Microbial Genetics

Ribose

A 5-carbon monosaccharide (sugar) found in RNA

Deoxyribose

A 5-carbon sugar that is an important component of DNA

Transposons

A DNA segment with an insertion sequence at each end, enabling it to migrate to another plasmid, to the bacterial chromosome, or to a bacteriophage

Point mutations

A change that involves the loss, substitution, or addition of one or a few nucleotides

Operon

A genetic operational unit that regulates metabolism by controlling mRNA production. In a sequence, the unit consists of a regulatory gene, inducer or repressor control sites, and structural genes.

Ames Test

A method for detecting mutagenic and potentially carcinogenic agents based upon the genetic alteration of nutritonally defective bacteria

Spontaneous

A mutation in DNA caused by a random mistake in replication and not know to be influenced by any mutagenic agent. These mutations give rise to an organism's natural, or background, rate of mutation

Missense

A mutation in which a change in the DNA sequence results in a different amino acid being incorporated into a protien, with varying results

Nonsense

A mutation that changes an amino acid-producing codon, leading to premature termination of a protein

Silent

A mutation that, because of the degeneracy of the genetic code, results in a nucleotide change in both the DNA and mRNA but not the resultant amino acid and thus, not the protein

Back mutations

A mutation which counteracts an ealier mutation, resulting in the restoration of the original DNA sequence

Mutations

A permanent inheritable alteration in the DNA sequence or content of a cell.

Nitrogen base

A ringed compound of which pyrimidines and purines are types

mRNA

A single stranded transcript that is a copy of the DNA template that corresponds to a gene

Gene

A site on a chromosome that provides infomation for a certain cell function. A specific segment of DNA that contains the necessary code to make a protein or RNA molecule.

Codons

A specific sequence of three nucleotides in mRNA (or the sense strand of DNA) that consititutes the genentic code for a particular amino acid

RNA polymerse

Enzyme process that translates the code of DNA to RNA

heredity

Genetic inheritance

Protiens

Predominant organic molecule in cells; formed by long chains of amino acids

Translation

Protien synthesis; the process of decoding the messanger RNA code into a polypeptide

Transcription

mRNA synthesis; the process by which a strand of RNA is produced against a DNA template.

Exons

A stretch of eukaryotic DNA coding for a corresponding portion of mRNA that is translated into peptides. Intervening stretches of DNA that are expressed are called introns. During transcription exons are separated from introns and are spliced together into a continous mRNA transcript

tRNA

A transcript of DNA that specializes in converting RNA language into protein language

Phosphate

An acidic salt containing phosphorus and oxygen that is an essential inorganic component of DNA, RNA, and ATP

Induced

Any alteration in DNA that occurs as consequence of exposure to chemical or physical mutagens

semiconservative

In DNA replication, the synthesis of the paired daughter strands, each retaining a parent strand template

Replication

In DNA synthesis, the semiconservative mechanisms that ensure precise duplication of the parent DNA strands

Conjugation

In bacteria, the contact between donor and recipient cells associated with the transfer of genetic material such as plamids. Can involve special (sex) pili. Also a form of sexual recombination in ciliated protozoans

Transformation

In microbial genetics, the transfer of genetic material contained in "naked" DNA fragments from a donor cell to a competent recipient cell

Adenine

One of the nitrogen bases found in DNA and RNA, with a purine form

Guanine

One of the nitrogen bases found in DNA and RNA, with a purine form

Cytosine

One of the nitrogen bases found in DNA and RNA, with a pyrimidine form

Thymine

One of the nitrogen bases found in DNA, but NOT in RNA. Thymine is in a pyrimidine form.

Uracil

One of the nitrogen bases in RNA, but Not in DNA. Uracil is in a pyrimidine form.

Nucleotides

The basic structural unit of DNA and RNA; each nucleotide consists of a phosphate, a sugar (ribose in RNA, deoxyribose in DNA), and a nitrogenous base such as adenine, guanine, cytosine, thymine (DNA only) or uracil (RNA only)

Genome

The complete set of chromosomes and genes in an organism

DNA

The nucleic acid often referred to as the "double helix". DNA carries the master plan for an organism's heredity

Genetics

The science of heredity

Introns

The segment on split genes of eukaryotes that do not code for a polypeptide. They have regulatory functions.

Chromosome

The tightly coiled bodies in cells that are the primary sites of genes

Transduction

The transfer of genetic material from one bacterium to another by means of a bacteriophage vector

Anticodons

The trinucleotide sequence of transfer RNA that is complementary to the trinucleotide sequence of messenger RNA (the codon)