Chapter 7: Cell Structure and Function

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Chapter 7 Cell Structure and Function

• 7.1 Life is Cellular
• 7.2 Eukaryotic Cell Structure
• 7.3 Cell Boundaries
• 7.4 The Diversity of Cellular Life

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Chapter 7 Concept Map pg. 169-173
The History of the Cell Theory
Scientists
Leeuwenhoek
Schleiden
Virchow
Robert Hooke
Schwann
Compound Microscope
Cell
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Chapter 7 Concept Map pg. 169-172, 190-193
Structures for Locomotion
Cilia
Flagella
Cellular Organization
Multicellular
Unicellular
Tissue
Organs
Types of Microscopes
Organ System
SEM
TEM
Electron
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Chapter 7 Concept Map pg. 182-189
Diffusion
Osmosis
Types of Solutions
Equilibrium
Isotonic Solution
Concentration Gradient
Hypotonic Solution
Passive Transport
Hypertonic Solution
Facilitated Diffusion
Active Transport
Exocytosis
Endocytosis
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The Discovery of Cells

• Cell The basic unit of living organisms.
• Cytology Branch of biology dedicated to the
  study of cells.
• Anton van Leeuwenhoek Described living cells by
  looking through a simple microscope.
• Compound Microscope has a series of lenses that
  magnify an object in steps. Used by Robert Hooke
  to study cork.

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Cell Theory

• Schleiden and Schwann concluded that all plants
  and animals were made up completely of cells.
• Virchow said new cells could be produced only
  from the division of existing cells
• The Cell Theory states that
• All organisms are composed of one or more cells.
• The cell is the basic unit of organization in all
  organisms.
• All cells come from pre-existing cells

• http//www.zoology.ubc.ca/courses/bio204/lab1_phot
  os.htm

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The Electron Microscope

• Capable of magnifying a specimen 2,0000,000X
  their actual size. Does this by sending
  electrons through a magnetic field to focus them
  on the specimen and then through another magnetic
  field to focus them and produce an image on a
  flourescent screen.
• Allows us to see structures
• within a cell!
• Several different kinds of
• electron microscopes
• now exist.

Weevil, mag. by electro microscope

• http//www.mos.org/sln/sem/weevil.html

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Two Cell Types

• There are two basic cell types that you need to
  be aware of
• Prokaryotes Cells that lack internal
• membrane-bound structures
• Ex. Bacteria, see Fig. 18.10 on p. 457
• Eukaryotes Contain membrane-bound
• structures.
• Many chemical rxns. can occur simultaneously
  because of compartmentalization.
• These membrane-bound structures are called
  organelles
• Ex. Animal cells, plant cells, see Fig. 7-6 on p.
  175

• http//micro.magnet.fsu.edu/cells/animalcell.html

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The Plasma Membrane
Found in both prokaryotes and eukaryotes.

• Extremely important in maintaining the
  concentrations of solutes inside and outside of
  the cell.
• It is selecvtively permeable only certain
  molecules are let in or out at any given time.
• Cell must maintain homeostasis the process of
  maintaining the cells chemical environment,
  internally and externally.

http//micro.magnet.fsu.edu/cells/animals/plasmame
mbrane.html
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The Plasma Membrane Structure

• Lipid Bilayer Lipids with a phosphate group
  attached to them and arranged in rows facing each
  other.
• Ex. See p. 182, Fig. 7.12
• These rows of phospholipids form the main
  structural component of the plasma membrane.

Phospholipid Bilayer
http//micro.magnet.fsu.edu/cells/animals/plasmame
mbrane.html
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The Plasma Membrane Structure

• Transport and Membrane-bound proteins Proteins
  found embedded in phospholipid bilayer, they also
  help give structural support.
• They let only certain molecules through
• Often span from the outside to the inside of the
  cell.
• They help connect the phospholipid bilayer to the
  interior framework of the cell.

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The Plasma Membrane Structure
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The Plasma Membrane Structure

• The model of the plasma membrane is called the
  fluid mosaic model because the phospholipid
  bilayer and its associated proteins can move like
  fluid and yet still create an impressive barrier
  against the outside environment.

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Cellular Boundries

• We have already discussed the plasma membrane
• Plant, fungi, most bacteria, and other cells have
  a cell wall. It is a rigid structure located
  right outside of the plasma membrane providing
  added protection and support.
• Made of cellulose, not selectively permeable
• See p. 175 Fig. 7.7

http//micro.magnet.fsu.edu/cells/plantcell.html
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The Nucleus

• Controls the activity of the organelles.
• Controls protein production (DNA)
• Contains chromatin In the form of DNA
• Chromatin is simply strands of DNA
• When the cell divides, chromatin condenses, or
  becomes packed into a small area. When this
  happens, the chromatin is then called a
  chromosome.

http//micro.magnet.fsu.edu/search/index.asp
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The Nucleus
http//micro.magnet.fsu.edu/search/index.asp
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The Nucleus

• Nuclear Envelope Creates enclosure for nucleus.
  Has a double membrane and has large pores for
  rapid transport of materials.
• Nucleolus An organelle within the nucleus that
  produces ribosomes.
• Ribosomes are the sites where proteins
• and enzymes are assembled
• according to the instructions
• given by the DNA.
• Not found only in the nucleus.

http//micro.magnet.fsu.edu/cells/animals/ribosome
s.html
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The Nucleus
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Cytoplasm

• Defined as the clear gelatinous fluid inside of a
  cell.
• Holds all of the organelles of the cell.
• Kept out of nucleus by nuclear envelope.

http//micro.magnet.fsu.edu/cells/animals/endoplas
micreticulum.html
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7.3 Assembly, Transport, and Storage

• Endoplasmic Reticulum A folded membrane found in
  the cytoplasm of a cell that provides a large
  surface area on which chemical rxns. can easily
  take place. See p. 177 Fig. 7-8.
• Can be rough (with ribosomes, RER) or smooth
  (without ribosomes, ER).
• One of cells delivery systems
• Also serve as site of lipid synthesis
• Ribosomes found on the RER are the site of many
  proteins synthesis.

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7.3 Assembly, Transport, and Storage
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7.3 Assembly, Transport, and Storage
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7.3 Assembly, Transport, and Storage

• Golgi Apparatus A series of closely stacked
  flattened membrane sacs that receives newly
  synthesized proteins and lipids from the ER and
  distributes them to the plasma membrane and other
  organelles throughout the cell. See p. 178, Fig.
  7-9.
• Vesicles Membrane-bound transport packages they
  transport proteins from the ER to the Golgi
  Apparatus.

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7.3 Assembly, Transport, and Storage
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7.3 Assembly, Transport, and Storage
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7.3 Assembly, Transport, and Storage

• Vacuole A sac of fluid surrounded by a membrane
  to store food, enzymes, and other materials
  needed by a cell.
• A small percentage of vacuoles store waste
  products.
• Vacuoles in plants cells are huge!
• Usually only one.
• See p. 179, Fig. 7-10
• Animal cells can have many small vacuoles.

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7.3 Assembly, Transport, and Storage
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7.3 Assembly, Transport, and Storage

• Lysosomes Contain digestive enzymes.
• They digest excess or worn out organelles, food
  particles, and engulfed viruses or bacteria.
• Their membrane prevents harmful enzymes from
  pouring into the cytoplasm of the cell.

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7.3 Assembly, Transport, and Storage
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7.3 Energy Transformers

• Mitochondria Organelles in which food molecules
  are broken down (glucose) to produce energy.
• P. 179
• Shaped like tiny sausages.
• Inner membrane forms long, narrow folds called
  cristae.

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7.3 Energy Transformers
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7.3 Energy Transformers
http//w3.dwm.ks.edu.tw/bio/activelearner/08/image
s/ch08c1.jpg
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7.3 Energy Transformers

• Chloroplasts Transform light energy into
  chemicals that can be used to produce food
  molecules.
• See p. 180 Mitochondria then change food
  molecules into energy.
• Chloroplasts are located in the cells of plants
  and some green one-celled organisms.

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7.3 Energy Transformers
Granum
Thylakoid
http//w3.dwm.ks.edu.tw/bio/activelearner/08/image
s/ch08c1.jpg
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7.3 Energy Transformers
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7.3 Energy Transformers

• Chloroplasts (cont.)
• Chlorophyll A green pigment that traps the
  energy from sunlight and gives plants their green
  color. It is found in the thylakoid membrane of
  the chloroplast.
• Chloroplasts are a type of plastid, or storage
  organelle
• Some plastids store starches or lipids, while
  others contain pigments or molecules that give
  color.

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7.3 Structures for Support

• Cytoskeleton A network of thin, fibrous elements
  that provide support for organelles and helps the
  cell maintain its shape.
• Microtubules Thin, hollow cylinders of protein.
• Microfilaments Thin, solid protein fibers.
• Both work together to provide support.

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7.3 Structures for Support
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7.3 Structures for Locomotion

• Cilia Short, numerous, hair-like projections
  from the plasma membrane of the cell.
• Often beat synchronously to produce motion.
• See p. 501, Fig. 20-5.
• Flagella Long projections that move in a
  whip-like motion to produce movement.
• The major method of locomotion in unicellular
  organisms.
• Found mainly in bacteria and Protists (Fig. 19-2)

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7.3 Structures for Locomotion
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7.3 Structures for Locomotion
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Diffusion

• Diffusion is the movement of particles through a
  medium from an area of high concentration to an
  area of low concentration. Diffusion continues
  until there is no more concentration gradient.
• Diffusion occurs because of Brownian motion, or
  the random movement of molecules caused by their
  kinetic energy.

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Cellular Transport

• Osmosis The diffusion of water across a
  selectively permeable membrane.
• Review
• Plasma Membrane- Phospholipid Bilayer
• Concentration Gradient
• Homeostasis
• Fig. 8.1 p. 202

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Types of Solutions

• Isotonic Solution Concentration of solutes is
  the same inside and outside the cell.
• No osmosis occurs
• A dynamic equilibrium is occurring molecules are
  moving back and forth across membrane but there
  is no concentration gradient created.
• Dynamic Movement or change
• Equilibrium An equality or balance

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Types of Solutions

• Hypotonic Solution The concentration of solutes
  is less outside the cell than inside the cell.
  See p. 186, Fig. 7.16
• Remember we call the cells environment the
  solution that it is in.
• Water moves by osmosis into the cell!
• The cell tends to swell.

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Types of Solutions

• Hypertonic Solution The concentration of solutes
  is more outside the cell than inside the cell.
  See p. 186 Fig. 7.16
• Osmosis causes water to flow out of the cell.
• Cells will shrink or shrivel for this reason.

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Comparison of Hypo, Iso, and Hypertonic Solutions
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Not in Book!!

• Turgor Pressure The pressure in a plant cell
  that results from water flowing into the cell.
• Associated with a hypotonic soltuion.
• Gives plants their shape and ability to stand up.
  Without it they wilt!

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Not in Book!!

• Contractile Vacuole A vacuole that contracts
  and removes water from the inside of the cell.
• Only found in certain organisms (common in
  one-celled).

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Not in Book!!

• Plasmolysis Loss of pressure within a cell
  causing the cell to shrivel
• Associated with a hypertonic solution
• In plants turgor pressure is lost (wilting
  occurs), animal cells just shrivel

http//www.apsnet.org/online/feature/xmasflower/im
ages/figure22sm.jpg
http//www.biology.arizona.edu/cell_bio/problem_se
ts/membranes/graphics/hypertonic_plt.gif
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Cell Membrane Proteins

• Carrier Proteins Span through plasma membrane
  (transport proteins) and change shape to help
  molecules get from one side to the other.
• Their exposed ends open and close like a gate.
• Channel Proteins Span through plasma membrane
  (transport proteins) and create an opening where
  molecules can pass through.
• They do not change shape.

Carrier
Channel
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Passive Transport

• Passive Transport the process of particles
  moving through a membrane with no assistance or
  energy from the cell or its parts.
• Water, lipids, and some lipid soluble substances
  can move by passive transport.
• Also O, N, and CO2
• Molecules can move through channel proteins or
  through membrane itself.

http//www.bmb.psu.edu/courses/bisci004a/cells/fac
iltat.jpg
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Facilitated Diffusion

• Facilitated Diffusion The process of proteins
  helping large molecules across the plasma
  membrane.
• No energy is used by the cell or its parts!
  (passive)
• Movement is powered by the concentration
  gradient.
• See p. 187 Fig. 7.17

http//www.mhhe.com/biosci/genbio/enger/student/ol
c/art_quizzes/genbiomedia/0086.jpg
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Active Transport

• Active Transport The process of the cell using
  its own energy to move molecules across the
  plasma membrane against the concentration
  gradient.
• These molecules are moving the opposite way they
  would naturally move due to diffusion.
• Carrier proteins receive the energy and then do
  the work.
• Energy comes from the mitochondria

http//www.bmb.psu.edu/courses/bisci004a/cells/act
ive.jpg
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Active Transport

• Endo- and Exocytosis
• Both forms of active transport
• See p. 189 Fig. 7.19
• Learn these on your own!
• Note Phagocytosis and Pinocytosis is a form of
  endocytosis
• Phagocytosis one cell engulfing another.
• Pinocytosis tiny pockets form along the cell
  membrane fill with liquid and pinch off to form
  vacuoles within the cell.

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Important Study Tips!

• Cell theory (three parts)
• Study of cells cytology
• Van Leeuwenhoek/Hooke
• Schleiden/Schwann/Virchow
• Prokaryote/Eukaryote
• The electron microscope electromagnets
• Selective permeability
• Fluid Mosaic Model
• Organelles/Components of Organelles
• Plant vs. Animal Cell Organelles Important!
• Why are there so many folded membranes inside the
  cell?
• Unicellular/Multicellular
• Atom/Cell/Tissue/Organ/Organ System/Organism

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Cell Theory Circle Map
Schleiden
All organisms are made of cells.
Come from pre-existing cells
Cell Theory
Cell Basic unit of all organisms
Schwann
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Microscope Parts Circle Map
What they do
Ocular
Base
Body Tube
Fine adjustment
Stage clips
Revolving Nose Piece
Microscope Parts
Diaphragm
Stage
Objectives
Inclination joints
Arm
Coarse Adjustment
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Types of Solutions Circle Map
10 NaCl90 H2O
25 NaCl75 H2O
10 NaCl90 H2O
Isotonic
Hypertonic
Types of Solutions
30 NaCl70 H2O
Hypotonic
10 NaCl90 H2O
5 NaCl95 H2O
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Types of Solutions
Types of Solutions
Hypotonic Solutes less on the outside of
cellTurgor pressureCell swells
Isotonic Dynamic equilibrium occursNo
concentration gradientNo osmosis
Hypertonic Solutes greater outside of the
cellPlasmolysisCell shrinks
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Fluid Mosaic Model
http//www.science.uva.nl/marieke/Images/fluidmos
aic.jpg
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Scientific Discoveries Map
Discovered by
Cell
Microscope
Cell Theory
Leuwenhoek
Schleiden and Schwann
Hooke
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Active vs. Passive Transport Double Bubble Map
Does NOT require energy
Types of Cellular Transport
Requires energy
Endocytosis
Facilitated diffusion
Passive
Exocytosis
Active
Involves channel proteins
Involves carrier proteins
Movement of water and lipids
Deals with proteins
Energy comes from the mitochondria
Phago and Pinocytosis
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Carrier vs. Channel Proteins Double Bubble Map
Types of transport protein
Types of transport protein
Types of Proteins
Change shape
Creates an opening
Channel
Carrier
Ends open and close like a gate
Does NOT change shape
Deals with cell transport
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Animal vs. Plant Cell Types Double Bubble Map
Chloroplasts with chlorophyll for photosynthesis
Cell membrane
Beginning of Life
Cell wall
Small vacuoles
Plant
Plastids
Animal
Circular
Big vacuoles
Rectangular
Made of organelles
Centrioles
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Eukaryotic Organelles Circle Map
Contain chlorophyll
Produces ribosomes
Chloroplasts
Nucleolus
Control center
Cellulose
Cell wall
Nucleus
Storage bin
Vacuole
Strands of DNA
Chromatin
Eukaryotic Organelles
PowerhouseSugar/starch
Cell membrane
Mitochondria
Semi-permeable
Lysosomes
Garbage disposal
Cytoplasm
Holds organelles
ER
Ribosomes
Protein factory
Highway system
Golgi Bodies
Packaging center
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Cell Types Diagram
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Diagrams