Parts are Parts! And together
they are life
Cell Anatomy and Function
Cells are the smallest unit that can
meet the 5 characteristics of life.
1. they are organized.
2. they respond to environmental
stimuli.
3. they metabolize.
4. they reproduce.
5. they are adapted to the environment
The cell is the smallest unit of life.
• The cellular level is important
because essential activities of life
occur in cells and disease originates
there.
• The CELL is the smallest structure
capable of maintaining life and
reproducing life.
Cyto means cell, so
• CYTOLOGY is the study of cells.
• Cytogenetics is the study of the
chromosomes within the cell
• Cells have many parts some of
the parts are the organelles,
cytoplasm & other structures each
with a specific function within the
cell
• Living cells are
about 60% water.
Cells vary
tremendously in
length - from 2
micrometers
(1/12,000th of an
inch) in the
smallest cells to
over a meter in
some nerve cells.
Form = Function
• There are many different
shapes of cells in the
body as well. Red blood
cells are disc-shaped;
nerve cells have threadlike extensions; smooth
muscle cells are shaped
like toothpicks; and
epithelial cells are cubelike.
Structures - main ones
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plasma membrane or cell membrane
nucleus
cytoplasm
organelles
fibers
inclusions
mitochondria
A TOUR OF THE CELL
• Internal structures or organelles are in two
groups
• Group 1 membranous organelles
• Membranous organelles, as the name
implies, are cellular structures made of
phospholipid bilayers.
• Group 2 non-membranous or protein
organelles
A Scanning EM of a cell
• Method of movement
Group 1 includes
• Nucleus
• Endoplasmic Reticulum (rough and
smooth)
• Golgi Apparatus
• Mitochondria
• Vacuoles
• In plants Chloroplasts
Nucleus
• Largest structure in a cell
• Usually spherical membrane shell that
houses DNA and makes RNA for use in
directing protein synthesis. By controlling
what proteins are made, the nucleus
controls most cellular functions.
• The cell nucleus is a
remarkable organelle
because it forms the
package for our
genes and their
controlling factors. It
functions to:
Store genes on the
chromosomes Organize genes into
chromosomes to
allow cell division.
The nucleus also
• Transport regulatory factors & gene
products via nuclear pores
• Produce messages ( messenger
Ribonucleic acid or mRNA that code for
proteins
Produce ribosomes in the nucleolus
Organize the uncoiling of DNA to
replicate key genes
Endoplasmic reticulum (ER)
• "Maze-like" network of membrane often
spanning out from the nucleus. The rough
ER is dotted with ribosomes and is often
an industrial complex for protein
production. The smooth ER, a site where
some of the proteins produced do their
job, is where detoxification, materials
processing and lipid synthesis occur.
• With
Rough ER
ribosomes
• Smooth ER
Without
ribosomes
Golgi apparatus
• (also Golgi
complex/body) Packaging and
special processing of
molecules (mainly
proteins) for export
out of the cell.
Mitochondria
• Nicknamed "the
powerhouse of the
cell," they are
membranous energy
transducers that
convert molecular
energy from one
molecule to another
(usually from sugars,
lipids, and amino
acids to ATP).
Chloroplasts (in plant cells)
• A collection of membranous structures
that convert sunlight and low-energy
molecules into carbohydrates.
Vacuole
• Typically a large
bubble of
membrane used
for storage inside
a cell.
http://content.answers.com/main/content/img/McGrawHill/Encyclopedia/images/C
E725300FG0010.gif
• Animal
Lots of small
Vacuoles
• Plant
1 large central
vacuole
And a host of small players
• Vesicle - Small storage bubble of
membrane.
• Lysosome - Vesicle or small vacuole
containing digestive enzymes.
Phagocytosis and lysosome in
action
• http://www.as.wvu.edu/~caldwell/101fig
_lysosome.jpg
• http://www.as.wvu.edu/~caldwell/101dia
grams.htm
Group 2
• The protein-based organelles are very
different, but no less important in their
support roles in the cell.
Protein based
• Cytoskeleton - Network of protein fibers
and tubes that support and move the cell.
• Flagella & cilia - contractile proteins
important for moving the cell (i.e. sperm)
or moving other substances in a
multicellular organism (i.e. ciliated
epithelium of the human respiratory tract).
• Finally, there are miscellaneous organelles
who's structure is less well defined, or
otherwise do not fall into the preceding
categories.
• Ribosomes - Debated by some as to
whether it is an organelle or a just a simple
(even if elegant) mixture of rRNA and
proteins; worksites for protein synthesis.
• Centro some - Area (containing the
centrioles in animal cells) responsible for
directing many aspects of cell division.
http://fig.cox.mia
mi.edu/~cmallery/
150/cells/organell
e.htm
Remaining organells
• Nucleolus - Area within the nucleus most
closely associated with RNA production.
• Microvilli - Folds in the plasma membrane
to increase surface area (for absorption,
transport, etc.).
• Cell wall - "Polysaccharide container"
associated with plant cells (and fungi).
• Fig 4.
They all
work
together
Similar but different
Differences between plant and
animal cells
• There are many different types of
cells. One major difference in cells occurs
between plant cells and animal
cells. While both plant and animal cells
contain the structures discussed above,
plant cells have some additional
specialized structures.
Support
• Many animals have skeletons to give their
body structure and support. Plants do not
have a skeleton for support and yet plants
don't just flop over in a big spongy
mess. This is because of a unique cellular
structure called the cell wall. The cell wall
is a rigid structure outside of the cell
membrane composed mainly of the
polysaccharide cellulose.
Plant Cell
• The cell wall gives the plant cell a defined
shape which helps support individual parts
of plants. In addition to the cell wall, plant
cells contain an organelle called the
chloroplast. The chloroplast allow plants
to harvest energy from sunlight.
• See the cell wall? And
the chloroplasts?
Plant Cell
• Specialized pigments in the chloroplast
(including the common green pigment
chlorophyll) absorb sunlight and use this
energy to complete the chemical reaction:
• 6 CO2 + 6 H2O + energy (from
sunlight) C6H12O6 + 6 O2
Plant Cell Characteristics
• Plant cells have a cell wall and a large
central vacuole. In the mature plant, the
central vacuole may occupy 50-90% of the
cell interior. It stores amino acids, sugars,
water. ions, and wastes. The vacuole
enlarges during growth and greatly
increases the cell's outer surface area.
The cytoplasm is forced into a very narrow
zone between the central vacuole and the
plasma membrane.
• Plant cells may also have chloroplast
or other plastids. Chloroplasts are oval
or disk shaped. They are bounded by a
double membrane, and are critical to
the process of photosynthesis. They
have stacked disks (grana), pigments
and enzymes which trap sunlight
energy to form ATP. Sugars are formed
in the fluid substance (stroma)
surrounding the stacks. Pigments such
as chlorophyll (green) confer
distinctive colors to the chloroplasts.
Animal Cell Characteristics
• Between animal cells is a matrix or
meshwork that holds animal cells and
tissues together and influences how
the cells will divide and metabolize.
• Complexity is the method to hold cells
together
Plant vs Animal Cell
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Plant cells have a cell wall, but animal cells do
not. In animals the cell membrane is the
outside boundary,
Plant cells have chloroplasts, but animal cells
do not.
Plant cells generally have a more rectangular
shape because the cell wall is more rigid.
Animal cells have a round or irregular shape
because they do not have a cell wall.
Both plant and animal cells contain a cell
membrane.