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The Eukaryotic Cell Fig 4.22, page 97

The Eukaryotic Cell Fig 4.22, page 97. Eukaryotic cells have many unique features that distinguish them from prokaryotes Cilia Membrane sterols Ribosome structure Membrane bound organelles Nucleus. Structures External to Cell. Tubulin in 9+2 array with membrane covering Flagella

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The Eukaryotic Cell Fig 4.22, page 97

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  1. The Eukaryotic Cell Fig 4.22, page 97

  2. Eukaryotic cells have many unique features that distinguish them from prokaryotes • Cilia • Membrane sterols • Ribosome structure • Membrane bound organelles • Nucleus

  3. Structures External to Cell • Tubulin in 9+2 array with membrane covering • Flagella • Function in cell motility • long in relation to cell size • Cilia • Shorter; more numerous • Move cell or propel substances across cell

  4. Glycocalyx • Carbohydrate coating in animal cells • Surrounds and stabilizes plasma membrane • Active in cell-cell recognition

  5. Cell wall • Plants, algae, fungi • Cellulose, chitin, glucan, mannan, silica, calcium carbonate • NO PTG! • Penicillin a “miracle drug”? • Protozoa have no cell wall but some have a pellicle surrounding the plasma membrane

  6. Eukaryotic Plasma Membrane • Similar in structure and function to prokaryote • Phospholipid bilayer embedded with proteins • Addition of carbohydrates and sterols (cholesterol, ergosterol) • Cell signaling • Cell recognition • Stability

  7. Membrane proteins functions: • Transport • Maintain cell integrity • Attachment of proteins to internal structures • Receptors for cell signaling • Proteins in outer layer • Receptors typically glycoproteins

  8. extracellular fluid (outside) binding site phospholipid bilayer carbohydrate cholesterol phospholipid receptor protein transport protein protein filaments recognition protein cytoplasm (inside)

  9. Transport across eukaryotic membrane • Passive • Simple and facilitated diffusion; osmosis • Active • Active transport; endocytosis; exocytosis

  10. Endocytosis • Bring in material from surrounding environment • Pinocytosis or Phagocytosis • Exocytosis • Releases contents into external environment

  11. Cytoskeleton • Dynamic network of protein filaments (microtubules, actin filaments, intermediate filaments) • Anchor organelles, Structural support, Shape alteration, Movement

  12. 10 µm Column of tubulin dimers Tubulin dimer

  13. Centrosome • Pair of centrioles and proteins found near nucleus • Involved in the assembly of microtubules

  14. 10 µm Actin subunit 7 nm

  15. Structural microfilaments and role in motility

  16. microtubules (red) nucleus microfilaments (blue)

  17. Membrane-bound Organelles • Compartmentalization • Allows for division of labor • Nucleus • Mitochondria and chloroplast • Endoplasmic reticulum • Golgi apparatus • Lysosome and peroxisomes

  18. Nucleus • nuclear envelope • Double membrane with pores • nucleolus • sites of rRNA synthesis • DNA typically in multiple pairs of linear chromosomes • associated with histones proteins

  19. Sexual or asexual reproduction • mitosis and meiosis

  20. Endoplasmic Reticulum • Network of flattened tubules • (cisterns) continuous with • nuclear membrane • rough ER • ribosomes present • Site of protein synthesis • smooth ER • no ribosomes • Site of lipid/fat synthesis

  21. Ribosomes 80S Large 60S and small 40S subunits Membrane-bound: Attached to ER & nuclear membrane Free: In cytoplasm 70S In chloroplasts and mitochondria

  22. Golgi Body • Curved cisterns • Not continuous • -Modifies, packages and secretes products of ER • - Produces lysosomes and vacuoles

  23. Lysosomes • Formed in Golgi • Membrane enclosed sacs of digestive enzymes • Peroxisome • Oxidation of fatty acids; destroys H2O2 • Formed by dividing perosiomes • Vacuoles • Derived from the Golgi • Store nutrients • Sequester harmful substances

  24. Mitochondria • Double membrane • - Inner membrane is folded into cristae • - Site of cellular respiration; ATP production • - 70S ribosomes and circular DNA; divide independently of cell Figure 4.26

  25. Plastids • - Chloroplasts • - Found in algae and green plants • - Contains chlorophyll pigment • in the coin-like thylakoids • - Stacked thylakoids - grana • 70S ribosomes and circular DNA; • divide independently of cell Figure 4.27

  26. Endosymbiotic Theory - Evolution from prokaryotes to eukaryotes 3.5 billion yrs ago - prokaryotes dominate 2.5 billion yrs ago - oxygen accumulates 1.5 billion yrs ago - 1st nucleated eukaryotes

  27. Extracellular Structures

  28. Intracellular Structures

  29. Genetic Structures

  30. Reproductive Processes

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