Genes and Heredity

Vocabulary

codon

series of three nucleotides on an mRNA strand that codes for a particular amino acid

conjugation

direct transfer of genetic material between two bacteria

DNA primer

anchor or starting point for DNA polymerase to add free nucleotides to a growing strand of DNA

exon

DNA sequence within a gene sequence that codes for a specific protein. Exons must be combined during mRNA processing.

frameshift mutation

insertion or deletion of a number of nucleotides that is not divisible by three, resulting in the ribosome reading a "shifted" codon code

genotype

genetic makeup of an organism

horizontal gene transfer

direct transfer of DNA between individuals without reproduction

inducer

protein that binds to and inactivates the repressor in order to permit transcription of the operon genes

intron

DNA sequence within a gene sequence that does not code for a specific protein. Introns must be removed from the mRNA during processing.

messenger RNA

molecule made from a DNA template that contains the complementary gene sequence, that is, the sequence opposite to the DNA strand

negative regulator

protein that prevents transcription or translation

nucleoid

area inside a prokaryotic cell where genetic material is found

nucleotide

organic compound consisting of a sugar, a phosphate, and a nitrogenous base; this compound forms the basis of a genetic sequence.

operon

collection of genes that are transcribed together and contain at least two regions of control called a promoter and an operator

phenotype

observable characteristics of an organism that result from genetic and environmental influences

plasmid

small, circular piece of bacterial DNA that replicates on its own and can be transferred between cells

point mutation

replacement of one nucleotide, resulting in a change to one codon

positive regulator

protein that promotes transcription or translation

regulator gene

gene that codes for functional proteins

repressor

protein that binds to the operator to prevent transcription of the operon genes

reverse transcription

process of using an RNA template to create a complementary strand of DNA

ribosomal RNA

component of ribosomes that catalyzes peptide bond formation

spontaneous mutation

change in the genetic sequence that occurs randomly and without external influence

structural gene

gene that is responsible for the coding of structural proteins, those that serve as structural support within a cell

transcription

formation of mRNA from the template DNA strand to be used to build proteins

transduction

process that occurs when a bacteriophage (a virus that infects bacteria) injects DNA into a bacterial cell

transfer RNA

molecule that carries each amino acid to the strand of mRNA during translation of protein synthesis

transformation

incorporation of foreign DNA by a bacterial cell

translation

assembly of amino acids into proteins in the ribosomes through the reading of mRNA by tRNA and the ribosome

vertical gene transfer

transmission of genes from parent to offspring