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Chapter 3

Chapter 3. Cell Structure. Introduction. The cell is the basic unit of biological organization Basic composition Protoplasm Cell membrane Organelles Eukaryotic vs. prokaryotic. History of the Cell Theory. History of the Cell Theory. Proposed in 1830s by Schleiden and Schwann

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Chapter 3

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  1. Chapter 3 Cell Structure

  2. Introduction • The cell is the basic unit of biological organization • Basic composition • Protoplasm • Cell membrane • Organelles • Eukaryotic vs. prokaryotic

  3. History of the Cell Theory

  4. History of the Cell Theory • Proposed in 1830s by Schleiden and Schwann • Modern cell theory • Cells are the smallest complete living things • All organisms are composed of one or more cells • Cells arise only from other cells • All existing cells are descendants of the first cells

  5. Anatomy of a Typical Eukaryotic Cell

  6. The Cell Membrane • Double phospholipid layer with embedded proteins • Membrane transport: selectively permeable membrane • Osmosis • Protein channels • Active transport • Fluid mosaic model

  7. The Cell Membrane

  8. Cytoplasm of the Cell • Mostly water with chemical compounds in solution or colloid • Solution vs. colloid • Individual vs. clumped atoms or ions distributed in medium • Polar compounds go into solution • Nonpolar compounds go into colloidal suspension

  9. The Nucleus • Control center of the cell • Nuclear membrane has pores to allow the passage of substances • Chromatin genetic material inside nucleoplasm • Nucleolus: site of ribosome formation

  10. The Mitochondria • Powerhouses of the cell • Cristae: inner folds where cellular respiration occurs • Energy requirements of cell determine cristae number

  11. Lysosomes • Digestive enzyme packages • Function • Digest stored food • Maintenance and repair of organelles • Suicide agents for old or weak cells

  12. Endoplasmic Reticulum • System of membranes that makes up channels • Connects with outer nuclear and cell membranes • Cisternae: sac like or channel like cavities

  13. Endoplasmic Reticulum (cont’d.) • Rough ER • For protein synthesis • Attached ribosomes • Smooth ER • Fat transport • Sex hormone synthesis

  14. Endoplasmic Reticulum (cont’d.) • Golgi apparatus • Collection of flat saclike cisternae • Concentration and collection of cellular compounds • Storage warehouses of the cell • Carbohydrate synthesis site

  15. Ribosomes • Distributed throughout cytoplasm • Attached to rough endoplasmic reticulum • No membrane covering • Site of protein synthesis

  16. Ribosomes (cont’d.) • Protein functions • Structure, enzymes or catalysts, immune response • DNA contains the code for a particular protein • DNA found in nucleus

  17. Ribosomes (cont’d.) • Transcription • Messenger RNA copies DNA code and leaves nucleus • Translation • Transfer RNA picks up amino acids • Ribosomes link amino acids together

  18. Ribosomes (cont’d.)

  19. Centrioles • Centrosome: two centrioles at right angles to each other • Composed of nine sets of triplet fibers • Form spindle fibers during cell division • Guide duplicated chromosomes to daughter cells

  20. Cilia and Flagella • Hairlike protrusions from cell membrane • Nine double fibrils around two single central fibrils • Cilia move materials across cell surface • Flagellum propels cell through a medium

  21. Plastids of Plant Cells • Chloroplasts • Most common plastid • Photosynthesis: conversion of light into chemical energy • Granum • Made of thylakoids • Connected by lamella • Chromoplasts: carotenoid pigments • Leucoplasts: store food

  22. Plastids of Plant Cells (cont’d.) • Cell membrane surrounded by cell wall • Cell wall composed of cellulose • Cellulose • Dietary fiber • Synthesized by Golgi bodies • Animal cells do not have cell walls

  23. Summary • Discussed the modern cell theory and its origins • Discussed the different parts of eukaryotic cells including the cell membrane, cytoplasm, and organelles • Discussed protein synthesis • Described some of the differences between plant and animal cells

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