Chapter 3

2. Chapter 3 Cell Structure

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

4. History of the Cell Theory

5. History of the Cell Theory • Proposed in 1830s by Schleiden and Schwann • Modern cell theory • Cells are 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

6. Anatomy of a Typical Eucaryotic Cell

7. Introduction

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

9. 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

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

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

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

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

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

15. 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

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

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

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

19. Ribosomes (cont’d.)

20. 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

21. 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

22. Animation – Anatomy of a Typical Cell • [Insert typical cell.swf]

23. 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 • Leukoplasts: store food

24. 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

25. 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