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3.1 The Cellular Level of Organization

3.1 The Cellular Level of Organization. The cell is the structural and functional unit of an organism, the smallest structure capable of performing all the functions necessary for life. 3.1 The Cellular Level of Organization. Prokaryotic cells lack membrane enclosed structures.

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3.1 The Cellular Level of Organization

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  1. 3.1 The Cellular Level of Organization • The cell is the structural and functional unit of an organism, the smallest structure capable of performing all the functions necessary for life.

  2. 3.1 The Cellular Level of Organization • Prokaryotic cells lack membrane enclosed structures. • Eukaryotic cells possess membrane enclosed structures.

  3. The Cell Theory • All organisms are composed of one or more cells. • Cells are the basic living unit of structure and function in organisms. • All cells come only from other cells.

  4. Sizes of Living Things

  5. Surface Area / Volume Ratio • The amount of surface area affects the ability to get materials in and out of a cell. • A cells increase in volume, the proportionate amount of surface area decreases.

  6. Surface Area / Volume Ratio

  7. Plasma Membrane and Cytoplasm • All cells are surrounded by a plasma membrane. • The material inside of a cell is the cytoplasm. • The plasma membrane regulates what enters and exits a cell.

  8. 3.2 Prokaryotic Cells

  9. 3.2 Prokaryotic Cells • Cell Wall • Capsule • Flagellum • Nucleoid • Ribosomes

  10. Prokaryotes are: • Structurally simple • Metabolically diverse • Adapted to most types of environments

  11. 3.2 Prokaryotic Cells

  12. 3.3 Eukaryotic Cells • Eukaryotic cells: • Are structurally complex • Have a nucleus • Possess membrane-bound organelles • May have a cell wall

  13. 3.3 Eukaryotic Cells

  14. 3.3 Eukaryotic Cells

  15. The Nucleus • Stores DNA

  16. The Nucleus • Stores DNA • Nucleolus - rRNA • Nuclear Envelope • Nuclear pores

  17. Ribosomes • Site of protein synthesis • Two subunits (large and small) • Subunits consist of rRNA and protein molecules • Polyribosomes • Several ribosomes with a single mRNA molecule

  18. Endoplasmic Reticulum • Consists of membranous channels and saccules

  19. Endoplasmic Reticulum • Rough ER • Processing and modification of proteins • Smooth ER • Synthesizes phospholipids • Various other functions

  20. Golgi Apparatus • The Golgi apparatus collects, sorts, packages, and distributes materials such as proteins and lipids.

  21. Lysosomes • Lysosomes contain digestive enzymes that break down unwanted, foreign substances or worn- out parts of cells

  22. Vacuoles • Vacuoles are membranous sacs that store substances. • For example: Water Pigments Toxins

  23. Peroxisomes • Membrane bound vesicles containing enzymes. • The enzymes break down molecules and as a result produce hydrogen peroxide.

  24. Energy-Related Organelles • Chloroplasts • Mitochondria

  25. Energy-Related Organelles Photosynthesis Cellular Respiration

  26. Chloroplasts • Site of photosynthesis • Structure: • Double-membrane • Stroma • Grana • Thylakoids • Chloroplasts contain: • Their own DNA • Ribosomes • Enzymes

  27. Mitochondria • Found in all eukaryotic cells • Site or cellular respiration • Structure: • Double-membrane • Matrix • Crista

  28. The Cytoskeleton • Maintains cell shape • Assists in movement of cell and organelles • Assemble and disassemble as needed • Three types of macromolecular fibers • Actin Filaments • Intermediate Filaments • Microtubules

  29. Actin Filaments • Anchored to the plasma membrane • Allows intestinal microvilli to expand and contract • Found in pseudopods allowing amoeboid movement • Play a role in animal cell division

  30. Actin Filaments • Actin interacts with motor molecules such as myosin. • In the presence of ATP, myosin pulls actin along • Example: muscle cells

  31. Intermediate Filaments • Intermediate in size between actin filaments and microtubules • Functions: • Support nuclear envelope • Cell-cell junctions, such as those holding skin cells tightly together

  32. Microtubules • Hollow cylinders made of two globular proteins • Assembly: • Under control of Microtubule Organizing Center (MTOC) • Most important MTOC is centrosome • Interacts with specific proteins to cause movement of organelles

  33. Microtubule Operation

  34. Centrioles • Short cylinders with a 9 + 0 pattern of microtubule triplets

  35. Centrioles • Help organize microtubules during animal cell division • May be involved with microtubule formation and in the organization of cilia and flagella

  36. Cilia and Flagella • Hairlike projections that aid in cell movement • In eukaryotic cells, cilia are much shorter than flagella • They are membrane-bound cylinders enclosing a matrix area • The matrix consists of microtubules in a 9 + 2 pattern

  37. Cilia and Flagella

  38. 3.4 Evolution of the Eukaryotic Cell

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