CHAPTER 7 CELL STRUCTURE & FUNCTION

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CHAPTER 7 CELL STRUCTURE FUNCTION
CELL- collection of living matter enclosed by a
barrier that separates the cell from its
surroundings basic unit of all forms of life.
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In the early 1600s (in Holland) the telescope
microscope were invented by putting several
simple glass lenses together. Anton Van
Leeuwenhoek (Dutch biologist) developed the
microscope. He was one of the 1st people to use
the microscope to study nature1st to see tiny
living organisms in a drop of water.
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Anton Van Leeuwenhoek
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Robert Hooke was the 1st to describe the
existence of cells.
Hooke was not the 1st to look at LIVING cellshe
was looking at dead cells. Hooke was the 1st to
coin the term cells. His discovery was
important because it opened up the study of cells.
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Hookes Cork Slide.CELLS
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In 1831, Robert Brown (Scottish scientist)
observed a dark spot
near the center of many cells. This dark center
became known as the NUCLEUS.
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• 1838 Mathias Schleiden (German Botanist) stated
  that all plants were made up of cells.

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In 1839, Theodor Schwann discovered that all
ANIMALS were
made up of cells. In 1855, Rudolf Virchow (German
physician) stated that cells come only from other
pre-existing cells. All of these observations led
to the development of the cell theory.
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THE CELL THEORY

• All living things are composed of cells.
• Cells are the basic units of structure function
  in living things.
• All cells come from existing cells.

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BASIC CELL STRUCTURES
Certain structures are common to most cells 1-
Cell Membrane-(outer boundary) a thin, flexible
barrier around the cell. 2-Nucleus- (plural
nuclei) a large structure that contains the
cells genetic material controls cell
activities.
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3. Cytoplasm- the material between the cell
membrane the nucleusthe material inside the
cell- but not including the nucleus! Some cells
have a cell wall (plants bacteria). The cell
wall surrounds the cell membrane. The cell wall
supports protects the cell!
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PROKARYOTES EUKARYOTES
Scientists divide cells into 2 categories based
on the cells nucleus 1- Prokaryotes (Pro
early/before) 2-Eukaryotes (Eu true)
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PROKARYOTES
(No TRUE nucleus!)single celled organism that
lacks a nucleus. Genetic material floats freely
in the cell. All bacteria are prokaryotes.
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EUKARYOTES
Cells that DO CONTAIN A NUCLEUSeukaryotes have a
nucleus that is enclosed in a membrane and also
have tiny organelles that are also enclosed by
a membrane.
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ORGANELLE- specialized structure that performs
important cellular functions within a eukaryotic
cell. Eukaryotes can be single cellular or
multicellular. All plant, animals, fungi are
eukaryotes.
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7-2 CELL STRUCTURES
CELL WALL Main Function provide support
protection for the cell. Unlike the cell
membrane, the cell wall is made up of tough
fibers (carbohydrates proteins). These
substances are produced by cell released by the
cell membrane
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Cell Wall
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Cell Wall Layers
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NUCLEUS
Main Function controls most cell processes
contains hereditary information of DNA
(deoxyribonucleic acid). Discovered by Robert
Brown!
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(Nucleus)
DNA holds the instructions for making proteins
other important molecules. Making proteins is
one of the main functions of cells.
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STRUCTURE OF NUCLEUS 1-CHROMATIN- granular
material visible within the nucleusit is DNA
bound to protein is USUALLY spread throughout
the nucleus. When a cell divides, CHROMATIN
condenses to form CHROMOSOMES!
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(Structure of nucleus) CHROMOSOMES- distinct
thread-like structures containing the genetic
information that is passed from one generation of
cells to the next.
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• 3- NUCLEOLUS- small, dense region within most
  nuclei in which the assembly of ribosomes begins.

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(Structure of nucleus) 4- NUCLEAR ENVELOPE-
double- membrane layer that surrounds the nucleus
of a cell.
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CYTOSKELETON Cyto cell Cytoskeleton- network of
protein filaments within some cells that helps
the cell maintain its shape is involved in many
forms of cell movement.
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In animal cells, microtubules form a pair of
structures called CENTRIOLES. Plant cells do not
have centrioles! Microtubules can also help form
cilia, hair-like projections flagella,
whip-like projectionsboth aid in movement of the
cell.
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(Cytoskeleton Structures) MICROFILAMENTS- long,
thin fibers that function in the movement
support of the cellthey are much narrower than
microtubules.
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• CYTOPLASMIC ORGANELLES
• RIBOSOMES- small round particle in the cell on
  which proteins are made.

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• 2. ENDOPLASMIC RETICULUM- internal membrane
  system in cells in which components of the cell
  membrane are assembled some proteins are
  modified.
• 2 Types of Endoplasmic Reticulum

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2 Types of Endoplasmic Reticulum Rough ER-
the part of the ER that is involved in protein
synthesis. It is named ROUGH because of the
ribosomes that are attached to the
surface. Smooth ER- the part of the ER that
does not have ribosomes attached to the surface.
It contains enzymes that perform special tasks.
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3. GOLGI APPARATUS- Stack of membranes in the
cell in which enzymes attach carbohydrates
lipids to proteins. From the golgi apparatus,
proteins are sent to their final destinations.
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4. LYSOSOMES- Cell organelle filled with
enzymes needed to break down certain materials in
the cell. Lysosomes break down old organelles
also remove debris from the cell.
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5. VACUOLES- Cell organelle that stores
materials such as water, salts, proteins
carbohydrates. This structure is very LARGE in
plant cells.
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6.CHLOROPLASTS- Found only in plants some
other organismsNOT in animals or
fungi! Chloroplasts contain chlorophyll (green
pigment in plants) use the energy from the sun
to make energy rich food molecules in a process
known as photosynthesis.
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7. MITOCHONDRIA- Organelles that use energy
from food to make HIGH energy compounds that the
cell can use for growth, development, movement.
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Mitochondria chloroplasts change energy from
one form to another. Mitochondria are found in
nearly all eukaryotic cells.
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The Cell As A Factory CYTOSKELETON- supporting
structure transportation system. NUCLEUS-
control center of cellsends out RNA to the rest
of the cell. The instructions for making proteins
travels to RIBOSOMES.
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Each ribosome is like a machine that makes
proteins from orders sent By the boss
(nucleus). Proteins move to Golgi Apparatus for
finishing touches are then shipped to their
final destination Energy comes from mitochondria
or chloroplasts.
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Endoplasmic reticulum is like an assembly line
for making the proteinsand helps make them along
with ribosomes!
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COMPARING CELLS The main distinction between
cells is whether or not they have a nucleus
(prokaryotic or eukaryotic). Eukaryotic cells are
larger, more specialized and contain nuclei.
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PLANT CELLS VS. ANIMAL CELLS Plant cells have
cell walls, large vacuoles, chloroplasts. Animal
cells do not have cell walls or
chloroplaststhey have small vacuoles. Animals
cells have centrioles plant cells do NOT.
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7-3 Movement Through the Membrane (2006 Cell
Boundaries) The cell membrane is the boundary
between the cell its environment. The function
of the cell membrane is to regulate which
materials enter leave the cell.
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The cell membrane is a LIPID BILAYER The cell
membrane contains channels pumps (made of
proteins)that help move materials from one side
of the cell membrane to the other.
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Cell Membrane
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There are also many other molecules that may be
attached to the cell membrane. Many scientists
call the membrane a mosaic of different
molecules Some of the carbohydrates act like
chemical ID cards, allowing cells to ID one
another.
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DIFFUSION Process by which molecules tend to
move from an area where they are more
concentrated (high concentration) to an area
where they are less concentrated (low
concentration).
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Diffusion occurs because molecules constantly
move collide with each other. Diffusion does
not cause the cell to use its energy! Diffusion
will occur until concentrations on each side of
the membrane are equalWe call this point
equilibrium.
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OSMOSIS The diffusion of water through a
selectively permeable membrane. Not all
substances can cross biological membranes.
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PERMEABLE- a membrane that allows substances to
pass through it. IMPERMEABLE- a membrane that
does NOT allow substances to pass through
it. SELECTIVELY PERMEABLE- a membrane that only
allows certain substances to pass through it.
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In osmosis water will move across a membrane
until the concentration on both sides of the
membrane are equal. ISOTONIC- same
strength HYPERTONIC-above strength HYPOTONIC-b
elow strength Water will move in a direction
that causes equilibrium to be reached.
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Isotonic Solution and Red Blood Cell
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Osmotic Pressure- the force exerted by osmosis
that moves water from solutions of different
concentrations across a membrane. This pressure
is exerted on the hypertonic side of the
selectively permeable membrane. Read page 186
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FACILITATED DIFFUSION- Movement of specific
molecules across cell membranes through protein
channels.this is still diffusion still does
not use cellular energy!
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ACTIVE TRANSPORT-energy-requiring process that
moves materials across a cell membrane against a
concentration difference. Requires cellular
energy!! Moves materials AGAINST a concentration
gradientfrom lo to hi!
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Types of Active Transport (Video..Animated
Concepts!) Sodium Potassium Pump
Endocytosis Phagocytosis Pinocytosis Exocytosis
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7-4 Diversity of Cellular Life Unicellular
Multicellular (Page 190) Levels of Organization
(Page 192-193) END OF NOTES FOR CH 7