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Understanding Cell Biology: Cell Structure and Organelles

Explore the fascinating world of cell biology with a focus on cell structure, organelles, and their functions. Dive into the details of the cell membrane, nucleus, Golgi apparatus, lysosomes, and endoplasmic reticulum. Learn about the role of different organelles in cellular processes and the importance of the cell in sustaining life.

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Understanding Cell Biology: Cell Structure and Organelles

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  1. The Cell

  2. The cell is the basic structural and functional unit of life • The organism activity depends on individual and collective activity of cells • Biochemical activities of cells are dictated by sub-cellular structure • For the Continuity of life the cellular basis is required Cell Theory

  3. Cell Structure

  4. Separates intracellular fluids from extracellular fluids • Plays a dynamic role in cellular activity • Double Layered (bi-layer) of lipids with imbedded, dispersed proteins • Bi-layer consists of phospholipids, cholesterol, and glyco-lipids • Glycolipids are lipids with bound carbohydrate • Phospholipids have hydrophobic and hydrophilic bipoles Plasma Membrane

  5. The phospholipid bi-layer is a • selectively permeablelipid bilayer found in all cells. • It contains a wide variety of biological molecules, primarily proteins and lipids • Theses structures are involved in a vast array of cellular processes such as • cell adhesion • ion channel conductance • cell signaling. • The plasma membrane also serves as the attachment point for both the intracellular cytoskeleton and, if present, the cell wall.

  6. Stephen Taylor http://sciencevideos.wordpress.com

  7. Stephen Taylor http://sciencevideos.wordpress.com

  8. Fluid Mosaic Model

  9. Functions of Membrane Proteins

  10. Functions of Membrane Proteins

  11. Adherance junctions: • Tight junction – impermeable junction that encircles the cell • Desmosome – anchoring junction scattered along the sides of cells • Hemi-desmosomes: anchoring the basal cell aspect to the basement membrane • Gap junction – a nexus that allows chemical substances to pass between cells Membrane Junctions

  12. Adhering junctions

  13. Membrane Junctions

  14. Tight junctions

  15. Membrane Junctions

  16. Hemi-desmosome Intercellular Junctions

  17. Gap Junctions

  18. Gap Junctions

  19. The nucleus is the most prominent organelle and can occupy up to 10% of the space inside a cell. • It contains the equivalent of the cell's gray matter—its genetic material, or DNA. • In the form of genes, each with a host of helper molecules, DNA determines the cell's identity, masterminds its activities, and is the official cookbook for the body's proteins. • The nucleus is surrounded by two pliable membranes, together known as the nuclear envelope. • Normally, the nuclear envelope is pockmarked with octagonal pits about an inch across (at this scale) and hemmed in by raised sides. • These nuclear pores allow chemical messages to exit and enter the nucleus. Nucleus: The Cell's Brain

  20. The nucleus is surrounded by two pliable membranes, together known as the nuclear envelope. • Normally, the nuclear envelope is pockmarked with octagonal pits about an inch across (at this scale) and hemmed in by raised sides. • These nuclear pores allow chemical messages to exit and enter the nucleus. If you exclude the nucleus, the rest of the cell's innards are known as thecytoplasm. Cell Nucleus

  21. Stacked and flattened membranous sacs • Functions in modification, concentration, and packaging of proteins • Transport vessels from the ER fuse with the cis face of the Golgi apparatus • Proteins then pass through the Golgi apparatus to the trans face • Secretory vesicles leave the trans face of the Golgi stack and move to designated parts of the cell Golgi Apparatus

  22. Role of the Golgi Apparatus

  23. System of organelles that function to: • Produce, store, and export biological molecules • Degrade potentially harmful substances EndomembraneSystem

  24. System includes: • Nuclear envelope, smooth and rough ER, lysosomes, vacuoles, transport vesicles, Golgi apparatus, and the plasma membrane

  25. Spherical membranous bags containing digestive enzymes • Digest ingested bacteria, viruses, and toxins • Degrade nonfunctional organelles • Breakdown glycogen and release thyroid hormone • Breakdown un-useful tissue • Breakdown bone to release Ca2+ Lysosomes

  26. Interconnected tubes and parallel membranes enclosing cisternae • Continuous with the nuclear membrane • Two varieties – rough ER and smooth ER Endoplasmic Reticulum (ER)

  27. Gough ER • External surface studded with ribosomes • Manufactures all secreted proteins • Responsible for the synthesis of integral membrane proteins and phospholipids for cell membranes Endoplasmic Reticulum (ER)

  28. Tubules arranged in a looping network • Catalyzes the following reactions in various organs of the body • In the liver – lipid and cholesterol metabolism, breakdown of glycogen and, along with the kidneys, detoxification of drugs • In the testes – synthesis of steroid-based hormones • In the intestinal cells – absorption, synthesis, and transport of fats • In skeletal and cardiac muscle – storage and release of calcium Smooth ER

  29. Stephen Taylor http://sciencevideos.wordpress.com

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