5A - Separation of photosynthetic pigments with chromatography Flashcards
What are the photosynthetic pigments present in chloroplasts?
Chloroplasts contain several different photosynthetic pigments within photosystems embedded in their thylakoid membranes.
How do photosynthetic pigments differ in color?
Photosynthetic pigments absorb different wavelengths of light, which causes them to appear different in color.
Why do chlorophyll pigments appear green?
Chlorophyll pigments absorb light at the red and blue ends of the visible spectrum and reflect light in the green part of the spectrum.
What is chromatography?
Chromatography is a technique used to separate mixtures by the differential movement of their components.
How can chromatography be used to separate and identify chloroplast pigments?
Chromatography can separate chloroplast pigments, and their identification can be based on their unique Rf values.
What are the two common techniques for separating photosynthetic pigments?
The two common techniques are paper chromatography and thin-layer chromatography (TLC).
How does paper chromatography work?
In paper chromatography, the mixture of pigments is passed through paper made of cellulose, and the pigments separate based on their rates of movement.
What is the advantage of thin-layer chromatography (TLC) over paper chromatography?
Thin-layer chromatography allows for better separation of pigments since they travel faster on a thin layer of an adsorbent like silica gel.
What apparatus is needed for chromatography?
The apparatus includes a leaf sample, dropping pipette, acetone, pestle and mortar, filter paper or TLC paper, pencil, ruler, capillary tube, beaker or boiling tube, and chromatography solvent.
What is the purpose of acetone in chromatography?
Acetone is used to grind up the leaf sample and release the pigments by dissolving fats, such as phospholipid membranes in plant cells.
How is the pigment extract applied to the chromatography paper?
The pigment extract is spotted onto a dot in the center of a pencil line drawn on the paper.
How does the separation of pigments occur in chromatography?
The paper is suspended over a beaker with a small amount of chromatography solvent, and as the solvent moves up the paper, the pigments are dissolved and carried along.
How are Rf values calculated in chromatography?
Rf values are calculated by dividing the distance traveled by a pigment spot by the distance traveled by the solvent.
What does the Rf value indicate?
The Rf value is a measure of how far a dissolved pigment has traveled, with larger, less soluble molecules having smaller Rf values and smaller, more soluble molecules having larger Rf values.
What is the significance of unique Rf values in chromatography?
Each pigment has a unique Rf value, allowing for the identification of specific pigments in the chromatogram.
