1. Cell Structure and Function Chapter 4

2. Cell Theory 1) Every organism is composed of one or more cells 2) Cell is smallest unit having properties of life 3) Continuity of life arises from growth and division of single cells

3. Smallest unit of life Can survive on its own or has potential to do so Is highly organized for metabolism Senses and responds to environment Has potential to reproduce Cell

4. 4.1 Structure of Cells All start out life with: –Plasma membrane –Region where DNA is stored –Cytoplasm Two types: –Prokaryotic –Eukaryotic

5. Main component of cell membranes Gives the membrane its fluid properties Two layers of phospholipids Lipid Bilayer one layer of lipids one layer of lipids Figure 4.3 Page 56

6. Membrane Proteins Protein pump across bilayer Protein channel across bilayer Protein pump Recognition protein Receptor protein extracellular environment cytoplasm lipid bilayer Figure 4.4 Page 57

7. Why Are Cells So Small? Surface-to-volume ratio The bigger a cell is, the less surface area there is per unit volume Above a certain size, material cannot be moved in or out of cell fast enough

8. 4.3 Eukaryotic Cells Have a nucleus and other organelles Eukaryotic organisms –Plants –Animals –Protistans –Fungi

9. Plasma membrane Nucleus Ribosomes Endoplasmic reticulum Golgi body Vesicles Mitochondria Cytoskeleton Figure 4.10b Page 61

10. Plant Cell Features Cell wall Central vacuole Chloroplast Plasma membrane Nucleus Ribosomes Endoplasmic reticulum Golgi body Vesicles Mitochondria Cytoskeleton Figure 4.10a Page 61

11. Keeps the DNA molecules of eukaryotic cells separated from metabolic machinery of cytoplasm Makes it easier to organize DNA and to copy it before parent cells divide into daughter cells 4.4 Functions of Nucleus

12. Components of Nucleus nuclear envelope nucleoplasm nucleolus chromatin Figure 4.11b Page 62

13. Nuclear Envelope Two outer membranes (lipid bilayers) Innermost surface has DNA attachment sites Nuclear porebilayer facing cytoplasmNuclear envelope bilayer facing nucleoplasm Figure 4.12b Page 63

14. Group of related organelles in which lipids are assembled and new polypeptide chains are modified Products are sorted and shipped to various destinations 4.5 Endomembrane System

15. Components of Endomembrane System Endoplasmic reticulum Golgi bodies Vesicles

16. Endoplasmic Reticulum In animal cells, continuous with nuclear membrane Extends throughout cytoplasm Two regions - rough and smooth

17. Golgi Body Puts finishing touches on proteins and lipids that arrive from ER Packages finished material for shipment to final destinations Material arrives and leaves in vesicles budding vesicle Figure 4.15 Page 65

18. Vesicles Membranous sacs that move through cytoplasm Lysosomes Peroxisomes

19. ATP-producing powerhouses Membranes form two distinct compartments ATP-making machinery embedded in inner mitochondrial membrane 4.6 Mitochondria

20. Mitochondrial Origins Mitochondria resemble bacteria –Have own DNA, ribosomes –Divide on their own May have evolved from ancient bacteria that were engulfed but not digested

21. Plastids Central Vacuole 4.7 Specialized Plant Organelles

22. Chloroplasts Convert sunlight energy to ATP through photosynthesis

23. Other Plastids Chromoplasts –No chlorophyll –Abundance of carotenoids –Color fruits and flowers red to yellow Amyloplasts –No pigments –Store starch

24. Present in all eukaryotic cells Basis for cell shape and internal organization Allows organelle movement within cells and, in some cases, cell motility 4.9 Cytoskeleton

25. Cytoskeletal Elements microtubule microfilament intermediate filament

26. Microtubules Largest elements Composed of tubulin Arise from microtubule organizing centers (MTOCs) Involved in shape, motility, cell division Figure 4.21 Page 71 tubulin subunit

27. Microfilaments Thinnest elements Composed of actin Take part in movement, formation, and maintenance of cell shape actin subunit Figure 4.21 Page 71

28. Intermediate Filaments Only in animal cells of certain tissues Most stable cytoskeletal elements Six known groups one polypeptide chain Figure 4.21 Page 71

29. 4.10 Flagella and Cilia Structures for cell motility 9 + 2 internal structure dynein microtubule Figure 4.25 Page 73

30. 4.11 Plant Cell Walls Primary cell wall Secondary cell wall (3 layers)

31. Plant Cuticle Cell secretions and waxes accumulate at plant cell surface Semitransparent Restricts water loss

32. Matrixes between Animal Cells Animal cells have no cell walls Some are surrounded by a matrix of cell secretions and other material

33. Cell-to-Cell Junctions Plants –Plasmodesmata Animals –Tight junctions –Adhering junctions –Gap junctions plasmodesma

34. Animal Cell Junctions tight junctions adhering junction gap junction

35. Archaebacteria and Eubacteria DNA is not enclosed in nucleus Generally the smallest, simplest cells No organelles 4.12 Prokaryotic Cells

36. Prokaryotic Structure DNA pilus flagellum cytoplasm with ribosomes capsule cell wall plasma membrane