What is the relationship between Granum and Stroma
Stroma- Stroma is a alkaline, aqueous fluid which is protein rich and is present within the inner membrane of Each granum contains around thylakoids. Explain the relationship between granum and stroma Grana are stacks of thylakoids inside a chloroplast; the stroma is the solution that surrounds the. A granum is a stack of thylakoids in the chloroplast and the stroma is the region outside the thylakoid membranes in the chloroplasts.
Stroma - The stroma is the liquid inside the chloroplast where other structures such as the thylakoids float. Thylakoids - Floating in the stroma is a collection of sacks containing chlorophyll called the thylakoids. The thylakoids are often arranged into stacks called granum as shown in the picture below. The granum are connected by disc-like structures called lamella. Pigments - Pigments give the chloroplast and the plant its color.
Biology for Kids: Plant Cell Chloroplasts
The most common pigment is chlorophyll which gives plants their green color. Chlorophyll helps to absorb energy from sunlight. Photosynthesis Chloroplasts use photosynthesis to turn sunlight into food.
The chlorophyll captures energy from light and stores it in a special molecule called ATP which stands for adenosine triphosphate. Later, the ATP is combined with carbon dioxide and water to make sugars such as glucose that the plant can use as food.The Chloroplast
Other Functions Other functions of chloroplasts include fighting off diseases as part of the cell's immune systemstoring energy for the cell, and making amino acids for the cell. Interesting Facts about Chloroplasts Simple cells, like those found in algae, may only have one or two chloroplasts.
More complex plant cells, however, may contain hundreds.
What is the relationship between the granum and the stroma? | Yahoo Answers
Chloroplasts will sometimes move around within the cell in order to position themselves to where they can best absorb sunlight. The "chloro" in chloroplast comes from the Greek word chloros meaning green.
The most abundant protein in chloroplasts is the protein Rubisco. Rubisco is likely the most abundant protein in the world. The redox state of the electron carrier plastoquinone in the thylakoid membrane directly affects the transcription of chloroplast genes encoding proteins of the reaction centers of the photosystems, thus counteracting imbalances in the electron transfer chain. Most thylakoid proteins encoded by a plant's nuclear genome need two targeting signals for proper localization: An N-terminal chloroplast targeting peptide shown in yellow in the figurefollowed by a thylakoid targeting peptide shown in blue.
Proteins are imported through the translocon of outer and inner membrane Toc and Tic complexes. After entering the chloroplast, the first targeting peptide is cleaved off by a protease processing imported proteins.
This unmasks the second targeting signal and the protein is exported from the stroma into the thylakoid in a second targeting step. This second step requires the action of protein translocation components of the thylakoids and is energy-dependent.
Proteins are inserted into the membrane via the SRP-dependent pathway 1the Tat-dependent pathway 2or spontaneously via their transmembrane domains not shown in figure. Lumenal proteins are exported across the thylakoid membrane into the lumen by either the Tat-dependent pathway 2 or the Sec-dependent pathway 3 and released by cleavage from the thylakoid targeting signal.
The different pathways utilize different signals and energy sources. The Sec secretory pathway requires ATP as energy source and consists of SecA, which binds to the imported protein and a Sec membrane complex to shuttle the protein across.
Proteins with a twin arginine motif in their thylakoid signal peptide are shuttled through the Tat twin arginine translocation pathway, which requires a membrane-bound Tat complex and the pH gradient as an energy source. Some other proteins are inserted into the membrane via the SRP signal recognition particle pathway. The chloroplast SRP can interact with its target proteins either post-translationally or co-translationally, thus transporting imported proteins as well as those that are translated inside the chloroplast.
Some transmembrane proteins may also spontaneously insert into the membrane from the stromal side without energy requirement.
These include light-driven water oxidation and oxygen evolutionthe pumping of protons across the thylakoid membranes coupled with the electron transport chain of the photosystems and cytochrome complex, and ATP synthesis by the ATP synthase utilizing the generated proton gradient. The water-splitting reaction occurs on the lumenal side of the thylakoid membrane and is driven by the light energy captured by the photosystems.
This oxidation of water conveniently produces the waste product O2 that is vital for cellular respiration.
The molecular oxygen formed by the reaction is released into the atmosphere. Electron transport chains[ edit ] Two different variations of electron transport are used during photosynthesis: Cyclic electron transport or Cyclic photophosphorylation produces only ATP.
The noncyclic variety involves the participation of both photosystems, while the cyclic electron flow is dependent on only photosystem I.
Difference Between Grana and Stroma
In cyclic mode, the energized electron is passed down a chain that ultimately returns it in its base state to the chlorophyll that energized it. The carriers in the electron transport chain use some of the electron's energy to actively transport protons from the stroma to the lumen. During photosynthesis, the lumen becomes acidicas low as pH 4, compared to pH 8 in the stroma. Source of proton gradient[ edit ] The protons in the lumen come from three primary sources.
Photolysis by photosystem II oxidises water to oxygenprotons and electrons in the lumen. The transfer of electrons from photosystem II to plastoquinone during non-cyclic electron transport consumes two protons from the stroma. These are released in the lumen when the reduced plastoquinol is oxidized by the cytochrome b6f protein complex on the lumen side of the thylakoid membrane.
From the plastoquinone pool, electrons pass through the cytochrome b6f complex. This integral membrane assembly resembles cytochrome bc1. The reduction of plastoquinone by ferredoxin during cyclic electron transport also transfers two protons from the stroma to the lumen.
ATP generation[ edit ] The molecular mechanism of ATP Adenosine triphosphate generation in chloroplasts is similar to that in mitochondria and takes the required energy from the proton motive force PMF.