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 -
- agglutination
- 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
- 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.
- amino
acids
- organic molecules that are building blocks of proteins. There are at 20 different kinds of amino acids in living things. Proteins are composed of different combinations of amino acids assembled in chain-like molecules. Amino acids are primarily composed of carbon, oxygen, hydrogen, and nitrogen.
- anemia
- weakness, fatigue, and paleness resulting from a deficiency of red blood cells or insufficient amounts of hemoglobin molecules within the red cells.
- antibodies
- 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
- molecules 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 and mobilization of antibodies. Antigens are found on the surface of blood and other tissue cells as well as bacteria and viruses.
-
autosomes
- any chromosomes other than a sex chromosome.
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- B -
- bacteria
- microscopic simple single celled organisms lacking chlorophyll and a membrane around their nuclei. They reproduce by mitosis. Many species of bacteria are parasites of humans and other animals and plants. Bacteria are classified as members of the Kingdom Monera.
- bilirubin
- the yellow-red pigment of human bile. Small amounts of it are normally found in blood and urine. At high bilirubin levels, blood and urine change color and the skin becomes yellow or jaundiced. This is one of the symptoms of mismatched blood transfusions and mother-fetus incompatibility in blood type.
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- C -
- chimera
(also spelled chimaera)
- an individual who is genetically two people. Fully chimeric individuals are usually the product of two fertilized ova fusing into a single embryo shortly after conception.
- codominance
- the situation in which two different alleles for a trait are expressed unblended in the phenotype of heterozygous individuals. Neither allele is dominant or recessive, so that both influence the phenotype. Type AB blood is an example. Such traits are said to be codominant.
- chromosomes
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- D -
- DNA
(deoxyribonucleic acid
)
- a large organic molecule that stores the genetic code for the synthesis of proteins. DNA is composed of sugars, phosphates and bases arranged in a double helix shaped molecular structure. Segments of DNA in chromosomes correspond to specific genes.
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- E -
- ectopic
pregnancy
- a pregnancy in which the fertilized ovum develops into an embryo in the fallopian tubes or elsewhere in the abdominal cavity outside of the uterus. In most cases, this is a life threatening condition for both the mother and the embryo. The pregnancy is usually terminated with a therapeutic abortion.
- edema
- abnormal fluid retention in the tissues and/or cavities of the body resulting in swelling.
- enzymes
- proteins that cause or regulate specific chemical reactions within cells.
- erythroblastosis
fetalis
- a blood disease of fetuses and newborn infants caused by the mother's anti-Rh+ antibodies agglutinating or bursting the red cells of her infant's Rh+ blood. Symptoms include life threatening anemia, jaundice, fever, swollen tissues from edema, and an enlarged liver and spleen. Serious cases are treated by blood replacement. Erythroblastosis fetalis is also referred to as "hemolytic anemia" and "hydrops fetalis."
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. See stem cells.
-
eukaryotic
cell
- a cell that has a true nucleus and that divides by mitosis. Complex single celled creatures such as protozoa as well as all multicelled plants and animals are primarily eukaryotes. With the exception of red blood cells, human cells are eukaryotic. See prokaryotic cell.
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- F -
- fetus
- an unborn child during the later stages of pregnancy. In humans, an embryo usually becomes a fetus after the 8th week of gestation. Unlike embryos, fetuses ultimately have clearly recognizable physical characteristics of the species and gender.
- fungi
- oraganisms that have a multicellular filamentous form with specialized eukaryotic cells. The fungi include funguses, molds, mushrooms, yeasts, mildews, and smuts
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- G -
- genes
- units of inheritance usually occurring at specific locations, or loci, on a chromosome. Physically, a gene is a sequence of DNA bases that specify the order of amino acids in a protein or, in some cases, a small RNA molecule referred to as a microRNA. A gene may be made up of hundreds to thousands of DNA bases. Genes are responsible for hereditary characteristics.
- genotype
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- H -
- hemoglobin
- heterozygous
- a genotype consisting of two different alleles of a gene for a particular trait (Aa). Individuals who are heterozygous for a trait are referred to as heterozygotes. See homozygous.
- homologous
chromosomes
- chromosomes that are paired during meiosis. Such chromosomes are alike with regard to size and also position of the centromere. They also have the same genes, but not necessarily the same alleles, at the same locus or location. All autosomes and the sex chromosomes of females occur in homologous pairs. The sex chromosomes of males are hemizygous.
- homozygous
- having the same allele at the same locus on both members of a pair of homologous chromosomes. Homozygous also refers to a genotype consisting of two identical alleles of a gene for a particular trait. An individual may be homozygous dominant (AA) or homozygous recessive (aa). Individuals who are homozygous for a trait are referred to as homozygotes. See heterozygous.
- hormones
- substances (usually proteins) that are produced by specialized cells and that travel to other parts of the body, where they influence chemical reactions and regulate various cellular functions. Hormones include the secretions of the endocrine glands that affect metabolism and behavior. Testosterone, estrogen, and insulin are examples of such hormones.
- HLA system
(HLA = human
leukocyte antigen
)
- referring to the over 100 antigens on the surface of human body tissue cells that can be recognized by some kinds of leukocytes and potentially lead to the rejection of these tissues if they are alien. This is by far the most polymorphic of all known human genetic systems--there are approximately 30,000,000 HLA genotypes. When organ transplants fail, it is usually due to HLA incompatibility. This can be prevented by making sure that the donor and the recipient have the same or very similar HLA types. Immunosuppressant drugs also are now available to restrain the HLA system and thereby allow successful transplants when there is an HLA incompatibility between donor and recipient.
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- I -
- immunization
- the development of antibodies to antigens that are alien to your body. Immunity can be developed to blood and tissue types as well as microorganism parasites (e.g., bacteria and viruses).
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- J -
- jaundice
- the condition in which the eyes, skin, and/or urine become unusually yellowish as a result of the build up of bilirubin in the blood.
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- K -
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- L -
- leukocytes
- 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
)
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
) have the function of getting rid of old unneeded
blood cells. See stem cells.
- lipids
- any of a group of organic molecules consisting of fats, oils, and waxes.
- locus
(plural, loci
)
- the position on a chromosome where a given gene occurs. The term is sometimes used interchangeably with gene, but this usage is technically incorrect.
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- M -
- meiosis
- the cell division process in specialized tissues of female ovaries and male testes which results in the production of sex cells, or gametes. Meiosis involves two divisions and produces four sperm cells in males and one ovum in females from a starting cell. Each sperm and ovum contains only half the original number of chromosomes--23 in the case of humans. Subsequently, meiosis is also called "reduction division." Spermatogenesis is the term used for meiosis in males and oögenesis refers to the same process in females. See mitosis.
- metabolism
- the chemical and physical processes continuously going on in the cells of living organisms. These are the processes by which energy and matter are made available for use by the cells of an organism. Heat is a byproduct of metabolism.
- mitosis
- the simple cell division process that occurs in somatic cells. One cell divides into two offspring cells that are identical to each other in their chromosome complement. One cell divides into two offspring cells that are identical to each other in their chromosome complement. Mitosis produces cells with diploid numbers of chromosomes--46 in the case of humans. See meiosis.
- mother-fetus
incompatibility
- the situation in which a mother's blood type is different from that of her unborn child. In the case of some combinations of types, the mother's blood system can produce antibodies to antigens on the surface of the red cells of her fetus resulting in their agglutination. This is the case when the mother is Rh- and her fetus is Rh+. As a result of this incompatibility, the fetus can develop erythroblastosis fetalis.
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- N -
- natural selection
- an evolutionary mechanism that occurs when some individuals of 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. Differential productive success between individuals is the key. Those who produce more offspring have a greater influence on the gene frequencies of the next generation. This mechanism of evolutionary change was first articulated by Charles Darwin.
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- O -
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- P -
- phenotype
- the observable or detectable characteristics of an individual organism; the detectable expression of a genotype.
- placenta
- an organ in the uterus of a mammal that develops from the chorion of an embryo during gestation. The placenta is connected to an unborn child by the umbilical cord. The placenta provides oxygen, nutrients, and antibodies for a fetus. Following birth the placenta and umbilical cord are naturally expelled from the uterus as the "after birth."
- plasma
- 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
- see thrombocytes.
- polymorphism
- prokaryotic
cell
- a cell that lacks a true nucleus and divides by simple fission rather than mitosis. Bacteria and blue-green algae are prokaryotes. See eukaryotic cell.
- proteins
- any of a large number of complex organic molecules that are composed of one or more chains of amino acids. Proteins can serve a wide variety of functions through their ability to bind to other molecules. Proteins may be enzymes, hormones, antibodies, structural components, or gas-transporting molecules.
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- Q -
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- R -
- red cells
- see erythrocytes.
-
Rho-GAM
- a serum containing anti-Rh+ antibodies given to women at high risk for having a baby with erythroblastosis fetalis (i.e., Rh- women with Rh+ mates). This must be done for the first and all subsequent pregnancies. The injected antibodies quickly agglutinate any fetal red cells as they enter the mother's blood, thereby preventing her from forming her own antibodies. Since the serum given the mother is a passive form of immunization, it will shortly leave her blood stream.
-
RNA
(ribonucleic
acid
)
- a type of nucleic acid that is found in both the nucleus and the cytoplasm of cells. Unlike DNA, RNA is single stranded. Messenger RNA (mRNA) carries the genetic code from the DNA in the chromosomes and translates it with the help of transfer RNA (tRNA) at the site of the ribosomes in the cytoplasm in order to assemble, or synthesize, proteins.
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- S -
-
somatic cell
- all the cells in the body except those directly involved with reproduction. Most cells in multicellular plants and animals are somatic cells. They reproduce by mitosis.
- stem
cells
- embryonic cells that have not yet become specialized tissue cells--they potentially can develop into any type of tissue in the body. Children and adults retain somewhat specialized stem cells in their bone marrow. These stem cells are the source of the major blood cells--erythrocytes, leukocytes, and thrombocytes (platelets).
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- T -
- thrombocytes
- a type of blood cell that coagulates and clots blood when there is an injury to a blood vessel. Thrombocytes are also called platelets. See stem cells.
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- U -
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- V -
- vascular
- relating to the system of capillaries, veins, and arteries used by our bodies to transport blood.
- virus
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- W -
- white cells
- see leukocytes.
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- X -
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- Y -
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- Z -
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Copyright © 1999-2012 by Dennis
O'Neil. All rights reserved.
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