Download Chapter 3 Review of the Cell

Chapter 3 Review of
the Cell
By: Cortney
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In 1665, a scientist named Robert Hooke first described what
cells really were. He did this by finding thousands of tiny
chambers in dried cork under an early light microscope. \After the
next 175 years he research led to the Cell Theory.
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Cell Theory is said to be the most important components of all
plant and animal tissues. There are several concepts to the Cell
Theory.
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Cells are the building blocks of all plants and animals.
Cells are produced by the division of preexisting cells.
Cells are the smallest units that perform all vital physiological functions.
Each cell maintains homeostasis at the cellular level.
And homeostasis at the tissue, organ, and individual levels reflects the combined
and coordinated actions.
Basic Concepts of the Cell Theory
Fluid Contents with Extracellular
Fluid
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Cells float in a watery medium known as the extracellular
fluid.
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The cell membrane separates the cell contents known as
the cytoplasm, from the extracellular fluid.
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But the cytoplasm can be further subdivided into a fluid
known as the cytosol, and the intercellular structures
collectively known as organelles.
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The cell membrane is the outer boundary of the cell also know as the
plasma membrane.
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The cell membrane is called the phospholipid bilayer because the
phospholipids form two distinct layers. And in each layer the
phospholipid molecules lie so that hydrophilic heads are at the
surface and the hydrophobic tails are on the inside.
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There are four many components of the cell membrane and they are
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Phospholipids
Proteins
Glycolipids
Cholesterol
The Cell Membrane
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The cell membrane is called the phospholipid bilayer because the
phospholipids form two distinct layers. And in each layer the
phospholipid molecules lie so that hydrophilic heads are at the
surface and the hydrophobic tails are on the inside.
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General Functions of the cell membrane are:
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Physical Isolation
Regulation of exchange with the environment
Sensitivity
Structural support
Continued..
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Cells in the body work together to maintain
homeostasis at the tissue, organ, and system levels.
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Communication and coordination activities involve
the cell membrane which forms the interface between
each cell and its surroundings.
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Regulation of the intracellular and extracellular
environments are different, and those differences are
must be maintained to preserve homeostasis.
Cell interactions with the
environment
• Nonmembranous organelles are always in contact
with the cytosol.
• These are the Nonmembranous Organelles and
their functions:
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Cytoskeleton: strength, movement of cellular structures
and materials.
Microvilli: Absorption of extracellular materials.
Centrioles: Movement of chromosomes during cell
division.
Cilia: Movement of materials over surface.
Ribosomes: Protein synthesis.
Nonmembranous Organelles
Membranous organelles are surrounded by lipid membranes that
isolate them from the cytosol, just as the cell membrane isolates
the cytosol from the extracellular fluid.
• These are the Membranous organelles and their functions:
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• Mitochondria: Produces 95% of the ATP required in a cell.
• Nucleus: Control of the metabolism; storage and processing of genetic
information.
• Nucleolus: Site of the RNA synthesis.
• Endoplasmic Reticulum: Synthesis secretory products; intracellular storage and
transport.
• Rough ER: Secretory protein synthesis.
• Smooth ER: Lipid and carbohydrate synthesis.
• Golgi Apparatus: Storage, alteration, and packaging secretory products and
lysosomes.
• Lysosomes: Intracellular removal of damaged or ganelles or of pathogens.
• Peroxisomes: Neutralization of toxic compounds.
Membranous Organelles
Smooth
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Continued…
Cell Energy
• The sun is the main component in giving the cell fuel to power
all of their functions.
• Cells also get energy and power from the mitochondria.
• Mitochondria- are small organelles that have an unusual
double membrane.
• Having both of these energizes that gives the cell al of its
energy to fuel all of it functions.
• The nucleus is the control center for cellular operations.
• The nucleus directs processes that take place in the cytosol and
must in turn receive information about conditions and activities
in the cytosol.
• It also controls the heredity information, control’s the cell’s
growth, and reproduction.
• Also, it controls the proteins in the cytoplasm and controls the
synthesis of ribosomes.
Nucleus: The Cell’s Control Center
• The G1 phase happens during interphase. The cell is doing its
everyday jobs. There are only two chromosomes, and each one
has one molecule of DNA.
• During S phase the DNA replicates. Now the chromosomes have
two molecules of DNA.
• In the G2 phase the cell carries out processes that are necessary
for mitosis to begin.
• Mitosis is the stages where the cell’s DNA gets divided into two
separate nuclei.
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There are four stages: Prophase, metaphase, anaphase, and telophase.
• At the end of the cell’s life cycle, daughter cells are formed. They
are each smaller to its parents but are two genetically identical
daughter cells.
Cell Cycle
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The Transmembrane potential is the characteristic of all living cells
because it results from the active and passive properties of their cell
membranes.
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Even though the transmembrane potential is not visible through a
microscope, it is just as an important as any other structural
characteristic or organelle.
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Cell functions that involve the cell membrane involve the transmembrane
potential. And because the transmembrane can magnify a stimulus, it
greatly increases the cell’s sensitivity to its environment.
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The mechanisms that maintain the transmembrane potential is the ions
that are rushed into or out of the cell, but it does not depend on the size
or nature of the stimulus.
Transmembrane Potential
Cells attachment is cells attaching to other cells or to the extracellular
protein fibers. These attachments happen at all cell junctions that are not
involved in the membrane flow. Also, there are four types of junctions:
 Tight Junctions- it blocks the passage of water or solutes between the cells, and is
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often found where cells are exposed to fluids that are very different from normal
extracellular fluids.
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Intermediate Junction- is held by a thick layer of proteoglycans that is also called
intercellular cement od hyaluronic acid. The cytoplasm at this junction anchor the
junction to the cytoskeleton with microfilaments, and help add strength to help
stabilize the shape of the cell.
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Desmosomes- is very strong in which it can help resist stretching and twisting. It
is a superficial layer of skin as well. It also creates dead skin cells that shed in thick
sheets rather individually.
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Junction Complexes- are the cells that line the digestive tract, respiratory tract,
and other passageways. But a single junctional complex of all the other three
junctions, but with the tight junction closest to the surface.
Cells attached to other cells and
body tissues