Class Notes (808,754)
Canada (493,378)
Biology (116)
BIOL 1010 (39)

Lec 19 Cell Metabolism.docx

6 Pages
Unlock Document

University of Lethbridge
BIOL 1010
Igor Kovalchuk

Cell Metabolism, Part II Lec 19 Cellular respiration and fermentation are catabolic - Oxidation-reduction reactions- chemical reaction which involve a partial or complete transfer of electrons from one reaction to another; called redox reactions for short - Oxidation partial or complete loss of electrons - Reduction partial or complete gain of electrons Election transport Phosphorylation - The electron transport chain is made of electron carrier molecules embedded in the inner mitochondrial membrane - Each successive carrier in the chain has a higher electro negativity than the carrier before it, so the electrons are pulled downhill toward oxygen, the final electron acceptor and the molecule with the highest electro negativity - Except for ubiquinone (Q), most of the carrier molecules are proteins and are tightly bound to prosthetic groups (non- protein cofactors) - Prosthetic groups alternate between reduced and oxidized states as they accept and donate electrons Electron transport chains - In cellular respiration, an electron transport chain breaks the “fall” of electron in this reaction into a series of smaller steps - If stores some of the released energy in a form that can be used to make ATP(the rest of the energy is released as heat) Electron Transport Phosphorylation Protein Election Carriers Prosthetic Group Flavoproteins (FVM_ Favlin mononucleotide Iron Sulfur proteins Iron and sulfur Cytochromes Heme group - Heme group- prosthetic group composed of four carbon rings surrounding a single iron atom - Cytochrome- type of protein molecule that contains a heme prosthetic group and function as an electron carrier in the electron transport chains of mitochondria and chloroplasts o There are several cytochromes, each a slightly different protein heme group o It is the iron of cytochromes that transfers electrons Electron Transport Chain - Each member of the chain oscillates between a reduced state and an oxidized state - A component of the chain becomes reduced when it accepts electrons from its “uphill” neighbour (Which has a lower affinity for the electrons) - Each members of the chain returns to its oxidized form as it passed electrons to its “downhill “neighbour (which has a greater affinity for the electrons) - A the bottom of the chain is oxygen, which is very electronegative - The overall energy from for electrons travelling from NADH to oxygen is 53 Kcal/mol, but this fall is broken up into a series of smaller steps by the electron transport chain - As molecular oxygen is reduced, it also picks up two protons from the medium to form water. For every two NADHs, one is O is red2ced to two H O molecul2s - FADH2 also donates electrons to the electron transport chain, but those electrons are added at a lower energy level then NADH - The electron transport chain does not make ATP directly - It generates a proton gradient across the inner mitochondrial membrane, which stores potential energy that can be used to phosphorylate ADP Chemiosmosis; the energy-coupling mechanism - Cytochromes are the molecules that pass the “hot potatoes” (electrons) along the ETC - Energy released by the “downhill” passage of electrons - The ADP is reduced by the gain of elections - ATP formed in this way is made by the process of oxidative phosphorylation. + - The mechanism for the oxidative phosphorylation process is the gradient H ions discovered across the inner mitochondrial membrane - This mechanism is known as Chemiosmotic coupling. - This involves both chemical and transport processes. - This protein complex which uses the energy of H+ gradient to drive ATP synthesis resides in mitochondrial and chloroplast membranes in the plasma membranes of prokaryotes - ATP synthase has three main parts: o cylindrical component, within the membrane o protruding knob in Which in mitochondria is in the matrix o a rod or stalk connecting the other two parts - The cylinder is a rotor that spins clockwise when H+ flows through it down a gradient - The attached rod also pins activating catalytic sites in the knob - The component that joins inorganic phosphate to ADP to make ATP - The chemiosmosis hypothesis was proposed by Peter Mitchell in 1961, later he would win the Nobel Prize for his work. - The mechanism for coupling Exergonic electron flow from the oxidation of food to the endergonic process of oxidative phosphorylation is chemiosmosis - Chemiosmosis the coupling of Exergonic electron flow down an electron transport chain to Energonic ATP production by the creation of a protein gradient across membrane - The proton gradient drives ATP synthesis as protons diffuse back across the membrane - The term chemiosmosis emphasizes a coupling between 1. Chemical reaction (phosphorylation) and 2. Transport process (proton transport) - Process involved in oxidative phosphorylation and photophosphorylation - Potential energy is captured by ADP and stored in the pyrophosphate bond. - NADH enters the ETS chain at the beginning, yielding 3 ATP per NADH - FADH2 enters at Co-Q, producing only 2 ATP per FADH2 - How does the electron transport chain pump hydrogen ions from the matrix to the intermembrane space? - The process is banded in spatial organization of the ETC in the membrane o Some electron carriers accept and release protons along with electrons. These carriers are spatially arranged so that protons are picked up from the matrix and are released into the intermembrane space o As complexes transpor
More Less

Related notes for BIOL 1010

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.