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CELL :ORGANIC UNIT OF LIFE

CELL :ORGANIC UNIT OF LIFE. CELL. basic unit of structure and function Can be: Unicellular Multicellular Bodies are cooperative of specialized cells Cannot survive for long on their own. How do we study cells?. Invention of lenses (merchants of Europe) Combination of lenses led to:

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CELL :ORGANIC UNIT OF LIFE

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  1. CELL:ORGANIC UNIT OF LIFE

  2. CELL • basic unit of structure and function • Can be: • Unicellular • Multicellular • Bodies are cooperative of specialized cells • Cannot survive for long on their own

  3. How do we study cells? • Invention of lenses (merchants of Europe) • Combination of lenses led to: • Telescope • Microscope* • 17th century: discovery and early study of cells thru*

  4. Invention and Development of Microscopes • Anton von Leeuwenhoek • Dutch biologist • first to explore things: microscopic view • Pond water (detailed illustration)

  5. ESSENTIAL SCIENTISTS • Robert Hooke • English scientist • Pieces of cork • Composed of thousands of chambers • After 200 years: cells were also found in other organisms

  6. ESSENTIAL SCIENTISTS • Robert Brown (1833) • Scottish • Nucleus • Dark structure • Matthias Schleiden • German • STATED: all plants are made up of cells

  7. ESSENTIAL SCIENTISTS • Theodor Schwann • STATED: all animals are made up of cells • Rudolf Virchow • German 1855 • Cells arise from the division of pre-existing cells

  8. The CELL THEORY • most fundamental discovery: nature of living things • forms basic framework • formulated by Schwann, Schleiden and Virchow

  9. STATES that: • ALL LIVING THINGS ARE COMPOSED OF CELLS • CELLS ARE THE BASIC UNIT OF STRUCTURE AND FUNCTION • ALL CELLS COME FROM PRE-EXISTING CELLS

  10. Prokaryotic VS Eukaryotic Cells • Pro- before • Karyon- kernel • NO NUCLEUS • DNA: concentrated in a NUCLEOID • With cytoplasm • w/ PM • Eu- true • Karyon- kernel • Has NUCLEUS • With cytoplasm • Cytosol • w/ PM

  11. ORGANELLES • NUCLEUS • contains most of the genes • averaging about 5µm in dm • *Nuclear envelope • Encloses nucleus • Double membrane (lipid bilayer with proteins) • 20 – 40 nm • Perforated by pores 100 nm in dm • pore complex*

  12. PARTS OF THE NUCLEUS • *Nuclear lamina • netlike array of protein filaments • maintains the shape of the nucleus • *Nucleolus • Site: components of ribosomes are synthesized and assembled • Components pass through the nuclear pore to the cytoplasm* • Appears as a mass of densely stained granules and fibers adjusting part of chromatin

  13. FUNCTION of NUCLEUS • information center of the cell • contains DNA • control protein synthesis • By sending molecular messengers: mRNA

  14. ORGANELLES • RIBOSOMES • Protein factory • cells with active protein synthesis • prominent nucleoli • build proteins: two cytoplasmic locales • Free ribosomes: cytosol • Bound ribosomes: for inclusion, transport, packaging

  15. ENDO-MEMBRANE SYSTEM • Membranes that are related either: • direct physical continuity • transfer of membrane segments • Includes:VAlyPLAneGOer • Nuclear Envelope • ER • Golgi Apparatus • Lysosomes • Vacuoles • Plasma Membrane

  16. Endoplasmic Reticulum • more than half the total membrane of cells • reticulum Greek word for network • Two types: • Smooth ER • Rough ER

  17. Smooth ER • Smooth walls of the sacs are not studded with ribosomes • Functions: SYLIPme carDE DRUP • Synthesis of lipids • Metabolism of carbohydrates • Detoxification of drugs and poison

  18. ROUGH ER • studded with ribosomes • FUNCTIONS: • synthesis of secretory protein • membrane production (membrane factory) • synthesis of proteins

  19. Golgi Apparatus • Center of: MWSS • Manufacturing • Warehousing • Sorting • Shipping • Products from the ER are: SMS • Modified • Stored • Sent to other destinations

  20. flattened membranous sacs- CISTERNAE • vicinity is concentrated with vesicles • Golgi apparatus- other ENDOMEMBRANE organelle CONNECTION • Parts of GA: • Cis face • Receiving part (near ER) • TV moves materials from ER to GA • Trans face • Shipping (vesicles)

  21. manufactures certain macromolecules • Hyaluronic acid • glue animal cells together • dispatches products by Budding of vesicles • gives molecular tags (phosphate groups)

  22. Vacuoles • membrane bound sacs in a cell • food vacuole- formed by phagocytosis • Contractile vacuole • Pumps out water out • Central Vacuole- filled with liquid • Tonoplast • organic compounds (proteins in seed) • Disposal sites for metabolic products

  23. FUNCTION Repository of inorganic ions Storage of pigments Helps to protect against predators

  24. LYSOSOMES • membrane bounded sacs of hydrolytic enzymes • digestion of macromolecules • works best in acidic medium ~pH 5 • maintains internal pH • excessive leak of a large number • leads to AUTODIGESTION

  25. hydrolytic enzymes and lysosomal membrane • by RER and Golgi Apparatus • Ex. Lysosomes in an Amoeba • Exhibits PHAGOCYTOSIS • Phagein Greek: to eat • Kytos: vessel • Food vacuole + lysosome = digests food

  26. AUTOPHAGY • use of its own HE to digest its own organelles • Recyle its parts • happens when it engulfs an organelle • after digestion • Organic monomers are returned to the cytosol • Absence of lysosomes • accumulation of indigestible substrates • Pompe’s Disease- glycogen • Tay Sachs Disease- lipid

  27. Other Membrane Organelles • not part of Endo-Membrane System • membranes not made by ER • Free ribosomes and Ribomes of Mitochondria and Cytoplasm • contain small amounts of DNA • semi- autonomous

  28. Mitochondria • power house of the cell • site of cellular respiration • Catabolic process that generates ATP* • number related to cell’s metabolic activity • 1-10µm long • enclosed by two membranes

  29. Membranes*: • Outer- smooth • Inner**- convoluted with infoldings (CRISTAE) • Inter-membrane space • Mitochondrial matrix

  30. Chloroplast • found in plants and eukaryotic algae • site of photosynthesis • Solar energy – chemical energy • member of plastids • Amyloplasts- colorless, stores starch • Chromoplast- stores pigments • Chloroplast, xanthophyll, fucoxanthin

  31. contains another membranous system • THYLAKOIDS • flattened sacs • forms GRANA • bathed with stroma

  32. Peroxisomes • specialized metabolic compartment bounded by a single membrane • sontains enzymes that produces* H2O2 as a by product • FUNCTION: • use O2 to break Fatty acids • detoxify alcohol • Transferring H2 from the poisons to oxygen

  33. BUT…. • H2O2 is toxic • but peroxisomes have enzymes that convert it to water • grow by incorporation of proteins and lipids made in the cytosol • splits into two

  34. Examples: • Glyoxysomes • fat storing tissues of plant seeds • has enzyme that initiates conversion of FA- sugar • food for the seedling

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