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What is this The Compound Light Microscope can produce magnifications of 50X to 500X Electron Microscope Uses a beam of electrons Magnifying powers in excess of 100,000X Specimens must be dead or non-living Robert Hooke (1665) British scientist used a microscope to study a thin slice of cork from the bark of an oak tree named the box-like structures “cells” saw only dead cells Anton van Leeuwenhoek (1600s) Dutch businessman; his single-lens microscope magnified objects 200X and allowed him to see tiny organisms in a drop of water (animalcules) Robert Brown (1831) Scottish botanist; used newly developed stains; first to describe the cell nucleus Matthias Schleiden (1838) German botanist; concluded that all plants are made up of cells Theodor Schwann (1839) German scientist; concluded that all animals are made up of cells Rudolf Virchow (1855) German physician; studied cell reproduction “Where a cell exists, there must have been a preexisting cell…” Cell Theory Cell Theory Song Cell Theory 1. All living things are made up of cells 2. Cells are the basic units of structure and function in living things 3. All cells arise from preexisting cells The Cell The Cell Intro Video Two Main Types of Cells Eukaryotic cells Found in plants, fungi, animals and Protists 1. Have a true nucleus containing chromosomes 2. Contain several membrane bound organelles 3. Cells are 10-100 um in length (1 mm = 1,000 um) Two Main Types of Cells Prokaryotic cells - Ex: Bacteria - 1/10th the size of eukaryotic cells - No nucleus - Cell Wall – (Peptidoglycan) Prokaryotic cell Why are Cells Small The Volume of a cell determines the amount of metabolic activity it carries out The Surface Area of the cell determines the amount of substances that are carried into the cell and the amount of waste removed from the cell Why are Cells Small As a cell gets bigger the volume increases compared to the surface area. At some point the cell won’t be able to function Parts of the Eukaryotic Cell Nucleus Nuclear Membrane/ Nuclear Pore Chromatin Nucleolus Riibosomes Rough Endoplasmic Reticulum Cell Membrane Lysosome Smooth Endoplasmic Reticulum Centrioles Mitochondria Golgi Body Cell Organelles “little organs” specialized parts of the cell which carry out specific life functions Inside the Cell 1. Plasma Membrane ( Cell Membrane ) separates cell from surrounding environment controls the movement of molecules into or out of the cell selectively permeable (semi-permeable) visible with the compound microscope The Cell Membrane Structure Fluid Mosaic Model Phospholipid Bilayer Made up of two layers of phospholipids Flexible structure with freely moving pieces Composed mainly of lipids and proteins phospholipid Phospholipid bilayer Polar heads: hydrophilic (water-loving); in contact with cytoplasm/extracellular fluid Non-polar tails: hydrophobic (water-hating); interior of membrane Phospholipid Bilayer Fluid Mosaic Model of Membrane Structure Integral proteins: are proteins extend through the membrane or are found on the outer/inner surface (transport proteins) Fluid Mosaic Model of Membrane Structure Peripheral Proteins are on the outer/inner surface of membrane They act as receptors and they attract substances to cell membrane and aide in communication with other cells. Fluid Mosaic Model of Membrane Structure Carbohydrates are on the outer surface for cell communication Cholesterol is imbedded in the bilayer to give the membrane additional support Cell Membrane Fluid Mosaic Model of Membrane Structure fluid mosaic model animation 2. Cytoplasm watery material within the cell membrane suspends organelles site of chemical reactions supported by a cytoskeleton: fibers that controls movement of cell or of its internal parts 3. Nucleus contains DNA on structures called chromosomes surrounded by a nuclear membrane that has pores (selectively permeable) visible under the compound light microscope Nucleus 4. Nucleolus located within the nucleus site of ribosome synthesis In notebook: Sketch and label the Nucleus, Cytoplasm and Cell Membrane of these three cells _____________________________________________________________________ Red Blood Cells Cheek Cell Brain Cell 5. Ribosomes site of protein synthesis some ribosomes are found in the cytoplasm other ribosomes are attached to the outside of an organelle called the endoplasmic reticulum (ER) The Endomembrane System Includes the: 1. Endoplasmic reticulum 2. Golgi apparatus 3. Lysosomes 4.Vacuoles 6. Endoplasmic Reticulum network of channels for carrying substances from one part of the cell to another usually found near the nucleus There are two types of endoplasmic reticulum (ER) Rough ER is dotted with ribosomes There are two types of endoplasmic reticulum (ER) smooth ER lacks ribosomes involved in synthesis of lipids metabolism of carbohydrates detoxification of drugs and other poisons 7. Golgi apparatus 8. Golgi apparatus stacks of membranes forming flattened sacs process, package, store cell products to be secreted (transported out of the cell) Ribosomes ►RER ►SER ►Golgi ► Vacuole ► cell membrane ►release from cell Golgi apparatus animation Endomembrane system animation Exocytosis – release of a substance outside of the cell membrane by the fusion of a vacuole 9. Lysosomes sac of digestive enzymes digest organic molecules, worn-out cell structures, harmful bacteria 10. Vacuoles variety of functions: 1) food vacuoles 2) contractile vacuoles in freshwater protists pump out excess water (In action) 3) plant cells have a large central vacuole for water and nutrient storage 4) Vesicle – A tiny vacuole 11. Mitochondria “powerhouse of the cell” site of cellular aerobic respiration: glucose + oxygen is converted to energy in the form of ATP each cell contains between 300-800 mitochondria depending on activity level has a double membrane inner membrane has many foldings = cristae Mitochondria although most of a cell's DNA is contained in the cell nucleus, mitochondria also have their own DNA (maternal) Endosymbiotic Theory mitochondria are descended from independent prokaryotes that were engulfed by other cells but not digested the mitochondria gave the cell that engulfed it a selective advantage over other cells Endosymbiotic Theory 12. Centrioles/Centrosome small bundle of microtubules found in pairs near cell nucleus A pair is called is called a Centrosome involved in cell division found in animal cells but not plant cells Plant Cells DO NOT have Centrioles Have Chloroplasts Have Cell Wall – Cellulose Have Large Central Vacuole 13. Plastids Found ONLY in plants and algae Double Membrane Three types: 1. Chloroplast – Green and site of Photosynthesis (See Next two slides) 2. Leucoplast – Colorless and store starch – mainly found in roots 3. Chromoplast – Carotenoid pigments: Responsible for red color in carrots and other plants Chloroplasts contain chlorophyll, a green pigment that absorbs light to start photosynthesis Chloroplasts Chloroplasts contain their own DNA chloroplasts are also part of the endosymbiotic theory 14. Cell Wall found in plant cells only made of cellulose provides protection & structure for the cell; prevents expansion 15. Cytoskeleton a network of fibers extending throughout the cytoplasm is made up of microtubules and microfilaments functions: mechanical support, maintains shape, allows for movement Microfilaments are made up of a protein called actin. They help support the shape of the cell and movement of the cell The cytoskeleton can change the shape of a cell – This allows cells like amoebae to move Video Figure 4.19B Microtubules are thick hollow tubes of protein that make up Cilia, Flagella and Spindle Fibers Cilia and Flagella Cilia and Flagella are motile appendages that help the cell move Flagella propel the cell in a whip like motion • Cilia move in a coordinated back-andforth motion Figure 4.20A, B Spindle Fibers Centrioles lie near the nucleus Help produce Spindle Fibers that help in cell division Microtubule Arrangement Centrioles and Spindle Fibers: ( 9 Triplets) Consists in 9 Triplets of microtubules arranged in a circle Microtubule Arrangement Cilia and Flagella: ( 9 + 2 ) Consists in 9 Pairs of microtubules around 2 single microtubule Electron Micrograph of the Cytoskeleton