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Warm Up:
Compare and contrast
prokaryotes and eukaryotes cells.
Hint: See section 7.1 in your text
Or use your notes
7.2 Cell Structure
pg. 165-173
Cell Organization
- eukaryotic cells are divided into two major parts:
the nucleus and the cytoplasm (they work
together to keep the cell alive)
- prokaryotic cells have cytoplasm but NO
nucleus
- cytoplasm: fluid portion of the cell outside the
nucleus
- organelles: structures in plant/animal cells that act
like specialized organs
Lesson Overview
Cell Structure
7.2 Cell Structure
Comparing the Cell to a Factory
The eukaryotic cell is much like a living version of a modern factory.
The specialized machines and assembly lines of the factory can be
compared to the different organelles of the cell.
Cells, like factories, follow instructions and produce products.
7.2 Cell Structure
pg. 165-173
Cell Organization
The Nucleus (Control Center)
- nucleus: control center of the cell
- prokaryotic cells have cytoplasm but NO
nucleus
- holds cell’s DNA: coded directions for making
proteins and other important molecules
- surrounded by a nuclear envelope made of
two membranes dotted with holes
7.2 Cell Structure
pg. 165-173
Cell Organization
The Nucleus (Control Center)
- surrounded by a nuclear envelope made of
two membranes dotted with holes
- holes allow materials such as proteins,
RNA and other molecules to move into
and out of the nucleus
- also contains a nucleolus: small dense spot
where ribosomes are FIRST put together
-ribosomes: used by cell to make proteins
7.2 Cell Structure
Cell Organization
The Nucleus (Control Center)
- chromosomes contain the
genetic information that is
passed from one generation of
cells to the next
- threadlike chromosomes
are spread throughout the
nucleus in the form of
chromatin—a complex of DNA
bound to proteins
- when a cell divides, its chromosomes
condense and can be seen under a
microscope
pg. 165-173
7.2 Cell Structure
pg. 165-173
Organelles That Store, Clean Up & Support
- vacuoles, lysosomes and the cytoskeleton are the
cell’s storage space, clean up crew and support
structure
Vacuoles & Vesicles (Storage Space)
- vacuoles: large membrane sacs that store
materials like water, salts, proteins and sugars
- in plants the central vacuole fills with liquid
allowing the cell to become firm enough to
hold heavy parts such as leaves and flowers
often in plants;
increases rigidity
contracts
rhythmically
pumping excess
water out of cell
7.2 Cell Structure
pg. 165-173
Organelles That Store, Clean Up & Support
Vacuoles & Vesicles (Storage Space)
- vesicles: smaller membrane sacs used to store
and move materials between organelles as well as
to and from the outside of the cell
7.2 Cell Structure
pg. 165-173
Organelles That Store, Clean Up & Support
Lysosomes/digestive sacs: (Clean Up Crew)
- lysosomes: small organelles filled with enzymes
that break down lipids, sugars and proteins into
smaller molecules
- helps break down organelles that are no
longer useful
- remove the “junk” that might otherwise pile
up
- many human diseases are linked to lysosomes
that stop working correctly
Lysosomes: break down large
molecules and old organelles
7.2 Cell Structure
pg. 165-173
Organelles That Store, Clean Up & Support
The Cytoskeleton (Conveyer Belt)
- cytoskeleton: web of proteins that give eukaryotic
cells their shape and internal organization
Organelles That Store, Clean Up & Support
The Cytoskeleton (Conveyer Belt)
Microtubules:
Centrioles:
Organelles That Store, Clean Up & Support
The Cytoskeleton (Conveyer Belt)
Microfilaments:
- form extensive networks in
some cells and produce a
tough, flexible framework
that supports the cell
- help cells move
Organelles Build Proteins
- proteins help carry out
chemical reactions and
make up important
parts if the cell
- proteins are made on
ribosomes, sometimes in
association with the rough
endoplasmic reticulum in
eukaryotes
Organelles That Build Proteins
Ribosomes (Small Machine)
- ribosomes are small particles of RNA and protein
found throughout the cytoplasm in all cells
- produce proteins by following coded instructions
that come from DNA
Organelles That Build Proteins
Endoplasmic Reticulum/canals
- endoplasmic reticulum (ER) internal
membrane system
- where lipid components of the cell membrane
are assembled, along with proteins and other
materials that are exported from the cell
- Two types: smooth and rough
Lesson Overview
Cell Structure
Organelles That Build Proteins
Endoplasmic Reticulum
Rough ER: involved in the synthesis of proteins
- “rough” because of the ribosomes found on its surface make it bumpy
.
Lesson Overview
Cell Structure
Organelles That Build Proteins
Endoplasmic Reticulum
- smooth ER: because ribosomes are not found on its surface
- smooth ER contains collections of enzymes that perform
specialized tasks, including the synthesis of membrane lipids
and the breaking down drugs.
Lesson Overview
Cell Structure
Organelles That Build Proteins
Golgi Apparatus/Packaging Structures- (a customization
shop)
- Proteins produced in the rough ER move next into the Golgi
apparatus,
which appears as a stack of flattened membranes.
The proteins are bundled into tiny vesicles that bud from the ER and
carry them to the Golgi apparatus.
Lesson Overview
Cell Structure
Golgi Apparatus (a customization shop)
Golgi apparatus: modifies, sorts, and package
proteins and other materials from the ER for
storage in the cell or release outside the cell.
Lesson Overview
Cell Structure
Golgi Apparatus (a customization shop)
From the Golgi apparatus, proteins are
“shipped” to their final destination inside
or outside the cell.
Lesson Overview
Cell Structure
Organelles That Capture and Release Energy
All living things require a source of energy. Most cells are powered by
food molecules that are built using energy from the sun.
Chloroplasts and mitochondria are both involved in energy conversion
processes within the cell.
Lesson Overview
Cell Structure
Chloroplasts
Plants and some other
organisms contain
chloroplasts.
Chloroplasts are the
biological equivalents of solar
power plants. They capture
the energy from sunlight and
convert it into food that
contains chemical energy in a
process called photosynthesis.
Lesson Overview
Cell Structure
Mitochondria
Nearly all eukaryotic cells, including plants, contain
mitochondria.
Mitochondria are the power plants of the cell. They
convert the chemical energy stored in food into
compounds that are more convenient for the cell to use.
Lesson Overview
Cell Structure
Mitochondria
One of the most interesting aspects of
mitochondria is the way in which they are
inherited.
In humans, all or nearly all of our mitochondria
come from the cytoplasm of the ovum, or egg
cell. You get your mitochondria from Mom!
Lesson Overview
Cell Structure
Mitochondria
Chloroplasts and mitochondria contain
their own genetic information in the form of
small DNA molecules.
Lesson Overview
Cell Structure
Cellular Boundaries
Lesson Overview
Cell Structure
Cell Walls
cell wall: provide support and protection for the cell.
Prokaryotes, plants, algae, fungi, and many prokaryotes
have cell walls. Animal cells do NOT have cell walls.
Cell walls lie outside the cell membrane and most are
porous enough to allow water, oxygen, carbon dioxide, and
certain other substances to pass through easily.
Lesson Overview
Cell Structure
Cell Membranes
All cells contain a cell membrane that regulates
what enters and leaves the cell and also protects
and supports the cell.
Lesson Overview
Cell Structure
Cell Membranes
Cell membranes are made from a double-layered
sheet called a lipid bilayer.
Lesson Overview
Cell Structure
The Fluid Mosaic Model
Most cell membranes contain protein molecules
that are embedded in the lipid bilayer.
Carbohydrate molecules are attached to many of
these proteins.