Dr. Paul's Virtually Biology
A unit of energy used in biology. One calorie with a small "c" is roughly
defined as the amount of heat it takes to raise one cubic centimeter of
water from 14.5 degrees to 15.5 degrees centigrade. The food Calorie "C"
is one thousand regular calories or one kilocalorie.
cycle. Part of the dark reactions of photosynthesis where carbon
is incorporated into the plant's metabolic pathway from carbon dioxide
and used to make PGAL.
adenine monophosphate). An important secondary messenger in cells.
One of its functions is to set up a series of chemical reactions in the
cytoplasm of cells in response to non steroid hormones joining with the
hormone receptor on the cell membrane.
A capillary is a tiny blood vessel with walls only a single cell thick.
Gas and nutrient exchange between the blood and the rest of the body take
place only though the capillaries!
A carbon compound consisting of carbon hydrogen and oxygen in the molecular
ratio of approximately one carbon : two hydrogens: one oxygen. Sugars and
compounds built from sugars are the most commonly encountered carbohydrates.
An element with an atomic number of 6 and an atomic mass of a bit more
than 12. Carbon is important to biology because of carbon's strong tendency
to form pure covalent bonds. Thus carbon atoms provide the skeletal framework
of the molecules found in living things. Naturally pure carbon is found
in three forms; graphite, buckminsterfullerine and its variants, and diamonds.
It might be some some interest to diamond purchasers to note that diamonds
eventually will decay into graphite.
Refers to a functional group containing a carbon atom double bonded to
an oxygen and single bonded to a hydroxyl(OH) group. Carboxyl groups are
characteristic of organic acids and thus relate to the "acid" in the name
A chemical that causes cancer. Tars from cigarettes, benzene and various
dyes are good examples.
A leaf like section of a flower's female reproductive parts(Pistil) and
that contains the ovules. Cut open a grapefruit. Each of the little sections
is the remnant of a carpel.
capacity. In ecology, the number of individuals of a particular
species that a region can sustain indefinitely. An important concept because
humans may have exceeded the carrying capacity of this planet.
Individual organisms in a social organization that have specialized functions.
Castes may be temporal meaning that as the organism ages it takes on different
sets of tasks within its group. Castes may also be based on morphology
as in ants, bees and wasps where some species have highly specialized workers.
The set of metabolic reactions involved in taking complex molecules and
breaking them down into simple molecules. Digestion is a set of reactions
that is part of catabolism. Another example is breaking glucose down into
carbon dioxide and water as part of cellular respiration.
A substance that speeds up a chemical reaction without being destroyed
by that reaction. A real important concept in biology because without organic
catalysts called enzymes, life could not exist at the temperatures that
In biology a structure surrounded by a membrane and containing genetic
material(DNA) on the inside. These structures are capable of self maintenance,
self replication, metabolism, homeostasis, and response to the environment.
These structures are considered by most biologist to be the basic unit
mediated immunity. The part of the immune system that largely involves
defense of the body by responding to infected cells rather than by the
production of antibodies.
A polysaccharide made of repeating glucose subunits characterized by relative
inability to dissolve in water. Cellulose makes up the cell walls of plants
and many algae and is one of the most abundant organic compounds on the
planet. Wood and cotton are examples of substances consisting of cellulose.
A cylindrical structure made from a series of 9 paired microtubules that
is involved in organization of microskeletal elements in the cells of animals
and some plants. The centriole found just beneath the surface of a eukaryote
flagellum or cilium is called a basal body
while the perpendicularly paired centrioles found near the nucleus during
interphase of animal cells is sometimes called the central
body(centrosome). The centriole is encountered during discussions
of mitosis and meiosis.
A region on a chromosome where microtubules attach from the spindle during
mitosis. Also serves as the point of attachment for the two chromatids
in a duplicated chromosome.
Bonds. An "attachment" between two or more atoms involving either
a complete transfer of electrons(ionic bonds) or a sharing of electrons(covalent
A cell either on the surface of an animal or inside the animal that senses
the presence or change in the concentration of certain molecules and relays
that information to the the central nervous system. The human nose contains
a sophisticated system of chemoreceptors.....abeit not a very sensitive
autotroph(Chemoautotroph). An organism that obtains its energy from
simple inorganic compounds such as sulfur compounds or nitrates.
A specialized polysaccharide containing nitrogen that occurs in the exoskeleton
of insects and other arthropods. Chitin also makes up a large part of the
cell walls in many fungi.
Any of several green pigments, found in plants and most other photosynthetic
autotrophs, the pigments all having a characteristic set of rings containing
carbon and nitrogen along with a magnesium atom. Chlorophylls are important
pigments in photosynthesis.
A bacteria like green organelle in the cells of plants as well as in many
protists. This organelle is the site of photosynthesis and gets its name
from the presence of the green pigments, the chlorophylls.
acronym for the most abundant elements in living things: Carbon, hydrogen,
nitrogen, oxygen, phosphorus and sulfur.
A single molecule of DNA and associated proteins found as part of a duplicated(replicated)
A chromosome is one or two large DNA molecules and associated proteins
that behave as a single unit in the cell.
A short hair like structure on the surface of many cells. Cilia are typically
much shorter than the length of the cells they are part of, and have a
return and a power stroke involving the whole length of the structure.
The plural of cilium is cilia.
A chemical reaction in which a large molecule is broken apart into two
or more subunits. Usually in biological systems the net effect is to add
water to the molecules, hence this type of cleavage is called hydrolysis.
A group of cells or organisms that are derived by mitosis from another
organism. Clones happen naturally as part of asexual reproduction in many
organisms, but clones have become of some interest in biotechnology.
In the immune system the process by which only those cells able to produce
an appropriate antibody to an antigen or otherwise respond in an appropriate
manner to the antigen are stimulated to multiply.
A mode of inheritance in which the heterozygote has a phenotype that is
different the phenotypes of either homozygotes. For instance for human
blood type, if one homozygote is Type A, the other Type B, then the heterozygote
will be Type AB. Codominance arises if both genes in the gene pair express
A triplet of three nucleotide bases in messenger RNA that relate to an
amino acid in the translation part of protein synthesis or an instruction
to stop translation.
A Non protein organic molecule that functions along with an enzyme to either
activate or deactivate the enzyme. Organic cofactors.
The idea that in a biological community, the adaptations that arise in
different species are at least in part in response to selective pressures
put on the species by each other. For example flowers and their pollinators
coevolve with respect to each other.
A chemical that works cooperatively with an enzyme to enhance the enzyme's
catalytic ability. Cofactors maybe metallic ions or small organic molecules.
The tendency of a substance to stick to itself or stick together. Water
molecules tend to stick together, a property that is important for living
A type of symbiosis in which one species benefits but the other species
is neither harmed or benefited by the relationship. Certain mites that
live in the skin of our faces are a good example.
In ecology..all the populations of all the species living a particular
A compound is a molecule consisting of at least two different elements.
For example the molecule carbon dioxide is a compound but oxygen gas is
also a molecule but not a compound.
gradient. A change in the number of molecules of a particular substance
per unit volume between two points. The steeper the concentration gradient
the greater the difference in concentration between the two points.
reaction. A type of chemical reaction in which two or more simple
molecules are joined together to make a more complex molecule. In biology
the most common type of condensation reaction takes place by effectively
removing a water from two molecules being joined. This type of condensation
reaction is called a dehydration synthesis.
A change in the behavior of an animal based its ability to associate an
environmental signal with some sort of positive or negative outcome. In
classical conditioning the animal learns to
associate an outcome with an environmental signal that normally is not
associated with the outcome. For example, Pavlov's dogs learned to salivate
upon hearing a bell that was rung whenever food was presented. In operant
conditioning the organism provides its behaviors based on the results
it obtains while manipulating its environment. Thus, caged pigeons can
learn that pecking a certain red button will lead to the release of a food
pellet or other reward.
A process by which genetic material is exchanged between two cells through
a bridge of cytoplasm that connects the cells. This happens in bacteria
and in many protists.
A an organism that feeds on plants or other autotrophs or feeds on other
consumers(e.g. a predator)
group. In an experiment, a group of subjects that have all variables
the same as those found in an experimental group except for just the variables
being investigated in the experiment.
Cytokinesis or division of the cytoplasm is the distribution of the cytoplasm
into two or more daughter cells that typically happens as part of cell
reproduction. Note that cytokinesis is not part of either mitosis or meiosis
The region of the cell that is between the nucleus and the cell membrane.
In prokaryotes the region of the cell outside of the region where the DNA