Download Notes Section 3.2: Cytoskeleton and Nucleus

Cell Organelles
Section 3.2: Cytoskeleton and Nucleus
A Mitochondrion
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Objectives
• SWBAT describe the internal structure of
eukaryotic cells.
• SWBAT visualize the structures and functions
of organelles in plant and animal cells.
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Vocabulary – Section 3.2
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Cytoskeleton (microtubules, intermediate filaments, microfilaments)
Nucleus
Rough endoplasmic reticulum (rough ER)
Smooth endoplasmic reticulum (smooth ER)
Ribosome
Golgi apparatus
Vesicle
Mitochondrion (mitochondria is plural)
Vacuole
Lysosome
Centriole
Cell wall
Chloroplast
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Animal Cell
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Plant Cell
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Cytoplasm
• Cytoplasm is a jellylike substance that contains
dissolved molecular building blocks.
• Molecular building blocks you will find in the
cytoplasm include:
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Glucose (to be used to create energy);
Amino acids and proteins;
Nucleic acids;
Fatty acids and lipids;
Minerals and ions;
etc.
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Cellular Structure
• Eukaryotic cell organization:
– Surrounded by a protective membrane.
– Containing membrane bound organelles, which
perform specific cellular processes, divide certain
molecules into compartments, and help to
regulate the timing of key events.
– Organelles and molecules are anchored to specific
sites in the cell – based on the cell’s type.
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Cellular Structure
• Each eukaryotic cell has a cytoskeleton.
– Network of proteins that is constantly changing
to meet the cell’s needs.
– the proteins form long threads which
“crisscross” the entire cell holding organelles in
place.
If the cell membrane were
“evaporated,” the cell
would maintain shape
through the cytoskeleton
(for a short time).
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Cytoskeleton
Cytoskeleton photo:
750X magnification
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Cytoskeleton
• Cytoskeleton is made up of three main types
of fibers:
– Microtubules – long hollow tubes giving cell its
shape and acting as tracks for organelle
movements.
– Intermediate filaments – smaller than
microtubules giving cell strength.
– Microfilaments – tiny threads which enable cells
to move and divide (during mitosis and meiosis).
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Microtuble Network
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Microfilament Bundles
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The Nucleus
• The storehouse for DNA (deoxyribonucleic
acid) in your cells.
• DNA contains the genes – which are
instructions – for making proteins.
• The Nucleus must:
– Protect the DNA and
– Make the DNA available for use at the proper
time (DNA transcription) for protein synthesis.
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The Nucleus
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The Nucleus
• The nucleus protects the cell’s DNA from
molecules that might damage it.
• At the same time, the nucleus makes the DNA
available to the many proteins that are
involved in turning genes on and off.
• The nucleus is composed of the cell’s DNA
enclosed in a nuclear envelope (a double
membrane).
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The Nucleus
• The nuclear envelope is pierced with pores
(nuclear pores) which allow large molecules to
pass between the nucleus and cytoplasm.
– RNA passes through the nuclear envelope
between the nucleus and cytoplasm.
• The nucleolus is also found in the nuclear
envelope.
– Its main purpose is producing the “subunits (the
parts)” from which ribosomes are assembled.
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