What is the function of the lumen in the chloroplast?
What is the function of the lumen in the chloroplast?
The aqueous lumen enclosed by the thylakoid membrane network of the chloroplast is the compartment where molecular oxygen is produced from water during photosynthetic light-dependent reactions.
What does the thylakoid lumen contain?
The lumen of the thylakoid contains proteins used for protein processing, photosynthesis, metabolism, redox reactions, and defense. The protein plastocyanin is an electron transport protein that transports electrons from the cytochrome proteins to Photosystem I.
What happens in the lumen?
The space inside the thylakoid discs is called the lumen, or, more specifically, the thylakoid lumen. This electrical energy is then passed from one membrane protein to another, providing the power to pump protons from the stroma into the thylakoid lumen.
What is lumen in biology in plants?
In biology, a lumen , meaning “an opening”; plural lumina) is the inside space of a tubular structure, such as an artery or intestine. By extension, the term lumen is also used to describe the inside space of a cellular component or structure, such as the endoplasmic reticulum.
Why does the lumen interior of thylakoid become positively charged during the light-dependent reactions?
Why does the space inside the thylakoid become positively charged during the light-dependent reactions? ATP synthase helps H+ ions in the thylakoid space to pass through the membrane to the stroma.
How is the function of the thylakoid membrane similar to that of the inner mitochondrial membrane?
The outer membrane of the chloroplast envelope, like that of mitochondria, contains porins and is therefore freely permeable to small molecules. In terms of its role in generation of metabolic energy, the thylakoid membrane of chloroplasts is thus equivalent to the inner membrane of mitochondria.
How does thylakoid aid in energy storage?
In the light-dependent reactions, energy absorbed by sunlight is stored by two types of energy-carrier molecules: ATP and NADPH. The hydrogen ions are allowed to pass through the thylakoid membrane through an embedded protein complex called ATP synthase. This same protein generated ATP from ADP in the mitochondrion.
What is the function of the lumen in the small intestine?
Large quantities of water are secreted into the lumen of the small intestine during the digestive process. Almost all of this water is also reabsorbed in the small intestine. Regardless of whether it is being secreted or absorbed, water flows across the mucosa in response to osmotic gradients.
What is lumen in anatomy and physiology?
In biology, a lumen (plural lumina) is the inside space of a tubular structure, such as an artery or intestine. It comes from Latin lumen ‘an opening’. The interior of a vessel, such as the central space in an artery, vein or capillary through which blood flows.
What is the purpose of lumen?
The lumen is a basic unit for measuring brightness, just as the gram is a basic unit for measuring mass. A typical light bulb in your home might produce about 1000 lumens. Lumen is related to the word luminous, which means “bright” or “radiant.”
What happens if the thylakoid membrane is permeable to hydrogen ions?
If the thylakoid membrane was highly permeable to hydrogen ions, then the electron transfer chain would not be able to produce a hydrogen ion gradient across the membrane. Hydrogen ions would not flow through ATP synthase, and ATP synthesis would cease.
Which reaction releases hydrogen ions inside the thylakoid?
photosynthesis
A photon strikes the antenna pigments of photosystem II to initiate photosynthesis. The energy travels to the reaction center that contains chlorophyll a to the electron transport chain, which pumps hydrogen ions into the thylakoid interior (the lumen). This action builds up a high concentration of hydrogen ions.
What is the function of thylakoid lumen?
Thylakoid lumen is the innermost aqueous compartment of the chloroplast. It is enclosed by a thylakoid membrane. It plays an important role in the ATP synthesis or phosphorylation driven by chemiosmosis. Protons are pumped across the membrane into the lumen, which generates concentration gradient across the thylakoid membrane.
How does the thylakoid membrane produce oxygen?
The first step is water photolysis, which occurs on the lumen site of the thylakoid membrane. Energy from light is used to reduce or split water. This reaction produces electrons that are needed for the electron transport chains, protons that are pumped into the lumen to produce a proton gradient, and oxygen.
What is the pH of the stroma and thylakoid membrane?
The light-dependent reactions in the membrane pump protons into the lumen, lowering its pH to 4. In contrast, the pH of the stroma is 8. The first step is water photolysis, which occurs on the lumen site of the thylakoid membrane.
How are thylakoids of two different grana connected by stroma lamellae?
Thylakoids of two different grana are connected by stroma lamellae. Each thylakoid is made up of thylakoid membrane and thylakoid lumen. Thylakoid membrane encloses the innermost compartment or thylakoid lumen. The inner membrane of chloroplast is sometimes continuous with the thylakoid membrane.
