1. Copyright 2010, John Wiley & Sons, Inc. Chapter 3 Cells

2. Copyright 2010, John Wiley & Sons, Inc. Cell Structure Plasma membrane Cytoplasm: cytosol + organelles Nucleus

3. Copyright 2010, John Wiley & Sons, Inc. Generalized View of Cell Structure

4. Copyright 2010, John Wiley & Sons, Inc. Cell Membrane Phospholipid bilayer Cholesterol Proteins (integral and peripheral) Attached carbohydrates (glycolipids and gycoproteins)

5. Copyright 2010, John Wiley & Sons, Inc. Plasma Membrane: Chemistry and Structure

6. Copyright 2010, John Wiley & Sons, Inc. Membrane Function Barrier between inside and outside of cell Controls entry of materials: transport Receives chemical and mechanical signals Transmits signals between intra- and extra- cellular spaces Note variety of proteins in Figure 3-2.

7. Copyright 2010, John Wiley & Sons, Inc. Terminology: Body Fluid Pools Intracellular (ICF)  Within cells: 2/3 of total Extracellular (ECF):  Between cells = Interstitial  In blood vessels = Plasma  In lymphatic vessels = Lymphatic

8. Copyright 2010, John Wiley & Sons, Inc. Terminology: Solutions Solvent: the liquid doing the dissolving  Usually water Solute: the dissolved material (particles or gas) Concentration  Amount of solute in a given amount of solvent Concentration gradient  Difference in concentration between 2 areas of solution

9. Copyright 2010, John Wiley & Sons, Inc. Principle of Diffusion

10. Copyright 2010, John Wiley & Sons, Inc. Passive Transport: Simple Diffusion Requirements for simple diffusion  Concentration gradient of solute present  Solute can diffuse across a membrane if membrane is present Pathways of simple diffusion:  Pass across lipid bilayer if lipid-soluble (O 2, CO 2, N 2, fatty acids, steroids, fat-soluble vitamins), or if polar molecules (H 2 O, urea)  Pass through ion channels (which may be gated: gates open and close) if ions such as K +, Ca 2+, Cl –

11. Copyright 2010, John Wiley & Sons, Inc. Simple Diffusion

12. Copyright 2010, John Wiley & Sons, Inc. Facilitated Diffusion Requires a carrier in membrane but not ATP Solute goes down concentration gradient Maximum transport speed depends on number of carriers  insulin increases number of carriers for glucose in plasma membrane

13. Copyright 2010, John Wiley & Sons, Inc. Facilitated Diffusion

14. Copyright 2010, John Wiley & Sons, Inc. Facilitated Diffusion

15. Copyright 2010, John Wiley & Sons, Inc. Osmosis Diffusion of water across selectively permeable membrane:  Permeable to solvent  Impermeable to solute Types of solutions surrounding human RBCs  Isotonic: solution outside RBC has same concentration of solute as RBC: 0.9% NaCl  Hypotonic: solution outside of RBC has lower concentration: 0% NaCl  hemolysis  Hypertonic: solution outside of RBC has higher concentration: 4% NaCl  crenation

16. Copyright 2010, John Wiley & Sons, Inc. Osmosis

17. Copyright 2010, John Wiley & Sons, Inc. Osmosis

18. Copyright 2010, John Wiley & Sons, Inc. Active Transport Requires a carrier (called a pump) Requires energy (ATP) Can transport up a concentration gradient Critical for moving important ions Major active transport in most cells is sodium-potassium (Na + /K + ) pump

19. Copyright 2010, John Wiley & Sons, Inc. Copyright 2009 John Wiley & Sons, Inc. 19 Active Transport Solutes are transported across plasma membranes with the use of energy, from an area of lower concentration to an area of higher concentration Example: Sodium-potassium pump 1 3 Na + K + gradient Cytosol 1 3 Na + expelled 3 Na + ADP P P 2 K + imported K + gradient Na + gradient Na + /K + ATPase Extracellular fluid Cytosol 2K + ATP 234

20. Copyright 2010, John Wiley & Sons, Inc. Transport in Vesicles Requires energy (ATP) Involves small membrane sac Endocytosis: importing materials into cell  Phagocytosis: ingestion of particles such as bacteria into white blood cells (WBCs)  Pinocytosis: ingestion of fluid Exocytosis: exporting materials

21. Copyright 2010, John Wiley & Sons, Inc. Transport Across the Plasma Membrane Transport Across the Plasma Membrane Interactions Animation You must be connected to the internet to run this animation.

22. Copyright 2010, John Wiley & Sons, Inc. Cell Organelles: Table 3.2 Cytoskeleton Flagella, cilia & centrioles Endoplasmic reticulum Golgi apparatus Mitochondrion Nucleus, nucleolus, nuclear envelope Vesicles, e.g. lysosome

23. Copyright 2010, John Wiley & Sons, Inc. Cytoplasm Cell contents Includes organelles and cytosol Excludes nucleus

24. Copyright 2010, John Wiley & Sons, Inc. Cytoskeleton Maintains shape of cell Positions organelles Changes cell shape Includes: microfilments, intermediate filaments, microtubules

25. Copyright 2010, John Wiley & Sons, Inc. Centrosome Structure:  Two centrioles arranged perpendicular to each other Composed of microtubules: 9 clusters of 3 (triplets)  Pericentriolar material Composed of tubulin that grows the mitotic spindle Function: moves chromosomes to ends of cell during cell division

26. Copyright 2010, John Wiley & Sons, Inc. Centrosome

27. Copyright 2010, John Wiley & Sons, Inc. Cilia and Flagella Specialized for motion Flagellum: single tail like structure on sperm  Propels sperm forward in reproductive tract Cilia: in groups  Found in respiratory system: move mucus

28. Copyright 2010, John Wiley & Sons, Inc. Ribosomes Made within the nucleus (in nucleolus) Sites of protein synthesis (on E.R. or freely within cytoplasm) Consist of ribosomal RNA (rRNA) + proteins Contain large and small subunits Can be attached to endoplasmic reticulum or free in cytosol

29. Copyright 2010, John Wiley & Sons, Inc. Endoplasmic Reticulum (E.R.) Structure: network of folded membranes Functions: synthesis, intracellular transport Types of E.R.  Rough E.R.: studded with ribosomes (sites of protein synthesis)  Smooth E.R. lacks ribosomes. Functions: lipid synthesis release of glucose in liver cells into bloodstream drug detoxification (especially in liver cells) storage and release of Ca 2+ in muscle cells (where smooth E.R. is known as sarcoplasmic reticulum or SR)

30. Copyright 2010, John Wiley & Sons, Inc. Endoplasmic Reticulum (E.R.)

31. Copyright 2010, John Wiley & Sons, Inc. Structure:  Flattened membranes (cisterns) with bulging edges (like stacks of pita bread) Functions:  Modify proteins  glycoproteins and lipoproteins that: Become parts of plasma membranes Are stored in lysosomes, or Are exported by exocytosis Golgi Complex

32. Copyright 2010, John Wiley & Sons, Inc. Golgi Complex

33. Copyright 2010, John Wiley & Sons, Inc. Small Bodies Lysosomes: contain digestive enzymes  Help in final processes of digestion within cells  Carry out autophagy (destruction of worn out parts of cell) and death of old cells (autolysis)  Tay-Sachs: hereditary disorder; one missing lysosomal enzyme leads to nerve destruction Peroxisomes: detoxify; abundant in liver Proteasomes: digest unneeded or faulty proteins  Faulty proteins accumulate in brain cells in persons with Parkinson or Alzheimer disease.

34. Copyright 2010, John Wiley & Sons, Inc. Mitochondria Structure:  Sausage-shaped with many folded membranes (cristae) and liquid matrix containing enzymes  Have some DNA, ribosomes (can make proteins) Function:  Nutrient energy is released and trapped in ATP; so known as “power houses of cell”  Chemical reactions require oxygen Abundant in muscle, liver, and kidney cells  These cells require much ATP

35. Copyright 2010, John Wiley & Sons, Inc. Mitochondria

36. Copyright 2010, John Wiley & Sons, Inc. Nucleus Round or oval structure surrounded by nuclear envelope with nuclear pores Contains nucleolus: makes ribosomes that pass into cytoplasm through nuclear pores Store genetic material (DNA) in genes arranged in 46 chromosomes (the human genome containing 30,000 genes!) DNA contains information for directing protein synthesis:  In this cell  In new cells (formed by cell reproduction)

37. Copyright 2010, John Wiley & Sons, Inc. Nucleus

38. Copyright 2010, John Wiley & Sons, Inc. Protein Synthesis 2 steps:  Nuclear = transcription  Cytoplasmic = translation

39. Copyright 2010, John Wiley & Sons, Inc. Protein Synthesis: Transcription

40. Copyright 2010, John Wiley & Sons, Inc. Protein Synthesis: Transcription

41. Copyright 2010, John Wiley & Sons, Inc. Transcription In nucleus RNA polymerase (enzyme) transcribes DNA into RNA; complementary base pairs  C-G, G-C, T-A, A-U Types of RNA formed:  1. Messenger RNA (mRNA) Directs synthesis of polypeptide  2. Ribosomal RNA Component of ribosomes  3. Transfer RNA (tRNA) Carries amino acids to ribosome for reaction

42. Copyright 2010, John Wiley & Sons, Inc. Translation Requires 3 different RNAs Messenger RNA- from nucleus (mRNA) direct sequencing of amino acids Ribosomes contain ribosomal RNA (rRNA) and are the sites of translation Transfer RNA- carry amino acids (tRNA) to sites on mRNA

43. Copyright 2010, John Wiley & Sons, Inc. 1 Key: Initiator tRNA attaches to a start codon. Amino acid (methionine) Anticodon mRNA binding site Initiator tRNA Start codon Small subunit = Adenine = Guanine = Cytosine = Uracil U U U G G G G G G A A A A A U A C C U C U A A C U C 1 Key: Initiator tRNA attaches to a start codon. Large and small ribosomal subunits join to form a functional ribosome and initiator tRNA fits into P site. Amino acid (methionine) Anticodon mRNA binding site Initiator tRNA Start codon Small subunit Initiator tRNA Small subunit Large subunit P site A site = Adenine = Guanine = Cytosine = Uracil U U U G G G G G G A A A A A U A C C U C U A A C U C G A U U U G G A A A A A C C G G U C U A C U U A C G 2 Translation

44. Copyright 2010, John Wiley & Sons, Inc. Translation

45. Copyright 2010, John Wiley & Sons, Inc. Translation

46. Copyright 2010, John Wiley & Sons, Inc. Translation

47. Copyright 2010, John Wiley & Sons, Inc. Translation

48. Copyright 2010, John Wiley & Sons, Inc. Translation

49. Copyright 2010, John Wiley & Sons, Inc. Translation

50. Copyright 2010, John Wiley & Sons, Inc. Somatic Cell Division In all body cells except gametes Interphase  Period of growth and development of cell  Preparation for reproduction: DNA synthesis Mitotic Phase = division of nucleus  4 phases Cytokinesis= division of cytoplasm

51. Copyright 2010, John Wiley & Sons, Inc. 1 Pericentriolar material Nucleolus Nuclear envelope Chromatin Plasma membrane Cytosol (a) INTERPHASE Centrioles Centrosome: all at 700x LM 1 Late Early Pericentriolar material Nucleolus Nuclear envelope Chromatin Plasma membrane Cytosol Chromosome (two chromatids joined at centromere (a) INTERPHASE (b) PROPHASE Centrioles Centrosome: Fragments of nuclear envelope Mitotic spindle (microtubules) Kinetochore 2 all at 700x LM Centromere 1 Pericentriolar material Nucleolus Nuclear envelope Chromatin Plasma membrane Cytosol Metaphase plate (a) INTERPHASE Centrioles Centrosome: (c) METAPHASE 2 3 Late Early (b) PROPHASE Fragments of nuclear envelope Mitotic spindle (microtubules) Kinetochore all at 700x LM Chromosome (two chromatids joined at centromere Centromere 1 Early Late (d) ANAPHASE Pericentriolar material Nucleolus Nuclear envelope Chromatin Plasma membrane Cytosol Chromosome (a) INTERPHASE Centrioles Centrosome: (c) METAPHASE 2 3 4 Cleavage furrow Late Early (b) PROPHASE Fragments of nuclear envelope Mitotic spindle (microtubules) Kinetochore Metaphase plate all at 700x LM Chromosome (two chromatids joined at centromere Centromere 1 Early Late (d) ANAPHASE Pericentriolar material Nucleolus Nuclear envelope Chromatin Plasma membrane Cytosol (a) INTERPHASE Centrioles Centrosome: Cleavage furrow (e) TELOPHASE (c) METAPHASE 2 3 4 5 Cleavage furrow Late Early (b) PROPHASE Fragments of nuclear envelope Mitotic spindle (microtubules) Kinetochore Metaphase plate Chromosome all at 700x LM Chromosome (two chromatids joined at centromere Centromere 1 Early Late (d) ANAPHASE Pericentriolar material Nucleolus Nuclear envelope Chromatin Plasma membrane Cytosol (a) INTERPHASE Centrioles Centrosome: (f) IDENTICAL CELLS IN INTERPHASE Cleavage furrow (e) TELOPHASE (c) METAPHASE Cleavage furrow 2 3 4 5 6 Late Early (b) PROPHASE Fragments of nuclear envelope Mitotic spindle (microtubules) Kinetochore Metaphase plate Chromosome all at 700x LM Centromere Chromosome (two chromatids joined at centromere Mitosis

52. Copyright 2010, John Wiley & Sons, Inc. Prophase Chromatin condenses into pairs of chromatids connected at centromeres Centrosomes form the mitotic spindle (composed of microtubules) that extends from pole to pole of the cell  Some chemotherapy drugs fight cancer cells by inhibiting formation of the mitotic spindle Nuclear envelope and nucleolus break down

53. Copyright 2010, John Wiley & Sons, Inc. Prophase

54. Copyright 2010, John Wiley & Sons, Inc. Metaphase Centromeres of chromatid pairs are aligned along microtubules at the center (“equator”) of the metaphase plate

55. Copyright 2010, John Wiley & Sons, Inc. Metaphase

56. Copyright 2010, John Wiley & Sons, Inc. Anaphase Centromeres split, separating “sister chromatids” (chromosomes) Chromosomes are pulled to opposite ends of spindle by microtubules of the mitotic spindle Cytokinesis (division of cytoplasm) begins by the formation of a cleavage furrow

57. Copyright 2010, John Wiley & Sons, Inc. Anaphase

58. Copyright 2010, John Wiley & Sons, Inc. Telophase Chromosomes revert to threadlike chromatin Nuclear envelope and nucleolus reappear Mitotic spindle breaks up Cytokinesis is completed

59. Copyright 2010, John Wiley & Sons, Inc. Cellular Diversity Because structure determines function, cells differ in structure related to their functions.  Nerve cells may reach several feet in length to carry nerve impulses from spinal cord to toe  Muscle cells can produce effective contractions because they are cylindrical or spindle-shaped  Microvilli increase surface area of intestinal cells to maximize absorptive ability Most cells are microscopic; the diameter of the largest human cell (an oocyte) can barely be seen with the unaided eye.

60. Copyright 2010, John Wiley & Sons, Inc. Aging A number of factors contribute to aging:  May be programmed genetically  Decreased rate of mitosis; nerve cells and skeletal muscle cells cannot be replaced  Telomeres (DNA at tips of chromosomes) Telomeres shorten with aging Progeria (rapid aging): profound telomere shortening  Protein damage by glucose cross-links  Free radicals damage. (See Focus on Wellness: action of antioxidants to reduce effects of free radicals.)  Autoimmune responses

61. Copyright 2010, John Wiley & Sons, Inc. End of Chapter 3 Copyright 2010 John Wiley & Sons, Inc. All rights reserved. Reproduction or translation of this work beyond that permitted in section 117 of the 1976 United States Copyright Act without express permission of the copyright owner is unlawful. Request for further information should be addressed to the Permission Department, John Wiley & Sons, Inc. The purchaser may make back-up copies for his/her own use only and not for distribution or resale. The Publishers assumes no responsibility for errors, omissions, or damages caused by the use of theses programs or from the use of the information herein.