Cell. ~ 75 trillion make up adult Living cells ~ 60% water Carry materials for exchange

Transcription

1 Chapter 3 Cells 1

2 Cell ~ 75 trillion make up adult Living cells ~ 60% water Carry materials for exchange 2

3 Cell Shapes Shape and size vary Ex: Nerve cells can be 3ft long! Epithelial often flat and thin Cell structure reflects function Ex: Nerve cells Muscle cells RBCs 3

4 Composite Cell Shows common cell structures No one type of cell 4

5 Cell Theory 1) Building blocks of organisms 2) Smallest functional unit 3) Come from other cells 4) Each maintains homeostasis

6 3 main regions 1)Nucleus Usually in center 2)Cytoplasm Semifluid surrounding organelles 3)Cell membrane Forms the outer boundary Composite Cell 6

7 Control center Contains genetic material DNA Blueprint for life Instructions for making proteins 1) Nucleus RBCs eject nucleus 7

8 Three regions: 1) Nucleus A) Nuclear envelope Nuclear pores B) Nucleolus C) Chromatin 8

9 1) Nucleus A)Nuclear envelope Outer boundary Double membrane Selectively permeable Nuclear pores Protein lined channels Allows certain substances in/out 9

10 B)Nucleolus 1) Nucleus Nucleoli = plural Inside nucleus One or two Dark staining Help build ribosomes 10

11 1) Nucleus C)Chromatin DNA long and thin Cell not dividing Chromosomes DNA coiled up Rod-like When cell divides 11

12 12

13 2) Cytoplasm Outside nucleus but inside cell membrane Where most cellular activity occurs 13

14 2) Cytoplasm A) Cytosol Clear liquid B) Organelles and membranes Metabolic machinery C) Cytoskeleton Framework formed by protein rods and tubules 14

15 Contains: Organelles Little organs Most bound by membranes Specific functions 2) Cytoplasm 15

16 Gate keeper Plasma membrane Outer boundary Thin, fragile, transparent 3) Cell Membrane Selectively permeable Bilayer of phospholipids and proteins 16

17 3) Cell Membrane 17

18 3) Cell Membrane Phospholipids Heads = hydrophilic (water loving) Interacts with water Tails = hydrophobic (water hating) Impermeable to water soluble molecules 18

19 Bilayer of phospholipids Carbs on some Also contains cholesterol 3) Cell Membrane 19

20 3) Cell Membrane Proteins Scattered Specialized functions: Receptors Messengers Hormones Transport Pores Carriers 20

21 Proteins in Membrane Transmembrane = membrane spanning - extend through lipid layer - may protrude to face(s) 21

22 22

23 Surface of Cell Membrane Microvilli Tiny, finger-like projections Increase surface area More absorption Ex: in small intestine 23

24 Organelles 24

25 Powerhouse Double membrane Cristae Inner membrane Folded Mitochondria 25

26 Site of cellular respiration Mitochondria Oxygen used to break down foods Energy released Heat ATP 26

27 Ribosomes Protein factories Site of protein synthesis Tiny round organelles Free floating of attached Made of protein + RNA 27

28 Endoplasmic Reticulum (ER) System of canals, sacs, and vesicles throughout cytoplasm Transports materials Connects w/ cell membrane, nuclear envelope, and organelles 28

29 Rough ER Endoplasmic Reticulum Has ribosomes Makes proteins Proteins enclosed in part of ER membrane Moves proteins being synthesized 29

30 Smooth ER Endoplasmic Reticulum No ribosomes Not involved in protein synthesis Contains enzymes important in lipid synthesis Fat absorption Metabolism of drugs 30

31 Post office Stack of ~ 6 flattened sacs Golgi Apparatus Modifies, packages, delivers proteins synthesized by ribosomes on rough ER 31

32 A) Proteins come in B) Chemically changed C) Part of apparatus pinches off to form transport vesicles D) Travel to cell membrane, fuses, and released outside Ex: Digestive enzymes Mucus Golgi Apparatus 32

33 Exocytosis = releases contents to outside of cell Also packages for inside cell use Ex: Glycoproteins for organelle use Golgi Apparatus 33

34 Bulk Transport 34

35 Lysosomes garbage disposal Sacs of powerful digestive enzymes Abundant in WBCs Digest engulfed bacteria Digest worn out cell structures 35

36 Peroxisomes Sacs of powerful enzymes Detoxify harmful substances Ex: Alcohols Hydrogen peroxide Disarm free radicals Highly reactive chemicals Can scramble proteins and nucleic acids Abundant in liver and kidney cells 36

37 Cytoskeleton Network of protein structures in cytoplasm Components: 1) Microfilaments Tiny rods of Actin (protein) Cell movement 2) Microtubules Long, skinny tubes Made of tubulin proteins 9+2 pattern 9 outside tubes around 2 inner Determines shape 37

38 Cytoskeleton Shape Support Intracellular transport Cell movements 38

39 Near nucleus and Golgi Body Made of 2 centrioles At right angles Made of microtubules Function in cell division Distribute chromosomes Centrosome 39

40 Microvilli Membrane extensions Contain microfilaments Increase surface area Absorption Ex: intestine 40

41 Membrane extension Contain microtubules Usually many Short Move substances along cell surface Ex: respiratory system move mucus Cilia 41

42 Flagella Projections on cell surface Usually just one Long Move cell Only example in human: sperm 42

43 Plasma Membrane Transport Aqueous Solutions Substances dissolved in water Intracellular fluid Fluid within cell Cytosol Nucleoplasm Interstitial fluid Outside of cell (between cells) Contains: Nutrients Hormones Salts 43

44 Plasma Membrane Transport Transport Movement of materials through the membrane Types Selectively permeable Passive transport Active transport 44

45 Passive Transport No energy required Move down concentration gradient Difference in concentration across an area Faster if: Smaller Warmer 45

46 Passive Transport 1)Diffusion Movement of particles from areas of greater concentration to areas of lesser concentration 46

47 2) Osmosis Passive Transport Diffusion of water across a selectively permeable membrane Passes through pores Based on concentration of water Higher to lower conc. 47

48 Osmosis and Cells Compares concentration of solutions inside and outside of cells Types of solutions: Hypertonic Hypotonic Isotonic 48

49 Osmosis and Cells 49

50 50

51 3) Facilitated Diffusion Ex: Passive Transport Protein carrier needed Particles move down concentration gradient No energy needed Glucose Too big for pores Lipid insoluble How Facilitated Diffusion Works 51

52 Passive Transport 4) Filtration Water and solutes are forced through a membrane by fluid hydrostatic pressure 52

53 Active Transport Uses ATP (energy) Moving against concentration gradient Low to high Particles: Too big Lipid insoluble 53

54 Active Transport Uses carrier proteins Like facilitated diffusion Ex: Amino acids Some sugars Some ions 54

55 Active Transport 1) Sodiumpotassium pump Potassium ions in (2) Sodium ions out (3) Needed for nerve impulses How the Sodium Potassium Pump Works 55

56 Active Transport 2) Vesicular Transport: A) Exocytosis Moves substances out of the cell B) Endocytosis Moves substances into the cell 56

57 A) Exocytosis Vesicle moves to membrane, fuses and then ruptures Ex: Hormones, mucus, proteins, and wastes 57

58 Membrane pouches inward forming vesicle Vesicle moves into cytoplasm B) Endocytosis 58

59 3 types: 1) Phagocytosis Cell eating B) Endocytosis Ex: Certain WBCS ingest bacteria and dead cells 59

60 2) Pinocytosis Cell drinking B) Endocytosis Ingests extracellular fluid 60

61 B) Endocytosis 3) Receptor-mediated protein molecules extend thru membrane to outer surface and bind with specific substances Ex: Cholesterol entering cell 61

62 Deoxyribonucleic acid Contains genetic code Genes code for specific proteins Genome all of the DNA in a cell DNA 62

63 Review - DNA Sugar and phosphate form backbone Nitrogen bases form rungs of ladder Complimentary base pairing Adenine with Thymine Guanine with Cytosine Twisted; double helix 63

64 Protein Synthesis Gene Expression 2 steps Transcription + Translation Genetic code method of storing info in DNA Sequence of nucleotides codes for aa Sequence of aa codes for proteins 64

65 RNA Single stranded Ribose instead of deoxyribose Uracil instead of thymine 65

66 Protein Synthesis Step 1 Transcription Copies genes Occurs in nucleus Makes mrna Synthesized from DNA 66

67 RNA mrna Contains triplets called codons code for aa moves out of nucleus and meets with ribosome 67

68 Protein synthesis Step 2 Translation Occurs in cytoplasm At ribosome trna with anticodon brings aa to ribosome Binds to codon aa form proteins 68

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71 DNA replication New cell has exact replica of parent DNA Occurs during interphase DNA molecule splits Complimentary strands formed Each new DNA molecule has 1 new and 1 old strand Teachers' Domain: From DNA to Protein 71

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73 Mutation Permanent change in DNA Can be fatal Can result from single nucleotide 73

74 Life of a Cell Begins when new cell forms Ends when cell divides 74

75 Series of changes from the time cell forms until it divides Cell cycle parts: Interphase Mitosis Cytokinesis The Cell Cycle 75

76 Interphase Longest part Looks normal 3 phases 1) G 1 = Cell Growth Hours to weeks 2) S = Synthesis 6-8 hours 3) G 2 = Cell growth Brief 76

77 Divides nucleus Mitosis Continuous Cells genetically same 4 stages: 1) Prophase 2) Metaphase 3) Anaphase 4) Telophase 77

78 Chromosomes become visible Centrioles separate Mitotic spindles form Nuclear membrane dissolves 1) Prophase 78

79 2) Metaphase Chromosomes line up equator of the cell 79

80 Centromeres split 3) Anaphase Chromatids separate now individual chromosomes Move toward opposite ends of the cell 80

81 4) Telophase Opposite of Prophase Chromosomes at poles uncoil Spindle breaks down Nuclear envelope reforms Nucleoli appear 81

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83 Cytokinesis Division of cytoplasm Begins in late anaphase Continues thru telophase Cleavage furrow appears Contractile ring of microfilaments Cell pinches in half 83

84 Results of Mitosis Creates new somatic cells body cells Two cells: Smaller ~ ½ of original organelles Genetically identical Same # chromosomes (diploid) 84

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86 Tumor (Neoplasm) Produced by abnormal cell cycle Benign confined Rarely life threatening Malignant spread Bad;life threatening Metastisis spreading to other areas

87 Cancer Results from malignant cells Cycle out of control Cells don t function normally Inefficient Divide rapidly

88 Cell Differentiation Process by which cells develop different characteristics in structure and function Express only some of the DNA info Some genes switched off 88