UNIT: #3
Cell Structure
and Function
Organelle Structures of the Cell
Organelle:
Specialized structure of
the cell that carries out a specific
function, “organ like”.
The cell is often compared to a
factory.
These organelle structures work to
produce a product.
Cell Membrane (Both)
Composed of several molecules, the most
important is Lipids, which form a bilayer.
 The cell membrane separates the cell from
its surroundings.
 It regulates what enters & leaves the cell.
 Functions: protection and support.
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Cell Wall (Plant)
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Found in Plant, Algae, & some Bacteria.
Is found outside the cell membrane, it actually
surrounds the cell membrane.
It is very porous, allows for water, oxygen, carbon
dioxide and others to pass through it.
The cell wall is both elastic & rigid.
Functions: Protection, Support, Regulation.
Nucleus (Both)
Large dark round structure usually in the
center of the cell.
 Is known as the information center of the
cell.
 Sometimes called the brain of the cell.
 Function: To direct all activities of the cell
and store DNA.
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Nucleolus (Both)
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Made up of RNA and other proteins.
Function: To make ribosomes.
Nuclear Envelope (Both)
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Two layer membrane that surrounds the nucleus,
Function: Acts as border between the nucleus and
the rest of the cell.
Chromosomes (Both)
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The DNA of the cell is stored on the chromosome
inside the nucleus. Shaped like an X.
The chromosome passes genetic information from
generation to generation.
Cytoplasm (Both)
The space or area between the nucleus and
the cell membrane.
 Gel or jelly like.
 Function: Hold and/or support the
organelles.
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Ribosomes (Both)
Small particles of RNA and protein found
throughout the cytoplasm.
 Function: To make proteins.
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Endoplasmic Reticulum (Both)
Is an internal membrane system.
 Function: It is the site where the lipid
components of the cell membrane are
assembled, along with proteins and other
materials.
 The part involved in making protein is
called the Rough Endoplasmic Reticulum,
it has ribosomes on its surface.
 The Smooth Endoplasmic Reticulum
(doesn’t have ribosomes) stores enzymes
used to make lipid membranes.
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Endoplasmic Reticulum
Golgi Apparatus (Both)
Stack of closely apposed membranes.
 Function: It modifies, sorts, and packages
molecules for cell storage or secretion.
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Lysosomes (Both)
Small organelles filled with enzymes that
act as a clean-up crew.
 Function: They digest or breakdown;
lipids, carbohydrates, and proteins into
smaller molecules so that they can be used
by the cell.
 They also break down organelles that have
outlived their usefulness (remove junk that
accumulates in the cell).
 Many serious diseases can be traced to
lysosomes that fail to function properly.
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Lysosome
Vacuoles (Both)
Saclike structure.
 Function: stores (warehouse) materials
like; water, salt, proteins, and
carbohydrates.
 Can be found in many different types of
cells (large central vacuole in plants, several
smaller vacuoles in animals).
 Play a major role in Homeostasis.
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Vacuole
Chloroplasts (Plant)
It stores food and pigments.
 Function: stores chlorophyll(pigment),
which captures energy from sunlight and
converts it into energy for the cell.
 May also be called a Plastid.
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Mitochondria (Both)
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Function: Converts chemical energy stored in
food into energy that is more convenient for the
cell to use. Known as the powerhouse.
Made of two membranes.
The inner membrane has many folds to increase
surface area to improve their function.
Microfilaments (Both)
Thread like structure made of protein
 Function: Helps in cell movement &
support.
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Microtubules (Both)
Hallow structure made up of a protein.
 Function: Plays a major role in maintaining
cell shape and has a role in cell
reproduction.
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Centrioles(Animal)
Microtubule bundles
 Function: Plays a role in cellular
reproduction
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Cytoskeleton (Both)
A network of protein filaments that
 Function: Helps the cell to maintain its
shape.
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– It also is involved in movement.
Cellular Organization
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Cell (Animal)--> Tissue (Cardiac)--> Organs (Heart)->Organ System(Cardiovascular)--> Organisms (Humans)