Every field of study has technical terms that are used by people within that field. Newcomers to the field may not be familiar with the terminology used by others and may find themselves unsure of what certain words and terms mean. This is where a Glossary comes in handy. This Glossary is designed to help both students and teachers understand new or unfamiliar vocabulary or specialized terminology in this field of study.

Below are some ideas on how you could use the Glossary with students. Students could:

• Create new glossary entries for terms not on the list.
• Group glossary terms into categories and explain the reasons for their grouping of the terms.
• Create labeled drawings to illustrate different terms.
• Add to the definitions based on further research.
• Compare the definitions in this glossary to definitions in other web-based glossaries.
• How are they similar and different? Have them think about why this may be the case.

Amyloplast (Starch Grain): PLANT CELLS ONLY
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.

Biomedical Informatics:
Science that deals with biomedical information, its structure, acquisition, and use. Biomedical informatics comprises the areas of computer science, information science, cognitive science, social science, and engineering, as well as clinical and basic sciences.

Cell (Plasma) Membrane:
The living membrane that surrounds the cytoplasm of all cells. 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.

Cell Wall: PLANT CELLS ONLY
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.

Central Vacuole: PLANT CELLS ONLY
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 usually 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.

Centrioles: ANIMAL CELLS ONLY
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.

Centrosome:
The microtubule organizing centre 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.

Chloroplast: PLANT CELLS ONLY
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 evolutionary trees called cladograms.

Cristae:
(Not shown on diagram) Inwardly-projecting, shelf-like membranes of the mitochondria where electrons flow along the cytochrome enzyme system.

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.

Cytoskeleton:
The network of microtubules and structural elements such as actin, that create the molecular scaffold. The cytoskeleton keeps all the organelles in place, cushions the cell against damage and maintains basic cell shape.
Endoplasmic Reticulum:
A complex system of membrane-bound channels extending throughout the cytoplasm of cells. The endoplasmic reticulum is often abbreviated as ER.
• Rough Endoplasmic Reticulum: Studded (dotted) with attached ribosomes on the side of the membrane that faces the cytoplasm.
• Smooth Endoplasmic Reticulum: Does not contain attached ribosomes.

Functional magnetic resonance imaging (fMRI):
A relatively new MRI technique that studies brain function. Using fMRI technology, scientists can determine which part of the central nervous system (CNS: brain and spinal cord) is active during a given task by tracking blood oxygen levels in the brain. Brain regions that are active require more oxygen. Oxygen is delivered by increasing the blood flow to these active brain regions. Scientists compare the differences in blood flow between a resting condition and an active condition, such as thinking, seeing, touching, or hearing, to find regions that are associated with one task and not the other.

Golgi Apparatus:
A series (stack) of flattened, membrane-bound sacs (saccules) involved in the storage, modification and secretion of proteins 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 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.

• Lysosome:(not shown in diagram) 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.

Infrared spectroscopy (IR spectroscopy):
Technique using the infrared portion of the electromagnetic spectrum to investigate the composition of a sample. By passing infrared radiation through the sample, and seeing which wavelengths are selectively absorbed by the sample, we build up a "spectrum" of absorptions that serves as a unique chemical fingerprint of the sample.
Scientists at NRC-IBD are using the mid-IR spectroscopic fingerprint of various biological fluids as the basis to perform many common clinical tests, including cardiovascular risk panels, blood tests, and urine tests, opening the door to routine diagnostic testing without the need for any chemical reagents

Mitochondrion:
Membrane-bound organelle and the site of aerobic respiration and adenosine triphosphate (ATP) production. Energy from the step-by-step oxidation of glucose (called the Krebs or citric acid cycle) is used to produce molecules of ATP.

Magnetic resonance imaging (MRI):
A diagnostic scanning system that uses powerful magnets to produce images of soft tissues in the body. MRI is especially effective for producing images of the brain and spinal cord. The powerful magnet in the scanners causes the nuclear magnetic moments within the atoms of the body to line themselves up in one direction, much like a compass needle aligns itself with the earth's magnetic field. The MRI machine applies a radio frequency pulse, specific only to hydrogen, causing the protons to be excited and de-align. As they realign themselves to the magnet, the protons give off a signal that can be recorded and converted electronically into images.

Magnetic resonance spectroscopy (MRS):
Technique allowing scientists and doctors to measure chemicals within the body and brain without removing tissue or blood samples. Because different chemicals resonate at different frequencies (like a tuning fork) when stimulated by a magnet, MRS is able to provide a biochemical fingerprint of various chemical species within the human body. The technique is still largely at the research level.
NRC-IBD researchers are developing a non-invasive test for colorectal cancer using MRS to assess stool samples and identify tumour biomarkers.

Near infrared spectroscopy (near IR):
Technique using the near infrared region of the electromagnetic spectrum, the "near" meaning that these wavelengths lay very near (in fact adjacent to) the red end of the visible light spectrum. These near IR wavelengths penetrate deep into tissue with no harmful effects. The light that has been transmitted through tissue provides a spectrum (again, a "molecular fingerprint") that may be used to evaluate tissue oxygenation due to differences in absorption properties of hemoglobin and deoxyhemoglobin.
Researchers at NRC-IBD are exploiting near IR spectroscopy and imaging to detect viable tissue beneath a burn, based on spectroscopic measurements of tissue oxygenation and blood volume that occur in the post burn period.

Nucleolus:
Dark-staining body within the nucleus where ribosomal RNA is synthesized. Metabolically active cells such as onion root tip cells are likely to have several nucleoli.

Phloem:
Tissue within plants which transports carbohydrate from the leaves throughout the plant. Phloem consists of tubes which are formed from columns of living cells in which the horizontal cross-walls have become perforated. This allows the carbohydrate in aqueous solution to move from one phloem cell into the next and thus through the plant. Because of their structure, phloem tubes are also called "sieve" tubes.

Ribosome:
Organelle site of protein synthesis. The ribosome is composed of large and small subunits separated by a central groove.

Spectroscopy:
The science of measuring the emission and absorption of different wavelengths (spectra) of visible and non-visible light. Spectroscopy has traditionally been used in the physical sciences to probe the composition (what is there and how much?) of materials ranging from medicinal ingredients to the stars in the sky. More recently, spectroscopy has been adapted for use in a wide range of biological research areas, such as biochemistry and toxicology, addressing the same fundamental questions for ever more complex samples.

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.

Xylem:
Tissue within plants which conducts water and mineral salts, absorbed by roots from the soil, throughout the plant. Xylem tissue consists of long continuous tubes formed from columns of cells in which the horizontal cross-walls have disintegrated and the cell contents have died. The vessels thus formed are strengthened by a compound called lignin, and ultimately form the wood of the plant. Associated with xylem vessels, and providing additional strength, are specialized fibrous cells called xylem fibres, some of which are useful to humans, for example, flax. Thus xylem is commercially important as a source of wood and fibres.