Microbiology Chapter 9 Vocabulary

Genetics

The science of heredity

Heredity

Genetic inheritance

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

RNA

Nucleic acid responsible for carrying out the hereditary program transmitted by an organism’s DNA

Chromosome

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

Deoxyribose sugar

A 5 carbon sugar that is an important component of DNA

Nitrogenous base

A nitrogen-containing molecule found in DNA and RNA that provides the basis for the genetic code.

Purine

A nitrogen base that is an important encoding component of DNA and RNA The two most common purines are adenine and guanine.

Pyrimidine

Nitrogen bases that help form the genetic code on DNA and RNA. Uracil, thymine and cytosine are the most important pyrimidines.

Adenine

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

Thymine

One of the nitrogen bases found in DNA and RNA .Thymine is in a pyrimidine form.

Guanine

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

Cytosine

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

Uracil

One of the nitrogen bases in RNA by not in DNA. Uracil is in a pyrimidine form

Replication

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

Okazaki fragments

In replication of DNA, a segment formed on the lagging strand in which biosynthesis is conducted in a discontinuous manner dictated by the 5’-3’ DNA polymerase orientation.

Transcription

mRNA synthesis

Translation

Protein synthesis

mRNA

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

tRNA

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

rRNA

A single stranded transcript that is a copy of part of the DNA template

Genotype

A genetic makeup of an organism. The genotype is ultimately responsible for an organism’s phenotype, or expressed characteristics

Phenotype

The observable characteristics of an organism produced by the interaction between its genetic potential (genotype) and the environment

Single stranded

having a single strand

Double stranded

having a double strand

Codons

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

Anticodon

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

RNA polymerase

Enzyme process that translates the code of DNA to RNA

Promoter region

Part of an operon sequence. The DNA segment that is recognized by RNA polymerase recognizes and binds to commence transcription

Start codon

The nucleotide triplet AUG that codes for the first amino acid in protein sequences

Translocation

Moving to another position

Nonsense codons

A triplet of mRNA bases that does not specify an amino acid but signals the end of a polypeptide chain

Triplets

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

Carcinogenic

any substance or agent that tends to produce a cancer

Operon

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

Locus

A site on a chromosome occupied by a gene. Plural: loci

Posttranslational

Of or relating to a substance or process, such as the addition of sugar groups to form a glycoprotein, that occurs or is formed after translation of protein

Exons

A segment of a gene that contains information used in coding for protein synthesis. Genetic information within genes is discontinuous, split among the exons that encode for messenger RNA and absent from the DNA sequences in between, which are called introns.

DNA polymerase

Enzyme responsible for the replication of DNA. Several versions of the enzyme exist, each completing a unique portion of the replication process.

Corepressor

A molecule that combines with inactive repressor to form active repressor, which attaches to the operator gene site and inhibits the activity of structural genes subordinate to the operator

Mutation

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

Spontaneous mutation

A mutation in DNA caused by random mistakes in replication and not known to be influenced by any mutagenic agent, These mutations give rise to an organism’s natural, or background, rate of mutation

Missense mutation

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

Point mutation

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

Induced mutation

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

Photoactivation

A mechanism for repairing DNA with ultraviolet-light-induced mutations using an enzyme (photolyase) that is activated by visible light

Ames Test

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

Conjugation

In bacteria, the contact between donor and recipient cells associated with the transfer of genetic material such as plasmids, 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

Transduction

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

Sex pilus

A conjugative pilus

Transposons

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

Allosteric

Pertaining to the altered activity of an enzyme due to the binding of a molecule to a region other than the enzyme’s active site

Modifications

Any of the changes in an organism caused by environment or activity and not genetically transmissable to offspring.

Introns

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