C D E
F G H
I J K L
M N O
P Q R S
T U V
W X Y
adenine (A) - a base in DNA and
RNA that always bonds with thymine (T) in DNA, and with
uracil (U) in RNA.
alleles - two different forms or versions of a
gene that occupy corresponding positions on homologous
chromosomes. A person has two alleles of a trait--one
from each parent.
amino acids - the basic building blocks of proteins;
there are twenty different types linked together in different
sequences to form different proteins.
anaphase - the third stage of mitosis in which
chromatids move to opposite poles of the cell.
antisense strand - the portion of DNA double helix
that is not transcribed during protein synthesis (as opposed
to the sense strand).
antisense technology - gene silencing or the process
of inactivating a gene.
autosome - any chromosome not involved in sex
determination. Twenty two of the human chromosome pairs
bases - the molecular building
blocks of DNA and RNA: adenine (A), cytosine (C), guanine
(G), thymine (T), and in RNA only, uracil (U). In DNA,
A attaches only to T, and C attaches only to G. In RNA,
A attaches only to U, and C attaches only to G.
base pairs - the pairs of complementary bases
that form the rungs of DNA: adenine (A) pairs with thymine
(T), cytosine (C) pairs with guanine (G).
base sequence - the order of bases in DNA.
biotechnology - the use of biological processes
to make products.
carrier - an individual who is
heterozygous for a recessive trait.
cell - the basic unit of life; the smallest basic
part of every living thing that can function by itself.
It is made of a nucleus surrounded by cytoplasm, organelles
(similar to organs in a body) and proteins. Each cell
contains the entire genome.
cell cycle - the time from one cell division to
the next. Varies from minutes to days, but the actual
division takes less than 10% of the cycle.
centromere - the region on a chromosome that ensures
proper pairing of sister chromatids.
chromatin - a complex of protein and DNA that
make up chromosomes.
chromosome - a long coiled strand in the nucleus,
made up of DNA and protein. There are 46 human chromosomes,
each containing DNA for hundreds or thousands of individual
chromosome jumping - the process of moving rapidly
up or down a chromosome in search of a particular gene
by jumping over uninformative areas of DNA.
chromosome map - a diagram showing the locations
and relative spacing of genes along a chromosome.
clone - a genetic duplicate.
cloning - the process of producing a genetically
identical group of cells from a single ancestor.
codominant - two genes that are neither dominant
or recessive; neither masks the other, as in the case
of red geraniums crossed with white geraniums yielding
codon - a special code to make amino acid; a sequence
of three nucleotides.
complementary DNA (cDNA) - a single strand of
DNA made in the lab to complement the bases in a strand
of messenger RNA.
conserved DNA sequences - sequences that have
not changed over time.
controlled breeding - the reproduction of desired
crossing-over/recombination - a process of chromsome
exchange during cell division, resulting in new combinations
cytogenics - the study of the genetic implications
of chromosome structure and behavior.
cytoplasm - all the organelles and materials inside
a cell between the cell membrane and the nucleus.
cytosine (C) - a base in DNA that always bonds
with guanine (G).
daughter cell - one of two cells
resulting from cell division.
daughter strand - the DNA, or chromosome, strand
deletion - the loss of a segment of genetic material.
deoxyribonucleic acid - see DNA
differentiated cells - cells in which some of
the DNA shuts off so that the cells can be different;
they make liver cell, bone cells, etc.
dihybrid cross - the graphing of two or more traits
in a Punnett Square to predict heredity.
diploid - a cell or organism that has two complete
sets of chromosomes, as opposed to haploid, or those with
only one member of each pair of the same chromosomes.
DNA (deoxyribonucleic acid) - a large double-stranded,
spiraling molecule that contains genetic instructions
for growth, development and replication. It is organized
into bodies called chromosomes and found in the cell nucleus.
DNA fingerprinting - the use of fragments of DNA
to identify the unique genetic makeup of an individual.
There are the RFLP method and the PCR method.
DNA replication - the process or copying a DNA
molecule just before cell division.
DNA sequencing - the process of determining the
order of bases in a segment of DNA.
dominant gene - a gene which passes on a certain
physical characteristic, dominating over a recessive gene
present on another chromosome.
double helix - a common name for DNA, referring
to the double-stranded, spiraling structure of the molecule.
egg - the female reproductive
electrophoresis - a method of separating large
molecules such as DNA fragments from a mixture of similar
enzymes - the biological catalysts that speed
up a chemical reaction.
eugenics - the use of genetic engineering to produce
a superior race.
eukaryotes - all living things whose cells have
nuclei (most living things).
excision - the removal of a DNA fragment from
exon - a gene segments that has instructions for
making a protein, as opposed to introns, which dont
have these instructions.
founder effect - the change in
gene frequency occurring when a population is based on
only a few individuals.
fraternal twins - twins resulting from fertilization
of separate eggs; genetically related as siblings.
gametes - the sex cells in human
beings--sperm in men and ova in women. Each gamete cell
has 23 chromosomes, half the number found in other body
gel electrophoresis - see electrophoresis
gene - the unit of heredity in chromosomes; a
segment of double-stranded DNA.
gene cloning - the process of separating a gene
and making identical copies of it.
gene expression - the way information in a gene
is changed to a protein or RNA. The DNA sequence is changed
into RNA and usually (not always) then changed into protein.
gene linkage map - a map of relative positions
of genes on a chromosome. Genes inherited together are
close to each other on the chromosome, and said to be
linked. (see gene mapping)
gene locus - the position a gene occupies on a
gene mapping - the process of determining the
relative positions of genes on a DNA molecule. (see gene
gene pool - the genetic make-up of a specific
gene silencing - the process of inactivating a
gene that may cause disease or be defective in another
gene splicing - the process of cutting the DNA
of a gene in order to add base pairs.
gene targeting - the process of changing or turning
off a particular gene.
gene therapy - a method of treating a disease
by exchanging the defective gene causing the disease with
a healthy one in a cell.
geneticist - a scientist who studies genes.
gene transcription - the first step in gene expression
where the genes DNA sequence is copied into messenger
gene translation - the method where transcribed
messenger RNA directs the making of proteins from amino
genetic code - all the genes a living thing has
inherited. They determine appearance, function, growth,
genetic disease - a disease caused by a genetic
genetic engineering - the technology used to genetically
manipulate living cells to produce new chemicals or to
perform new functions.
genetic marker - a landmark that identifies a
certain spot on a chromosome.
genetics - the study of genes and heredity, or
how characteristics are passed from parents to children.
genetic testing or screening - a technique used
to find out whether a person or organism has a particular
genome - all the genetic information necessary
to build a living organism. It is species-specific.
genotype - all the traits, dominant and recessive,
that an organism inherits. This is different from the
phenotype, or acquired observable traits.
germ cells - the cells that give rise to sperm
germplasm - the protoplasm of germ cells containing
guanine (G) - a base in DNA and RNA that always
bonds with cytosine (C).
haploid - cells that have a single
set of chromosomes, or half the full set of genetic material,
as opposed to diploids. Sperm and egg cells are haploid.
Hardy-Weinberg principle - states that the allele
frequency for dominant and recessive alleles remains the
same over the generations in a particular population as
long as certain conditions exist.
helix - spiral in form.
heredity - all of the traits passed on to children
by parents (plant or animal) or the process of transferring
heteromorphic chromosome pairs - chromosomes that
visibly differ, like X and Y.
heterosis/hybrid vigor - the superiority of hybrids.
heterozygous - refers to having dissimilar alleles
of one or more genes, as opposed to homozygous.
homologous recombination - the process of replacing
one DNA segment with a similar sequence.
homozygous - refers to having an identical pair
of alleles, one from each parent, as opposed to heterozygous.
Human Genome Project - a large project to map
and sequence all DNA in human chromosomes.
hybrid - a plant or animal that results from two
different breeds or varieties of parents; carries two
different genes for a characteristic.
hybridization - the cross-fertilization or breeding
of plants and animals to get the best.
hybrid vigor/heterosis - the superiority of hybrids.
identical twins - the offspring
resulting from a fertilized egg splitting into two separate
inbreeding - the crossing of two closely related
inbreeding depression - the decrease in health
or fertility because of inbreeding.
interphase - the period of cell growth between
introns - DNA sequences without instructions for
making protein that come between those sequences with
instructions for making protein (exons). Introns are not
in messenger RNA, and it is not known what they are for.
inversion - a mutation occurring where a segment
of DNA flips upside down in a sequence, but remains in
karyotype - a photograph of a
cells chromosomes, arranged in order from largest
linkage - the tendency of genes
on the same chromosome to be associated in inheritance.
linkage group (linked genes) - genes found near
each other on a chromosome.
locus - the position of a particular gene on a
mass selection - large-scale controlled
maternal inheritance - the inheritance of a trait
from the female gamete.
meiosis - the process of cell division, where
the number of chromosomes is reduced by half, then the
new cells divide again by mitosis. Results in four daughter
messenger RNA (mRNA) - a single strand of RNA
that directs protein production.
metaphase - the second stage of mitosis during
which the chromatid pairs align at the cells equator.
mitochondria - the part of a cell that turns food
into energy for chemical reactions, movement, and growth.
mitosis - cell division resulting in daughter
(new) cells that are genetically identical to each other
and to the parent; the chromosomes are divided before
the cell divides.
molecular genetics - the study of molecules of
DNA in order to identify the form and function of the
genes in them.
monohybrid cross - the graphing of only one trait
in a Punnett Square, used for predicting heredity.
mRNA - see messenger RNA.
multifactorial trait - a trait that is determined
by heredity and environment.
mutagens - substances which increase the likelihood
mutation - a permanent change in a DNA sequence
that can be passed on. It can be a change in genetic information,
addition of information, or deletion of information.
natural selection - the process
by which only the organisms better adapted to the environment
survive and reproduce.
nuclear transfer technology - the process of taking
the nucleus with the DNA from one cell and putting it
nucleotide - the building block of DNA (rungs
on the ladder of the DNA double helix) made
up of four molecules that occur in pairs--adenine (A)
with thymine (T), and cytosine (C) with guanine (G). Thousands
of nucleotides are linked to form a DNA or RNA molecule.
nucleus - the center part of the cell. It contains
6 feet of DNA in 23 pairs of chromosomes and is the largest
part of the cell. Living things are divided into eukaryotes
(whose cells have nuclei) and prokaryotes (whose cells
have no nuclei).
oligonucleotide - a short string
of nucleotides; a single-stranded segment of DNA. Used
as a probe to find matching sequence of DNA or RNA.
organelle - an organized structure within a cell,
with a specific function.
outcrossing - an inbreed crossed with a less related.
ovule - the structure in a seed plant that develops
into a seed after fertilization.
ovum - the human female reproductive cell.
parent cell - the original cell
before cell division.
paternal inheritance - the inheritance of a trait
from the male gamete.
PCR (polymerase chain reaction) - a process developed
in mid-1980s to make a large number of copies of
a DNA sequence from very little DNA. It is used in forensics
when little DNA is available for testing.
pedigree - a diagram representing family relationships
peptide - two or more amino acids linked together.
phenotype - all the observable traits a person
inherits, as opposed to the genome, or all the traits
plasma membrane - the fatty layer surrounding
the molecules of a cell.
plasmids - the rings of DNA in bacteria.
pollen - the grains that contain the male reproductive
cells of a seed plant.
pollination - the transfer of pollen in a flower
from the stamen to the pistil (male to female).
polymerase chain reaction - see PCR.
polymorphisms - the differences in DNA sequences
that occur naturally. They are used as genetic markers
because researchers can use them to tell apart DNA from
polyploidy - cells that have extra chromosomes.
population - all the members of a species that
live in a particular location.
population genetics - the study of how genetic
principles apply to entire generations.
positional cloning - the process of finding the
gene for a specific trait by comparing the DNA of people
with the trait to the DNA of relatives without the trait.
principle of segregation - the principle, first
noted by Gregor Mendel, that explains why children dont
always directly inherit their parents characteristics.
probe - a radioactive DNA or RNA molecule used
in DNA-RNA or DNA-DNA hybridization trials.
prokaryotes - the living things whose cells do
not have nuclei; includes only single-celled bacteria.
propagation - the multiplication of plants.
promoter - a segment of DNA that acts as controlling
element in expression of a gene. Marks the place of the
beginning of gene transcription.
prophase - the first stage of mitosis or meiosis.
protein - a molecule made up of amino acids linked
together. They are the bodys workhorses whose function
can be as enzymes, structural components, or signaling
Punnett Square - a chart that shows all possible
genetic outcomes of a mating.
recessive gene - a gene which
is hidden by a dominant gene; it must be present on both
chromosomes in a pair (one from the father, one from the
mother) to show outward signs of the characteristic.
recombinant DNA - the new DNA resulting from combining
two or more types of DNA.
recombinant DNA technology - the technique for
cutting apart, splicing together and producing pieces
of DNA from different sources.
recombination/crossing-over - a process of chromosome
exchange during cell division, resulting in new combinations
restriction enzyme - an enzyme capable of cutting
DNA into fragments.
retrovirus - a cancer-causing virus that transforms
cells by altering the function of host-cell genes or by
carrying cancer-causing genes from one host to another.
ribosome - the small cellular structure where
RNA translates the genetic code into proteins.
RFLP (restriction fragment length polymorphism)
- considered to be the most accurate DNA test; it takes
several weeks to complete, and is becoming more frequently
used in forensics cases.
RNA (ribonucleic acid) - single-stranded nucleic
acid (similar to double-stranded DNA) containing the bases
adenine (A), cytosine (C), guanine (G), and uracil (U).
The different forms include messenger RNA (mRNA), transfer
RNA (tRNA), and ribosomal RNA (rRNA), which are all part
of making protein.
sense strand - the portion of
the DNA double helix that is transcribed during protein
synthesis (as opposed to the antisense strand).
sex chromosome - the X or Y chromosome, which
determines sex. Females have two X chromosomes in each
cell, and males have an X and a Y.
sex-influenced trait - a trait whose expression
depends on the sex of the individual organism.
sex-limited trait - a trait expressed in one sex
and not in the other.
sex-linked trait - a trait whose gene is located
on or linked to the X chromosome.
single-stranded DNA - the result of genes being
changed or copied before a cell division; half of the
normal two strands that form the double helix.
somatic cell - any cell in the body other than
the sex cells.
species - a group of closely related organisms
capable of mating and producing fertile offspring.
sperm - the male reproductive cells.
stamen - the male part of a plant, which produces
telephase - the fourth stage of
mitosis where chromosomes uncoil and new nuclear membranes
thymine (T) - a base in DNA that always bonds
with adenine (A).
transcription - the process by which DNA passes
genetic information to RNA. The first step in producing
transfer RNA (tRNA) - a class of RNA that carries
amino acids into ribosomes and bonds with mRNA for protein
transformation - a process by which some bacteria
can absorb DNA from their surroundings.
transgenic - organisms with inserted genes.
translation - process by which RNA makes proteins.
translocation - a mutation in which a chromosomal
piece becomes attached to another chromosome.
uracil (U) - a base in RNA that
bonds only with adenine (A).
vector - a DNA molecule into which
a gene or DNA segment is inserted by recombinant DNA techniques;
a cloning vehicle.
virus - an infectious parasite.
wildtype - the most common phenotype
or genotype in a population.
X chromosome - one of the chromosomes
that determines sex. Females have two X chromosomes in
each somatic cell, and males have one X and one Y chromosome..
Y chromosome - one of the chromosomes
that determines sex. Males carry one X chromosome and
one Y chromosome in each somatic cell.
zygote - the new cell formed when
the male sperm unites with a female egg.