The Cell
Cell Parts
• Cell Membrane, Cell Wall, Cytoplasm
• Protein Production- Nucleus,
Nucleolus, Endoplasmic Reticulum,
Ribosomes, Golgi Bodies,
Lysosomes
• Energy- Mitochondrion, Chloroplasts
(Energy- Mitochondrion, Chloroplasts)
• Miscellaneous- Microtubules,
Microfilaments, Plastids
Cell Membrane
It also connects the the endoplasmic
reticulum, and the nuclear membrane.
In the image below we have colored the
membrane to highlight its composition.
The yellow represents the
phospholipids. The purple represents
the membrane proteins
Cell Membrane
• The Cell membrane
performs a number of
critical functions for the
cell. It regulates all that
phospholipids
enters and leaves the cell;
in multicellular organisms it
allows self recognition. In
order to understand the
function of the cell
membrane you must
understand its structure.
Cell Membrane
Close-up
• Here we see a cross section of the cell
membrane you should notice two
different structures: The
phospholipids are the round yellow
structures with the blue tails, the
proteins are the lumpy structures that
are scattered around among the
phospholipids.
This is a simple representation
of a phospholipid. the yellow
structure represents the
HYDROPHILLIC or water loving
section of the phospholipid. The
blue tails that come off of the
sphere represent the
HYDROPHOBIC or water
fearing end of the Phospholipid.
Below is a structural model of a
phospholipid that explains what
these terms mean.
• Cell walls are
the rigid
structure
found
surrounding
plant cells.
They provide
support for
the plant
Cell Wall
Cytoplasm
• The term cytoplasm refers to
everything between the cell
membrane and the nuclear
envelope. It consists of primarily
of water. It also contains various
organelles as well as salts,
dissolved gasses and nutrients.
Cytoplasm
• Protein Producing Organelles:
Endoplasmic Reticulum,
Ribosomes, Golgi Apparatus,
Lysosomes
• Energy Producing Organelles Mitochondrion, Chloroplasts
• Specialty Structures -centrioles,
vacuoles, cell walls, cilia,
flagella, plastids
NUCLEUSnuclear envelope
The nuclear envelope is a double
membrane. Is has 4 phospholipid
layers. It is also has large pores
through which materials pass
back and forth.
Nucleus
The headquarters of the cell. It is a large
dark spot in EUKARYOTIC cells. It
controls all cell activity. Close up you
will see that the nuclear membrane has
many pores. The nuclear membrane is
continuous with the E.R.
With the outer membrane removed it is
much easier to see the contents of the
nucleus.
The thick ropy strands
are the CHROMATIN.
The large solid spot is
the NUCLEOLUS. The
nucleolus is a knot of
chromatin. It
manufactures
ribosomes.
Chromatin
Within the nucleus are found chromatin
and a structure called the nucleolus.
Chromatin is DNA in its active form. It
consists of DNA looped around histone
proteins. The nucleolus is a knot of
chromatin. It is the nucleolus that
manufactures ribosomes .
Endoplasmic Reticulum
• Smooth, no
ribosomes
• rough, has
ribosomes
Smooth E.R.
• The endoplasmic reticulum is a series of
double membranes that loop back and forth
between the cell membrane and the
nucleus.
• These membranes fill the cytoplasm but you
cannot see them because they are very
transparent. There are two distinct types of
E.R.: The rough E.R. has ribosomes and is
the site of protein synthesis; the smooth
E.R. has no ribosomes
•
R.E.R.
The endoplasmic
reticulum is a series
of double membranes
that loop back and
forth between the cell
membrane and the
nucleus. These
membranes fill the
cytoplasm but you
cannot see them
because they are very
transparent.
• The ribosomes
are the organ-elles
which
manufacture
proteins. They are
made of two
separate parts.
These structures
are both made of
ribosomal RNA.
Ribosome
GOLGI BODY
The golgi body is
Golgi Apparatus
responsible for
packaging proteins
for the cell. Once
the proteins are
produced by the
rough E.R. they
pass into the sacklike cisternae that
are the main part of
the golgi body.
These proteins are then squeezed off into the
little blebs which drift off into the cytoplasm.
Lysosomes are called
suicide sacks. They
are produced by the
golgi body. They
consist of a single
membrane
surrounding powerful
digestive enzymes.
From this screen you
can cut the lysosome
and move it around.
Lysosome
Lysosomes
• With the outer
membrane
removed it is much
easier to see the
contents of the
lysosome. Those
lumpy brown
structures are
digestive enzymes.
"suicide sacks”
• They dissolve
bacteria and other
foreign bodies.
Under some
conditions the
lysosomes in a cell
will break open and
a cell will self
destruct in a
process called
autolysis (giving rise
to the name "suicide
sacks").
Vacuole
Vacuoles are large empty
appearing areas found
in the cytoplasm. They
are usually found in plant
cells where they store
waste. As a plant cell
ages they get larger. In
mature cells they occupy
most of the cytoplasm.
CENTRIOLE ENLARGED
Microfilament
These are hair like
extensions off of the cell
membrane. Cilia tend to be
small and numerous and
flagella tend to be large
&few. They beat back and
forth rhythmically. In
unicellular organisms their
job is locomotion. In large
multicell organisms their
role is to move fluid past
the cell. Notice the 9+2
arrangement of the
microtubles.
Microtubule
• Centrioles are found
only in animal cells.
They function in cell
division. Zoom in and
notice the 9 groups of
3 arrangement of the
protein fibers.
The MITOCHONDRION is
the powerhouse of the cell. It is
the site of respiration. It has a
double membrane. From this view
you can see very little >>>>>>>>>>
The outer membrane is cut
to get a better look. With
the outer membrane
removed it is much easier
to see the contents of the
mitochondrion. The white
folded structure is the
inner membrane. Most of
AEROBIC RESPIRATION
occurs along this
membrane. Get a really
good look by cutting the inner
membrane. >>>next slide>>>>>
The inner membranes is ruffled. It has
a very large surface area. These ruffles are
called cristae. Mitochondria have their
own DNA and manufacture some their
own proteins. It is thought that the
mitochondrion evolved from symbiotic
bacteria that took up residence inside
the first eukaryotic cells.
INSIDE THE INNER
MITOCHONDRION
• Plastids are large
organelles found on
plants and some protists
but not in animals or
fungi. They can easily be
seem through a light
microscope. The other
class of plastid are called
leucoplasts (colorless
plastids);
Plastids
they usually store food molecules. Included
in this group are amyloplasts or starch
plastids shown here in potato root cell.
PLASTIDS- Chloroplast
•
• Chloroplasts
represent one
group of
plastids called
chromoplasts
(colored
plastids).
The chloroplast is the
site of photosynthesis.
It consists of a double
membrane. Cut the
outer membrane to get
a better look inside.
With the outer membrane removed it is much
easier to see the contents of the chloroplast.
The stacks of disk-like structures are called
the GRANA. The membranes connecting
them are the THYLAKOID MEMBRANES.
Grana and Thylakoid
Membranes
Dissolve the Remaining
membrane and zoom in
to get a better look.
• The membranes
that you see here
are the site of
photosynthesis. It
is here that the
energy harnessing
process of
photosynthesis
occurs.