Glossary of Terms

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

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- A -

ABO click this icon to hear the preceding term pronounced blood system
a human blood typing system in which there are 4 distinct types: A, B, AB, and O.  An individual inherits an ABO type from his or her parents and does not change it throughout life.  The ABO system is not unique to humans but is shared by many other primates including apes and monkeys.  Humans and other primates share other blood typing systems as well.
agglutination   click this icon to hear the preceding term pronounced
the clumping together of red cells in blood as a result of antibodies attaching to antigens on the surface of the cells.  This occurs when blood of incompatible types is mixed together outside of the body, as for example during blood typing.  When different types of blood come into contact within the body as a result of a mismatched transfusion, the alien red cells usually burst instead of agglutinate.  
alleles   click this icon to hear the preceding term pronounced
alternate forms or varieties of a gene.   The alleles for a trait occupy the same locus or position on homologous chromosomes and thus govern the same trait.  However, because they are different, their action may result in different expressions of that trait.
anatomy   click this icon to hear the preceding term pronounced
referring to the structural parts of organisms.  See physiology.
antibodies   click this icon to hear the preceding term pronounced
proteins produced by the body to identify and neutralize or destroy alien antigens.  Antibodies are involved in the rejection of mismatched blood transfusions and organ transplants.  They are also responsible for recognizing and eliminating bacteria and viruses.  Antibodies provide a major defense for our bodies against invasion by alien organisms.
antigens   click this icon to hear the preceding term pronounced
proteins that provide the specific signature or identity to blood or other tissue cells.  When alien antigens are introduced into the body, they stimulate the production or mobilization of antibodies.  Antigens are found on the surface of blood and other tissue cells as well as bacteria and viruses.

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- C -

Caucasoid  click this icon to hear the preceding term pronounced  (Caucasian click this icon to hear the preceding term pronounced)
a presumed human "race" consisting of Europeans and other closely related people. The classification is based on the discredited typological model.  The term "Caucasoid" was derived from the Caucasus Mountains on the southeast fringe of Europe between the Black and Caspian Seas.  This region was once thought to be the homeland of Indo-Europeans.
clinal model  click this icon to hear the preceding term pronounced    (of human variation)
a system for classifying people based on the knowledge that genetically inherited traits often gradually change in frequency from one geographic region to another--that is, they change in clines.
clines  click this icon to hear the preceding term pronounced
progressively changing zones of degree difference in frequency of a trait with movement from one region to another.  The gradual decrease in frequency of the B blood allele going west in Europe is an example of such a gradation or clinal distribution.  See discontinuous distribution.

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- D -

Diego click this icon to hear the preceding term pronounced blood system
a human blood typing system in which there are 2 distinct types: Diego positive and Diego negative.  An individual inherits a Diego type from his or her parents and does not change it throughout life.  Apparently, the only people in the world who are Diego positive are some Native Americans and East Asians.
discontinuous distribution   click this icon to hear the preceding term pronounced
the geographic distribution of a trait such that it appears in high or low frequencies in various areas with little or no gradation between them.  See clines.

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- E -

enzymes  click this icon to hear the preceding term pronounced
proteins that cause or regulate specific chemical reactions within cells.
erythrocytes  click this icon to hear the preceding term pronounced
the relatively large red cells in blood that transport oxygen from the lungs to all of the living tissues of the body.  Normally, 40-45% of human blood volume consists of erythrocytes.
ethnocentrism  click this icon to hear the preceding term pronounced
the feeling that your own group's cultural traditions and values are correct and superior to all others.  This is usually coupled with a generalized dislike and even contempt for people who have other cultural traditions.   Ethnocentrism is universal in that all people around the world are ethnocentric to some degree.

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- F -

frequency
the number of times that something happens.  For example, the number of people out of 100 who get divorced would be the frequency of divorce.

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- G -

gene pool
all of the genes in all of the individuals in a breeding population.  More precisely, it is the collective genotype of a population.
genotype  click this icon to hear the preceding term pronounced
the genetic makeup of an individual.  Genotype can refer to an organism's entire genetic makeup or the alleles at a particular locus.  See phenotype.

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- H -

hemoglobin  click this icon to hear the preceding term pronounced
the gas transporting protein molecule that normally makes up 95% of the volume of red cells in blood. 

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- L -

leukocytes  click this icon to hear the preceding term pronounced
the so-called white cells in blood.  They exist in variable numbers and types but make up a very small part of human blood volume.  Some leukocytes (i.e., lymphocytes click this icon to hear the preceding term pronounced) provide a physiological defense against infection.  As a result, their numbers increase when the body is under attack by bacteria and viruses.  Some other types of leukocytes (i.e., macrophages click this icon to hear the preceding term pronounced)  have the function of getting rid of old unneeded blood cells.

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- M -

malaria  click this icon to hear the preceding term pronounced
a group of similar life threatening diseases found mostly in tropical and subtropical regions of the world.  Malaria is caused by any of four different microorganisms called plasmodia (Plasmodium falciparum, vivax, ovale, and malariae).  These single-celled organisms are transmitted from person to person by anopheles mosquitoes as they extract blood.  Symptoms of malaria include chills, high fever, and sometimes fatal irregularities of the brain, liver, kidney, and/or blood.  There are at least 100,000,000 new cases of malaria reported annually around the world.  Approximately 1,500,000 people die from it each year (mostly children--3,000 children die of malaria every day).
 
  map of the Southwest Pacific Ocean with Melanesia highlighted
Melanesia  click this icon to hear the preceding term pronounced
New Guinea and other nearby islands in the Southwest Pacific Ocean. Indigenous people from this region are referred to as Melanesians.
metabolism  click this icon to hear the preceding term pronounced
the chemical and physical processes continuously going on in the cells of living organisms; the processes by which energy and matter are made available for use by the cells of an organism.  Heat is a byproduct of metabolism.
Mongoloid   click this icon to hear the preceding term pronounced
a presumed human "race" consisting of Asians and other closely related people. This classification is based on the discredited typological model.  The term "Mongoloid" was derived from the Mongolians of North Asia.
monozygotic twins  click this icon to hear the preceding term pronounced
identical twins.  Twins that come from the same zygote and are, subsequently, the same genetically in terms of their nuclear DNA.  Any differences between monozygotic twins later in life are mostly the result of environmental influences rather than genetic inheritance.  Fraternal twins may look similar but are not genetically identical.  Monozygotic twins may not share all of the same sequences of mitochondrial DNA.  This is due to the fact that the mitochondria in a cell may have somewhat different versions of DNA, and the mitochondria can be dispersed unequally when a zygote fissions.  Female monozygotic twins can also differ because of differences between them in X-chromosome inactivation.  Subsequently, one female twin can have an X-linked condition such as muscular dystrophy and the other twin can be free of it.

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- N -

natural selection
an evolutionary mechanism that occurs when some individuals in a population are better able to adapt to their environment and, subsequently, produce more offspring.  Nature, in effect, selects which members of a population are fit to survive long enough to reproduce.  Those who are more successful at reproduction will have a greater influence on the genetic makeup of the next generation.
Negroid  click this icon to hear the preceding term pronounced
a presumed human "race" consisting mostly of Sub-Saharan Africans.  This classification is based on the discredited typological model.  The term "Negroid" was derived from the Latin word for the color black.

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- O -

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- P -

phenotype  click this icon to hear the preceding term pronounced
the observable or detectable characteristics of an individual organism.  The detectable expression of a genotype.  
physiology  click this icon to hear the preceding term pronounced
referring to the organic or bodily processes of an organism.   See anatomy.
plasma  click this icon to hear the preceding term pronounced
the relatively clear liquid medium in blood which carries the red cells, white cells, and platelets.  Most of blood's volume is made up of plasma.  As the heart pumps blood to cells throughout the body, the plasma brings them nourishment and removes the waste products of metabolism.  Plasma also contains salts, sugars, lipids, amino acids, hormones, and blood clotting substances. 
platelets  click this icon to hear the preceding term pronounced   (thrombocytes click this icon to hear the preceding term pronounced)
see thrombocytes.
populational model   click this icon to hear the preceding term pronounced    (of human variation)
a system for classifying people based on the assumption that the only biologically distinct groups are long isolated breeding populations whose evolutionary paths have separated from other populations.  Since physical and cultural barriers to interbreeding between most groups have broken down to some extent, this approach is of marginal value in grasping the reality of human variation today.
population genetics
the study of biological inheritance patterns and changing gene pool frequencies in populations largely through the determination of allele frequencies.  Population geneticists also identify processes resulting in evolution.
proteins   click this icon to hear the preceding term pronounced
any of a large number of organic molecules that are composed of one or more chains of amino acids.  These chains are twisted and folded back on themselves in complex patterns.  Proteins can serve a wide variety of functions through their ability to bind to other molecules.  Proteins may be transporting molecules in blood, structural components, enzymes, hormones, antibodies, or neurotransmitters.

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- R -

race
any of the different varieties of humanity assumed by some people to exist, based on the discredited typological model of human variation.  Such "races" are commonly distinguished on the basis of visibly observable traits such as skin color, hair form, and body shape.  From a biological perspective, the term race should be reserved for distinct varieties or sub-species.  In the U.S. and other nations that use the concept of race, it refers mainly to culturally created realities rather than biological differences.
red blood cells
see erythrocytes.

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- S -

selective pressure
environmental pressure that is placed on individuals within a population that results in change of the genetic makeup of the next generation.   Selective pressure is the driving force of natural selection.
sickle-cell trait  click this icon to hear the preceding term pronounced
a genetically inherited recessive condition in which some or all of the red blood cells are abnormally distorted to a sickle shape.  Symptoms include pain and severe anemia as well as heart, lung, and kidney problems.  People who are heterozygous for this trait rarely have these debilitating and ultimately fatal problems but do have a high degree of immunity to malaria.  Sickle cell trait is at its highest frequency among Central African populations and among people whose ancestors came from that region.  Sickle-cell trait is often referred to as sickle-cell anemia.
 
sub-Saharan Africa   click this icon to hear the preceding term pronounced
the region of Africa south of the Sahara desert.

 

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- T -

thrombocytes   click this icon to hear the preceding term pronounced
types of blood cells that coagulate and clot blood when there is an injury to a blood vessel.  Thrombocytes are also called platelets. 
typological  model   click this icon to hear the preceding term pronounced    (of human variation)
a system for classifying people based on the false assumption that humans can be unambiguously placed into "races" on the basis of selected traits such as skin color, hair form, and body shape.  Advocates of this approach incorrectly believe that there are more or less distinct populations of people from different geographic regions.  Negroid, Mongoloid, and Caucasoid are examples of typological groupings.

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- U -

ultraviolet radiation   click this icon to hear the preceding term pronounced
electromagnetic radiation ranging in wave length just beyond violet in the visible spectrum of light.  The human eye cannot detect u.v.  Our sun is the major source of u.v. radiation on earth.  Prolonged exposure to u.v. can result in destructive skin burns and can promote the onset of skin cancer.
universal donor
someone who has type O blood.  Such people lack antigens for the ABO blood system.  As a result, their blood will not be agglutinated when it is transfused into people with any other ABO type.
universal receiver
someone who has type AB blood. Such people do not produce antibodies for the ABO blood system.  As a result, they can receive transfusions from people with any ABO type without agglutinating it.

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- W -

white blood cells
see leukocytes.

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Copyright 1998-2012 by Dennis O'Neil. All rights reserved.
illustration credits