What is chemosynthesis and where does it occur?
Chemosynthesis is the process by which food (glucose) is made by bacteria using chemicals as the energy source, rather than sunlight. Chemosynthesis occurs around hydrothermal vents and methane seeps in the deep sea where sunlight is absent.
Where does pheochromocytoma occur in the body?
Pheochromocytoma is a rare type of tumor that arises in adrenal glands, specifically from certain cells known as chromaffin cells in the center of the adrenal gland called the adrenal medulla. These cells secrete hormones epinephrine and norepinephrine, and the pheochromocytoma continuously overproduces them.
What happens during chemiosmosis Quizlet?
During chemiosmosis, protons (H+) are moved across the inner mitochondrial membrane (from the matrix into the intermembrane space). This causes a voltage- as protons have a positive charge. One side of the membrane has a positive charge relative to the other. The voltage differential is used to make ATP.
Where does the majority of photosynthesis occur?
What are the 5 stages of photosynthesis?
- Light Dependent. CO2 and H2O enter the leaf.
- Light Dependent. Light hits the pigment in the membrane of a thylakoid, splitting the H2O into O2.
- Light Dependent. The electrons move down to enzymes.
- Light Dependent. …
- Light independent. …
- Light independent. …
- calvin cycle.
Where does chemiosmosis take place?
The generation of ATP by chemiosmosis occurs in mitochondria and chloroplasts, as well as in most bacteria and archaea. For instance, in chloroplasts during photosynthesis, an electron transport chain pumps H+ ions (protons) in the stroma (fluid) through the thylakoid membrane to the thylakoid spaces.
Where is chemiosmosis in mitochondria?
Ultimately, chemiosmosis or ATP synthesis occurs at complex V or ATP synthase via an endergonic reaction induced by the electrochemical gradient, resulting in the movement of protons through the ATP synthase (complex V) into the mitochondrial matrix, and transferring an inorganic phosphate to ADP.
Why does chemiosmosis occur across a membrane?
During chemiosmosis, the free energy from the series of reactions that make up the electron transport chain is used to pump hydrogen ions across the membrane, establishing an electrochemical gradient.
What is chemiosmosis in chloroplasts?
Chemiosmosis in chloroplasts is the movement of protons for the production of ATP in plants. In chloroplast, chemiosmosis takes place in the thylakoid. Thylakoid harvests light and serves as the location for light reactions during photosynthesis. The light reactions generate ATP by chemiosmosis.
Is chemiosmosis part of the electron transport chain?
The electron transport chain forms a proton gradient across the inner mitochondrial membrane, which drives the synthesis of ATP via chemiosmosis.
Where does the electron transport chain take place?
mitochondriaThe electron transport chain is a series of four protein complexes that couple redox reactions, creating an electrochemical gradient that leads to the creation of ATP in a complete system named oxidative phosphorylation. It occurs in mitochondria in both cellular respiration and photosynthesis.
Which of the following is a part of the process of chemiosmosis?
The process of ATP synthesis using 'free energy' obtained when electrons are passed to several carriers (ETC) is known as chemiosmosis. The actual point of the synthesis of ATP takes place when electrons pass the inner mitochondrial membrane. Energy is released within this process, resulting in the synthesis of ATP.
Where is the electron transport chain located?
inner mitochondrial membraneSince the electron transport chain is located in the inner mitochondrial membrane in eukaryotes, and since NADH cannot be transported from the cytosol into the mitochondrial matrix, NADH formed in the cytosol needs to be oxidized by another route.
Where is the electron transport chain located?
inner mitochondrial membraneSince the electron transport chain is located in the inner mitochondrial membrane in eukaryotes, and since NADH cannot be transported from the cytosol into the mitochondrial matrix, NADH formed in the cytosol needs to be oxidized by another route.
Where does the electron transport chain take place?
mitochondriaThe electron transport chain is a series of four protein complexes that couple redox reactions, creating an electrochemical gradient that leads to the creation of ATP in a complete system named oxidative phosphorylation. It occurs in mitochondria in both cellular respiration and photosynthesis.
Does Chemiosmotic ATP synthesis occurs in the cytosol of the cell?
Photorespiration is the process by which light is used to release the stored energy in carbohydrate molecules to perform all work in plant cells. Chemiosmotic ATP synthesis occurs in the cytosol of the cell. The light-dependent reactions of photosynthesis occur in the stroma of the chloroplast.
What's the inner membrane of mitochondria?
The inner membrane forms invaginations, called cristae, that extend deeply into the matrix. The cristae define the third mitochondrial compartment, the crista lumen. The crista membranes contain most, if not all, of the fully assembled complexes of the electron transport chain and the ATP synthase (Fig.
What is the process of building up substances on one side of the plasma membrane?
This allows substances to build up on one side of the membrane if there isn't a door to let them through. This creates what we call a gradient . A gradient is a situation in which there is more of a substance on one side than another. Energy can be stored in a gradient over the plasma membrane.
What is diffusion in chemistry?
What Is Diffusion? Chemiosmosis is the process of a molecule moving from high to low concentration, based on its charge and concentration inside a cell. This sounds pretty complicated. So, before talking about chemiosmosis, it will be important to understand a basic rule of the world: diffusion.
How does ATP synthase work?
The ATP synthase then harvests the energy stored in the electrochemical gradient to make ATP, just like the water mill takes the energy from the flowing water to make the wheel turn. The body is converting one kind of energy into another. Think about the water wheel.
How does diffusion work?
Diffusion not only works to equalize concentration on both sides of the membrane, but also to equalize charge. If there are more positive ions outside compared to inside the cell, positive ions will want to move down their electrical gradient into the cell. However, chemiosmosis also takes into consideration the concentration gradient. ...
Why do cells have an electrochemical gradient?
This creates an electrochemical gradient because there is a greater concentration of hydrogen ions outside the cell and a greater positive charge, because cells are naturally negative, and hydrogen ions have a positive charge.
How does hydrogen get into a cell?
The only way to let hydrogen back into the cell is through a protein called ATP synthase. The hydrogen ions flow through the protein, causing it to spin like a water mill. The wheel of the mill is the ATP synthase, and the water flowing down it is the hydrogen ions.
Why are diffusion examples so ubiquitous?
The examples are so ubiquitous because diffusion is everywhere! Everything always moves from where there is more to where there is less.
Which cell does chemiosmotic proton transfer occur in?
Directions of chemiosmotic proton transfer in the mitochondrion, chloroplast and in gram-negative bacterial cells ( cellular respiration and photosynthesis ). The bacterial cell wall is omitted, gram-positive bacterial cells do not have outer membrane.
What is the process of a hydrogen ion diffused from an area of high proton concentration to an area
This process is related to osmosis , the diffusion of water across a membrane, which is why it is called "chemiosmosis".
How does photosynthesis produce ATP?
The light reactions of photosynthesis generate ATP by the action of chemiosmosis. The photons in sunlight are received by the antenna complex of Photosystem II, which excites electrons to a higher energy level. These electrons travel down an electron transport chain, causing protons to be actively pumped across the thylakoid membrane into the thylakoid lumen. These protons then flow down their electrochemical potential gradient through an enzyme called ATP-synthase, creating ATP by the phosphorylation of ADP to ATP. The electrons from the initial light reaction reach Photosystem I, then are raised to a higher energy level by light energy and then received by an electron acceptor and reduce NADP+ to NADPH. The electrons lost from Photosystem II get replaced by the oxidation of water, which is "split" into protons and oxygen by the oxygen-evolving complex (OEC, also known as WOC, or the water-oxidizing complex). To generate one molecule of diatomic oxygen, 10 photons must be absorbed by photosystems I and II, four electrons must move through the two photosystems, and 2 NADPH are generated (later used for carbon dioxide fixation in the Calvin Cycle).
What causes ions to move across the membrane?
The movement of ions across the membrane depends on a combination of two factors: 1 Diffusion force caused by a concentration gradient - all particles tend to diffuse from higher concentration to lower. 2 Electrostatic force caused by electrical potential gradient - cations like protons H + tend to diffuse down the electrical potential, from the positive (P) side of the membrane to the negative (N) side. Anions diffuse spontaneously in the opposite direction.
What is the process of ATP synthase?
ATP synthase is the enzyme that makes ATP by chemiosmosis. It allows protons to pass through the membrane and uses the free energy difference to phosphorylate adenosine diphosphate (ADP), making ATP.
Why is thermodynamic efficiency lower in eukaryotic cells?
In fact, the thermodynamic efficiency is mostly lower in eukaryotic cells because ATP must be exported from the matrix to the cytoplasm, and ADP and phosphate must be imported from the cytoplasm. This "costs" one "extra" proton import per ATP, hence the actual efficiency is only 65% (= 2.4/3.67).
Where does ATP come from?
The theory suggests essentially that most adenosine triphosphate (ATP) synthesis in respiring cells comes from the electrochemical gradient across the inner membranes of mitochondria by using the energy of NADH and FADH 2 formed from the breaking down of energy-rich molecules such as glucose .
How does ATP production occur in cellular respiration?
Chemiosmosis. The actual production of ATP in cellular respiration takes place through the process of chemiosmosis (see Chapter 4). Chemiosmosis involves the pumping of protons through special channels in the membranes of mitochondria from the inner to the outer compartment. The pumping establishes a proton (H +) gradient.
How many molecules of ATP are produced during cellular respiration?
The energy production of cellular respiration is substantial. Most biochemists agree that 36 molecules of ATP can be produced for each glucose molecule during cellular respiration as a result of the Krebs cycle reactions, the electron transport system, and chemiosmosis.
How much energy does ATP release in a cell?
Each ATP molecule is capable of releasing 7.3 kilocalories of energy per mole.
Overview
Chemiosmosis is the movement of ions across a semipermeable membrane bound structure, down their electrochemical gradient. An important example is the formation of adenosine triphosphate (ATP) by the movement of hydrogen ions (H ) across a membrane during cellular respiration or photosynthesis.
Hydrogen ions, or protons, will diffuse from a region of high proton concentratio…
The chemiosmotic theory
Peter D. Mitchell proposed the chemiosmotic hypothesis in 1961. The theory suggests essentially that most adenosine triphosphate (ATP) synthesis in respiring cells comes from the electrochemical gradient across the inner membranes of mitochondria by using the energy of NADH and FADH2 formed from the breaking down of energy-rich molecules such as glucose.
Proton-motive force
The movement of ions across the membrane depends on a combination of two factors:
1. Diffusion force caused by a concentration gradient - all particles tend to diffuse from higher concentration to lower.
2. Electrostatic force caused by electrical potential gradient - cations like protons H tend to diffuse down the ele…
In mitochondria
The complete breakdown of glucose releasing its energy is called cellular respiration. The last steps of this process occur in mitochondria. The reduced molecules NADH and FADH2 are generated by the Krebs cycle, glycolysis, and pyruvate processing. These molecules pass electrons to an electron transport chain, which releases the energy of oxygen to create a proton gradient across the inner mitochondrial membrane. ATP synthase then uses the energy stored in this gradi…
In plants
The light reactions of photosynthesis generate ATP by the action of chemiosmosis. The photons in sunlight are received by the antenna complex of Photosystem II, which excites electrons to a higher energy level. These electrons travel down an electron transport chain, causing protons to be actively pumped across the thylakoid membrane into the thylakoid lumen. These protons then flow down their electrochemical potential gradient through an enzyme called ATP-synthase, creating …
In prokaryotes
Bacteria and archaea also can use chemiosmosis to generate ATP. Cyanobacteria, green sulfur bacteria, and purple bacteria synthesize ATP by a process called photophosphorylation. These bacteria use the energy of light to create a proton gradient using a photosynthetic electron transport chain. Non-photosynthetic bacteria such as E. coli also contain ATP synthase. In fact, mitochondria and chloroplasts are the product of endosymbiosis and trace back to incorporated …
Emergence of chemiosmosis
A stepwise model for the emergence of chemiosmosis, a key element in the origin of life on earth, proposes that primordial organisms used thermal cycling as an energy source (thermosynthesis), functioning essentially as a heat engine:
self-organized convection in natural waters causing thermal cycling → added β-subunit of F1 ATP Synthase (generated ATP by thermal cycling of subunit during suspension in convection cell: the…
See also
• Cellular respiration
• Citric acid cycle
• Electrochemical gradient
• Glycolysis
• Oxidative phosphorylation