Plant Cell Biology PDF

MODULE 2: PLANT CELL Spontaneous generation Theory -​ Living organisms originate from inanimate objects Robert Hooke (1965) ​ Observed cell in cork ​ Coined the term “cells” Antonie Van Leeuwenhoek (1673) ​ Observed living cells ​ Father of Microscopy Robert Brown (1827-1833) ​ Coi...

MODULE 2: PLANT CELL Spontaneous generation Theory -​ Living organisms originate from inanimate objects Robert Hooke (1965) ​ Observed cell in cork ​ Coined the term “cells” Antonie Van Leeuwenhoek (1673) ​ Observed living cells ​ Father of Microscopy Robert Brown (1827-1833) ​ Coined the term “nucleus” ​ Brownian motion Matthias Schleiden (1838) ​ Botanist who concluded all plants are made of cells Theodor Schwann (1839) ​ Zoologist who concluded all animals are made of cells Rudolph Virchow (1855) ​ Said, “All cells come from pre-existing cells -​ Cells are so small they can efficiently exchange materials with their environment -​ Surface area decreases as size of sell increases (limits cell size) Visible light microscopy Bright Field Microscopy​ ​ ​ ​ -​ Visible light transmitted through specimen -​ Use compound light microscope -​ Multipurpose use Dark Field Microscopy -​ Visible light reflected through sides of specimen -​ Use compound light microscope with “stop” on condenser -​ View shape and movement of cells Phase-contrast Microscopy -​ Light patterns moving through denser Regions of cell transformed into a Density map  -​ Used to visualize ​ Internal structures -​ Endospores -​ Granules -​ Organelles ​ External Structures -​ Cilia Differential interference contrast microscopy -​ Two beams of light -​ Two prisms -​ Colored -​ 3D Ultraviolet Microscopy Fluorescence Microscopy -​ Fluorescent dyes attach to Specific cell structures ​ DAPI ​ Fluorescein ​ Texas-red -​ View internal/external structures Of cells and viruses -​ View interactions of cell biomolecules in 2D Confocal Microscopy -​ Fluorescent dyes attach to Specific cell structures -​ View internal/external structures Of cells and viruses -​ View interactions of cell biomolecules in 2D or 3D The Cell Theory 1.​ All living things are composed of 1 or more cells 2.​ Cells are the basic units of structure and function in an organism 3.​ Cells come only from pre-existing cells Modern Cell Biology ​ Energy flows within cells ​ Heredity information is passed from cell to cell ​ All cells have the same basic chemical composition in organisms of the same species Cell types Prokaryotes -​ Simple cells that do not have internal membranes -​ Comes from greek word (pro) “before” and (karyon) “nut or kernel” Eukaryotes -​ More complex cells that do have internal, membrane bound structures *The common features between Prokaryotic cells and Eukaryotic cells are 1.​ DNA - the genetic material located in a nonmembrane bound nucleoid region in prokaryotes and a membrane-bound nucleus in eukaryotes 2.​ Plasma membrane - a phospholipid bilayer with proteins that separates the cell from the surrounding environment and acts as a barrier for the import and export of materials  3.​ Cytoplasm - the rest of the material of the cell withing the plasma membrane, excluding the nucleoid region or nucleus, the consists of a fluid portion called the cytosol and the organelles and other particles suspended by it 4.​ Ribosomes - the organelles in which protein synthesis takes place Organelles ​ Cellular machinery ​ Two general kinds -​ Derived from membranes -​ Bacteria-like organelles Symbiogenesis/Endosymbiotic Theory 1.​ Grow in size and develop infoldings. 2.​ Infoldings pinch off forming endomembrane system and enclosing the nucleoid → eukaryote. 3.​ Aerobic proteobacteria becomes endosymbiont or a cell living inside another cell. 4.​ Proteobacterium becomes mitochondria → cellular respiration. 5.​ Another endosymbiont like cyanobacteria, became chloroplasts → photosynthesis. Evidences for the Endosymbiotic Hypothesis Mitochondria and Chloroplasts 1.​ Similar to bacteria in both size and structure. 2.​ Bounded by a double membrane – the outer membrane may represent the engulfing vesicle, and the inner membrane from the prokaryote. 3.​ Each contains circular DNA and divides by splitting. 4.​ Have their own ribosomes and produce some proteins like prokaryotes. 5.​ Have RNA base sequences suggesting a prokaryotic origin. Function categories of Cell Structures ​ Manufacturing ​ Breakdown ​ Energy Processing ​ Support, movement, and communication between cells PARTS OF THE PLANT CELL Nucleus -​ Cellular organelle that contains the DNA -​ Control center of the cell -​ Contains the nucleuolus -​ Separated from the cytoplasm by nuclear membrane Plastid -​ Group of membrane bound organelles occuring in photosynthetic eukaryotic cells -​ Chloroplasts (green, site of photosynthesis) -​ Leucoplasts (colorless, storage of starch or oil) -​ Chromoplast (colored or pigmented, produce pigments that contribute to the color of fruits) Mitochondrion -​ An intracellular organelle that is associated with Cellular Respiration Ribosome -​ cellular organelle for protein synthesis Endoplasmic Reticulum (ER) -​ Smooth type: Lacks ribosomes -​ Rought type: ribosombes embedded in the surface Golgi body -​ Modifies, packages, and sorts proteins that will be secreted or sent to the plasma membrane or other organelles Vacuole -​ A large fluid-filled, membrane bound sac withing the cytoplasm that contains a solution of salts, ions, pigments, and waste materials Cytoskeleteon -​ Maintains the cell’s shape -​ Involved in cellular movement -​ Composed of microtubules and microfilaments Cell wall -​ Comparitively rigid supporting wall exterior to the plasma membrane in plant, fungi, prokaryotes, certain protists Cellulose -​ Most abundant organic polymer on Earth Plasmodesmata -​ A narrow thread of cytoplasm that passes through the cell walls of adjacent plants cells and allows communication through them Plasma membrane -​ Surface membrane of a cell  -​ Acts as a selective barrier to passage materials in and out of the cell Phospholipids -​ Have two fatty acids attached to glycerol and a phosphate group at the third position Cytoplasm -​ Gel like mixture -​ Surrounded by cell membrane