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Are All Cells Alike?

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Title: Are All Cells Alike?


1
Are All Cells Alike?
Section 7-1
  • All living things are made up of cells. Some
    organisms are composed of only one cell. Other
    organisms are made up of many cells.
  • 1. What are the advantages of a one-celled
    organism?
  • 2. What are the advantages of an organism that
    is made up of many cells?

2
Section Outline
Section 7-1
  • 71 Life Is Cellular
  • A. The Discovery of the Cell
  • 1. Microscopes
  • 2. The Cell Theory
  • B. Exploring the Cell
  • C. Prokaryotes and Eukaryotes
  • 1. Prokaryotes
  • 2. Eukaryotes

3
Section 7-1
  • Discovery of the Cell
  • Robert Hooke 1665 named cell
  • Leeuwenhoek 1674 observed living
    microorganisms
  • Schleiden 1838 all plants made of cells
  • Schwann 1839 all animals made of cells
  • Virchow 1855 - all cells come from cells

4
Section 7-1
  • Exploring the Cell
  • Microscopy
  • - the history of cytology is tied to the
    development of the microscope.
  • Light microscopes - pass light through the
    specimen
  • - can magnify up to about 1200x
  • - easy to prepare specimens and can look at
    living specimens.

5
Section 7-1
2. Transmission Electron Microscope - send a
beam of electrons through the specimen -
focused with magnets - resolving power up to
100,000()x - specimens have to be prepared and
cant be alive
6
Section 7-1
3. Scanning Electron Microscope - bounce
electrons off the surface of the specimen -
gives detailed three-dimensional images of the
surface of the specimen
7
Section 7-1
  • Cell Theory
  • Cells are the basic structural and functional
    units of life
  • Under the conditions present on Earth today all
    cells come from other cells.
  • All living things are composed of cells

8
Section 7-1
Prokaryotes-cells that have genetic material that
is not contained in the nucleus. Generally
smaller and more simple than eukaryotes. Bacteria
are prokaryotes.
Eukaryotes-contains a nucleus in which their
genetic material is separated from the rest of
the cell. Plants, animals, fungi, and protists
are Eukaryotes.
9
Prokaryotic and Eukaryotic Cells
Section 7-1
Prokaryotic Cell
Nucleus
Eukaryotic Cell
Organelles
10
Venn Diagram
Section 7-1
11
Division of Labor
Section 7-2
  • A cell is made up of many parts with different
    functions that work together. Similarly, the
    parts of a computer work together to carry out
    different functions.
  • Working with a partner, answer the following
    questions.
  • 1. What are some of the different parts of a
    computer? What are the functions of these
    computer parts?
  • 2. How do the functions of these computer parts
    correspond to the functions of certain cell
    parts?

12
Section Outline
Section 7-2
  • 72 Eukaryotic Cell Structure
  • A. Comparing the Cell to a Factory
  • B. Nucleus
  • C. Ribosomes
  • D. Endoplasmic Reticulum
  • E. Golgi Apparatus
  • F. Lysosomes
  • G. Vacuoles
  • H. Mitochondria and Chloroplasts
  • 1. Mitochondria
  • 2. Chloroplasts
  • 3. Organelle DNA
  • I. Cytoskeleton

13
Section 7-2
  • Nucleus
  • control center of the cell
  • Contains the chromosomes on which the genes are
    located
  • Fine threads called chromatin in nondividing
    cells
  • Condense into visible chromosomes during cell
    division
  • Nuclear membrane has two parallel membranes with
    nuclear pores penetrating them
  • Nuclear pores allow mRNA to leave the nucleus to
    go to the cytoplasm
  • Also contains the nucleolus where ribosomal
    subunits are produced

14
Section 7-2
Ribosomes - sites of protein synthesis where
amino acids are joined - many are attached to
Rough ER others are free in the cytoplasm -
composed of RNA and protein - attached ribosomes
make proteins for export - free ribosomes make
proteins for intracellular use
15
Section 7-2
Endoplasmic Reticulum - membranous-walled canals
and flat sacs that extend from the plasma
membrane to the nucleus - important in the
synthesis, modification, and movement of
materials within the cell
A. Rough Endoplasmic Reticulum - has ribosomes
attached to its surface - ribosomes make
proteins which move into the cisternae of the
ER and are transported toward the Golgi
apparatus
16
Section 7-2
B. Smooth Endoplasmic Reticulum - lacks
ribosomes - transports, synthesizes, and
chemically modifies small molecules -
synthesizes certain lipids and carbohydrates and
creates membranes for use throughout the cell
17
Section 7-2
Golgi Apparatus - series of flattened
membranous sacs that modify protein products of
the rough endoplasmic reticulum - final
products are packaged in vesicles which can then
be moved to the cell membrane for export - some
of these vesicles remain in the cell as
lysosomes - can also give rise to new
membrane structures for the cell
18
Section 7-2
  • Lysosomes
  • - digestive system of the cell
  • - membranous sacs which pinch off the Golgi
    apparatus
  • - contain hydrolytic enzymes which digest
    particles or large molecules that enter them
  • - also responsible for digesting unneeded or
    unhealthy cells and cell parts

19
Section 7-2
20
Section 7-2
  • Vacuoles
  • - saclike structures used for storage within the
    cell
  • - stores water, salts, proteins, and
    carbohydrates
  • - discerning feature in many plant cells that is
  • large and liquid filled
  • makes possible for plants to support heavy
  • structures such as leaves and flowers
  • - in many cases the vacuole is controls the
    water content of the cell which maintains
    homeostasis

21
Section 7-2
  • Mitochondria
  • - power plants of cells
  • - double membraned organelle with fluid between
    the membranes
  • - lots of enzymes attached to both membranes
  • - enzymes catalyze oxidation reactions of
    cellular respiration and capture the energy of
    sugars in the bonds of ATP
  • - provide 95 of the cells energy
  • - contain their own ribosomes and DNA and can
    replicate themselves

22
Section 7-2
  • Chloroplasts
  • - capture the energy of the sunlight and convert
    it into the chemical energy of sugar in a
    process called photosynthesis
  • - double membraned organelle like mitochondria
  • - also contain their own DNA
  • - contain large stacks of membranes containing
    chlorophyll

23
Section 7-2
Cytoskeleton Internal support framework made up
of rigid, rodlike proteins that support the cell
and allow movement and mechanisms that can move
the cell or its parts Acts as both muscle and
skeleton for cell Cell Fibers - form a
three-dimensional support framework - support
endoplasmic reticulum, mitochondria, and free
ribosomes
24
Section 7-2
  • 1. Microfilaments smallest fibers
  • - cellular muscles that provide for movement
  • 2. Intermediate filaments form much of the
    support network of the cell
  • 3. Microtubules maintain cell shape and move
    things within the cell made up of proteins known
    as tublin
  • 4. Tubulin is also used to make structures in
    animal cells known as the centrioles. These
    aid in organization during cell division

25
Figure 7-11 Cytoskeleton
Section 7-2
26
Figure 7-5 Plant and Animal Cells
Section 7-2
Plant Cell
27
Figure 7-5 Plant and Animal Cells
Section 7-2
Animal Cell
28
Venn Diagram
Section 7-2
29
In or Out?
Section 7-3
  • How is a window screen similar to a cell
    membrane? Read on to find out.
  • 1. What are some things that can pass through a
    window screen?
  • 2. What are some things that cannot pass through
    a window screen? Why is it important to keep
    these things from moving through the screen?
  • 3. The cell is surrounded by a cell membrane,
    which regulates what enters and leaves the cell.
    Why is it important to regulate what moves into
    and out of a cell?

30
Section Outline
Section 7-3
  • 73 Cell Boundaries
  • A. Cell Membrane
  • B. Cell Walls
  • C. Diffusion Through Cell Boundaries
  • 1. Measuring Concentration
  • 2. Diffusion
  • D. Osmosis
  • 1. How Osmosis Works
  • 2. Osmotic Pressure
  • E. Facilitated Diffusion
  • F. Active Transport
  • 1. Molecular Transport
  • 2. Endocytosis and Exocytosis

31
Section 7-3
  • Cell Membrane
  • All of the membranes of the cell have similar
    structure.
  • Plasma Membrane
  • -Fluid Mosaic Model developed by Singer and
    Nicolson
  • -Molecules are arranged in a sheet
  • -Molecules are held together by chemical
    attractions between them and their interactions
    with water.
  • -Primary structure is a double layer of
    phospholipid molecules
  • Phosphate heads are hydrophilic tails are
    hydrophobic

32
Section 7-3
  • Cell Membrane-cont.

-Cholesterol molecules within the membrane help
it function at body temperatures. -Because the
hydrophobic tails make-up most of the membrane,
water soluble materials cant pass through the
membrane. -Channel proteins which are embedded in
the membrane help control movement of materials
into and out of the cell -Glycoproteins have
carbohydrates attached and serve as cell surface
identifiers -Receptor proteins react to specific
chemicals and cause changes within the
cell. -Overall, the plasma membrane is
selectively permeable.
33
Figure 7-12 The Structure of the Cell Membrane
Section 7-3
34
Section 7-3
  • Cell Walls

-Provide support and protection for the
cell. -Most are composed of fibers of
carbohydrate and protein -Plant cell walls are
mostly cellulose
35
Passive and Active Transport
Section 7-3
36
Section 7-3
  • Movement Through the Cell Boundaries
  • Passive Transport Processes
  • -Do not require energy expenditure by the cell
  • -Second Law of Thermodynamics
  • Diffusion
  • - movement of particles from an area of high
    concentration to an area of low concentration
    down a concentration gradient.
  • - continues until equilibrium is reached
  • - membrane channels are pores through which
    specific ions or small water-soluble molecules
    can pass
  • - gases also move by diffusion

37
Diffusion and Osmosis Video
Section 7-3
38
Section 7-3
Passive Transport Processes cont. Osmosis -
diffusion of water through a selectively
permeable membrane - water moves down its
concentration gradient this often means it is
moving toward higher salt concentrations -
Osmotic Pressure water pressure that develops
as a result of osmosis - healthy cells are
normally in an environment where the net movement
of water is 0.
39
Section 7-3
Passive Transport Processes cont. Osmosis
cont. - Tonicity ability of a solution to move
water in/out of a cell and change its shape a.
Isotonic osmotic pressure is inside and
outside b. Hypertonic osmotic pressure is
greater than within the cell water moves out of
cell causing crenation c. Hypotonic osmotic
pressure is less than within the cell water
moves into the cell causing lysis.
40
Figure 7-15 Osmosis
Section 7-3
41
Figure Osmosis
Section 7-3
42
Osmosis Video
Section 7-3
43
Facilitated Diffusion
Section 7-3
  • Facilitated Diffusion
  • - movement through carrier proteins along the
    concentration gradient
  • - rate is dependent on concentration gradient
    and availability of carrier molecules

44
Section 7-3
  • Active Transport

-cell uses metabolic energy to move materials
1. Molecular Transport - carrier-mediated
process that moves substances against their
concentration gradients - opposite of
diffusion - substances are moved by pumps which
use ATP to change shape and move their cargos -
carrier proteins bind to cargo, change shape, and
release the cargo
45
Video 4
Active Transport
Section 7-3
46
Section 7-3
  • Active Transport (cont.)

2. Endocytosis and Exocytosis - allow things to
enter and leave a cell without actually passing
through the plasma membrane. A. Endocytosis
plasma membrane traps some extracellular material
and moves it to the interior in a vesicle. -
Phagocytosis large particles are engulfed
within a vesicle that then fuses with lysosomes
to digest particles - Pinocytosis fluid and
the substances dissolved in it enter the cell
47
Endocytosis and Exocytosis
Section 7-3
48
From Simple to More Complex
Section 7-4
  • Many multicellular organisms have structures
    called organs that have a specific function and
    work with other organs. Working together, these
    organs carry out the life processes of the entire
    organism.

49
Section 7-4
  • 1. Some activities cannot be performed by only
    one person, but need a team of people. What type
    of activity requires a team of people to work
    together in order to complete a task?
  • 2. What do you think are some characteristics of
    a successful team?
  • 3. How is a multicellular organism similar to a
    successful team?

50
Section Outline
Section 7-4
  • 74 The Diversity of Cellular Life
  • A. Unicellular Organisms
  • B. Multicellular Organisms
  • 1. Specialized Animal Cells
  • 2. Specialized Plant Cells
  • C. Levels of Organization
  • 1. Tissues
  • 2. Organs
  • 3. Organ Systems

51
Section 7-4
  • Unicellular Organisms
  • Single-celled organisms that grow, respond to
    the environment, transform energy, and reproduce
  • Multicellular Organisms
  • Organisms that are made up of many cells that
    are developed for different tasks through a
    process called cell specialization

52
Levels of Organization
Section 7-4
Levels of Organization 1. Cells 2.
Tissues 3. Organs 4. Organ Systems
53
Section 1 Answers
Interest Grabber Answers
  • 1. What are the advantages of a one-celled
    organism?
  • A one-celled organism has simpler needs and can
    respond immediately to its environment because
    its entire cell is immersed in its environment.
  • 2. What are the advantages of an organism that
    is made up of many cells?
  • In a multicellular organism, different jobs are
    divided among different groups of cells that work
    together. Also, a multicellular organism can
    continue to survive even if it loses some of its
    cells.

54
Section 2 Answers
Interest Grabber Answers
  • Working with a partner, answer the following
    questions.
  • 1. What are some of the different parts of a
    computer? What are the functions of these
    computer parts?
  • Answers may include monitor (interfaces with
    the computers environment), software
    (instructions for how to carry out different
    jobs), CPU (directs the computer's activities),
    recycle bin or trash can (storage area for
    wastes), and so on.
  • 2. How do the functions of these computer parts
    correspond to the functions of certain cell
    parts?
  • Students should try to link the functions they
    described in question 1 to the functions of the
    different cell structures. The cell needs a way
    to interface with its environment (cell
    membrane), instructions for carrying out
    different jobs (DNA), and a CPU to direct the
    cells activities (nucleus).

55
Section 3 Answers
Interest Grabber Answers
  • 1. What are some things that can pass through a
    window screen?
  • Answers may include air, fine dust, and
    rainwater.
  • 2. What are some things that cannot pass through
    a window screen? Why is it important to keep
    these things from moving through the screen?
  • Insects, leaves, and other matter that may fall
    from trees. The screen keeps out annoying insects
    and objects that may bring dirt into the home.
  • 3. The cell is surrounded by a cell membrane,
    which regulates what enters and leaves the cell.
    Why is it important to regulate what moves into
    and out of a cell?
  • Materials such as oxygen and food that are
    needed by the cell have to be able to get inside
    the cell. At the same time, excess materials have
    to leave the cell.

56
Section 4 Answers
Interest Grabber Answers
  • 1. Some activities cannot be performed by only
    one person, but need a team of people. What type
    of activity requires a team of people to work
    together in order to complete a task?
  • Answers might include building a human pyramid
    or constructing an arch out of blocks.
  • 2. What do you think are some characteristics of
    a successful team?
  • Divide up jobs and cooperate well with one
    another.
  • 3. How is a multicellular organism similar to a
    successful team?
  • The functions of the organism are divided up
    among its parts (organs and organ systems). All
    the parts cooperate to carry out all the
    functions of the whole organism.

57
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