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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 block of proteins. There are
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.
ANALOGUES are likenesses found in humans and
animals.
CHROMOSOMES
Thread-like, gene-carrying bodies in the cell nucleus. Chromosomes
are composed primarily of DNA and protein. They are visible only
under magnification during certain stages of cell division. Humans
have 46 chromosomes in each somatic cell and 23 in each sex cell.
COLLECTIVELY means altogether
.DIPLOID NUMBER
Referring to the full component of chromosomes normally found in
somatic cells. In humans, the number is 46. See haploid number.
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.
DOMINANT ALLELE
An allele that masks the presence of a recessive allele.
DOUBLE HELIX
The twisted ladder shape that is characteristic of DNA molecules.
ETHICAL is a principle of right or wrong or
good conduct.
FERTILIZATION
Conception; the process of sexual reproduction by which the chromosomes
from a sperm cell enter the nucleus of an ovum and combine with
its chromosomes.
GAMETES
Reproductive cells--sperm or unfertilized ovum cells produced in
the testes and ovaries of animals. Gametes are produced by meiosis.
They normally have half the number of chromosomes found in somatic
cells.
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 an entire protein or, in
some cases, a portion of a protein. A gene may be made up of hundreds
of thousands of DNA bases. Genes are responsible for hereditary
characteristics in plants and animals.
GENETIC CODING refers to the genetic make-up
of humans and other species.
GENOME is the human gene make-up.
GENOTYPE
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.
HAPLOID NUMBER
Referring to the number of chromosomes in gametes. Human sperm and
ova normally contain only 23 chromosomes, which is the result of
the halving of chromosome pairs in meiosis. See diploid number.
HEMOPHILIA
An X-linked genetically inherited recessive disease in which one
or more of the normal blood clotting factors is not produced. This
results in prolonged bleeding from even minor cuts and injuries.
Hemophilia most often afflicts males.
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.
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.
HUNTINGTON'S DISEASE
A severe genetically inherited fatal degenerative nerve disorder.
The symptoms usually do not appear until early middle age. There
is a progressive loss of muscle control that inevitably leads to
paralysis and death.
INDIVIDUALLY means each person.
INDIVIDUATION is the distinctiveness or uniqueness
of an individual.
INTERRELATEDNESS is to come into mutual relationship.
LIVING SPECIES are animals other than humans.
MEIOSIS
Cell division in specialized tissues of ovaries and testes which
results in the production of sperm or ova. Meiosis involves two
divisions and results in four daughter cells, each containing only
half the original number of chromosomes--23 in the case of humans.
These cells can develop into gametes. See mitosis
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. Mitosis produces cells with
diploid numbers of chromosomes--46 in the case of humans. See meiosis.
MORAL means the judgment of the goodness or
badness of human actions.
MUTATION
An alteration of genetic material such that a new variation is produced.
For instance, a trait that has only one allele (A) can mutate to
a new form (a). This is the only mechanism of evolution that can
produce new alleles of a gene. Technically, mutation refers to changes
in DNA bases as well as changes in chromosome number and /or structure.
NUCLEIC ACIDS
The largest type of molecule in living organisms. It is composed
of a chain of nucleotides that code for the synthesis of specific
proteins. DNA and RNA are types of nucleic acid.
NUCLEOTIDE
The basic building block of nucleic acid. It consists of any one
of four specific purine or pyrimidine bases attached to a ribose
or deoxyribose sugar and phosphate group.
OVUM (PLURAL OVA )
A female sex cell or gamete.
PHENOTYPE
The observable or detectable characteristics of an individual organism;
the detectable expression of a genotype.
POLYMORPHISM
A genetic trait controlled by more than one allele, each of which
has a frequency of 1% or greater in the population gene pool. See
balanced polymorphism.
population a1 more or less distinct group of individuals within a
species who tend to restrict their mate selection to members of
their group. Members of a population tend to have similar genetic
characteristics due to generations of interbreeding.
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.
RECESSIVE ALLELE
An allele that is masked in the phenotype by the presence of a dominant
allele. Recessive alleles are expressed in the phenotype when the
genotype is homozygous recessive (aa).
RECOMBINATION
The exchange of genetic material between homologous chromosomes
at the beginning of meiosis. This results in sperm and ova with
greater genetic diversity. Specifically, a portion of a chromosome
is broken and reattached on another chromosome. Recombination is
also referred to as crossing-over.
RETINAL ATROPHY concerns the wasting away
of the inner lining of the eye.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.
SEX CELL
A gamete, either a sperm or an ovum. Sex cells are produced by the
meiosis process. See somatic cell.
SEX-LINKED
Referring to a gene that is part of a sex chromosome. Since all
of the genes on a chromosome are inherited as a package, they are
essentially linked together.
SICKLE-CELL TRAIT
A genetically inherited recessive condition in which red blood cells
are distorted resulting in severe anemia and related symptoms that
are often fatal in childhood.
SOLIDARITY is a togetherness or unity.
SOMATIC CELL
Basically, 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 and have a diploid
number of chromosomes. See sex cell.
SPECIES
The largest natural population of organisms that can interbreed
to produce fertile offspring. Members of one species are reproductively
isolated from members of all other species (i.e., they cannot mate
with them to produce fertile offspring).
SPERM
A male sex cell or gamete.
TAY-SACHS DISEASE
An inherited metabolic abnormality that is fatal in early childhood.
Eastern European Jews have an unusually high frequency of this harmful
recessive allele in their population. However, it can occur in any
human group.
TRANSGENIC is moving of genes.
X-LINKED
Referring to a gene that is carried by an X chromosome. See sex-linked
gene.
ZYGOTE
A "fertilized" ovum. More precisely, this is a cell that
is formed when a sperm and an ovum combine their chromosomes at
conception. A zygote contains the full complement of chromosomes
(in humans 46) and has the potential of developing into an entire
organism.Sources include: Synthetic Theory of Evolution: Glossary
of Terms by Dennis O’Neil http://anthro.palomar.edu/glossary.htm#somatic_cell
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