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7-2 Eukaryotic Cell Structure
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7-2 Eukaryotic Cell Structure
Eukaryotic Cell Structures
Eukaryotic Cell Structures
Structures within a eukaryotic cell that perform
important cellular functions are known as
organelles.
Cell biologists divide the eukaryotic cell into two
major parts: the nucleus and the cytoplasm.
The Cytoplasm is the jelly-like substance of the
cell outside the nucleus that supports the
organelles.
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7-2 Eukaryotic Cell Structure
Eukaryotic Cell Structures
Plant Cell
Nucleolus
Nucleus
Smooth
endoplasmic
reticulum
Nuclear envelope
Ribosome (free)
Rough endoplasmic
reticulum
Ribosome
(attached)
Golgi
apparatus
Cell wall
Cell membrane
Chloroplast
Mitochondrion
Vacuole
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7-2 Eukaryotic Cell Structure
Eukaryotic Cell Structures
Animal Cell
Nucleolus
Smooth endoplasmic
reticulum
Nucleus
Ribosome (free)
Nuclear envelope
Cell membrane
Rough
endoplasmic
reticulum
Ribosome
(attached)
Centrioles
Golgi
apparatus
Mitochondrion
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7-2 Eukaryotic Cell Structure
Cytoskeleton
What are the functions of the
cytoskeleton?
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7-2 Eukaryotic Cell Structure
Cytoskeleton
The cytoskeleton is a network of protein
filaments that helps the cell to maintain
its shape. The cytoskeleton is also
involved in movement.
The cytoskeleton is made up of:
• microfilaments
• microtubules
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7-2 Eukaryotic Cell Structure
Cytoskeleton
Cytoskeleton
Cell membrane
Endoplasmic
reticulum
Microtubule
Microfilament
Ribosomes
Mitochondrion
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7-2 Eukaryotic Cell Structure
Nucleus
What is the function of the nucleus?
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7-2 Eukaryotic Cell Structure
Nucleus
Nucleus
The nucleus is the control center of the cell.
The nucleus contains nearly all the cell's
DNA (genetic information) and with it
the coded instructions for making
proteins and other important molecules.
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7-2 Eukaryotic Cell Structure
Nucleus
The Nucleus
Chromatin
Nuclear envelope
Nucleolus
Nuclear
pores
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7-2 Eukaryotic Cell Structure
Endoplasmic Reticulum
What is the function of the endoplasmic
reticulum?
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7-2 Eukaryotic Cell Structure
Endoplasmic Reticulum
There are two types of ER—rough and smooth.
Endoplasmic
Reticulum-
Ribosomes
responsible for
the production
and
transportation of
ribosomes
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7-2 Eukaryotic Cell Structure
Ribosomes
What is the function of the ribosomes?
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7-2 Eukaryotic Cell Structure
Ribosomes
Ribosomes
•One of the most important jobs carried out in the cell is
making proteins.
•Proteins are assembled on ribosomes.
•Ribosomes are small particles of RNA and protein
found throughout the cytoplasm and on the
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endoplasmic reticulum.
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7-2 Eukaryotic Cell Structure
Golgi Apparatus
What is the function of the Golgi
apparatus?
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7-2 Eukaryotic Cell Structure
Golgi Apparatus
The Golgi apparatus appears as a stack of closely apposed
membranes.
Responsible for processing, sorting and delivering proteins.
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7-2 Eukaryotic Cell Structure
Vesicles
• What is the function of the vesicles?
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7-2 Eukaryotic Cell Structure
Vesicles
• Vesicles are sacs that
separate some
materials from the rest
of the cytoplasm.
• When a cell needs to
move a molecule many
times, it uses vesicles.
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7-2 Eukaryotic Cell Structure
Mitochondria
What is the function of the mitochondria?
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7-2 Eukaryotic Cell Structure
Mitochondria
Mitochondria
Nearly all eukaryotic
cells contain
mitochondria.
Mitochondria convert
the chemical energy
stored in food into
compounds that are
more convenient for
the cell to use.
Mitochondrion
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7-2 Eukaryotic Cell Structure
Vacuoles
What is the function of vacuoles?
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7-2 Eukaryotic Cell Structure
Vacuoles
In many plant cells there
is a single, large central
vacuole filled with liquid.
Vacuole
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Vacuoles are also found
in some unicellular
organisms and in some
animals. They are much
smaller in animal cells.
Vacuoles
Contractile vacuole
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7-2 Eukaryotic Cell Structure
Lysosomes
What is the function of lysosomes?
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7-2 Eukaryotic Cell Structure
Lysosome
• Lysosomes are sacs containing enzymes that defend a cell
from invaders and break down wornout cell parts
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Centrioles
• What is the function of the centrioles?
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Centrioles
Centrioles are located near the nucleus and help to
organize cell division (meiosis and mitosis).
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7-2 Eukaryotic Cell Structure
Centrioles
• Centrioles consist of
microtubules arranged
in a circle.
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7-2 Eukaryotic Cell Structure
Cell Wall
• What is the function of the cell wall?
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Cell Wall
• The cell wall is found in
plant cells only. It is a
rigid layer surrounding
the cell membrane in
plant, algae, and fungi
that provides protection,
support and shape.
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Chloroplasts
What is the function of chloroplasts?
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7-2 Eukaryotic Cell Structure
Chloroplasts
Chloroplasts
Chloroplast
Plants contain
chloroplasts.
Chloroplasts capture
energy from sunlight
and convert it into
chemical energy in a
process called
photosynthesis.
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7-2 Eukaryotic Cell Structure
What is the function of the cell
membrane?
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Cell Membrane
• The Cell membrane is a barrier that separates a cell from
the external environment
• Cell membranes are composed of two phospholipid
layers.
–
The cell membrane has two major functions
• Forms a boundary between inside and outside of the cell
• Controls passage of materials
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Cell Membrane
• Phospholipid bilayer forms double layer surrounding a cell. It is
composed of a charged phosphate group, gylcerol and two fatty acid
chains. The head is polar and forms hydrogen bonds with water and the
tail is nonpolar.
• The fluid mosaic model describes the molecules making up a cell
membrane; the membrane is flexible like a fluid and has a variety of tiles
in a mosaic.
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Other molecules
• There are other molecules embedded in the membrane.
• Other molecules
-cholesterol strengthens membranes.
-Proteins aid cell identification and movement of molecules across membranes
and cell signaling.
-Carbohydrates aid cell identification
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Cell Membrane
The cell membrane is
selectively permeable.
•
Some molecule can
cross the membrane
while others cannot.
•
Can also use terms
semipermeable and
selectively permeable
•
Enables a cell to
maintain homeostasis
•
Molecules can cross
in a variety of ways
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Cell Membrane
• Chemical signals are transmitted across the cell membrane.
–
Receptors detect a signal molecule and perform an action in
response. They bind with ligands and change shape.
• intracellular receptor-located inside the cell; bind to molecules
that can cross the membrane
• Membrane receptor-located in the membrane; binds to
molecules that cannot cross the membrane; change in shape
transmits the message to the cell interior
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• Receptors and ligands
play a crucial role in all
biological systems by
allowing cells to
communicate with each
other
• Ligands can be substrates,
inhibitors, activators, and
neurotransmitters
• Receptors are proteins
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7-2
In the nucleus of a cell, the DNA is usually visible
as
a. a dense region called the nucleolus.
b. the nuclear envelope.
c. granular material called chromatin.
d. condensed bodies called chloroplasts.
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7-2
Two functions of vacuoles are storing materials
and helping to
a. break down organelles.
b. assemble proteins.
c. maintain homeostasis.
d. make new organelles.
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7-2
Chloroplasts are found in the cells of
a. plants only.
b. plants and some other organisms.
c. all eukaryotes.
d. most prokaryotes.
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7-2
Which of the following is NOT a function of the
Golgi apparatus?
a. synthesize proteins.
b. modify proteins.
c. sort proteins.
d. package proteins.
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7-2
Which of the following is a function of the
cytoskeleton?
a. manufactures new cell organelles
b. assists in movement of some cells from one
place to another
c. releases energy in cells
d. modifies, sorts, and packages proteins
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