Glossary
allele One of two or more alternative
forms of a gene that exist at a specific gene location on a chromosome.
amino acid The base chemical subunit
of proteins. There are 20 common amino acids.
autosomal traits Traits carried
on the chromosomes other than the sex chromosomes (X and Y).
base One of five compounds--adenine,
guanine, cytosine, thymine, and uracil--that form the genetic code in DNA
and RNA.
chromosomes Long threadlike structures
made of DNA and protein that are the gene-bearing structures of eukaryotic
cells.
codon A three-nucleotide sequence
that codes for a specific amino acid stop or start signal in protein synthesis.
deoxyribonucleic acid (DNA) A double-stranded,
helical nucleic acid molecule that is the carrier of genetic information.
DNA replication The copying of a
DNA molecule.
DNA sequencing The process of deciphering
the precise order of nucleotide bases in a DNA molecule.
dominant trait A characteristic determined
by an allele that is expressed over any other alleles for a given trait.
enzymes A class of proteins that
acts as catalysts, chemical agents that change the rate of a reaction without
being consumed by the reaction.
gel electrophoresis The separation
and identification of molecules based on their movement through an electrically
charged field.
gene A discrete unit of hereditary information that
consists of DNA and is located on the chromosomes.
gene cloning The process of synthesizing
multiple copies of a particular DNA sequence using a bacteria cell or another
organism as a host.
genetic code The set of sixty-four
codons corresponding to each amino acid.
genetic engineering The technique
of altering the genetic makeup of cells or organisms by deliberately inserting,
removing, or altering individual genes.
gene expression The process in which
a cell produces the protein encoded by a particular gene.
gene therapy A method of treating
diseases that involves inserting new genetic material into a patient's cells.
genetics The study of how traits
pass from parents to children and the molecular basis of those traits.
genome The entire set of genetic
instructions for a given organism.
heterozygous Having two different
alleles for a given gene.
homozygous Having two identical
alleles for a given gene.
messenger RNA (mRNA)
A type of RNA that relays the genetic information from the DNA in the nucleus
to ribosomes in the cytoplasm.
nucleotide A chemical subunit composed
of a five-carbon sugar, bonded to a phosphate group and nitrogenous base,
which makes up DNA and RNA.
protein A molecule chain containing
amino acid subunits linked together in a specific sequence.
recessive trait A characteristic
determined by an allele that requires the presence of two identical alleles
to be expressed.
recombinant DNA (rDNA)
A DNA sequence produced by artificially joining pieces of DNA from different
organisms.
restriction enzyme An enzyme that cuts DNA molecules
at a specific base sequence.
ribonucleic acid (RNA)
A single-stranded nucleic acid molecule involved in protein synthesis. The
structure of RNA is determined by DNA.
ribosome A structure within cells that manufactures
proteins by linking together amino acids according to the coded sequence
on a strand of messenger RNA.
transcription The process
of converting genetic instructions coded in a segment of DNA into messenger
RNA.
transfer RNA (tRNA)
A type of RNA that carries amino acids to ribosomes for the purpose of constructing
a protein.
translation The conversion
of genetic information coded in a segment of mRNA into a sequence of amino
acids.
X-linked trait A trait that is
passed on from mother to child or father to daughter on the X chromosome.
Activities
- Genes, DNA, and Mutations
- Genetic Inheritance
- Predicting Genetic Combinations
- Genetic Testing
- Genetic Counseling
- Gene Therapy
Links
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Resource Book Index: Promises and Perils
