Bioenergetics I- Metabolism Flashcards
What are the two Bioenergetic objectives of life?
- acquire the energy to do stuff “work”
(includes grow, reproduce, move, maintain homeostasis). - acquire the nutrients/molecules needed to do that stuff
(new cells, enzymes, stress response proteins, etc.)
all require: CHONPS
(carbon, hydrogen, oxygen, nitrogen, phosphorus , Sulfur)
define metabolism and its two main components
metabolism: the chemical processes that occur within a living organism in order to maintain life
anaerobic: metabolic pathway that synthesizes larger molecules from smaller ones
think ana trying to build
catabolic: metabolic pathway that breaks larger molecules into smaller ones.
think a cat trying to break down the tower ana is building.
What is free energy and how does the change in free energy vary in an anabolic vs catabolic reaction?
Gibb’s free energy (G): a measure of the energy (thermodynamic potential) of a system that combines enthalpy and entropy.
we use free energy to determine: change in free energy.
in an anabolism, delta G is greater than 0 (amount of free energy increases in the reaction)
in a catabolism, delta G is less than 0 (amount of free energy decreases during the reaction).
ATP stores energy.
what are the three ways to release energy:
- hydrolysis at the first bond
- hydrolysis at the second bond
- instead of using water, you can take an organic molecule, break the organic molecule and get the energy out (how to get energy without water)
what is ATP synthesis tied to?
oxidation/reduction reaction
what is an oxidation/reduction reaction and who is involved?
- taking electrons from something and giving it to something else.
i.e
taking the electron from a donor and oxidizing it, giving the electron to an acceptor, that is reduced in charge.
Reduction potential example
- determine the Eknot’ and deltaG’ going from NAD to oxygen using the reduction potential tower
NADH + H+ –> NAD+ + 2H+ + 2e- +320 (Eknot’) deltaG(-62)
1/2O2 + 2H+ + 2e- –> H2O
= NADH + H+ + 1/2O2 –> NAD+ + H2O +1,140 (Eknot’). deltaG (-158)
what microbial lifestyles would be the most ecologically competitive (in term of reduction potential table).
Reactions that provide a lot of deltaG (lots of energy allows for replication, metabolism, etc.).
what is a terminal electron acceptor?
- the final molecule receiving electrons
- must have a higher (more positive) reduction potential than the molecule giving electrons.
- electrons don’t need to directly go to the terminal electron acceptor. They can make a bunch of “pit stops” in the middle.
what are electron carriers and what are 2 common electron carriers?
- electron carriers are intermediate electron carriers. Electron carriers cannot be terminal electron carriers.
common electron carriers:
NAD (most often used) and FAD.
- you can give electrons from NAD to FAD in the passage down the table, but they are NOT terminal electron acceptors. they need to give away the electron terminal electron acceptor.
what are the two goals of catabolism: (remember cat… breakdown)
- to generate the energy (ATP) for cellular processes through either:
- oxidation/reduction reactions
- substrate-levelme phosphorylation - generate metabolites for biosynthetic reactions.
what are the two major forms of catabolism?
- fermentation
central catabolic pathway + fermentation pathway
- respiration
central catabolic pathway + TCA cycle + electron transport chain
what are the three routes from glucose to pyruvate?
(Central catabolic pathways)
- Embden-Meyerhod-Parnas (EMP)
-Entner-Doudoroff (ED)
- Pentose phosphate shunt (PPS or PPP).
what happens in the central catabolic pathways that result in fermentation
- the reduced electron carriers (NADH, NADPH) need to give their electrons to something because they are not terminal electron acceptors.
- if NO TERMINAL ELECTRON ACCEPTOR IS AVAILABLE: the electrons are given to pyruvate.
- because the electron was taken from carbon (glucose specifically) and given back to carbon, there is NO NET CHANGE IN oxidation state.
- THEREFORE,
the electron carrier is regenerated and the waste products are excreted, providing no energy to the cell.
what happens in the central catabolic pathways during respiration?
- pyruvate will continue into the TCA cycle
- pyruvate will be converted to acetyl-CoA, producing another 2 NADH.
- acetyl-CoA combines with oxaloacetate to enter the TCA cycle (krebs cycle).
- this generates many electrons that need to go somewhere!!
- electron carriers are regenerated and we will have an electron transport chain from one electron acceptor to the next, eventually reaching the terminal electron acceptor.
- this generates a lot of ATP (lots of energy!) (GOAL 1 OF CATABOLISM IS TO GENERATE ATP FOR CELLULAR PROCESSES)
