Chapters 7 & 10 1

Chapter 7 2

Discovery of cells  light microscopes Anton van Leeuwenhoek  1 st light microscope Simple  1 lens, natural light First living unicellular organism  pond water Compound light microscope  series of lenses Greater magnification 3

Scientific American October 2009 and December

Dyed cotton fibers 5

Stopwatch 6

Fish Scales 7

Algae with diatoms 8

Wrinkled photoreist 9

Lobster egg 10

Aquatic fly larva 11

Magmatic rock olivine 12

Stained zebra fish 13

Zebra fish embryo 14

Draining soap film 15

Human skin on fibronectin 16

Young sea star 17

Adult sea star 18

Anglerfish ovary 19

Butterfly wing scales 20

Butterfly wing 21

Diatom from Southern Ocean 22

Fern sporangia 23

Snail tongue 24

Mouse retinal astrocytes 25

Leaf hairs 26

Fluorescent actin filaments 27

Crystallized DNA 28

More Crystallized DNA 29

And one more! 30

Bee eye with pollen 31

Clam shrimp 32

African clawed toad tadpole 33

Fossilized bone 34

Human muscle 35

Moth antenna 36

Mouse colon 37

Chinese pottery from the Song dynasty 38

A single snowflake 39

Electron micrograph of a snowflake 40

Cell phone 41

Discovery cont. Robert Hooke  studies cork Cells  monk’s rooms Matthias Schleiden  all plants are made of cells Theodore Schwann  all animals are made of cells Rudolph Virchow  cells arise from other cells 42

Statements of cell theory 1. All organisms are made of one or more cells and their products 2. The cell is the basic unit of structure of organisms 3. All cells come from preexisting cells 43

Exceptions to cell theory The first cell Simple organisms lack separations that divide their bodies into cells Fungi and algae Viruses Mitochondria and chloroplasts divide on their own 44

Electron microscopes No light  beam of electrons Magnifies up to 500,000 X 45

Scanning electron microscope (SEM) Scans surface of objects  3-D image 46

Transmission electron microscope (TEM) Can see internal structures 47

Scanning tunneling microscope (STM) Atoms on surface 48

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Prokaryotes Simple Lack internal structure No membrane- bound organelles Smallest organisms  bacteria 50

Eukaryotes More complex Definite internal structure Presence of membrane- bound organelles 51

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Maintains balance between internal and external conditions Regulates entering and departing substances Maintains cellular homeostasis 53

Selectively permeable Also known as semipermeable Allows only certain molecules in or out Water may move freely Ions allowed in only at certain times 54

Structure of the plasma membrane Phospholipid bilayer Lipids with phosphate groups (replace 1 fatty acid) Fatty acid tails nonpolar  avoid water Water insoluble  dissolved substances can’t easily pass through Inner portion of membrane 55

Structure cont. Phosphate heads polar  attracted to water Cell can interact with watery environment Edges of membrane 56

Structure cont. Cholesterol  stabilizes phospholipids Prevents fatty acids from sticking together Transport proteins  span membrane Act as channels (doors) through membrane 57

Structure cont. Protein and carb identity markers Extend from outer surface for communication Proteins along inner surface attach membrane to internal support structures Fluid mosaic model  phospholipids move within the membrane Provides flexibility 58

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Cellular boundaries All cells have plasma membranes Some also have cell walls Rigid structure outside the membrane providing extra support and protection Plant cells, fungi, some protists (unicellular) Fibrous  made of cellulose Porous  allows substances through arbitrarily 61

Cellular boundaries cont. Nucleus  control center Contains blueprints for making proteins  chromatin (DNA) Separated from cell by porous nuclear envelope Nucleolus  located within nucleus Site of ribosome production 62

Cellular boundaries cont. Ribosomes  protein synthesis Not membrane-bound Cytoplasm  clear, gelatinous fluid inside cells Mostly water Site of cellular metabolism 63

Assembly, transport, and storage Endoplasmic reticulum (ER)  highly folded membrane in the cytoplasm Rough ER  has ribosomes Protein synthesis and transport Smooth ER  no ribosomes Lipid synthesis and transport 64

Assembly cont. Lysosomes  organelles containing digestive (hydrolytic) enzymes Digestion of excess or worn out organelles, food, engulfed viruses or bacteria Fuse with vacuoles to digest contents Can digest cells that made them Tadpole tails Fetal finger webbing Natural aging 65

Assembly cont. Golgi apparatus  flattened system of tubular membranes Modify proteins and lipids Enclose finished products in vacuoles 66

Assembly cont. Vacuoles  sacs surrounded by a membrane Temporary storage of food, enzymes, wastes, cell secretions 67

Energy transformers Chloroplasts  plant cells & some protists Capture light energy to make food Surrounded by a double membrane Grana  stacks of membranous sacs Contain chlorophyll  light-capturing pigment Stroma  fluid-filled spaces 68

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Energy transformers cont. Mitochondria  all cells Transform carbs into energy Smooth outer membrane Highly folded inner membrane  increased surface area for chemical reactions This is where energy molecules are produced 70

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Support and locomotion Cytoskeleton  provides support, maintains shape Microtubules  hollow tubes made of protein Microfilaments  smaller, solid protein fibers Intermediate fibers  mid-sized 72

Support cont. Cilia and flagella Both composed of 9 pairs of microtubules surrounding a tenth pair Microtubules slide along each other  bending Cilia  short, numerous, wave-like motion Flagella  long, 1 or 2, whip-like motion 73

Cilia and flagella Paramecium Human spermatozoa 74

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Osmosis Diffusion of water across a selectively permeable membrane Important in maintaining homeostasis Caused by concentration gradient of particles 76

Isotonic solutions Concentration of solutes in solution = concentration of solutes inside cell Water moves in and out at the same rate No change in cell shape 77

Hypotonic solutions Concentration of solutes in solution is lower than that inside the cell Water moves into cell  cell bursts (plasmolysis) 78

Hypertonic solutions Concentration of solutes in solution is higher than that inside the cell Water moves out of cell  cell shrivels Wilting plants 79

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Passive transport Uses no energy Osmosis and diffusion (Play DVD #5) Facilitated diffusion  uses transport proteins Moving sugars and amino acids 81

Active transport  requires energy Uses carrier proteins Molecule binds to carrier protein Release of energy changes protein shape Molecule released on other side of membrane Protein returns to original shape 82

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Active transport cont. Endocytosis  cell surrounds and take in particles Particle engulfed and enclosed by a membrane Membrane breaks away  vacuole Exocytosis  opposite of endocytosis Play DVD #7 84

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Size limitations Diffusion is slow  inefficient if cell is large It would take too long for nutrients to reach cell organelles DNA  there must be enough to provide blueprints for sufficient amounts of protein Larger cells  more than 1 nucleus 86

Size limitations cont. Surface area-to-volume ratio Volume increases faster than surface area The higher the ratio, the more efficient diffusion will be Small cells have high ratios 87

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Cell reproduction  chromosomes Chromatin  long strands of DNA wrapped around proteins Chromosomes are in this form for most of a cell’s life During cell division, chromosomes become tightly coiled and visible under a microscope 89

The cell cycle  sequence of growth and division Most of the cycle is spent in growth Following growth, cells undergo nuclear division Mitosis  process by which 2 daughter cells are formed, each identical to the original parent After mitosis, the entire cell divides 90

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Interphase  3 parts 1. Growth and protein synthesis  G1 2. Cell copies chromosomes  S 3. Mitochondria and other organelles replicate  G2 Not considered a part of mitosis 92

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Prophase  longest phase Chromatin coils into compact chromosomes Sister chromatids  2 halves of doubled structure Exact copies of each other Held together by a centromere Nuclear membrane and nucleolus disappear 94

Prophase cont. Centrioles begin to migrate to opposite poles Organelles found only in animal cells Spindle fibers form between centrioles 95

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Metaphase Spindle fibers attach to centromeres Chromosomes line up along cell equator  metaphase plate 97

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Anaphase Chromatids move to opposite poles  pulled by shortening spindle fibers 99

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Telophase Chromatids reach opposite poles Reversal of prophase 101

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Cytokinesis Division of the cytoplasm Animal cells  membrane pinches in at edges (cleavage furrow) Plant cells  cell plate forms along equator from center of cell 103

Differences in Cytokinesis Animal cell Plant cell 104

Results of mitosis 2 new daughter cells identical to the original parent, but smaller Unicellular organisms  remain as single cells Multicellular organisms  organization Play DVD #16 105

Multicellular cellular organization Cells  basic unit of structure Differentiate  specialized for certain functions Tissue  group of cells performing a specific function Smooth muscle Organ  combination of tissues performing a specific function Stomach 106

Organization cont. Organ system  combination of organs performing a specific function Digestive system Organism 107

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Normal control  enzymes Enzymes monitor cell’s progress from phase to phase Specific enzymes are used for each phase Enzymes encoded by genes on DNA 109

Abnormal cell cycles  cancer Cancer  uncontrolled cell division Results from changes in genes encoding enzymes that control cell cycle Form masses of tissue  tumors Deprive normal functioning cells of nutrients May metastasize  spread through body #2 killer in USA 110

Cancer cont. Causes: Genetic  inherited Environmental  cigarette smoke, air and water pollution, radiation, exposure to chemicals Viral infections 111

Cancer cont. Prevention: Low fat, high fiber diets Vitamins and minerals Exercise Avoiding risk situations 112

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