Are All Cells Alike?

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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?

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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

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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

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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.

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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
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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
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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

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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.
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Prokaryotic and Eukaryotic Cells
Section 7-1
Prokaryotic Cell
Nucleus
Eukaryotic Cell
Organelles
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Venn Diagram
Section 7-1
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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?

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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

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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

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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
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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
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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
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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
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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

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Section 7-2
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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

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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

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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

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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
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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

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Figure 7-11 Cytoskeleton
Section 7-2
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Figure 7-5 Plant and Animal Cells
Section 7-2
Plant Cell
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Figure 7-5 Plant and Animal Cells
Section 7-2
Animal Cell
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Venn Diagram
Section 7-2
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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?

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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

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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

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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.
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Figure 7-12 The Structure of the Cell Membrane
Section 7-3
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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
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Passive and Active Transport
Section 7-3
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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

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Diffusion and Osmosis Video
Section 7-3
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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.
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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.
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Figure 7-15 Osmosis
Section 7-3
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Figure Osmosis
Section 7-3
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Osmosis Video
Section 7-3
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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

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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
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Video 4
Active Transport
Section 7-3
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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
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Endocytosis and Exocytosis
Section 7-3
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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.

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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?

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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

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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

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Levels of Organization
Section 7-4
Levels of Organization 1. Cells 2.
Tissues 3. Organs 4. Organ Systems
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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.

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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).

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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.

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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.

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