Related Experiment Video
Updated: Aug 11, 2026
10:18
Analysis of Protein Import into Chloroplasts Isolated from Stressed Plants
Published on: November 1, 2016
Properties of chloroplasts isolated by phase partition
Molecular and Cellular Biochemistry
|June 15, 1976
Summary
Spinach chloroplasts were separated into three populations. Sucrose synthesis occurs in the cytoplasm, not the chloroplast, using exported intermediates, revealing organelle cooperation.
Area of Science:
- Plant cell biology
- Biochemistry
- Photosynthesis research
Background:
- Chloroplasts are key organelles for photosynthesis.
- Understanding chloroplast function requires isolating intact organelles and studying their metabolic products.
- Previous methods lacked sufficient resolution to separate distinct chloroplast populations.
Purpose of the Study:
- To separate spinach chloroplasts into distinct populations using countercurrent distribution.
- To characterize the biochemical and ultrastructural differences between these populations.
- To investigate the site of sucrose synthesis and inter-organelle cooperation.
Main Methods:
- Countercurrent distribution in polymer two-phase systems for chloroplast separation.
- Analysis of protein/chlorophyll ratio, ultrastructure, and metabolism of separated fractions.
- 14C-labeling experiments to trace metabolic pathways and product synthesis.
Main Results:
- Three distinct chloroplast populations (Peak I, II, III) were isolated, differing in integrity and associated cytoplasmic components.
- Peak I chloroplasts (intact) primarily produced glycolate and Calvin cycle intermediates.
- Peak III chloroplasts (with cytoplasmic layers) showed broader 14C incorporation, with significant amounts in sucrose, malate, and amino acids.
Conclusions:
- Sucrose is synthesized in the cytoplasm, utilizing intermediates exported from the chloroplast.
- Peak III particles offer a model for studying chloroplast-cytoplasm cooperation, including mitochondria and peroxisomes.
- The study elucidates the compartmentalization of metabolic processes in plant cells.
More Related Videos
12:25Isolation of Physiologically Active Thylakoids and Their Use in Energy-Dependent Protein Transport Assays
Published on: September 28, 2018
10:28Preparation of Chloroplast Sub-compartments from Arabidopsis for the Analysis of Protein Localization by Immunoblotting or Proteomics
Published on: October 19, 2018
Related Concept Videos
01:07Anatomy of Chloroplasts
Green algae and plants, including green stems and unripe fruit, harbor chloroplasts—the vital organelles where photosynthesis takes place. In plants, the highest density of chloroplasts is found in the mesophyll cells of leaves.
01:08The Anatomy of Chloroplasts
Green algae and plants, including green stems and unripe fruit, harbor specialized organelles called chloroplasts to carry out photosynthesis. They coordinate both stages of photosynthesis — the light-dependent reactions and the light-independent reactions. The light-dependent reactions use sunlight to release oxygen and produce chemical energy in the form of ATP and NADPH, and the light-independent reactions capture CO2 and use ATP and NADPH to produce sugar.
Structure of Chloroplasts
A...
Structure of Chloroplasts
A...
01:32Photosystems
Photosystems are multiprotein complexes that form the functional units of photosynthesis in plants, algae, and cyanobacteria. They are found embedded in the membrane of tiny sac-like structures called thylakoids placed inside the chloroplast.
Functioning of Photosystems
Photosystems contain many pigment molecules, such as chlorophylls and carotenoids, arranged in a particular organization across two domains — the antenna complex and the reaction center. The main aim of the pigment molecules...
Functioning of Photosystems
Photosystems contain many pigment molecules, such as chlorophylls and carotenoids, arranged in a particular organization across two domains — the antenna complex and the reaction center. The main aim of the pigment molecules...
01:10Chromatography: Introduction
Chromatography is a technique used to separate compounds based on differences of partitioning between two phases, the stationary phase and the mobile phase.
The phase in which the compounds linger or on which the compounds adsorb is called the stationary phase, whereas the mobile phase is the solvent that carries the solutes to be analyzed. In traditional column chromatography, the mixture flows through the stationary phase, and the compounds partition between the stationary and mobile phases...
The phase in which the compounds linger or on which the compounds adsorb is called the stationary phase, whereas the mobile phase is the solvent that carries the solutes to be analyzed. In traditional column chromatography, the mixture flows through the stationary phase, and the compounds partition between the stationary and mobile phases...
01:20Overview Of Cell Separation And Isolation
Cell separation was first achieved in 1964 by S. H. Seal, who separated large tumor cells from the smaller blood cells using filtration. Two years later, Pohl and Hawk performed experiments on how cells respond differently to a nonuniform electric field based on the cell type. Such observations were the inception of cell separation methods, which allow isolating a single cell type from a heterogeneous sample.
01:32Subcellular Fractionation
The homogenate obtained after cell lysis contains various membrane-bound organelles that can be further separated into pure fractions by subcellular fractionation. These isolates are used to study specific cellular components, analyze localized protein activity, and are even employed in diagnostics. Fractionation is typically achieved using centrifugation methods, the most common being density-gradient and differential centrifugation.
Differential Centrifugation
Differential centrifugation is...
Differential Centrifugation
Differential centrifugation is...