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Cells

Cells. Inside and Out. Cell Theory. English scientist Robert Hooke used a crude microscope to look at a slice of cork . He saw little boxes that reminded him of the small rooms that monks lived in – Cells. Cell Theory.

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Cells

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  1. Cells Inside and Out

  2. Cell Theory • English scientist Robert Hooke used a crude microscope to look at a slice of cork. • He saw little boxes that reminded him of the small rooms that monks lived in – Cells

  3. Cell Theory • Later the observations of scientists Schleiden, Schwann and Virchow led to what we call the Cell Theory: • All living things are composed of one or more cells • Cells are the basic units of structure and function in organisms • All cells arise from existing cells

  4. Size Chart Atom Molecule Organelle Cell Tissue Organ Organ System Organism Population Community Ecosystem

  5. Cell Size • Having many small cells is more efficient than having a few large cells • Small cells have larger surface to volume ratios than large ones • So, substance exchange is faster in small cells than in large.

  6. Surface to Volume Ratio Example • Surface area Equation on a cube • L2 X 6 • Volume Equation of a cube • L2 X H

  7. Magnification • Light microscope • Visible light passes through object • A Lens magnifies the image • Magnification • Making an image seem larger than what it is • Resolution • What measures the clarity of an object • What limits a particular type of scope

  8. Magnification • Electron Microscope • 100,000 X magnification power • Scanning Electron Microscope (SEM)‏ • Allows for better resolutions on the surface of an object • Shows object in 3D • Good for observing living organisms

  9. Magnification • Electron Microscopes • Transmission Electron Microscope (TEM)‏ • Observer to sees through cells • allows the observer to see specimen's internal structure

  10. Features Common to All Cells • Cell Membrane • All cells share this outer boundary • This membrane encloses and separates the interior of the cell – the cytoplasm • The cell membrane also regulates what enters and leaves the cell

  11. Features Common to All Cells • Cytoplasm (Cyto= cell, -plasm= formative material)‏ • Everything between plasma membrane and nucleus or nucleoid region. • Cytoskeleton (Cyto= cell, -skeleton= structural framework)‏ • Structure made of microfibers & microtubules within the cytoplasm that suspends the cells structures • Most cells have ribosomes • Cellular Structures on which proteins are made

  12. Prokaryotes • Bacteria Cells • Have no nucleus • Evolved before eukaryotic cells • Structures Common to Prokaryotes • Nucleoid region- where the chromosome is • ribosomes- protein synthesis • Cell membrane- “gate keeper” • Cell wall (different than plants)‏- support • Some have capsules outside wall- resistance to antibiotics • Pili- exchange of genetic info • Flagella- movement

  13. Prokaryotes

  14. Eukaryotes • Plant and Animal Cells • Cells are more complex than prokaryotic cells • Much like Prokaryotes Eukaryotic Cells • have a cell wall (plants/protists/fungi)‏ • have a plasma membrane • have Cytoplasm • have ribosomes • But within their cytoplasm eukaryotes have • Organelles • Cytosol - fluid in cytoplasm

  15. Major Organelles to know • Cytoskeleton- support & protection • Cell membrane- “gate keeper” controls what enters or leaves the cell • Nucleus- holds the chromosomes, directs cell • Endoplasmic Reticulum- transport & protein formation • Golgi Apparatus- packages things • Lysosomes- hold digestive enzymes, “suicide sac” • Vesicles- storage • Mitochondria- “Power house” respiration, ATP energy • Cell Wall- support, protection • Chloroplasts- photosynthesis, make glucose • Central Vacuole- storage, especially of water • Ribosomes- protein making

  16. Cytoskeleton • Provides interior framework to support cell • Made of network of protein fibers tied to the plasma membrane.

  17. Cytoskeleton • There are three kinds of cytoskeleton fibers • Microfilaments (or Actin Fibers)‏ • Made of protein actin • Works in the shape and movement of a cell • Microtubules • Tiny tubules made up tubulin protein • Highway for transportation of info. from nucleus to parts of the cell • Intermediate Fibers • Rope-like fibers where enzymes and ribosomes anchor in the cell

  18. Cell Membrane • Phospholipidbilayer - barrier separating inside of cell (cytoplasm) from outside • Selectively permeable (penetrable) - controls what enters & leaves cell

  19. Proteins Embedded in the Plasma Membrane • ** Proteins are macromolecules made of amino acids • Some proteins embed in the plasma membrane • Enzymes • Transport Proteins • Receptor Proteins • Must have both polar & non polar ends to embed in the membrane

  20. Nucleus • Nucleus and mitochondria contain genes • Nucleus consists of: • Envelope • Double membrane • Pores let messages in and out • Chromatin • DNA • Protein • Nucleolus • ProducesrRNA • rRNA with proteins makes up ribosomes

  21. Nucleus

  22. Endoplasmic Reticulum (endo = Inside, plasm = formed material)‏ • Major system of internal membranes- move proteins and other stuff through cell • Is a lipid bilayer with embedded proteins • Makes steroids, lipids • Detoxifies chemicals

  23. Endoplasmic Reticulum (ER)‏ • Rough ER • Has ribosomes embedded so looks “rough” • Processes proteins • Smooth ER • No ribosomes embedded so looks “smooth” • Makes lipids and breaks down toxic chemicals

  24. Golgi Apparatus/Lysosomes • Golgi Apparatus • Flattened pancake like membrane-bound sacs- the packaging distribution center of the cell

  25. Lysosomes/Vesicles • Lysosomes (lyso-breaking, -some=body)‏ • Small spherical organelles- • hold digestive enzymes • Work with Golgi to produce, package and distribute protiens • Vesicles • Small bubble-like membrane bound sacs • carry material from ER to Golgi and out of cell • Some will become lysosomes

  26. Here’s the Protein Flow

  27. Mitochondria • Harvests energy from organic compound (sugars) to make ATP • ATP: energy “Money” in the cells • Cellular respiration • Most eukaryote cells contain mitochondria • Double membrane • Big bag stuffed in smaller bag • Folds of inner bag = cristae • Space inside inner bag called matrix • Holds enzymes and DNA • This DNA ONLY inherited from mom

  28. Mitochondria

  29. Organelles Common to Plants • Plants contain all of the organelles now mentioned plus more • Organelles Only in Plants (not animals) • Cell Wall • Chloroplast • Central Vacuole

  30. Cell Wall • Surrounds the cell membrane • Made of proteins and carbohydrates • Cellulose - polysaccharide(poly=many, saccharide=sugars) cellulose can NOT be digested by all us, but some can. • Supports and Maintains the shape of a cell • Protects from damage

  31. Chloroplasts • Plant cells contain mitochondria to produce the energy “bucks” (ATP), AND they contain chloroplasts to make the glucose the mitochondria “burns” to make the ATP • Chloroplasts use light energy to convert carbon dioxide and water into sugar, oxygen and energy (ATP)‏ • Also found in algae and some protozoans. • Chloroplasts • have two membranes • have enzymes & DNA

  32. Chloroplasts

  33. Central Vacuole • Largest organelle in a plant cell • Contains ions (charged atoms), nutrients (macromolecules), and wastes • When full, makes cell rigid which enables the plant to stand upright.

  34. Plant Cell

  35. The Endosymbiotic Hypothesis • Evolution of the Eukaryotic cell – (with mitochondria and chloroplasts) • Theory:one large prokaryotic cell ingested another which became mitochondria and/or chloroplast in the now eukaryotic cell.

  36. Evidence • Both are similar to bacteria in size and shape • Both have a double membrane • Outer from being taken into cell • Inner from original bacterial cell • Contain DNA in loop like bacteria • Contain ribosomes - make proteins • RNA in ribosomes like bacterial cells

  37. The Endosymbiotic Theory

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