1. Chapter 6 notes A Tour of the Cell

2. Concept 6.1 Light Microscope: visible light is passed through a specimen and then through glass lenses - magnification - resolving power

3. Concept 6.1 Electron Microscope: focuses beams of electrons through the specimen or onto its surface. - transmission electron microscope (TEM): used to study the internal ultrastructure of cells - Scanning electron microscope (SEM): used for detailed study of the surface

4. Concept 6.1 Cell Fractionation: take cells apart and study the fcn. of organelles - use of ultracentrifuges -fig. 7.3

5. Concept 6.2 All cells have several basic features: - have a plasma membrane - cytsol: semifluid substance that contains organelles - chromosomes/DNA - ribosomes

6. Concept 6.2 Prokaryotic cell vs. Eukaryotic cell - nucleiod vs. nucleus - eukaryotes are 10X bigger Larger organisms do not have larger cells, just more cells

7. Pili Nucleoid Ribosomes Plasma membrane Cell wall Bacterial chromosome Capsule 0.5 µm Flagella (a) A typical rod-shaped bacterium (b) A thin section through the bacterium Bacillus coagulans (TEM) Concept 6.2

8. Concept 6.2 Internal membranes compartmentalize the fcns. of a eukaryotic cell - membranes consist of a double layer of phospholipids and other lipids; attached to the surface are proteins

9. (a) TEM of a plasma membrane Outside of cell Inside of cell 0.1 µm Carbohydrate side chain Hydrophilic region Hydrophobic region Hydrophilic region Phospholipid Proteins (b) Structure of the plasma membrane Concept 6.2

10. Concept 6.2

11. Concept 6.3 The nucleus is a double membrane - inside is lined by the nuclear lamina (protein filaments that help the nucleus maintain shape) - DNA is organized w/ proteins into chromatin

12. Concept 6.3 As a cell prepares to divide, the chromatin fibers coil up into chromosomes Nucleolus: ribosomal RNA is synthesized w/ proteins into ribosomal subunits

13. Concept 6.3 Nucleus Nucleolus Chromatin Nuclear envelope: Inner membrane Outer membrane Nuclear pore Pore complex Rough ER Surface of nuclear envelope Ribosome 1 µm Close-up of nuclear envelope Pore complexes (TEM) Nuclear lamina (TEM)

14. Concept 6.3 Ribosomes: organelles that carry out protein synthesis - cells that have high rates of protein synthesis have several ribosomes - free ribosomes: - suspended in the cytosol - fcn. within the cell

15. Concept 6.3 - bound ribosomes: - attached to the outside of the ER or nuclear envelope - protein insertion into membranes, packaging (lysosomes), or export from cell (excretion)

16. Concept 6.4 Endomembrane system: made up of many different membranes Endoplasmic reticulum: manufactures membranes and performs many other biosynthetic functions - accounts for more than half the total membrane in many eukaryotic cells

17. Concept 6.4 Smooth ER: - surface lacks ribosomes - synthesis of lipids, metabolism of carbohydrates, detoxification of drugs and poisons

18. Concept 6.4 Rough ER: - specialized cells secrete proteins produced by ribosomes attached to rough ER - ex. Secretion of insulin in pancreas

19. Concept 6.4 The Golgi apparatus finishes, sorts, and ships cell products - after leaving the ER, many transport vesicles travel to the Golgi - consists of flattened sacs, called cisternae

20. Concept 6.4 A Golgi stack has distinct polarity - cis face: “receiving” side, gets material from the ER - trans face: “ shipping” side, gives rise to vesicles that will travel to other sites

21. Concept 6.4

22. Concept 6.4 Lysosomes are digestive compartments - membrane-bound sac of enzymes that digest macromolecules - different enzymes digest different molecules Many protists use lysosomes to digest food through phagocytosis

26. Concept 6.4 Vacuoles have diverse fcns. in cell maintenance - food vacuole: formed by phagocytosis - contractile vacuole: pump excess water out of a cell - central vacuole: hold reserves of organic compounds, disposal site for byproducts, contains pigments

27. Concept 6.4

29. Concept 6.5 Mitochondria and chloroplasts are organelles that convert energy that cells can use for work Membrane proteins are not made by the rough ER, but by free ribosomes Organelles also contain DNA

30. Concept 6.5 Mitochondria: site of cellular respiration - found in most all eukaryotic cells; number of mitochondria is correlated with the cells metabolic activity - enclosed in a double membrane - outer layer is smooth, inner contains infoldings called cristae (gives a large surface area)

31. Concept 6.5 - mitochondrial matrix is enclosed in the inner membrane - contains many enzymes, mitochondrial DNA, and ribosomes

32. Concept 6.5

33. Concept 6.5 Chloroplasts are specialized plant organelles (contain chlorophyll) - thylokoids: membranous system of flattened sacs (each stack is a grana) - stroma: fluid outside the thylokoids - contains chloroplast DNA and ribosomes

34. Concept 6.5