Chapter 3 Cells and Their Functions

1. Chapter 3Cells and Their Functions

2. Key Terms

3. The Cell Cytology • The study of cells The Cell • The basic unit of life • Shows life characteristics • Organization • Metabolism • Responsiveness • Homeostasis • Growth • Reproduction

4. Microscopes Microscope • An instrument that magnifies structures not visible to the naked eye • Types of microscopes: • Compound light microscope • Transmission electron microscope • Scanning electron microscope

5. Microscopes (cont.) Figure 3-1 Cilia photographed under three different microscopes.

6. Microscopes (cont.) ? Pop Quiz 3.1 Which microscope is most commonly used in laboratories? • Scanning electron microscope • Transmission electron microscope • Compound light microscope • Simple light microscope

7. Microscopes (cont.) ? Pop Quiz Answer 3.1 Which microscope is most commonly used in laboratories? • Scanning electron microscope • Transmission electron microscope • Compound light microscope • Simple light microscope

8. Cell Structure (cont.) General Cell Organization • Plasma membrane • Nucleus • Cytoplasm • Cytosol • Organelles

9. Cell Structure (cont.) Plasma Membrane • Encloses cell contents • Regulates what enters and leaves cell • Participates in many cell activities (e.g., growth, reproduction, cell-to-cell interactions) • Plasma membrane components • Phospholipid bilayer • Cholesterol • Proteins

10. Cell Structure (cont.) Table 3-1Proteins in the Plasma Membrane and Their Functions

11. Cell Structure (cont.) Figure 3-3 The plasma membrane. Why is the plasma membrane described as a bilayer?

12. Cell Structure (cont.) Plasma Membrane (cont.) • Membrane potential • The difference in electric charge on either side of the plasma membrane • Caused by separation of positive and negative ions and proteins on either side of the membrane • Ion concentrations are determined by • Channels • Pumps • Membrane potential allows the plasma membrane to act as a battery. It uses electrical energy to power membrane functions.

13. Cell Structure (cont.) Nucleus • Largest organelle of cell • Surrounded by a nuclear membrane • Contains • Chromosomes • Units of heredity; govern all cellular activity • Nucleolus • Assembles ribosomes

14. Cell Structure (cont.) Cytoplasm • Material between the nuclear membrane and plasma membrane • Cytosol • Fluid portion of cytoplasm • Organelles • Specialized cell structures that perform different cell functions

15. Cell Structure (cont.) Table 3-2Cell Parts

16. Cell Structure (cont.) Surface Projections • Structures that extend from the cell • Cilia • Short, hairlike projections • Move fluids around cells • Flagellum • Long, whiplike extension from the cell • Moves cell

17. Cell Structure (cont.) Cellular Diversity • Cell shape is related to cell function. • A neuron’s long fibers transmit electric energy from place to place in the nervous system. • Small round red blood cells slide through tiny blood vessels. • Cell organelle number is related to cell function. • Lipid-producing cells have lots of smooth ER. • Metabolically active cells have lots of mitochondria to manufacture ATP.

18. Cell Structure (cont.) Figure 3-4 Cellular diversity. Which of the cells shown would best cover a large surface area?

19. Cell Structure (cont.) ? Pop Quiz 3.2 What is the main substance of the plasma membrane? • Cholesterol • Phospholipid • Protein • Steroid

20. Cell Structure (cont.) ? Pop Quiz Answer 3.2 What is the main substance of the plasma membrane? • Cholesterol • Phospholipid • Protein • Steroid

21. Cell Structure (cont.) ? Pop Quiz 3.3 Which organelle generates ATP? • Centriole • Golgi apparatus • Mitochondrion • Ribosome

22. Cell Structure (cont.) ? Pop Quiz Answer 3.3 Which organelle generates ATP? • Centriole • Golgi apparatus • Mitochondrion • Ribosome

23. Movement of Substances across the Plasma Membrane (cont.) Selective Permeability • Plasma membrane regulates what enters and leaves. • Travel across membrane is based on several factors. • Molecular size • Solubility • Electrical charge • Types of travel: • Movement that does not require cellular energy • Movement that requires cellular energy

24. Movement of Substances across the Plasma Membrane (cont.) Figure 3-5 Diffusion of a solid in a liquid.

25. Movement of Substances across the Plasma Membrane (cont.) Figure 3-6 Diffusion using transporters. How would a change in the number of transporters affect a solute’s movement by facilitated diffusion?

26. Movement of Substances across the Plasma Membrane (cont.) Figure 3-7 A simple demonstration of osmosis. What would happen in this system if the solute could pass through the membrane?

27. Movement of Substances across the Plasma Membrane (cont.) Figure 3-8 Osmotic pressure. What would happen to osmotic pressure if the concentration of solute were increased on side B of this system?

28. Movement of Substances across the Plasma Membrane (cont.) How Osmosis Affects Cells • Another way to think about osmosis is in terms of solute concentration. Water Follows the Salt High solute Low water Low solute High water Osmosis

29. Movement of Substances across the Plasma Membrane (cont.) Table 3-3 Solutions and Their Effects on Cells

30. Movement of Substances across the Plasma Membrane (cont.) Figure 3-9 The effect of osmosis on cells. What would happen to red blood cells in the body if blood lost through injury were replaced with pure water?

31. Movement of Substances across the Plasma Membrane (cont.) Table 3-4 Membrane Transport

32. Movement of Substances across the Plasma Membrane (cont.) Figure 3-10 Phagocytosis.

33. Movement of Substances across the Plasma Membrane (cont.) Figure 3-11 Exocytosis.

34. Movement of Substances across the Plasma Membrane (cont.) ? Pop Quiz 3.4 Which process uses transporters but not ATP? • Active transport • Endocytosis • Facilitated diffusion • Simple diffusion

35. Movement of Substances across the Plasma Membrane (cont.) ? Pop Quiz Answer 3.4 Which process uses transporters but not ATP? • Active transport • Endocytosis • Facilitated diffusion • Simple diffusion

36. Movement of Substances across the Plasma Membrane (cont.) ? Pop Quiz 3.5 Which method transports bulk amounts of material into the cell using vesicles? • Active transport • Endocytosis • Exocytosis • Osmosis

37. Movement of Substances across the Plasma Membrane (cont.) ? Pop Quiz Answer 3.5 Which method transports bulk amounts of material into the cell using vesicles? • Active transport • Endocytosis • Exocytosis • Osmosis

38. Movement of Substances across the Plasma Membrane (cont.) ? Pop Quiz 3.6 Cells crenate when they are placed in solutions that are • Catatonic • Hypertonic • Hypotonic • Isotonic

39. Movement of Substances across the Plasma Membrane (cont.) ? Pop Quiz Answer 3.6 Cells crenate when they are placed in solutions that are • Catatonic • Hypertonic • Hypotonic • Isotonic

40. Protein Synthesis (cont.) Overview • Proteins give a cell its structure and function. • DNA directs protein synthesis. • Nucleotides make up DNA • DNA organized into genes • Genes organized into chromosomes • RNA participates in protein synthesis but is not part of chromosomes.

41. Protein Synthesis (cont.) Figure 3-12 Chromosomes and DNA.

42. Protein Synthesis (cont.) Table 3-5 Comparison of DNA and RNA

43. Protein Synthesis (cont.) Table 3-6 The Genetic Code The nucleotide triplet code in DNA and RNA is shown for four amino acids.

44. Protein Synthesis (cont.) Table 3-7 Role of RNA

45. Protein Synthesis (cont.) Two-Step Process of Protein Synthesis • Transcription • First step; occurs in nucleus • DNA code is transcribed into mRNA by nucleotide base pairing • Translation • Second step; occurs in cytoplasm • mRNA leaves nucleus and travels to ribosomes • Ribosomes and tRNA translate mRNA into protein’s amino acid sequence

46. Protein Synthesis (cont.) Figure 3-13 Transcription.

47. Protein Synthesis (cont.) Figure 3-14 Translation.

48. Protein Synthesis (cont.) ? Pop Quiz 3.7 Which DNA nucleotide pairs with adenine? • Cytosine • Guanine • Thymine • Uracil

49. Protein Synthesis (cont.) ? Pop Quiz Answer 3.7 Which DNA nucleotide pairs with adenine? • Cytosine • Guanine • Thymine • Uracil

50. Protein Synthesis (cont.) ? Pop Quiz 3.8 Which RNA is transcribed from DNA? • Amino acid • Messenger RNA • Ribosomal RNA • Transfer RNA