Transcript Eukaryotic Cells

Chapter 4
Section 2 Eukaryotic Cells
Bellringer
What are three differences between
prokaryotic and eukaryotic cells?
Write your answer in your science journal.
Chapter 4
Section 2 Eukaryotic Cells
What You Will Learn
• Eukaryotic cells have many parts--such as
cell membranes, a nucleus, and ribosomes-in common.
• Plant cells and animal cells have some cell
parts that are different.
Chapter 4
Section 2 Eukaryotic Cells
Cell Wall
• Eukaryotic cells have many organelles in
common to carry out important functions.
• Plants are eukaryotes that have some
structures and organelles not seen in animal
cells.
• Plant cells have a rigid structure that
surrounds the cell membrane called the cell
wall. Animal cells lack a cell wall.
Chapter 4
Section 2 Eukaryotic Cells
Chapter 4
Section 2 Eukaryotic Cells
Cell Membrane
• All cells have a cell membrane made up of
proteins and phospholipids.
• A phospholipid has a water-loving, or
hydrophillic, head and a water-fearing, or
hydrophobic, tail.
• The phospholipids form a two-layer protective
membrane.
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Section 2 Eukaryotic Cells
Cell Membrane, continued
• The two-layer membrane makes it difficult
for materials to pass into or out of the cell.
• Some materials, like nutrients and wastes,
move through the membrane using protein
passageways within the membrane.
Chapter 4
Section 2 Eukaryotic Cells
Chapter 4
Section 2 Eukaryotic Cells
Cytoskeleton
• The cytoskeleton is a web
of proteins in the cytoplasm
of some cells. It plays a key
role in cell movement,
shape, and division.
• Different cells have different
shapes because of the
arrangement of their
cytoskeletons.
Chapter 4
Section 2 Eukaryotic Cells
Nucleus
• All eukaryotic cells have a nucleus. The nucleus is
the large organelle that contains the cell’s DNA.
• The DNA provides messages for making proteins.
The messages are sent out of the nucleus through
pores in the nucleus membrane.
• Some cells have a dark area within the nucleus
called the nucleolus. Ribosome assembly begins
here.
Chapter 4
Section 2 Eukaryotic Cells
Chapter 4
Section 2 Eukaryotic Cells
Ribosomes
• Ribosomes are small organelles that make
proteins. There are more ribosomes than any
other organelle in the cell.
• Because all cells need to make proteins, all
cells have ribosomes.
• Unlike most organelles, ribosomes are not
covered by a membrane.
Chapter 4
Section 2 Eukaryotic Cells
Endoplasmic Reticulum
• The endoplasmic reticulum, or ER, is a
system of folded membranes in which
proteins, lipids, and other materials are
made.
• Rough ER is covered with ribosomes that
make proteins near the nucleus. Smooth ER
lacks ribosomes.
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Section 2 Eukaryotic Cells
Endoplasmic Reticulum, continued
• Smooth ER makes lipids and breaks down
toxic materials. The ER also functions as a
delivery system for the cell.
Chapter 4
Section 2 Eukaryotic Cells
Mitochondria
• A mitochondrion is the main power source of
a cell. Mitochondria are organelles in which
sugar is broken down to release energy.
• Mitochondria have two membranes. The
folded inner membrane of a mitochondrion is
where ATP is made.
• ATP is the energy storing molecule used by the
cell to carry out its functions.
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Section 2 Eukaryotic Cells
Mitochondria, continued
• Most eukaryotic cells have mitochondria.
They are unusual organelles in that they
have their own DNA and divide on their
own, like bacteria.
Chapter 4
Section 2 Eukaryotic Cells
Chloroplasts
• Chloroplasts are organelles in which
photosynthesis takes place. Plants, algae, and
some prokaryotes have cells with chloroplasts.
• Chloroplasts are green because they contain
chlorophyll, the pigment that traps the energy
of sunlight.
• This energy is used to make sugar during
photosynthesis.
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Section 2 Eukaryotic Cells
Chloroplasts, continued
• Chloroplasts, like mitochondria, have their
own DNA and two membranes.
Photosynthesis takes place in the inner
membrane.
Chapter 4
Section 2 Eukaryotic Cells
Golgi Complex
• The Golgi complex packages and distributes
proteins and lipids. The materials may be taken to
other parts of the cell or may exit the cell.
• Materials may be modified in the Golgi complex to
do different jobs before they are sent off.
• The Golgi complex pinches off portions of its
membrane to create bubbles. The bubbles contain
the materials to be transported.
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Section 2 Eukaryotic Cells
Golgi Complex, continued
• The Golgi complex looks much like the
smooth ER.
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Section 2 Eukaryotic Cells
Cell Compartments
• The bubble that forms from the Gogi
complex’s membrane is an example of a
vesicle.
• A vesicle is a small sac that surrounds
materials to be moved into or out of the cell.
Vesicles also move materials within the cell.
• All eukaryotic cells have vesicles.
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Section 2 Eukaryotic Cells
Lysosomes
• Lysosomes are vesicles that contain
digestive enzymes. They carry out digestion
inside a cell.
• Lysosomes destroy worn-out organelles,
engulf foreign invaders, and get rid of
wastes.
• Lysosomes are found mainly in animal cells.
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Section 2 Eukaryotic Cells
Vacuoles
• A vacuole is another type of vesicle found in
cells. They play an important role in plants.
• Vacuoles in plants and fungi may act like
lysosomes. The large central vacuole in a plant
cell stores water and other liquids.
• Some plants wilt when their large central
vacuoles lose water.
Chapter 4
Section 2 Eukaryotic Cells