Section 7.3
EUKARYOTIC CELL STRUCTURE
OBJECTIVES
Identify the structures and function of the parts
of a typical eukaryotic cell.
 Explain the advantages of highly folded
membranes in cells
 Compare and contrast the structures of plant
and animal cells.

CELLULAR BOUNDARIES

As we know : the fluid mosaic model describes
the plasma membrane as a flexible boundary
of a cell but other things like plant cells,
bacteria and fungi have additional boundaries
like the cell wall

The cell wall is a fairly rigid structure located
outside the plasma membrane that provides
additional support and protection.
A plants cell wall is made up
of cellulose. Cellulose forms
a thick, tough mesh of
fibers. It does not select
which molecules can enter
into the cell.
CELL CONTROL
The nucleus is the leader of the eukaryotic cell
because it contains the directions to make
proteins.
 All parts of the cells depends on proteins. So
therefore, nucleus controls the activity of the
organelles.
 Master set of directions for making protein is
contained in the Chromatin, which are strands
of DNA

CELL CONTROL
In the nucleus a prominent organelle call
nucleolus, it makes ribosomes.
 Ribosomes are the sites where the cell
produces proteins according to the directions of
DNA . The are simple structures made of RNA
and protein.

CELL CONTROL
When proteins are made, ribosomes leave nucleus
and enter into the cytoplasm
 Before they enter the cytoplasm, blueprints of the
DNA are translates into RNA and sent into the
cytoplasm through the nuclear envelope.
 Nuclear envelope is a double membrane made up
of two phospholipids bilayers containing small
nuclear pores for substances to pass through.
 Cytoplasm is the clear, gel fluid inside of the cell.

ENDOPLASMIC RETICULUM (ER)
The site of cellular chemical reactions.
 ER is arranged in series of highly folded
membranes in the cytoplasm.
 Ribosomes in the cytoplasm attach to the
surface called the rough endoplasmic reticulum
where they carry out function of protein
synthesis.

ENDOPLASMIC RETICULUM (ER)

Smooth endoplasmic reticulum does not work
with protein but is involved in biochemical
activities like production and storage of lipids.
GOLGI APPARATUS
A flattened stack of
tubular membranes
that modifies the
proteins that were
made.
 Sorts proteins into
packages and packs
them into membranebound structures called
vesicles and sent to
appropriate destination.

VACUOLES
Membrane- bound
compartments to temporary
storage of materials.
 Is a sac used to store food,
enzymes, and other
materials needed by a cell.
 Animal cells usually don’t
contain them but if they do
its much smaller.

LYSOSOMES
Are the organelles that contain digestive
enzymes.
 Digest excess or worn out organelles, food
particles, and engulfed viruses or bacteria.
 The membrane that surrounds a lysosome
prevents the digestive enzymes from destroying
the cell.

Cool fact:
When a tadpole develops
into a frog, lysosomes within
the cells of the tadpole’s tail
causes its digestion.
Other molecules that are
released are used to build
different cells.
ENERGY TRANSFORMERS

Protein production, modification,
transportation, and digestion requires
energy!!!!!!!

Energy providers are the organelles called
chloroplasts and mitochondria.
CHLOROPLASTS


Are cell organelles
that capture light
energy and convert
it to chemical
energy.
Has a double
membrane that
protects thylakoid
membranes that
the energy from
sunlight is trapped
by. (look like stack
of coins)
PLASTIDS
Plant organelle that is used for storage that the
chloroplast belongs to
 Some store starches or lipids.
 Plastids are named according to their color or
the pigment they contain.

CHLOROPHYLL

Traps light energy and gives leaves and stems
their green color.
MITOCHONDRIA
Membrane-bound organelle in a plant and
animal cells that transform energy for the cell.
 This energy is then stored in the bonds of other
molecules that cell organelles can access
easily and quickly when energy is needed.
 Has an outer membrane and highly folded
inner membrane.

MITOCHONDRIA
CYTOSKELETON
Forms a framework for the cell (like a skeleton)
 It is a constantly changing structure.
 It is a network of tiny rods and filaments called:

Microtubules – thin, hollow cylinders made of
protein
 Microfilaments- smaller, solid protein fibers

MICROTUBULES & MICROFILAMENTS


Together
maintain shape
of the cell and
anchor and
support many
organelles.
They also
provide a sort
of highway
system through
which materials
move within the
cell.
CENTRIOLES
Organelles found in the cells of animals and
most protists.
 Occur in pairs are made up of microtubules
 Play an important role in cell division.

CILIA AND FLAGELLA
Organelles that are made up of microtubles
that aid the cell in locomotion or feeding.
 Cilia are short, numerous projections that look
like hairs.
 Flagella are longer projections that move with a
whip-like motion.

EUKARYOTIC VS PROKARYOTIC
ANIMAL VS PLANT CELL
QUESTIONS OVER 7.3
How are highly folded membranes an advantage
for the functions of cellular parts? Name an
organelle that has highly folded membranes?
 If a cell synthesizes large quantities of protein
molecules, which organelles might be numerous in
that cell?
 Compare and contrast the functions of a cell wall
to the functions of a plasma membrane.
 Compare the number of vacuoles in plant cells
and animal cells.
