Microbiology terms - A
- habitat
- The natural environment/area/location in which where an organism normally grows.
- halophile
- An organism requiring salt (NaCl) for growth.
- halotolerant
- An organism capable of growing in the presence of NaCl but not requiring it.
- haploid
- In eukaryotes, an organism or cell containing one chromosome complement and the same
number of chromosomes as the gametes.
- hapten
- A substance not inducing antibody formation but able to combine with a specific antibody.
- helix
- a spiral structure in a macromolecule that contains a repeating pattern.
- hemagglutination
- Agglutination of red blood cells.
- hemolysin
- Bacterial toxins capable of lyzing red blood cells.
- hemolysis
- Lysis of red blood cells.
- herd immunity
- Resistance of a group to a pathogen due to immunity of a large proportion of the group to
that pathogen.
- heterocyst
- A differentiated cyanobacterial cell which carries out nitrogen fixation.
- heteroduplex
- A double-stranded DNA in which one strand is from one source and the other strand from
another, usually different but related, source.
- heterofermentation
- 1. Any fermentation in which there is more than one major end-product.
2. Synonym of heterolactic fermentation.
- heterolactic fermentation
- A type of lactic acid fermentation in which sugars (e.g. lactose, glucose) are fermented to a
range of products.
- heterotroph
- In reference to carbon source - an organism that uses reduced, preformed organic molecules
as its principal carbon source.Compare with autotroph, lithotroph, organotroph, and
phototroph.
- hexose monphosphate pathway
- A metabolic pathway present in a wide range of prokaryotic and eukaryotic microorganisms
as well as in plants and animals; it involves the oxidative decarboxylation of glucose
6-phosphate, via 6-phosphogluconate, to ribulose 5-phosphate, followed by a series of
reversible, non-oxidative interconversions whereby hexose and triose phosphates are formed
from pentose phosphates. Also called: HMP pathway, HMP shunt; oxidative pentose
phosphate pathway, pentose phosphate pathway/cycle, phosphogluconate pathway;
Warburg-Dickens pathway.
- homofermentation
- 1. Any fermentation in which there is only one major end-product.
2. Synonym of homolactic fermentation.
- homolactic fermentation
- A type of lactic acid fermentation in which sugars (e.g. glucose, lactose, etc) are converted
entirely, or almost entirely, to lactic acid.
- homologous antigen
- An antigen reacting with the antibody it had induced.
- hopanoid Hopanoid is a chemical component in the cytoplasmic membranes of many bacteria.
Hopanoid is a pentacyclic saturated derivative of mevalonic acid (mevalonic acid is a key
intermediate in cholesterol biosynthesis) and is assumed to be functioning in a similar way to sterols,
which serve to stabilize the structure of eukaryotic membranes. While sterols can make up 5-25
percent of the total lipids of eukaryotic membranes, they are absent from most of the prokaryotic
membranes.
- host
- An organism capable of supporting the growth of a virus or other parasite.
- humoral immunity
- An immune response involving antibodies.
- hybridization
- The formation of double-stranded nucleic acid (e.g., DNA, RNA, or DNA/RNA duplex by
complementary base pairing between two molecular strands.
- hybridoma
- The fusion of an immortal cell with a single B lymphocyte to produce an immortal lymphocyte
which produces a monoclonal antibody.
- hydrocarbon
- Any chemical compound containing only carbon and hydrogen elements. Some simple
examples of hydrobarbons are: methane (CH4), ethylene (C2H4), ethane (C2H6), etc.
- hydrogen bond
- A weak chemical bond between a hydrogen atom and a second, more electronegative
element, usually an oxygen or nitrogen atom.
- hydrophobic interaction
- The attractive force between molecules due to the close positioning of nonhydrophilic
portions of the two molecules.
- hydrothermal vent
- A warm or hot water emitting springs associated with crustal spreading centers on the sea
floor.
- hypersensitivity
- An immune reaction, usually harmful to the animal, caused either by antigen-antibody
reactions or cellular immune processes. See also allergy.
- hyperthermophile
- A prokaryote having a growth temperature optimum of 80 °C or higher.
- hypha (plural hyphae)
- Long filaments of cells in fungi or actinomycetes (filamentous bacteria).
Compiled by Tsute Chen, Converted by Ben Hoyt