* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download H ions
Survey
Document related concepts
Cytoplasmic streaming wikipedia , lookup
Extracellular matrix wikipedia , lookup
Lipid bilayer wikipedia , lookup
P-type ATPase wikipedia , lookup
Phosphorylation wikipedia , lookup
Organ-on-a-chip wikipedia , lookup
Purinergic signalling wikipedia , lookup
Signal transduction wikipedia , lookup
Cytokinesis wikipedia , lookup
Membrane potential wikipedia , lookup
Cell membrane wikipedia , lookup
Endomembrane system wikipedia , lookup
Adenosine triphosphate wikipedia , lookup
Transcript
Electron Transport System As mentioned, electron transport system (ETS) takes place in the inner membrane or cristae of the mitochondrion where a series of Cytochromes and Coenzymes act as carrier molecules and transfer electrons.They accept high-energy electrons (NADH,FADH formed in Krebs cycle), then pass these electrons to the next molecule in the system. Electrons lose energy as they pass down the ETS. Some of energy is used to pump protons (H ions) into the outer compartment of mitochondrion. Each NADH molecule is highly energetic, which accounts for the transfer of 6 protons (3ATP) into the outer compartment of mitochondrion.FAD transfers 4 protons (2ATP). Electrons pass from NAD to FAD to the Cytochromes and Coenzymes, some of energy is capable of driving the formation of ATP from ADP and inorganic phosphate. This ATP production is called oxidative phosphorylation. The final acceptor of electrons is an oxygen atom. The electron-oxygen combination then reacts with two hydrogen ions to form water molecule. Oxidative phosphorylation occurs in mitochondria by what is called chemiosmosis mechanism (H ions "protons" will diffuse from an area of high proton concentration to an area of low concentration. ATP from Respirationِ 1-From Glycolysis The reaction from Glucose to Fructose -1,6 diphosphate requires 2 ATP Glucose + 2 ATP Fructose -1,6 diphosphate +2 ADP Then Fructose -1,6 diphosphate converts to pyruvic produces 4 ATP 2molecules from each Triose sugar acid that 1,3 diphosphoglyceric acid + ADP 3-phosphglyceric acid+ ATP Phosphoenolpyruvic acid + ADP pyruvic acid + ATP i.e Glucose is broken down to 2 molecules of Pyruvic acid + net (2ATP) + 2 pairs of H ions 4 H ions produced will go subsequently through oxidative phosphorylation to produce 3 ATP per unit So, 4H= 2 pairs 2X 3ATP= 6 ATP Total ATP= 2 +6= 8ATP 2- In initial step, the formation of Acetyle Co A: Coversion of Acetyle Co A from Pyruvic acid produces 2 pairs of H ions 2NADH2, these H ions will go through oxidative phosphorylation to produce 3 ATP per each pair of H ions i.e 2 X 3ATP= 6ATP 3- From Krebs Cycle Isocitric Oxalosuccinic acid α- ketogltaric acid Succinic Malic NADH+ H+ succinyle CoA NADH + H + Fumaric FADH + H+ Oxaloacetic 3ATP NADH+ H+ 2ATP 3ATP Plus 1 ATP resulted from GTP formation during the conversion of Succinic CoA to Succinic acid Overall ATP from krebs = 12X2= 24ATP 3ATP The oxidation of glucose to carbon dioxide plus water yields 38 ATP Glycolysis 8 ATP Acetyle CoA 6 ATP Krebs Total 24 ATP 38 ATP Substances that cells need can be taken up from their surrounding either by passive or by active transport Passive transport: Moving molecules across the cell membrane, does not need energy Types: 1-Simple diffusion: The movement of molecules from an area of high concentration to an area of low concentration. Water, oxygen, carbon dioxide, ethanol and urea are examples of molecules that readily cross cell membranes by simple diffusion. They pass either directly through the lipid bilayer or through pores created by certain integral membrane proteins. The relative rate of diffusion is roughly proportional to the concentration gradient across the membrane. For example, oxygen concentrations are always higher outside than inside the cell and oxygen therefore diffuses down its concentration gradient into the cell; the opposite is true for carbon dioxide. There are several factors affecting this movement through a membrane: a-Permeability of the membrane b- The concentration gradient. 2- Facilitated Diffusion: Carrier Proteins and Ion Channels Glucose, sodium ions and chloride ions are just a few examples of molecules and ions that must efficiently get across the plasma membrane but to which the lipid bilayer of the membrane is impermeable. Their transport must therefore be "facilitated" by proteins that embedded within the cell membrane and provide an alternative route. Facilitated diffusion does not require expenditure of metabolic energy and transport is again down an electrochemical gradient. 3-Osmosis: Is another kind of passive transport. It is a special case of diffusion by which cells obtain water. The movement of water will be from the area of high water concentration to the area of low water concentration. Hypertonic Solutions: contain a high concentration of solute relative to another solution (e.g. the cell's cytoplasm). When a cell is placed in a hypertonic solution, the water diffuses out of the cell, causing the cell to shrivel. Hypotonic Solutions: contain a low concentration of solute relative to another solution (e.g. the cell's cytoplasm). When a cell is placed in a hypotonic solution, the water diffuses into the cell, causing the cell to swell and possibly explode. Active transport: The extracellular concentration of nutrients such as sugar and inorganic salts is often low. The cellular membrane are not very permeable to these nutrients, which are hydrophilic, water soluble, and hence do not dissolve in membrane lipids. Passive uptake, which does not require energy, tends to be inadequate for a cell’s nutrient needs. Cells through active up take (need energy) improve the nutrient up take by bringing these nutrients from a dilute source and can accumulate them inside the cell to concentration much higher than that outside. The membrane contains carrier proteins having carrier sites, which are similar to the active site of an enzyme ( ATPase) into which the transported molecules or ions fits. The carrier is thought to change shape within the membrane, moving bound molecule or ion to the other side the cell and releasing it.