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Chapter 7 Cellular Structure and Function

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Chapter 7 Cellular Structure and Function 7.1 Cell Discovery and Theory * * Cells in Solutions Isotonic Solution = same solutes Hypotonic Solution = lower solutes ... – PowerPoint PPT presentation

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Title: Chapter 7 Cellular Structure and Function


1
Chapter 7 Cellular Structure and Function
  • 7.1 Cell Discovery and Theory

2
The History of the Cell Theory
  • Cells are the basic units of living things
  • Before microscopes people believed diseases were
    caused by curses and supernatural spirits (wrath
    of God)
  • The idea that a living thing like a bacteria
    could cause disease or infection never occurred.
    Why?

3
Development of the Light Microscope
  • Today's microscope is a compound microscope with
    two lenses
  • Eyepiece lens
  • Objective lens
  • Can magnify 1500 times

4
Simple Light Microscope
  • Developed by Anton van Leeuwenhoek in the mid
    1600
  • One lens
  • Much like a magnifying glass

5
The Cell Theory
  • Robert Hook
  • First to use the term cell
  • Looked a cork under a microscope, saw the cell
    walls

6
Robert Hook
  • Contemporary of Anton van Leeuwenhoek
  • English
  • Published and encouraged others to use microscopes

7
Matthias Schleiden
  • 1838
  • German botanists
  • Examined plants of all types
  • All plants are made of cells

8
Theodore Schwann
  • 1839
  • German zoologist
  • Contemporary of Schleidens
  • Examined animal tissues of many types
  • All animals are made of cells

9
Rudolph Virchow
  • 1855
  • German physician
  • All cells come from preexisting cells

10
The Cell Theory
  • All organisms are composed of one or more cells
  • Unicellular or multicellular
  • The cell is the basic unit of organization of all
    organisms
  • Structure
  • Function
  • All cells come from preexisting cells

11
Technology Since the 1800s
  • Compound light microscopes continued to improve
    so that bacteria were able to be classified
  • Most magnification possible with light
    microscopes cannot see inner cell parts

12
Electron Microscopes
  • Developed in the 1940s
  • Uses magnets to focus a beam of electrons (in
    place of light)
  • Can magnify 500,000X
  • Several types
  • Scanning looks at surface get 3-D
  • Transmission looks at interior
  • Scanning-Tunneling atoms on surface

13
Microscope Aids
  • Both light and electron microscopes use dyes and
    stains which helps to contrast cell and parts
  • Most dyes and stains kill the cells
  • Most specimens of electron microscopes need to be
    in a vacuum and/or coated with gold

14
Two Basic Cell Types
  • Eukaryote
  • Have plasma membrane
  • Internal membrane bound structures
  • Unicellular and multicellular
  • Larger size
  • Much specialization
  • Example animal
  • Prokaryote
  • Have plasma membrane
  • No internal membrane bound structures
  • Unicellular
  • Smaller in size
  • No specialization
  • Example bacteria

15
Two Basic Cell Types
Prokaryote
Eukaryote
16
Two Basic Cell Types
17
Chapter 7 Cellular Structure and Function
  • 7.2 The Plasma Membrane

18
Plasma Membrane Diagram
19
Plasma Membrane Micrograph
20
Plasma Membrane Structure
  • Made of phospholipid bilayer
  • Polar ends are hydrophilic
  • Nonpolar ends are hydrophobic

21
Plasma Membrane Function
  • Job of plasma membrane is homeostasis- maintain
    balance
  • For cells to survive they must keep the inside in
    and the outside out, yet allow some materials to
    move into and out of the cell

22
Structure Fits Function
  • The structure of the plasma membrane (how it is
    put together) allows the plasma membrane its
    function or job, selective permeability
  • Selective permeability the ability to allow some
    materials into or out of the cell but not other
    materials

23
Selective Permeability
Out side of cell is different from inside of cell
24
Structure Fits Function
  • Both the inside of the cell and the outside are
    water environment so the hydrophilic ends face in
    and out
  • The hydrophobic fatty tails are in the middle so
    that materials cant pass through easily

25
Structure Fits Function
  • Role of proteins in plasma membrane
  • Channels or tunnels for substances to pass
    through with specific fit
  • Identification of organism and tissue type
  • Signal sending proteins
  • Provide support for the phospholipids

26
Plasma Membrane Proteins
27
Plasma Membrane
  • Cholesterol stabilizes the plasma membrane in
    animal cells
  • Animal cells have no cell wall as do plant cell
  • High blood cholesterol is a risk factor for heart
    disease and stroke
  • Animals (including us) produce cholesterol for
    the stabilization of the cell membrane

28
Fluid Mosaic Model
29
Fluid Mosaic Model
  • FLUID Plasma membrane in constant motion with
    the phospholipids of one layer moving one
    direction and the phospholipids of the other
    layer moving in the opposite direction
  • MOSAIC something consisting of a number of
    different things of different types

30
Chapter 7 Cellular Structure and Function
  • 7.3 Structures and Organelles

31
Cellular Boundaries
  • Plant Cell outer most part is the cell wall
    plasma membrane is inside of the cell wall
  • Also fungi, algae and other Kingdom Protista
    organisms
  • Animal Cell outer most part is the plasma
    membrane
  • Also protozoans (Kingdom Protista)

32
Cell Wall
  • Functions to protect and support
  • NOT selectively permeable
  • Porous let anything in
  • Plant cell wall made of cellulose (wood)

33
Plant Cell Wall
34
Nucleus
  • Controls all cell activities
  • Contains information to make proteins all parts
    of the cell depend on proteins to do its job

35
Nucleus
  • Contains DNA in strands known as chromatin
    (chromosomes are chromatin that is condensed and
    visible during cell reproduction)

36
Nucleolus
  • Found in the nucleus
  • Organelle that makes ribosomes
  • Ribosomes are sites where proteins are
    manufactured

37
Ribosomes
  • Ribosomes are unique because they do not have a
    membrane around them
  • Found in prokaryotes and eukaryotes
  • Look like pepper on the ER (spaghetti)

38
Nuclear Membrane
  • Also called Nuclear Envelope
  • Surrounds the nucleus
  • Same composition as the plasma membrane
  • Contains pores to allow large materials to pass
    out (ribosomes and RNA)

39
Cytoplasm
  • All the gelatinous material with the organelles
    inside the cell between the nucleus and the cell
    membrane
  • Cytosol is that part of the cytoplasm that is
    liquid

40
Organelles for Assembly, Transport and Storage
  • Endoplasmic Reticulum (ER)
  • Golgi Apparatus
  • Vacuoles
  • Lysosomes
  • All have phospholipid bilayer membrane structure

41
Endoplasmic Reticulum (ER)
  • Folded membrane like an accordion for workspace
  • Rough ER contains ribosomes for protein
    production
  • Smooth ER (No ribosomes) for lipid production
  • Tube-like for transport of materials

42
Golgi Apparatus
  • Takes protein from the ER and makes it ready to
    be transported
  • Like UPS, packages it and gives it a destination
    address

43
Vacuoles
  • Large central vacuole in plant cells to store
    water
  • Smaller vacuoles for storage of food, waste,
    water, enzymes and other substances in both plant
    and animal cells

44
Lysosomes
  • Double membrane bound sac containing digestive
    enzymes
  • Digests food particles, engulfed viruses and
    bacteria, and worn out cell parts
  • Can fuse with vacuole to digest contents of
    vacuole

45
Energy Transformers
  • Chloroplasts
  • Mitochondria
  • Both have phospholipid bilayer membrane structure

46
Chloroplasts
  • Capture light energy and produce food to be used
    later
  • Pigment chlorophyll give plants their green color
  • Other plastids store starch, lipids and other
    pigments

47
Chloroplasts
  • Double membrane
  • Clear outer
  • Folded inner thylakoid
  • Stacks of membranes sacs grana and liquid stroma
  • Site of photosynthesis

48
Mitochondria
  • Break down food to release energy
  • Found in eukaryotes

49
Mitochondria
  • Double membrane
  • Outer
  • Folded Inner to increase membrane space
  • Some cells need much energy and have hundreds of
    mitochondria other cell have few mitochondria
    because these cells use little energy
  • Site of cellular respiration

50
Structures for Support and Locomotion
  • Cytoskeleton
  • Cilia
  • Flagella

51
Cytoskeleton
  • Internal framework in the cell to keep the
    organelles in place
  • Maintains the cells shape
  • Made of microtubules (hollow) and microfilaments
    (solid) protein fibers
  • Shown in green

52
Centrioles
  • Made of groups of microtubules
  • Function in cell division (Ch. 9)

53
Cilia and Flagella
  • Enclosed by plasma membrane
  • Used for locomotion and feeding
  • Made of pair of microtubules surrounded by 9
    additional pairs

54
Cilia
  • Short numerous hair like projections
  • Beat like oars on a boat
  • Line our respiratory system

55
Flagella
  • Tail like structure that is whip like
  • May have one flagella or several
  • Mostly used for locomotion

56
Chapter 7 Cellular Structure and Function
  • 7.4 Cellular Transport

57
Passive Transport
  • NO energy expended by cell
  • Diffusion
  • Facilitated diffusion
  • Osmosis

58
Diffusion
  • All molecules are in constant motion called
    Brownian Motion
  • The high the temperature the faster the motion
    because they have more energy
  • Diffusion is the net movement of particles from
    higher concentration to lower concentration
    because of this movement of particles
  • Diffusion is slow because it is a random process

59
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60
Rates of Diffusion
  • Concentration of substances involved
  • More concentrated substances speed up rate of
    diffusion
  • Energy by temperature or agitation
  • Increased temperature speeds up rate of diffusion
  • Agitation or stirring speeds up rate of diffusion
  • Pressure
  • Increased pressure speeds up diffusion because
    pressure increases molecular movement

61
Dynamic Equilibrium
  • Equilibrium is reached when there is no net
    concentration change
  • Dynamic because Brownian motion continues

62
Diffusion in Living Systems
  • In living things materials must diffuse into and
    out of cells all the time
  • Concentration gradient exists so that substances
    will move into the cell until there is the same
    number on each side
  • Liquids, solids and gasses can diffuse into and
    out of a cell

63
Facilitated Diffusion
  • Diffusion of materials through proteins in cell
    membranes
  • NO energy required
  • Common for sugars and amino acids

64
Osmosis
  • Diffusion of water through a cell membrane
  • Cell membranes are selectively permeable
  • NO energy expended by the cell
  • Moves water from high concentration to low
    concentration
  • Must occur for homeostasis to occur

65
Control of Osmosis
  • Unequal distribution of particles on either side
    of a selectively permeable membrane
  • Water moves through the membrane until
    equilibrium is reached (no net change)

66
Cells in Solutions
  • Isotonic Solution same solutes
  • Hypotonic Solution lower solutes
  • Hypertonic Solution higher solutes

67
Cells in Isotonic Solutions
  • Isotonic solutions have the same solute
    concentration as the cell, so water moves in and
    out at the same rate no osmosis no net change
  • Dissolved substances outside the cell equals
    dissolved substances inside the cell
  • Examples Normal saline IV solution (0.9 salt)
    and tap water in most areas

68
Cells in Hypotonic Solutions
  • Dissolve substances lower outside the cell than
    inside the cell
  • Water moves into the cell cell swells
  • Animal cell bursts
  • Plant cell becomes more firm (higher turgor
    pressure) reason why plants are sprayed at
    grocery store
  • Example Distilled water

69
Cells in Hypotonic Solutions
70
Cells in Hypertonic Solutions
  • Dissolved substances higher outside the cell than
    inside the cell
  • Water leaves the cell cell shrinks
  • Animal cell wrinkled (reason why meat is salted
    after cooking)
  • Plant cell plasmolyzed cell membrane moves away
    from cell wall
  • Example salt water, syrup

71
Cells in Hypertonic Solutions
72
Cells in Solutions
73
Comparing Plant and Animal Cells
74
Active Transport
  • ENERGY used by the cell
  • Carrier proteins with a SPECIFIC FIT with a
    specific molecule
  • Bringing substances into the cell against the
    concentration gradient

75
Active Transport
  • When molecule fits with carrier protein the
    carrier protein molecule changes shape to allow
    the molecule to move into or out of the cell
  • When movement complete, the carrier protein
    changes back to original shape for another
    molecule

76
Active Transport
  • Also used to rid the cell of materials against
    the concentration gradient
  • Takes energy to use a pump
  • Much of your cells energy is expended in the
    sodium-potassium pump
  • (2 K in 3 Na out)

77
Large Materials Into Cells
  • Endocytosis, getting large materials INTO the
    cell
  • Cell expends energy
  • Engulfs and forms a vacuole
  • Example white blood cells engulfing a bacteria

78
Large Materials Out of Cells
  • Exocytosis large materials out of a cell
  • Cell expends energy
  • Example secretions or hormones
  • Example waste products

79
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80
Pseudopodia
  • Structure of locomotion
  • Used for capture of food
  • Extensions of the cell contents within the cell
    membrane
  • Example Amoeba

81
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