Download Chapter 7- Cell structure and Function

Chapter 7- Cell structure and
Function
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I. Cellular Life
A.
Life is cellular
1. In 1665 Robert Hooke was the first
person to view the cell.
2. Hooke looked at a plant cork and
called them “empty chambers.” Later
on he called these chambers cells.
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3. Anton van
Leeuwenhoek used
a microscope to
view LIVE cells.
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B. The cell theory
1. Numerous observations made it
clear that cells are the basic unit of life.
2. Many biologists came to form the
cell theory. It has three parts
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a. All living things are composed of
cells.
b. Cells are the basic unit of
structure and function in living thing
c. New cells are produced from
existing cells.
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C. Exploring the Cell
1.
Scientists and biologists use the
microscope to explore the cell.
2.
Today researchers have better technique
and equipment to study the cell.
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D.
Prokaryotes and Eukaryotic
1.
Cells come in a great a variety of shapes
and a range of sizes.
2.
Cells fall into two broad categories,
depending on whether they contain a nucleus
or no.
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3. The nucleus is a large membraneenclosed structure that contains the cell’s
genetic material in the form of DNA.
4. Eukaryotes are cells that contain nuclei
5. Prokaryotes are cells that do not contain
nuclei.
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E. Prokaryotes
1. Prokaryote cells are usually smaller
and simpler.
2. Prokaryotic cells have genetic
material that is NOT contained in a
nucleus.
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F. Eukaryotes
1.
Eukaryotic cells are generally larger and
more complex than prokaryotic cells.
2.
Eukaryotic cells contain a nucleus in which
their genetic material is separated from the
rest of the cell.
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II. Eukaryotic cell Structure
A. Comparing cell structure
1. The cell acts like a factory with
the many different departments that all
work together for a unifying result.
2. The specialized organs in the cell
are known as organelles.
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3. Cell biologists divide the cell into two main
parts the nucleus and the cytoplasm.
4. The cytoplasm is the portion of the cell
outside the nucleus.
5. The nucleus and cytoplasm work together.
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B. Nucleus
1. The nucleus contains nearly all the cell’s
DNA and with it the coded instructions for
making proteins and other important
molecules.
2. The nucleus is surrounded by a nuclear
envelope composed of two membranes
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3. The nuclear envelope allows materials to
move into and out of the nucleus.
4. The granular material you can see in the
nucleus is called chromatin.
5. Chromatin consists of DNA bound to
protein.
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6. Most of the time
it is condensed to a
form called
chromosomes
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7. Most nuclei also
contain a small,
dense region known
as the nucleolus.
The nucleolus is
where the assembly
of ribosomes begins.
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C. Ribosomes
1.
One of the most important jobs carried out
in the cellular factory is making proteins.
2.
Proteins are assembled on ribosomes.
3.
Ribosomes are small particles of RNA and
protein found throughout the cytoplasm.
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D. Endoplasmic reticulum (ER)
1.
The ER is the site where lipid (fats) components of
the cell membrane are assembled, along with
proteins and other materials that are exported from
the cell.
2.
The ER can be smooth (lacking ribosomes) or
rough (containing ribosomes)
3.
The ER acts like a highway transporting the
ribosomes to where they need to go.
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E. Golgi Apparatus
1.
The function of the Golgi apparatus is to
modify, sort and package proteins and other
materials from the ER for storage in the cell
or secretions outside of the cell.
2.
It acts like the UPS- packages, distributes
and ships.
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F. Lysosomes
1. Lysosomes are small organelles filled
with digestive enzymes.
2. Lysosomes go around and eat all the
“junk” of the cell.
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G. Vacuoles
1. Cells contain a saclike structure
called a vacuole to store waste- water,
salt, protein and carbohydrates.
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H. Mitochondria and chloroplasts
1.
All living things require energy.
2.
Nearly all-Eukaryotic cells, including plants contain
mitochondria.
3.
Mitochondria are organelles that convert the
chemical energy stored in food into compounds that
are more convenient for the cell to use.
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4. Mitochondria are the powerhouse of the cell, they
make ATP- adenoine triphosphate.
5. Chloroplasts are organelles that capture the
energy from sunlight and convert it into chemical
energy in a process called photosynthesis.
6. Chloroplasts and mitochondria contain their own
genetic information of small DNA molecules.
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I. Cytoskeleton
1.
The cytoskeleton helps support the cell.
2.
The cytoskeleton is a network of protein filaments
that help the cell to maintain its shape.
3.
The cytoskeleton is also involved in movement.
4.
Microfilaments and microtubules are two of the
principal protein filaments that make up the
cytoskeleton.
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III. Cell boundaries
A.
Cell Membrane
1.
The cell membrane regulates what enters and
leaves the cell and also provides protection and
support.
2.
The composition of nearly all cell membranes is a
double-layered sheet called the lipid bilayer.
3. In addition to lipids, most cell membranes contain
protein molecules that are embedded in the lipid
bilayer.
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B. Cell Walls
1.
The main function of the cell wall is to
provide support and protection for the cell.
2.
Most cell walls are made from fibers of
carbohydrate and protein.
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C. Diffusion through the cell boundaries
1.
Every living cell exists in a liquid
environment that it needs to survive.
2.
One of the most important functions of the
cell membrane is to regulate the movement
of dissolved molecules from the liquid on one
side o the membrane to the liquid on the
other side.
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3. The cytoplasm of a cell contains a
solution of many different substances in
water.
4. The concentration of a solution is
the mass of solute in a given volume of
a solution, or mass/volume.
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D. Diffusion
1.
Diffusion is the movement of a concentration from
a low concentration to an area of greater
concentration.
2.
When the concentration of the solute is the same
throughout a system, the system has reached
equilibrium.
3.
Because diffusion depends upon random particles
movements, substances diffuse across membranes
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without requiring the cell to use energy.
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E. Osmosis
1.
Osmosis is the diffusion of water through
a selectively permeable membrane.
2.
When two solutions are the same strength
they are referred to as isotonic.
3.
When there is “above strength” it is
referred to as hypertonic.
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4. When there is “below strength” it is
referred to as hypotonic.
5. For organisms to survive, they must have
a way to balance the intake and loss of water.
6. Osmotic pressure could cause great
problems for the cell- see figure 7.16 page
186.
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F. Facilitated
Diffusion
1.
The cell
membrane can help
molecules through
the membrane in
facilitated diffusion.
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G. Active Transport
1.
2.
Cells sometimes must move materials in
the opposite direction against concentration
differences this is called active transport.
Active transport requires energy.
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3. Active transport acts like a pump and pumps
things inside our outside of the membrane.
4. Small molecules and ions are carried across
membranes by proteins in the membrane that act like
energy-requiring pumps.
5. Movements of the cell membrane may transport
larger molecules and even solid clumps of material.
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6. Endocytosis is
the process of
taking materials
INTO the cell.
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7. In phagocytosis
(cell eating) the cell
engulfs the particles.
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8. Pinocytosis (cell
drinking) is when
the cell takes in
fluid.
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9. Exoctytosis
forces materials OUT
of the cell.
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IV. The Diversity of Cellular
Life
A.
1.
Unicellular organisms
Some organisms only have one cell.
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B. Multicellular organisms
1. Cells throughout an organisms can
develop in different ways to perform different
tasks this is called cell specializations.
2. Animal cells are specialized in many ways.
Red blood cells transfer oxygen, white blood
cells fight infection, and these are just a few.
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C. Levels of organization
1. The levels of organization in a
multicellular organisms are
Cells
Tissues
Organ
Organ system
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