Cell Parts ID Practice
http://www.cellsalive.com/cells/3dcell.htm
http://biology.clc.uc.edu/courses/bio104/cells.htm
http://www.ibiblio.org/virtualcell/tour/cell/cell.htm
http://www.johnkyrk.com/CellIndex.html
http://www.syvum.com/cgi/online/serve.cgi/squizzes/biology/cell_functions.html
(1) nucleolus (2) nucleus (3) ribosome (4) vesicle (5) rough endoplasmic reticulum (ER)
(6) Golgi apparatus (7) Cytoskeleton (8) smooth ER (9) mitochondria (10) animal cell
vacuole (11) cytoplasm (12) lysosome (specialized vesicle) (13) centrioles
Mitochindria (plural) / Mitochindrion (singular)
Ribosomes
Golgi Body / Golgi Apparatus
Chloroplasts
Chloroplasts (cont…)
1. outer membrane
2. intermembrane space
3. inner membrane (1+2+3: envelope)
4. stroma (aqueous fluid)
5. thylakoid space/lumen (inside of thylakoid)
6. thylakoid membrane
7. granum (stack of thylakoids)
8. thylakoid lamella
9. starch
10. ribosome
11. plastidial DNA
12. plastoglobule (drop of lipids)
Vesicles and Vacuoles: What’s the DIFFERENCE?!?!?!?!
name
status
age
Colin
student
11
Question - My science book says that both plant and animal cells have vacuoles. My sister's AP Biology book says
animal cells do not have vacuoles, only plants do. Which is right?
-----------------------------------------------Actually, both are wrong.
It may be a matter of definition. In advanced textbooks, vesicles are small membrane-bound structures found in animal
cells that typically act as small transporting containers. Usually these vesicles carry materials like food and water to and
from the cell membrane to other destinations in the cell, like the Golgi. You may see structures called food vesicles in
diagrams of animal cells—or even structures labeled “food vacuoles”; transport vesicle and secretory vesicle are better
terms for these structures. Technically, the term food vacuole is incorrect in an animal cell.
True, there are large food vacuoles in some Protists (single-celled eukaryotes) that act to digest food, but these Protist
cells are not plant or animal by definition. True vacuoles, which are found in both plant cells and Protist cells (singlecelled eukaryotes) are larger than vesicles and usually serve major structural, long term storage, or locomotion
purposes, usually involving water regulation.
Another key distinguishing feature? Most vacuoles can be seen in school microscopes. Vesicles cannot be seen by most
microscopes; they are tiny in comparison to vacuoles!
In middle school textbooks, to make things a little easier to understand, I have seen the two terms combined into the term
"vacuoles." It is not correct, but to understand basic cell concepts without confusing science terms, a vesicle could be
called an animal vacuole without harming the important ideas being taught (so he says; I disagree). Animal vacuoles are
not plant vacuoles, so a distinction is made, but this is not really correct.
Plant cells make their own food of course, using photosynthesis. Some Protists (single-celled eukaryotes) move and act
like animals in order get their food, while also having the ability to employ photosynthesis like plants. Some Protists do
have vacuoles, and this may be what the middle school textbook is talking about when they say that some animals have
vacuoles. Therefore, if your sister said that only plants have vacuoles, she is incorrect!
Just review your sister's book and you will see that your textbook does not have the level of detailed explanations. These
will come later when you are in high school biology courses. Your teachers chose your textbook (hahaha…if only I
COULD choose our textbook!!!) because it helps them teach you biology. It may not be 100% correct. However, it should
be pointed out that even AP Biology textbooks have mistakes in them. I know, I have seen them all.
Steve Sample
A.P. Biology Teacher
Food/Storage/Transport/Secretory/Digestive Vesicles and Vacuoles
“Animal” Food Vacuoles Vesicles and
Transport Vesicles: In animal cells,
transport and secretory vesicles assist in
the processes of exocytosis and
endocytosis and transport of materials.
These vesicles are often mistakenly called
animal vacuoles or animal food vacuoles;
these structures are actually vesicles.
Animal vesicles are relatively smaller than
the LARGE vacuoles of plants, but
vesicles usually occur in much greater
NUMBERS in animal cells.
Secretory Vesicles: Cell secretions—e.g.
hormones, neurotransmitters—are
packaged in secretory vesicles by the
Golgi apparatus. The secretory vesicles
are then transported to the cell surface for
release.
(For more on transport and secretory vesicles, see also images of Golgi)
Exocytosis is the extrusion process of proteins and lipids from the cell. These
materials are packaged into secretory vesicles by the Golgi apparatus before being
transported to the cell membrane and secreted into the extracellular environment. In
this capacity, “vacuoles” are simply transport vesicles which allow for the
containment, transport and disposal of selected proteins and lipids to the extracellular
environment.
Endocytosis is the reverse of exocytosis and can occur in a variety of forms.
Phagocytosis ("cell eating") is the process by which bacteria, dead tissue, or other bits
of material visible under the microscope are engulfed by cells. The material makes
contact with the cell membrane, which then invaginates (dents in towards the cell).
The invagination is then pinched off, leaving the engulfed material in a membraneenclosed vacuole vesicle while leaving the cell membrane intact. Pinocytosis ("cell
drinking") is essentially the same process, the difference being that the substances
ingested are in solution and therefore the contents are not visible under the
microscope. Phagocytosis and Pinocytosis are both undertaken in association with
lysosomes which complete the breakdown of the material which has been engulfed.
MORE ON VESICLES
COOL FACT: Salmonella is able to survive and reproduce in the vacuoles of several mammal species after being
engulfed.
SPECIALIZED VESICLES: Vesicles with specific jobs. These often will be very hard to distinguish from
transport and secretory vesicles, either in diagrams or under the microscope.
Lysosomes: Lysosomes (common in animal cells but rare in plant cells) are specialized vesicles that contain hydrolytic
enzymes necessary for intracellular digestion (that’s a fun description). In white blood cells that eat bacteria, lysosome
contents are carefully released into the vacuole transport vesicle around the bacteria and serve to kill and digest those
bacteria. Uncontrolled release of lysosome contents into the cytoplasm is also a component of necrotic cell death.
Lysosomes
Lysosomes contain chemicals that break down materials in
the cell. They break down large food particles into smaller ones as
well as break down old cell parts (old organelles). Lysosomes are
the cell's cleanup crew. They are small and round, just like all the
other vesicles.
Lysosomes are common in animal cells but very rare in plant cells.
Peroxisomes: This organelle is responsible for protecting the cell from its own production of toxic hydrogen peroxide. As
an example, white blood cells produce hydrogen peroxide to kill bacteria. The oxidative enzymes in peroxisomes break
down the hydrogen peroxide into water and oxygen.
Large Central Vacuole:
Found in Plants and some Protists!
Most mature plant cells have one large central
vacuole that typically occupies more than 30% of
the cell's volume, and that can occupy as much
as 80% of the volume for certain cell types and
conditions. Strands of cytoplasm often run
through the vacuole.
In plants, the large central vacuole is surrounded
by a membrane called the tonoplast (word origin:
greek root “tono-” meaning “stretching”,
“tension”, “tone” plus the root “-plastos” meaning
formed, molded). The tonoplast separates the
contents of the vacuole from the plant cell's
cytoplasm. As a membrane, it is mainly involved
in regulating the movements of ions and water
between the cytoplasm and the vacuole space,
which is made mostly of water.
The large central vacuole can be used for storage
and for isolating materials that might be harmful
or pose a threat to the cell. But perhaps one of its
most important functions is that is provides
structural support for the cell. The large central
vacuole allows plant cells to develop turgor
pressure, which is the OUTWARD pressure of the
cell contents against the cell wall. If a plant
becomes dehydrated during drought conditions,
the large central vacuole shrinks
Contractile Vacuoles:
Mainly found in Protists.
Video Showing Contractile Vacuole
Cell Membrane = Phospholipid Bi-Layer
CELLULAR JUNCTIONS
Three Main Types: gap, tight, anchoring
A GAP JUNCTION or nexus is a
specialized intercellular connection
between a multitude of animal celltypes. It directly connects the
cytoplasm of two cells, which allows
various molecules and ions to pass
freely between cells.
TIGHT JUNCTIONS are the closely
associated areas of two cells whose
membranes join together forming a virtually
impermeable barrier to fluid. It is a type of
cell junction complex present only in
vertebrates.
Anchoring junctions on next page…
ANCHORING JUNCTIONS may also be called adhering junctions, adherens junctions,
and desmosomes. Anchoring-type junctions not only hold cells together but provide
tissues with structural cohesion. These junctions are most abundant in tissues that are
subject to constant mechanical stress (tearing, pulling, pushing) such as skin and heart.
Cytoskeleton
Eukaryotic cells have a wide variety of
distinct shapes and internal
organizations. Cells are capable of
changing their shape, moving organelles,
and in many cases, move from place to
place. This requires a network a protein
filaments placed in the cytoplasm known
as the cytoskeleton.
The two most important protein filaments are called the actin filaments and the
microtubules. The actin is responsible for contraction (like in muscles) and the
microtubules are for structural strength.