The following is a glossary of animal cell terms:
cell membrane - the thin layer of protein and fat that surrounds the cell. The cell
membrane is semipermeable, allowing some substances to pass into the cell and
blocking others.
centrosome - (also called the "microtubule organizing center") a small body located
near the nucleus - it has a dense center and radiating tubules. The centrosomes is
where microtubules are made. During cell division (mitosis), the centrosome divides
and the two parts move to opposite sides of the dividing cell. The centriole is the
dense center of the centrosome.
cytoplasm - the jellylike material outside the cell nucleus in which the organelles are
located.
Golgi body - (also called the Golgi apparatus or golgi complex) a flattened, layered,
sac-like organelle that looks like a stack of pancakes and is located near the nucleus. It
produces the membranes that surround the lysosomes. The Golgi body packages
proteins and carbohydrates into membrane-bound vesicles for "export" from the cell.
lysosome - (also called cell vesicles) round organelles surrounded by a membrane and
containing digestive enzymes. This is where the digestion of cell nutrients takes place.
mitochondrion - spherical to rod-shaped organelles with a double membrane. The
inner membrane is infolded many times, forming a series of projections (called
cristae). The mitochondrion converts the energy stored in glucose into ATP
(adenosine triphosphate) for the cell.
nuclear membrane - the membrane that surrounds the nucleus.
nucleolus - an organelle within the nucleus - it is where ribosomal RNA is produced.
Some cells have more than one nucleolus.
nucleus - spherical body containing many organelles, including the nucleolus. The
nucleus controls many of the functions of the cell (by controlling protein synthesis)
and contains DNA (in chromosomes). The nucleus is surrounded by the nuclear
membrane.
ribosome - small organelles composed of RNA-rich cytoplasmic granules that are
sites of protein synthesis.
rough endoplasmic reticulum - (rough ER) a vast system of interconnected,
membranous, infolded and convoluted sacks that are located in the cell's cytoplasm
(the ER is continuous with the outer nuclear membrane). Rough ER is covered with
ribosomes that give it a rough appearance. Rough ER transports materials through the
cell and produces proteins in sacks called cisternae (which are sent to the Golgi body,
or inserted into the cell membrane).
smooth endoplasmic reticulum - (smooth ER) a vast system of interconnected,
membranous, infolded and convoluted tubes that are located in the cell's cytoplasm
(the ER is continuous with the outer nuclear membrane). The space within the ER is
called the ER lumen. Smooth ER transports materials through the cell. It contains
enzymes and produces and digests lipids (fats) and membrane proteins; smooth ER
buds off from rough ER, moving the newly-made proteins and lipids to the Golgi
body, lysosomes, and membranes.
vacuole - fluid-filled, membrane-surrounded cavities inside a cell. The vacuole fills
with food being digested and waste material that is on its way out of the cell.
Animal Cell Mitosis Label Me! Printout
Label the mitosis diagram using the terms below.
Animal Cell
Mitosis is the duplication and division of a eukaryotic cell's nucleus and nuclear
material (DNA). The stages of mitosis are: [interphase (the cell when not undergoing
mitosis, but the DNA is replicated)], prophase, metaphase, anaphase, and telophase.
Terms to Use:
Anaphase - the phase of mitosis in which Interphase - the phase of a cell's life cycle in which
the chromosomes begin to separate.
DNA is replicated.
Centrioles - paired cylindrical organelles, Microtubules - tiny filaments (about 25 nanometers
arranged at right angles to each other,
in diameter) that are active in mitosis.
located at the center of a microtubule.
Metaphase - the phase of mitosis in which the
Centromeres - a centromere is the
chromosomes line up at the equator (the central
constricted region of a nuclear chromosome plane) of the cell.
- microfibers attach to the centromere
Prophase - the phase of mitosis in which the
during mitosis.
duplicated chromosomes condense, the nuclear
Chromosomes - structures in the nucleus envelope dissolves, and centrioles divide and move
that contain DNA molecules that contain
to opposite ends of the cell.
the genes.
Telophase - the last phase of mitosis, when the
chromosomes migrate to opposite ends of the cell,
two new nuclear envelopes form, and the
chromosomes uncoil.
Label the Neuron
Brain Glossary
Read the definitions, then label the neuron diagram below.
axon - the long extension of a neuron
that carries nerve impulses away from
the body of the cell.
axon terminals - the hair-like ends of
the axon
myelin sheath - the fatty substance that surrounds and
protects some nerve fibers
node of Ranvier - one of the many gaps in the myelin
sheath - this is where the action potential occurs during
saltatory conduction along the axon
cell body - the cell body of the neuron; nucleus - the organelle in the cell body of the neuron
it contains the nucleus (also called the that contains the genetic material of the cell
soma)
Schwann's cells - cells that produce myelin - they are
dendrites - the branching structure of located within the myelin sheath.
a neuron that receives messages
(attached to the cell body)
Plant Cell Label Me! Printout
Comparing Plant And Animal Cells
Directions: Complete the chart below, then answer the questions.
Cell Part or Organelle
Cell Membrane
Is It Found In A Plant Cell?
Is It Found In A Animal Cell?
Cell Wall
Chloroplast
Chromatin
Cytoplasm
Endoplasmic Reticulum
Golgi Bodies
Lysosome
Mitochondrion
Nucleus
Nuclear Membrane
Nucleolus
Ribosome
Vacuole
Questions:
1.
2.
3.
4.
What cell parts do Animal cells have that Plant cells do not have?
What cell parts do Plant cells have that Animal cells do not have?
Why do Plant cells have cell walls and Animal cells do not?
Why do think Plant cells have bigger vacuoles than Animal cells?
Plant Cell Illustration With Hyperlinked Labels
Click On Each Label For More Information
Illustration Of A Generalized Plant Cell
Animal Cell Illustration With Hyperlinked Labels
Click On Each Label For More Information
Illustration of a generalized animal cell.
Eukaryotic Cell Definitions:
= Typically Found Only In Plant Cells
= Typically Found In Animal Cells
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Golgi Apparatus: A series (stack) of flattened, membrane-bound sacs
(saccules) involved in the storage, modification and secretion of proteins
(glycoproteins) and lipids destined to leave the cell (extracellular) and for use
within the cell (intracellular). The Golgi apparatus is abundant in secretory
cells, such as cells of the pancreas.
Golgi Vesicle: A membrane-bound body that forms by "budding" from the
Golgi apparatus. It contains proteins (glycoproteins), such as digestive
enzymes, and migrates to the cell (plasma) membrane. Golgi vesicles fuse with
the cell membrane and discharge their contents into the exterior of the cell
through a process called exocytosis. Some Golgi vesicles become lysosomes
which are involved in intracellular digestion.
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Pinocytotic Vesicle: A membrane-bound vacuole formed by a specific type of
endocytosis called pinocytosis. The plasma membrane invaginates (pinches
inwardly) to form a vesicle that detaches and moves into the cytoplasm.
Macromolecular droplets and particles up to 2 micrometers in diameter enter
the cell within these pinocytotic vesicles. Larger particles (including bacteria)
enter special white blood cells (phagocytes) through a form of endocytosis
called phagocytosis. The Amoeba is a unicellular protist that ingests food
(including algal cells) by phagocytosis.
Lysosome: A membrane-bound organelle containing hydrolytic (digestive)
enzymes. Lysosomes originate as membrane-bound vesicles (called Golgi
vesicles) that bud from the Golgi apparatus. They are primarily involved with
intracellular digestion. Lysosomes fuse with vesicles (small vacuoles) formed
by endocytosis. The contents of these vesicles are digested by lysosomal
enzymes. Autodigestion by lysosomes also occurs during embryonic
development. The fingers of a human embryo are webbed initially, but are
separated from each other by lysosomal enzymes. Cells in the tail of a tadpole
are digested by lysosomal enzymes during the gradual transition into a frog.
Peroxisome: A membrane-bound organelle that contains specific enzymes
imported from the cytoplasm (cytosol). For example, certain peroxisomes
contain the enzyme catalase which rapidly breaks down toxic hydrogen
peroxide into water and oxygen. This reaction can be easily demonstrated by
pouring some hydrogen peroxide on raw meat or an open wound.
Glycolysis: An anaerobic oxidation pathway outside of the mitochondria in
which glucose is oxidized to pyruvate with a net gain of 2 ATP molecules.
Pyruvate is converted into a 2-carbon acetyl group which enters the Krebs cycle
within the mitochondria.
Mitochondrion: Membrane-bound organelle and the site of aerobic respiration
and ATP production. Energy from the step-by-step oxidation of glucose (called
the Krebs or citric acid cycle) is used to produce molecules of adenosine
triphosphate (ATP). The Krebs cycle starts when a 2-carbon acetyl group
combines with a 4-carbon group to form a 6-carbon citrate. Including
glycolysis (which occurs outside the mitochondria), a total of 38 ATP
molecules are generated from one molecule of glucose.
In eukaryotic cells, including the cells of your body, ATP is produced within special
membrane-bound organelles called mitochondria. During this process, electrons are
shuttled through an iron-containing cytochrome enzyme system along membranes of
the cristae which result in the phosphorylation of ADP (adenosine diphosphate) to
form ATP (adenosine triphosphate). ATP is the vital energy molecule of all living
systems which is absolutely necessary for key biochemical reactions within the cells.
The actual synthesis of ATP from the coupling of ADP (adenosine diphosphate) with
phosphate (PO4) is very complicated and involves a mechanism called chemiosmosis.
The electron flow generates a higher concentration (charge) of positively-charged
hydrogen (H+) ions (or protons) on one side of the membrane. When one side of the
membrane is sufficiently "charged," these protons recross the membrane through
special channels (pores) containing the enzyme ATP synthetase, as molecules of ATP
are produced. In the membranes of prokaryotic bacterial cells, ATP is produced by a
similar process. In fact, some biologists believe that mitochondria and chloroplasts
within eukaryotic animal and plant cells may have originated from ancient symbiotic
bacteria that were once captured by other cells in the distant geologic past. This
fascinating idea is called the "Endosymbiont Theory" (or "Endosymbiont
Hypothesis" for those who are more skeptical). Chloroplasts and mitochondria have
outer phospholipid bilayer membranes and circular DNA molecules like those of
prokaryotic bacterial cells. In addition, the layers of thylakoid membranes in the grana
of chloroplasts are remarkably similar to photosynthetic cells of cyanobacteria.
Acquiring cells and genomes from other organisms is known as symbiogenesis.
According to L. Margulis and D. Sagan (Acquiring Genomes: A Theory of the
Origins of Species 2002), symbiogenesis is a major factor in the evolution of life of
earth. In fact, the author's state that long-term genomic mergers result in much greater
evolutionary change than DNA mutations and natural selection.
A Simplified Illustration Of An ATP Molecule
Illustration Of The Cristae Of A Mitochondrion
Symbiogenesis: Genomic Mergers & Evolution
A Theory For The Origin Of Vascular Plants
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Cristae: Inwardly-projecting, shelf-like membranes of the mitochondria where
electrons flow along the cytochrome enzyme system.
See The Structure Of A Mitochondrion
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Chloroplast: Membrane-bound organelle and the site of photosynthesis and
ATP production in autotrophic plant cells. Like mitochondria, chloroplasts
contain their own circular DNA molecules. In fact, chloroplast DNA, including
the protein-coding RBCL gene, is often used at the family level to show the
relationships between genera and species within plant families. Intron regions
from chloroplast DNA are also used to construct family trees. Introns are
sections of messenger RNA that are removed prior to translation at the
ribosome. Comparative DNA between different genera and species of a plant
family can be shown with computer generated evoltionary trees called
cladograms.
Evolutionary Tree (Cladogram) Of The Duckweed Family
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Some biologists believe that mitochondria and chloroplasts within eukaryotic
animal and plant cells may have originated from ancient symbiotic bacteria that
were once captured by other cells in the distant geologic past. This fascinating
idea is called the "Endosymbiont Theory" (or "Endosymbiont Hypothesis" for
those who are more skeptical). Chloroplasts and mitochondria have outer
phospholipid bilayer membranes and circular DNA molecules like those of
prokaryotic bacterial cells. In addition, the layers of thylakoid membranes in
the grana of chloroplasts are remarkably similar to photosynthetic cells of
cyanobacteria. Acquiring cells and genomes from other organisms is known as
symbiogenesis. According to L. Margulis and D. Sagan (Acquiring Genomes:
A Theory of the Origins of Species 2002), symbiogenesis is a major factor in
the evolution of life of earth. In fact, the author's state that long-term genomic
mergers result in much greater evolutionary change than DNA mutations and
natural selection.
Illustration Of The Grana Of A Chloroplast
A Simplified Illustration Of An ATP Molecule
Symbiogenesis: Genomic Mergers & Evolution
A Theory For The Origin Of Vascular Plants
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Grana: Region of chloroplast composed of stacks of thylakoid membranes.
This is the site of the "light reactions" where ATP and NADPH2 are generated.
These two products are utilized in the "dark reactions" where carbon dioxide is
converted ("reduced") to glucose.
Stroma: Region of the chloroplast where the "dark reactions" occur. Carbon
dioxide (CO2) is gradually converted into glucose through a series of reactions
called the Calvin cycle.
See The Structure Of A Chloroplast
Fluorescence In A Chlorophyll Solution
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Endoplasmic Reticulum: A complex system of membrane-bound channels
extending throughout the cytoplasm of cells. Like the emergency room of a
hospital, the endoplasmic reticulum is often abbreviated as ER.
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Smooth Endoplasmic Reticulum: Does not contain attached ribosomes.
Rough Endoplasmic Reticulum: Studded (dotted) with attached ribosomes on
the side of the membrane that faces the cytoplasm.
Ribosome: Organelle site of protein synthesis. The ribosome is composed of
large and small subunits separated by a central groove. A strand of messenger
RNA (m-RNA) fits into the groove and the ribosome moves along the m-RNA
in a 5' to 3' direction. Molecules of cloverleaf-shaped transfer-RNA (t-RNA),
each with a unique amino acid, temporarily attach to the m-RNA at the
ribosome in a process called translation. Transfer-RNA anticodons hook up
with m-RNA codons and the amino acids bond together by dehydration
synthesis. As the ribosome moves toward the 3' end of the m-RNA strand, the
amino acid chain (polypeptide) grows longer and longer. Finally the completed
polypeptide leaves the ribosome site and moves away to become a protein
utilized within the cell or secreted from the cell. The simplified animated gif
images below illustrate this remarkable process. A series of several ribosomes
moving along the same m-RNA strand is called a polyribosome. Ribosomes are
composed of ribosomal RNA and they are not membrane-bound. They occur in
prokaryotic as well as eukaryotic cells. In eukaryotic cells, ribosomal RNA is
synthesized in the nucleolus. The large and small subunits of ribosomes are
synthesized by specific genes. One gene in the nucleolus codes for the smaller
subunit of the ribosome. The gene is called SSU rDNA or small subunit
ribosomal DNA. Base sequences from this gene are sometimes used to compare
taxa at the species level. The results from comparative DNA studies using
mitochondrial and chloroplast DNA are illustrated in computer generated
evoltionary trees called cladograms.
Ricin from the castor bean (Ricinus communis) is a potent cytotoxic protein
that is lethal to eukaryotic cells by inactivating the organelle sites of protein
synthesis called ribosomes. Just one single ricin molecule that enters the
cytosol of a cell (the semifluid medium between the nucleus and plasma
membrane) can inactivate over 1,500 ribosomes per minute and kill the cell.
One of the two protein subunits of ricin (RTA) is a deadly enzyme that removes
purines (such as adenine) from ribosomal RNA, thus altering its molecular
structure and function.
See Article About The Castor Bean
See Cloverleaf Model Of Transfer RNA
See Explanation Of Protein Synthesis
Cladogram Of The Duckweed Family
Animated Gif Image Of Transcription Inside Nucleus
Animated Gif Image Of Translation At The Ribosome
Animated Gif Image Of Protein Synthesis Inside Cell
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Nucleolus: Dark-staining body within the nucleus where ribosomal RNA is
synthesized. Plant nuclei in onion root tip cells may have several nucleoli.
Nucleus: Membrane-bound organelle containing chromatin, a term applied to
all the chromosomes collectively when they are in a tenuous (threadlike) stage.
During the prophase of mitosis, the chromosomes become shorter and thicker,
and appear as distinct doubled bodies called "chromosome doublets."
Cell (Plasma) Membrane: The living membrane that surrounds the cytoplasm
of all cells. It is composed of a phospholipid bilayer with embedded
glycoproteins. In the "sandwich model" the two phospholipid layers are
sandwiched between two layers of protein. The membranes of organelles are
also composed of a phospholipid bilayer, including vacuoles, nuclei,
mitochondria and chloroplasts. [Riubosomes are not membrane-bound.]
Embedded glycoproteins in plasma membranes include membrane transport
"carrier molecules" and cell recognition antigens. The plasma membrane is
permeable to water molecules by osmosis, but not to other molecules and ions
by simple diffusion. Ions pass through the plasma membrane via carrier
molecules by active transport and facilitated diffusion. Active transport requires
ATP.
See A Diagram Of Osmosis
Sandwich Model Of Cell Membrane
Fluid Mosaic Model Of Cell Membrane
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Cell Wall: A cellulose layer that surrounds the plasma membrane of plant
cells. Because it is very porous, the cell wall is permeable to molecules and
ions that cannot pass through the plasma membrane by simple diffusion.
During plasmolysis, the cell membrane loses water and its contents shrink up
into a ball, while the outer cell wall remains intact. Shrubs and trees have a
thickened secondary cell wall containing lignin, a brown phenolic polymer that
imparts great strength and hardness to wood. Ironwoods such as lignum vitae
sink in water because of the density of their heavy, thick-walled, lignified cells.
Plasmolysis In A Leaf Cell
Anatomy & Grain Of Wood
Trees With Very Hard Wood
The Anatomy Of Stems & Roots
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Vacuole: A membrane-bound, fluid-filled sac inside plant and animal cells.
Contractile vacuoles of protists, such as the Paramecium, are specialized
organelles for expelling excess water. Food vacuoles of the Amoeba digest
smaller cells captured by phagocytosis. Plant cells have large central vacuoles
that occupy much of the cell volume.
Paramecium: A Ciliated Protozoan
Amoeba: An Amoeboid Protozoan
Trypanosome: A Flagellate Protozoan
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Large Central Vacuole: A membrane-bound, fluid-filled sac that occupies
much of the volume of a plant cell. For this reason, the chloroplasts, nucleus
and other organelles are displaced to the periphery of the cytoplasm (around the
central vacuole). In addition to water, this large vacuole stores salts, water
soluble pigments (anthocyanins), and potentially toxic molecules in the form of
crystals. In the crystalline state, oxalates are relatively innocuous to the plant
cell. Crystals of calcium oxalate may be needle-like (raphide crystals) or
many faceted like a glistening diamond (druse crystals). Plant cells with high
levels of calcium oxalate can be toxic to humans. The primary reason that
wolffia (world's smallest flowering plant) is more palatable to humans as a high
protein food source is that its vacuoles lack raphide crystals that are abundant
in other duckweeds (Lemna & Spirodela). Comparative chloroplast DNA
studies have shown that the duckweed family (Lemnaceae) is closely related to
the arum family (Araceae). In fact, members of both families have cells
containing abundant raphide crystals of calcium oxalate. Chewing on leaves of
the cultivated arum called "dumb cane" (Dieffenbachia) can cause difficulty in
talking and swallowing. Symptoms of ingestion include burning pain,
inflammation and swelling of the tongue, throat and larynx tissues. A
proteolytic enzyme in the leaves called dumbcaine is injected into the cells via
microscopic punctures by thousands of needlelike raphide crystals. Mast cells
(basophils), special white blood cells in connective tissue, may also be injured.
In allergic reactions, sensitized mast cells release stinging histamines into the
afflicted tissues.
Druse Crystal Inside Cell Of Basswood
Nutritious Wolffia Gourmet Dishes
Mast Cells In Allergic Reactions
Duckweed Family Home Page
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Amyloplast (Starch Grain): A membrane-bound organelle containing
concentric layers of starch (amylopectin). This organelle is commonly found in
subterranean storage organs, such as tubers (potatoes), corms (taro & dasheen),
and storage roots (sweet potatoes). Amyloplasts are also found in bananas and
other fruits.
See Amyloplasts In Cells Of Potato Tuber
Underground Vegetables That Store Starch
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Centrioles Nonmembrane-bound organelles that occur in pairs just outside
the nucleus of animal cells. Each centriole is composed of a cylinder or ring of
9 sets of microtubule triplets with none in the middle (9 + 0 pattern). During
cell division a pair of centrioles moves to each end of the cell, forming the
poles of the mitotic spindle. Centrioles also give rise to basal bodies that
control the origin of cilia and flagella in motile cells of protists. In cross
section, flagella and cilia have 9 sets of microtubule doublets surrounding a
pair of single microtubules in the center (9 + 2 pattern). This characteristic
pattern also occurs in motile cells of higher organisms, such as human sperm.
Cell Division (Mitosis) In Eukaryotic Cells
See Flagellum On A Human Sperm Cell
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Centrosome: The microtubule organizing center that forms the mitotic spindle
in dividing cells. In animal cells the centrosome includes a pair of centrioles
surrounded by radiating strands of microtubules called the aster.
Microtubules: Protein filaments composed of a polymer called tubulin. The
centrosome of animal cells (including a pair of centrioles and radiating aster)
are composed of microtubules. Microtubules are involved in cell movement,
cell shape and the formation of mitotic spindles during cell division (mitosis).
Some cancer chemotherapy drugs cause the dissolution (depolymerization) of
tubulin in microtubules, thus destroying mitotic spindles and effectively
stopping cell division in tumor cells.
Medical Alkaloids & Glycosides From Plants
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Cytoplasm: All the contents of a cell within the plasma membrane. The
nucleus and its contents (nucleoplasm) are generally excluded from the
cytoplasm. The semifluid medium between the nucleus and the plasma
membrane is called cytosol.