Microbiology terms - D
- defined medium
- A medium whose exact chemical composition is quantitatively known. Compare with
complex medium.
- degeneracy
- In relation to the genetic code, the fact that more than one codon can code for the same
amino acid.
- deletion
- A removal of a portion of a gene.
- denaturation
- Irreversible destruction of a macromolecule, as for example the destruction of a protein by
heat.
- denitrification
- Conversion of nitrate into nitrogen gases under anaerobic conditions, resulting in loss of
nitrogen from ecosystems.
- dental plaque
- Bacterial cells encased in a matrix of extracellular polymers and salivary products, found on
the teeth.
- deoxyribonucleic acid (DNA)
- A polymer of nucleotides connected via a phosphate-deoxyribose sugar backbone; the
genetic material of the cell.
- desiccation
- Drying
- dideoxynucleotide
- A nucleotide lacking the 3'-hydroxyl group on the deoxyribose sugar. Used in the Sanger
method of DNA sequencing.
- differential medium
- A medium which is used to differentiate different types of microorganisms based on their
different e.g. colors or shapes of colonies. Examples of differential media are: Macconkey's
agar and SS agar.
- differentiation
- The modification of a cell in terms of structure and/or function occurring during the course of
development.
- diplococcus
- A pair of cocci.
- diploid
- In eukaryotes, an organism or cell with two chromosome complements, one derived from
each haploid gamete.
- disinfectant
- An agent that kills microorganisms, but may be harmful to human tissue.
- disproportionation
- The splitting of a chemical compound into two new compounds, one more oxidized and one
more reduced than the original compound.
- DNA fingerpriting
- Use of the techniques of genetic engineering to determine the origin of dDNA in a sample of
tissue.
- DNA library
- A collection of cloned DNA fragments which in total contain genes from the entire genome of
an organism; also called a gene library.
- domain
- 1. The highest level of biological classification, superseding kingdoms. The three domains of
biological organisms are the Bacteria, the Archaea, and the Eukarya.
- 2. Also used to describe a region of a protein having a distinct function.
- doubling time
- The time needed for a population to double. See also generation time.
- downstream position
- Refers to nucleic acid sequences on the 3'-side of a given site on the DNA or RNA
molecule. Compare with upstream position.
Compiled by Tsute Chen, Converted by Ben Hoyt