Download Cell structure

The Cell
• The basic
living,
structural, and
functional
unit of all
organisms
Cell Membrane
• Floating around in the cell
membrane are different
kinds of proteins. These
are generally globular
proteins. They are not held
in any fixed pattern but
instead float around in the
phospholipid layer.
Generally these proteins
structurally fall into three
catagories...
Proteins in the cell Membrane
• There are carrier proteins
that regulate transport and
diffusion
!
• Marker proteins that identify
the cell to other cells
!
• And receptor proteins that
allow the cell to recieve
instructions
Phospholipid
• 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.
Cell Membrane (carrier proteins)
• These are carrier
proteins. They do not
extend through the
membrane. They bond
and drag molecules
through the bilipid
layer and release them
on the opposite side.
Cell Membrane (channel proteins)
• In some cases the channel
proteins simply act as a
passive pore. Molecules
will randomly move
through the opening in a
process called diffusion.
This requires no energy,
molecules move from an
area of high concentration
to an area of low
concentration.
Phospholipid Structure
•
The two long chains coming off of the
bottom of this molecule are made up of
carbon and hydrogen. Because both of
these elements share their electrons evenly
these chains have no charge (gasoline is
also a hydrocarbon). Molecules with no
charge are not attracted to water; as a result
water molecules tend to push them out of
the way as they are attracted to each other.
This causes molecules with no charge not
to dissolve in water (this is why gasoline
and water do not mix). At the other end of
the phospholipid is a phosphate group and
several double bonded oxygens. The atoms
at this end of the molecule are not shared
equally. This end of the molecule has a
charge and is attracted to water.
Nucleus
• The nucleus is the
headquarters of the cell. It
regulates all cell activity. It
consists of a nuclear
envelope, (the outer
membrane) and
nucleoplasm. In the
nucleoplasm you can see
chromatin and the
nucleolus.
Nucleus - Structure - Nucleolus
• 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
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. There
are 3 groups of organelles in the cytoplasm:
Protein producers, Energy Producers and
Specialty structures.
Ribosomes
(protein producer)
• The rough E.R. has
ribosomes attached to
it. This gives it its
texture. These
ribosome manufacture
proteins for the cell.
Golgi Complex (Body) (protein producer)
• The golgi body is
responsible for packaging
proteins for the cell. Once
the proteins are produced
by the rough E.R. they pass
into the sack like 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.
The Endoplastic Reticulum
• Spreading throughout the cytoplasm is the
endoplasmic reticulum. It is a folded system
of membranes that loop back and forth
giving it a very large surface area. This
membrane provides a surface area for cell
reactions. It is also the Site of lipid
production. Protien Producing Organelles
• The E.R. comes in two forms:
Smooth E.R. (protein producer)
• Smooth E.R. has no
ribosomes associated
with it
Rough E.R. (protein producer)
• The rough E.R. has
ribosomes
Lysosomes (protein producer)
• Lysosomes are called
suicide sacks. They are
produced by the golgi
body. They consist of a
single membrane
surrounding powerful
digestive enzymes.
Mitochondria (Energy producer)
• Power house of the
cell.
• The mitochondrion is the
site of aerobic respiration.
Most of the key processes
of aerobic repiration occur
accross its inner
membrane. One theory
holds that they evolved
from endosymbiotic
bacteria.
Chloroplast (Energy producer)
• The Chloroplast is the
photosynthesis. It is
here that plant cells
trap the energy of light
and use it to
manufacture food
proteins for the cell.
Centriole (Specialty Structures)
• Centrioles are found
only in animal cells.
They function in cell
division. Notice the 9
sets of 3 arrangement
of the protein fibers.
Cilia and Flagella (Specialty Structures)
•
These are hair like extentions off
of the cell membrane. Their
structures are similar except that
cilia tend to be small and
numerous and flagella tent to be
large and fewer. Their they beat
back and forth rythmically. In
unicellular organisms their job is
locomotion. In large
multicellular organisms their
role is to move fluid past the
cell. Notice the 9+2 arrangement
of the microtubles.
Vacuoles (Specialty Structures)
• 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.
Cell wall (Specialty Structures)
• Cell walls are the rigid
structure found
surrounding plant cells.
They provide support
for the plant
Plastids (Specialty Structures)
• 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. Chloroplasts
represent one group of plastids
called chromoplasts (colored
plastids). The other class of
plastid are called leucoplasts
(colorless plastids); they usually
store food molecules. Included in
this group are amyloplasts or
starch plastids shown here in
potato root cell.