecules “float” in the lipid bilayer forming a “mosaic”. Cytoplasm Found in all cells. Clear, thick watery material. Provides support for the cell contents. cytoplasm Ribosomes a. Function: make proteins b. Structure: composed of protein and rRNA c. Found in 2 places in the cell -in the cytoplasm -rough ER. Surrounds the cell membrane Nucleus (found only in eukaryotic cells) Functions: 1. Cell control 2. Stores genetic material -nuclear envelope -genetic material -nucleolus Mitochondria Function : Breaks down sugar to release energy (ATP) Structure: Two membranes. The inner membrane is folded. Interesting Facts: The mitochondria has its own chromosome. Chloroplast Function: Photosynthesis, converts energy from the sun into chemical energy (sugar) Structure: two outer membranes thylakoids Interesting Fact: The chloroplast has its own chromosome. Endoplasmic Reticulum Functions: site of protein and lipid synthesis Structure: made of folded membranes, network of tubes Smooth ER (SER): NO ribosomes, makes lipids Rough ER (RER): ribosomes, makes proteins Golgi Apparatus Structure: stacks of membrane sacs Function: -processes and packages proteins and lipid made in the ER -sends them to their proper location Vacuoles Function: Store food, water and wastes Structure: Fluid filled membrane sacs Animal Cell Many small vacuoles Plant Cell One large vacuole Lysosomes Found only in animal cells. Function: Break down food and old cell parts Structure: Small, round membrane sacs with digestive enzymes. How did the first eukaryotes evolve? Or Where did organelles come from? Eukaryotic Cells evolved from a combination of different prokaryotic cells. The Endosymbiotic Theory Endosymbiosis – One organism engulfs another but does not digest it. Instead, they work together. Mitochondria, chloroplasts originated through endosymbiosis. These organelles started as free-living bacteria that were taken inside another prokaryotic cell. Mitochondria developed from proteobacteria and chloroplasts from cyanobacteria. Eukaryotic cells evolved from a combination of different prokaryotic cells. http://highered.mcgrawhill.com/sites/9834092339/student_view0/chapter4/ animation_-_endosymbiosis.html Evidence for the Endosymbiotic Theory 1) Mitochondria and chloroplasts have their own DNA. 2) These organelles have two outer membranes. 3) These organelles are the same size as the prokaryotes from which they originated. Path Of A New Protein Inside the Cell