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Organization of the Cell

Discover the foundational concepts of cell organization and function, tracing back to the Cell Theory by Schleiden, Schwann, and Virchow. Learn about cell diversity, surface area-to-volume ratio, microscopes, cell fractionation, cell types (prokaryotic and eukaryotic), organelles, and cellular processes like respiration and photosynthesis.

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Organization of the Cell

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  1. Organization of the Cell

  2. Cell theory • Cells are the basic living units of organization and function • All cells come from other cells • Work of Schleiden, Schwann, and Virchow contributed to this theory • Each cell is a microcosm of life

  3. Biological size and cell diversity

  4. Cell surface area-to-volume ratio • Plasma membrane must be large enough relative to cell volume to regulate passage of materials • Cell size and shape related to function

  5. Cell surface area-to-volume ratio

  6. Microscopes • Light microscope, referred to as compound microscope, used by most students • Two features determine how clearly an object is viewed • Magnification • Resolution • Light microscope has 500 times more resolution than human eye

  7. Special optical mechanisms for light microscopes • Bright-field microscopy • Phase contrast microscopy • Differential-interference-contrast microscopy • Fluorescence microscope, including confocal fluorescence microscope

  8. Electron microscope • Developed in the 1950s • Allows study of the ultrastructure of cells • 10,000 times more resolution than human eye

  9. Types of electron microscope • Transmission electron microscope • Scanning electron microscope

  10. Comparing light and electron microscopy

  11. Cell fractionation • Used to determine function of organelles • Cells broken apart and the resulting cell extract spun in a centrifuge • Centrifugal force separates extract • Pellet • Supernatant

  12. Cell fractionation

  13. Prokaryotic • Bacteria and archaea • DNA not enclosed in a nucleus • Eukaryotic • All other known organisms • Highly organized membrane-enclosed organelles • Cytoplasm • Nucleoplasm

  14. Functions of cell membranes • Divide cell into compartments, allowing for specialized activities • Interacting membranes form endomembrane system • Vesicles transport materials between compartments

  15. Diagram ofa plant cell

  16. Diagram ofan animal cell

  17. The cell nucleus • Contains DNA • Bounded by • Nuclear envelope • Double membrane perforated with nuclear pores • DNA forms chromatin, which is organized into chromosomes • Nucleolus • RNA synthesis and ribosome assembly

  18. The cellnucleus

  19. Endoplasmic reticulum (ER) • Network of folded internal membranes in the cytosol • Smooth ER • Site of lipid synthesis • Site of detoxifying enzymes • Rough ER • Ribosomes manufacture proteins • Proteins may be moved into the ER lumen

  20. Endoplasmicreticulum (ER)

  21. Golgi complex • Cisternae that process, sort, and modify proteins • In animal cells, Golgi complex also manufactures lysosomes • Glycoproteins transported to the cis face • Golgi modifies carbohydrates and lipids and packages into vesicles

  22. Golgi complex

  23. Lysosomes break down worn-out cell structures, bacteria, and other substances • Peroxisomes • Involved in lipid metabolism and detoxification • Contain enzymes that produce and degrade hydrogen peroxide

  24. Lysosomes

  25. Mitochondria • Sites of aerobic respiration • Organelles enclosed by a double membrane • Place important role in apoptosis • Cristae and matrix contain enzymes for aerobic respiration • Nutrients broken down and energy packaged in ATP • Carbon dioxide and water by-products

  26. Mitochondria

  27. Chloroplasts • Plastids that carry out photosynthesis • Inner membrane of chloroplast encloses the stroma • During photosynthesis, chlorophyll traps light energy • Energy converted to chemical energy in ATP

  28. Chloroplast

  29. Cellular respiration and photosynthesis

  30. Cytoskeleton • Internal framework made of • Microtubules • Microfilaments • Intermediate filaments • Provides structural support • Involved with transport of materials in the cell

  31. TheCytoskeleton

  32. Cilia and flagella • Thin, movable structures that project from cell surface • Function in movement • Microtubles anchored in cell by basal body

  33. Structureof cilia

  34. Glycocalyx, cell coat formed by polysaccarides extending from plasma membrane • Many animal cells also surrounded by an extracellular matrix (ECM) • Most bacteria, fungi, and plant cell walls made of carbohydrates

  35. Extracellular matrix

  36. Plantcell walls

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