Biomaterial Database

A chloroplast membrane lacking photosystem I. Changes in unstacked membrane regions. 1980

K R Miller

The structure and polypeptide composition of the photosynthetic membrane of a mutant of maize has been investigated. The thylakoid membranes of the mutant plants are deficient in Photosystem I activity, although Photosystem II is at near normal levels. SDS polyacrylamide gel electrophoresis of thylakoid membranes from the mutant shows them to be deficient in two polypeptide bands which have been associated with Photosystem I. Freeze-fracture studies of the membrane show that the absence of these polypeptides is associated with a measurable reduction in particle diameter on the unstacked protoplasmic fracture face. This fracture face is derived from the splitting of membranes in unstacked regions of the thylakoid membrane system. It is suggested that in membranes stacked by salts in vitro, Photosystem I activity may be confined to this region.

UI	MeSH Term	Description	Entries
D007425	Intracellular Membranes	Thin structures that encapsulate subcellular structures or ORGANELLES in EUKARYOTIC CELLS. They include a variety of membranes associated with the CELL NUCLEUS; the MITOCHONDRIA; the GOLGI APPARATUS; the ENDOPLASMIC RETICULUM; LYSOSOMES; PLASTIDS; and VACUOLES.	Membranes, Intracellular,Intracellular Membrane,Membrane, Intracellular
D009154	Mutation	Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.	Mutations
D010788	Photosynthesis	The synthesis by organisms of organic chemical compounds, especially carbohydrates, from carbon dioxide using energy obtained from light rather than from the oxidation of chemical compounds. Photosynthesis comprises two separate processes: the light reactions and the dark reactions. In higher plants; GREEN ALGAE; and CYANOBACTERIA; NADPH and ATP formed by the light reactions drive the dark reactions which result in the fixation of carbon dioxide. (from Oxford Dictionary of Biochemistry and Molecular Biology, 2001)	Calvin Cycle,Calvin-Benson Cycle,Calvin-Benson-Bassham Cycle,Carbon Fixation, Photosynthetic,Reductive Pentose Phosphate Cycle,Dark Reactions of Photosynthesis,Calvin Benson Bassham Cycle,Calvin Benson Cycle,Cycle, Calvin,Cycle, Calvin-Benson,Cycle, Calvin-Benson-Bassham,Photosynthesis Dark Reaction,Photosynthesis Dark Reactions,Photosynthetic Carbon Fixation
D010944	Plants	Multicellular, eukaryotic life forms of kingdom Plantae. Plants acquired chloroplasts by direct endosymbiosis of CYANOBACTERIA. They are characterized by a mainly photosynthetic mode of nutrition; essentially unlimited growth at localized regions of cell divisions (MERISTEMS); cellulose within cells providing rigidity; the absence of organs of locomotion; absence of nervous and sensory systems; and an alternation of haploid and diploid generations. It is a non-taxonomical term most often referring to LAND PLANTS. In broad sense it includes RHODOPHYTA and GLAUCOPHYTA along with VIRIDIPLANTAE.	Plant
D002736	Chloroplasts	Plant cell inclusion bodies that contain the photosynthetic pigment CHLOROPHYLL, which is associated with the membrane of THYLAKOIDS. Chloroplasts occur in cells of leaves and young stems of plants. They are also found in some forms of PHYTOPLANKTON such as HAPTOPHYTA; DINOFLAGELLATES; DIATOMS; and CRYPTOPHYTA.	Chloroplast,Etioplasts,Etioplast
D003313	Zea mays	A plant species of the family POACEAE. It is a tall grass grown for its EDIBLE GRAIN, corn, used as food and animal FODDER.	Corn,Indian Corn,Maize,Teosinte,Zea,Corn, Indian
D005614	Freeze Fracturing	Preparation for electron microscopy of minute replicas of exposed surfaces of the cell which have been ruptured in the frozen state. The specimen is frozen, then cleaved under high vacuum at the same temperature. The exposed surface is shadowed with carbon and platinum and coated with carbon to obtain a carbon replica.	Fracturing, Freeze,Fracturings, Freeze,Freeze Fracturings