Organization of the Cell

1. Organization of the Cell Chapter 4 2nd edit BTT2 3/06 AD2nd edit BTT2 3/06 AD

2. Cell Theory Cells are basic units of organization and function in all living organisms All cells come from other cells All living cells have evolved from a common ancestor

3. Homeostasis Cells have many organelles, internal structures that carry out specific functions help maintain homeostasis

4. Plasma Membrane Plasma membrane surrounds the cell separates cell from external environment maintains internal conditions allows the cell to exchange materials with outer environment

5. Prokaryotes Prokaryotic cells No internal membrane organization nuclear area (not nucleus) cell wall ribosomes flagella

6. Figure 4.6: Structure of a prokaryotic cell. This colorized TEM shows a thin lengthwise slice through an Escherichia coli bacterium. Note the prominent nuclear area containing the genetic material (DNA). E. coli is a normal inhabitant of the human intestine, but under certain conditions some strains can cause infections.Figure 4.6: Structure of a prokaryotic cell. This colorized TEM shows a thin lengthwise slice through an Escherichia coli bacterium. Note the prominent nuclear area containing the genetic material (DNA). E. coli is a normal inhabitant of the human intestine, but under certain conditions some strains can cause infections.

7. Eukaryotes Eukaryotic cells membrane-enclosed nucleus cytoplasm contains organelles cytosol (fluid component)

8. Figure 4.8: Composite diagram of an animal cell. This generalized animal cell is shown in a realistic context surrounded by adjacent cells, which cause it to be slightly compressed. The TEMs show the structure of various organelles. Depending on the cell type, certain organelles may be more or less prominent.Figure 4.8: Composite diagram of an animal cell. This generalized animal cell is shown in a realistic context surrounded by adjacent cells, which cause it to be slightly compressed. The TEMs show the structure of various organelles. Depending on the cell type, certain organelles may be more or less prominent.

9. Plant Cells Plant cells rigid cell walls large vacuoles plastids chloroplasts mitochondria

10. Figure 4.7: Composite diagram of a plant cell. Chloroplasts, a cell wall, and prominent vacuoles are characteristic of plant cells. The TEMs show specific structures or areas of the cell. Some plant cells do not have all the organelles shown here. For example, leaf and stem cells that carry on photosynthesis contain chloroplasts, whereas root cells do not. Many of the organelles, such as the nucleus, mitochondria, and endoplasmic reticulum (ER), are characteristic of all eukaryotic cells.Figure 4.7: Composite diagram of a plant cell. Chloroplasts, a cell wall, and prominent vacuoles are characteristic of plant cells. The TEMs show specific structures or areas of the cell. Some plant cells do not have all the organelles shown here. For example, leaf and stem cells that carry on photosynthesis contain chloroplasts, whereas root cells do not. Many of the organelles, such as the nucleus, mitochondria, and endoplasmic reticulum (ER), are characteristic of all eukaryotic cells.

11. Cell Membranes Divide cell into compartments Vesicles: transport materials between compartments Endomembrane system Rough ER Smooth ER Golgi apparatus

12. The Nucleus Control center of cell genetic information coded in DNA Nuclear envelope double membrane Nuclear pores communicate with cytoplasm

13. Nuclear Structures Chromatin DNA and protein Chromosomes DNA condensed for cell division Nucleolus ribosomal RNA synthesis ribosome assembly

14. The Nucleus

15. Endoplasmic Reticulum (ER) Network of folded membranes in cytosol Smooth ER lipid synthesis calcium ion storage detoxifying enzymes Rough ER ribosomes on outer surface produces proteins

16. ER

17. The Golgi Complex Processes proteins synthesized by ER Manufactures lysosomes Cisternae stacks of flattened membranous sacs

18. Other Organelles Lysosomes enzymes break down structures Vacuoles store materials in plant cells Peroxisomes produce and degrade hydrogen peroxide (catalase)

19. Mitochondria Site of aerobic respiration Double membrane inner membrane folded (cristae) matrix (cristae and inner compartment)

20. Mitochondria

21. Plastids Plastids organelles that produce and store food in cells of plants and algae Chloroplasts plastids that carry out photosynthesis

22. Chloroplast Structure Stroma fluid-filled space enclosed by inner membrane of chloroplast Grana stacks of membranous sacs (thylakoids) suspended in stroma

23. Chloroplasts

24. Photosynthesis Chlorophyll green pigment in thylakoid membranes traps light energy Light energy converted to chemical energy in ATP used to synthesize carbohydrates from carbon dioxide and water

25. The Cytoskeleton Microtubules hollow tubulin cylinders role in cell division Microfilaments actin filaments important in cell movement Intermediate filaments strengthen cytoskeleton stabilize cell shape

26. Cytoskeleton

27. Centrosome Anchor microtubules Usually contains two centrioles Each centriole has 9 x 3 arrangement of microtubules

28. Figure 4.24: Centrioles.Figure 4.24: Centrioles.

29. Cilia and Flagella Cilia and flagella thin, movable structures project from cell surface function in movement Cilia are short…flagella are long

30. Flagella Bacterial flagella: composed of flagellin rotates like a propeller Eukaryotic flagella: composed of microtubules 9 + 2 arrangement wave back and forth

31. Figure 4.25: Structure of cilia.Figure 4.25: Structure of cilia.

32. Cell Coat Glycocalyx (cell coat) Surrounds cell Polysaccharides extend from plasma membrane

33. ECM Extracellular matrix (ECM) Surrounds many animal cells Carbohydrates and protein Fibronectins glycoproteins of ECM bind to integrins Integrins receptor proteins in plasma membrane

34. ECM

35. Cell Wall Cellulose & other polysaccharides form rigid cell walls in bacteria, fungi, and plant cells

36. Figure 4.29: Plant cell walls. The cell walls of two adjacent plant cells are labeled in this TEM. The cells are cemented together by the middle lamella, a layer of gluelike polysaccharides called pectins. A growing plant cell first secretes a thin primary wall that is flexible and can stretch as the cell grows. The thicker layers of the secondary wall are secreted inside the primary wall after the cell stops elongating.Figure 4.29: Plant cell walls. The cell walls of two adjacent plant cells are labeled in this TEM. The cells are cemented together by the middle lamella, a layer of gluelike polysaccharides called pectins. A growing plant cell first secretes a thin primary wall that is flexible and can stretch as the cell grows. The thicker layers of the secondary wall are secreted inside the primary wall after the cell stops elongating.