1. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 3 Lecture Slides

2. Functions Basic unit of life Synthesis of molecules Communication Cell metabolism and energy release Reproduction and inheritance (DNA) 2

3. Cell Structure Organelles: - specialized structures in cells that perform specific functions - Ex. Nucleus, mitochondria, ribosomes, etc. Cytoplasm: jelly-like substance that holds organelles 3

4. 4 Cell Membrane What is it? outermost component of a cell Functions: - selective barrier - encloses cytoplasm Extracellular: material outside cell Intracellular: material inside cell

5. 5 Structure of Cell Membrane Called Fluid Mosaic Model Made of phospholipids and proteins Phospholipids form a double layer or bilayer Phospholipids contain 2 regions: polar and nonpolar

6. 6 Polar regions: - “heads” - hydrophilic (H 2 O loving) - exposed to H 2 O Nonpolar regions: - “tails” - hydrophobic (H 2 O fearing) - away from H 2 O

7. 7 Figure 2.14b

8. Figure 3.2a

9. 9 Movement through Cell Membrane Cell membrane selectively determines what can pass in and out of the cell. Enzymes, glycogen, and potassium are found in higher concentrations INSIDE the cell. Sodium, calcium, and chloride are found in higher concentrations OUTSIDE the cell.

10. 10 Ways molecules Pass through Cell Membrane 1.Directly through (diffusion): O 2 and CO 2 (small molecules) 2.Membrane channels: - proteins that extend from one side of cell membrane to other - size, shape, and charge (+/-) determine what can go through - Ex. Na + passes through Na + channels

12. 12 3.Carrier molecules: - bind to molecules, transport them across, and drop them off - Ex. glucose 4.Vesicles: - can transport a variety of materials - fuse with cell membrane

13. Figure 3.7

15. 15 Diffusion What is it? movement of molecules from areas of high to low concentration Solution: solid, liquid, or gas that contains one or more solutes Solute: substance added to solvent that dissolves Solvent: substance such as H 2 O that solute is being added to Ex. Add salt to H 2 O. H 2 O =solvent, salt=solute, mixture=solution

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18. 18 Concentration gradient: - measures conc. difference at 2 points - greater the distance the faster the solute will travel Filtration: movement of fluid through a partition with holes

19. 19 Mediated Transport Mechanisms Facilitated diffusion: - diffusion with aid of a carrier molecule - requires no ATP Active transport: - moves substances from low to high conc. - requires ATP - Ex. Sodium-potassium pump

22. 22 Osmosis What is it? diffusion of water across a cell membrane Osmotic pressure: force required to prevent movement of water across cell membrane

24. 24 Types of Osmotic Solutions Hypotonic solution: - lower conc. of solutes outside cell - higher conc. of H 2 O outside cell - H 2 O moves into cell - lysis (burst) Hypertonic solution: - higher conc. of solutes outside cell - higher conc. H 2 O inside cell - H 2 O moves out - crenation (shrinks)

25. 25 Isotonic solution: - equal conc. of solutes - water doesn’t move - cell remains intact

27. 27 Endocytosis What is it? process that brings materials into cell using vesicles 2 types - Phagocytosis: cell eating (solid particles) - Pinocytosis: cell drinking (liquid particles)

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29. 29 Exocytosis What is it? process that carries materials out of cell using vesicles

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33. 33 Cell Structures Cytoplasm Location: inside cell Characteristic: jelly-like fluid Function: give cell shape and hold organelles in place Nucleus Location: center of cell Characteristic: all cells contain nucleus at some point Function: houses DNA

35. Nuclear envelope: Location: edge of nucleus Nuclear pores: Location: surface of nucleus Function: where materials pass in and out of nucleus 35

36. Figure 3.12a

37. Chromosome: Location: inside nucleus Characteristic: made of DNA and proteins Function: part of genetic makeup Chromatin: Location: inside nucleus Characteristic: loosely coiled chromosomes 37

39. 39 Nucleolus Location: in nucleus Function: produce ribosomes Ribosome Location: attached to RER or cytoplasm Function: produce proteins

40. 40 RER (Rough Endoplasmic Reticulum) Location: cytoplasm Characteristic: membranes with ribosomes attached Function: site of protein synthesis SER (Smooth Endoplasmic Reticulum) Location: cytoplasm Characteristic: membranes with no ribosomes Function: site of lipid synthesis (Ex. Cholesterol)

41. Figure 3.15a

42. 42 Golgi apparatus Location: cytoplasm Characteristic: closely, packed stacks of membranes Function: collect, sort, package, and distribute proteins and lipids Secretory vesicle Location: cytoplasm Function: distributes materials out of cell

44. 44 Lysosome Location: cytoplasm Function: enzymes that digest foreign material Mitochondria Location: cytoplasm Characteristic: contains folds (cristae) Function: produces ATP

47. 47 Cilia Location: cell surface Characteristic: many per cell Function: move materials across cell’s surface Flagella Location: cell surface Characteristic: 1 per cell Function: move cell, Ex. sperm

48. 48 Microvilli Location: cell surface Characteristic: shorter than cilia Function: increase surface area

49. 49 Cytoskeleton What is it? - cell’s framework - made of proteins Functions: - provide support - hold organelles in place - enable cell to change shape

50. 50 Types of Cytoskeleton Microtubules: - largest diameter - provide structural support - form cilia and flagella Intermediate filaments: - medium diameter - maintain cell shape Microfilaments: - smallest diameter - involved in cell movement

52. Whole Cell Activity A cell’s characteristics are determine by the type of proteins produced Proteins’ function is determined by genetics Information in DNA provides the cell with a code for its cellular processes 52

53. DNA What is it? - double helix in nucleus - composed of nucleotides - contains 5 carbon sugar (deoxyribose, nitrogen base, phosphate 53

55. Flow of Genetic Information Also called Central Dogma Occurs in three stages: –DNA replication –Transcription –Translation

56. DNA Replication

57. Gene Expression What is it? - information in DNA directs protein synthesis - proteins provide code for gene expression - enzymes regulate chemical reactions - uses transcription and translation 57

59. Transcription What is it? - process by which DNA is “read” - occurs in ribosomes - produces mRNA (messenger RNA) - mRNA contains codons - codons: set of 3 nucleotide bases that code for a particular amino acid 59

61. Translation What is it? - process by mRNA is converted into amino acids (polypeptides) - produces proteins - codons pair with anticodons - anticodons: 3 nucleotide bases carried by tRNA 61

63. Cell Division What is it? - formation of 2 daughter cells from a single parent cell - uses mitosis and meiosis - each cell (except sperm and egg) contains 46 chromosomes (diploid) - sperm and egg contain 23 chromosomes 63

64. Mitosis What is it? - cell division that occurs in all cells except sex cells - forms 2 daughter cells 64

65. Components of Mitosis Chromatid: 2 strands of chromosomes that are genetically identical Centromere: where 2 chromatids are connected Centrioles: small organelle composed of 9 triplets 65

67. Stages in Mitosis 1.Interphase: - time between cell divisions - DNA is in strands (chromatin) - DNA replication occurs 2. Prophase: - chromatin condenses into chromosomes - centrioles move to opposite ends 67

68. 3.Metaphase: chromosomes align 4.Anaphase: - chromatids separate to form 2 sets of chromosomes - chromosomes move towards centrioles 5.Telophase: - chromosomes disperse - nuclear envelopes and nucleoli form - cytoplasm divides to form 2 cells 68