Eukariotic Cell Structure


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Eukariotic Cell Structure

  1. 1. Eukaryotic Cells
  2. 2. A Generalized Eukaryotic Cell
  3. 3. Pores through the Cell Nucleus
  4. 4. <ul><li>Nucleus </li></ul><ul><li>The nucleus consists of the nuclear envelope, nucleolus, chromatin, and nucleoplasm. </li></ul><ul><li>Nuclear Envelope </li></ul><ul><li>Structure -two unit membranes with a fluid-filled space                 -nuclear pores present                 -outer membrane may be continuous with endoplasmic                   reticulum </li></ul><ul><li>Function -selectively permeable to control movement in or out                -contains nuclear contents </li></ul><ul><li>Chromatin </li></ul><ul><li>Structure -composed of long thin strands of DNA </li></ul><ul><li>Function -contains instructions that control cell metabolism and heredity </li></ul><ul><li>Nucleolus </li></ul><ul><li>Structure -non-membraneous matrix of RNA (ribonucleic acid) and protein. </li></ul><ul><li>Function - instructions in DNA are copied here                - works with ribosomes in the synthesis of protein </li></ul>
  5. 6. Centriole Structure - nine triplets of microtubules form one centriole                - two centrioles form one centrosome. Function  - forms spindle fibres to separate chromosomes during cell                  division Vacuole Structure    - a single layer of unit membrane enclosing fluid in a sack Function    - produces turgor pressure against cell wall for support    - stores water and various chemicals    - may store insoluble wastes Cytoskeleton Structure - Composed of microtubules Function - Supports cell and provides shape - Aids movement of materials in and out of cells
  6. 7. Mitochondria <ul><li>Power house of cell and account for 20% of the cell volume, 1 µm diameter. </li></ul><ul><li>Enzymes carry out oxidative reactions that capture energy in ATP. </li></ul><ul><li>Glucose  +  Oxygen  ------> Carbon Dioxide  +  Water  + Energy (ATP) </li></ul><ul><li>Mitochondria contains mitochondrial DNA and can replicate independently. </li></ul>
  7. 8. Mitochondrial DNA
  8. 9. Chloroplasts <ul><li>Like mitochondria chloroplast too have outer and inner membrane (stroma), it corresponds mitochondrial matrix. </li></ul><ul><li>Unlike mitochondria chloroplast have separate inner membrane (thylacoids), that contain chlorophyll (in Grana), that capture energy during photosynthesis. </li></ul><ul><li>chlorophyll CO 2 + H 2 O ---------------> Glucose + O 2 (food)                      radiant energy   </li></ul><ul><li>Chloroplast contains chloroplast DNA and can replicate independently. </li></ul>
  9. 10. Ribosome Structure - non-membraneous, spherical bodies composed of      RNA (ribonucleic acid) and protein enzymes. Function - site of protein synthesis Endoplasmic Reticulum (ER) Structure - sheets of unit membrane with ribosomes on the                  outside (rough ER) and without ribosome (smooth ER).                - forms a tubular network throughout the cell   Function - transports chemicals between cells and within cells                - provides a large surface area for the organization                  of chemical reactions and synthesis
  10. 11. Lysosome Structure - membrane bound bag containing hydrolytic enzymes                - hydrolytic enzyme = (water split biological catalyst)                  i.e. using water to split chemical bonds. Function - break large molecules into small molecules by                  inserting a molecule of water into the chemical bond Peroxisome: -Membrane bound organelle, contains enzymes. -These enzymes in plant cell oxidize fats and in animal cell oxidizes amino acids. -Peroxisomal enzymes converts hydrogen peroxide to water, to prevent the toxic effect of hydrogen peroxide. Golgi Apparatus Structure - stacks of flattened sacs of unit membrane (cisternae)                - vesicles pinch off the edges Function - modifies chemicals to make them functional                - secretes chemicals in tiny vesicles                - stores chemicals                - may produce endoplasmic reticulum
  11. 12. Prokaryotic and Eukaryotic Flagella Compared <ul><li>One central pair and 9 peripheral pair of microtubules, made up of tubulin. </li></ul><ul><li>Each pair of peripheral microtubules associated with a protein Dynein, which cross-bridges with other flagellar proteins for movement. The movement is dependent on ATP hydrolysis by dynein. </li></ul>
  12. 13. Oxytricha The Ciliated Protozoan
  13. 14. The Stroke-and-Recovery Motion of a Cilium
  14. 15. Cilia on an Organism Move in a Synchronized Fashion, Creating a Wave that Propels the Organism Forward
  15. 16. Pseudopodia
  16. 17. Amoeba (132X) Amoeba engulfing food particle Food particles
  17. 18. Endosymbiosis <ul><li>According to the endosymbiotic theory, organelles of eukaryotic cells came from prokaryotic cells those have developed symbiotic relation with eukaryote. If one organism lives inside the other, is called endosymbiosis. </li></ul><ul><li>Especially in case of mitochondria and chloroplast. They have outer and inner membranes, self replicating DNA and their structure resembles Gram negative and photosynthetic bacteria respectively. </li></ul>The cytoplasm of Pyrsonympha , a protist that live symbiotically in the hideouts of termites,. Bacteria acts as mitochondria for the protist.
  18. 19. <ul><li>Passive Transport: Cell expends no energy to move substances down a concentration gradient (high to low concentration) </li></ul><ul><li>Simple Diffusion </li></ul><ul><li>Facilitated Diffusion </li></ul><ul><li>Osmosis </li></ul><ul><li>Active Transport: Cell expends energy from ATP, enabling it to transport substances against a concentration gradient </li></ul>Movement of substances across the membrane
  19. 20. Simple Diffusion: The random movements of molecules cause them to spread out (diffuse) from an area of high concentration to area of low concentration
  20. 21. Facilitated Diffusion: Carrier protein molecules aid in the movement of substances through cell membrane from high to low concentration
  21. 22. Osmosis: The diffusion of water from an area of high water concentration to an area of low water concentration through a semi or, selectively permeable membrane (Cell Membrane)
  22. 23. Experiments that examine the effects of tonicity on osmosis
  23. 24. Active Transport: Carrier protein molecules aid in movement of molecules against a concentration gradient requires energy in form of ATP
  24. 25. Endocytosis and Exocytosis <ul><li>Eukaryotic cells move substances by forming membrane-enclosed vesicles </li></ul><ul><li>Endocytosis: Form by invagination (poking in) and surrounding substances from outside the cell </li></ul><ul><li>Exocytosis: Vesicles inside the cell fuse with the plasma membrane and extrude contents from the cell </li></ul>
  25. 26. 1.Phagocytosis (solid/ semisolid) 2. Pinocytosis (liquid)