First 402 words of the document:
Cellular Control Key Words
Gene: A length of DNA that codes for one or more particular proteins.
Polypeptide: A polymer consisting of chains of amino acids joined together by peptide bonds.
Genome: The entire DNA sequence of an organism. The human genome consists of about 3 billion
nucleotide base pairs.
Protein: A large polypeptide, usually made of 100 or more amino acids. Some proteins consist of
one polypeptide chain, and some consist of more.
Transcription: The creation of a singlestranded mRNA copy of the DNA coding template strand.
Translation: The assembly of polypeptides at ribosomes.
Mutations: A change in the amount of, or arrangement of the genetic material in a cell. This can be a
chromosome mutation where the structure or number of chromosomes changes, or DNA mutations
where changes occur to the nucleotide bases.
Allele: A different version of the same gene. It is still located at the same gene locus on the
chromosome and codes for the same proteins, but the alteration to the DNA base sequence may alter
the protein structure, therefore the phenotype of an organism.
Locus: (plural loci) The position of a gene on a chromosome.
Operon: A length of DNA made up of structural genes and control sites. The structural genes code for
proteins, such as enzymes. The control sites are the operator and the promoter region.
Meiosis: A reduction division that creates 4 daughter cells that have half the original number of
chromosomes. They are haploid and can be used for sexual reproduction.
Crossing Over: When lengths of DNA are swapped from one chromatid to another.
Maternal Chromosomes: The set of chromosomes in an individual's cells that were contributed by
the egg cell (mother).
Paternal Chromosomes: The set of chromosomes in an individual's cells that were contributed by
the sperm cell (father).
Dominant: The allele responsible is expressed causing a particular characteristic in the phenotype
even in those that have a heterozygous genotype.
Codominant: Alleles that both contribute to the phenotype.
Recessive: The allele responsible is only expressed causing a particular characteristic in the
phenotype if there is no dominant allele present.
Epistasis: The interaction of different gene loci so that one gene locus makes or suppresses the
expression of another gene locus.