metabolism Flashcards
energy flow and chemical recycling in ecosystems
glucose used to produce ATP, initial step in all of this is photosynthesis (in chloroplasts); photosynthesis produces organic molecules and O2, cellullar respiration produces CO2 and H2O, photosynthesis uses these and light energy
energy and systems
energy can take on a number of different forms, the type depends on the stability and complexity of system
heat
energy that results from random molecular movement, temperature measures that energy, heat is often end point of metabolic processes
potential energy
capacity to do work, energy within a molecule is potential energy
kinetic energy
energy contained within a moving object, heat is kinetic energy of randomly moving molecules
entropy
a measure of the degree of disorder in a system, the organization of matter tends towards an increasing degree of disorder unless energy is expending to keep entropy low, increase in entropy in universe every time there is an energy transfer
entropy of biological systems
usually have great order (low randomness and low entropy), to maintain this low entropy, energy is required
free energy
the amount of energy in a system that is available to do work, at any given temp. free energy is difference between total energy of system and its degree of entropy; unstable system (low entropy greater free energy
delta G, free energy equation
free energy of system (G) = total energy (H) - (temp x its entropy (TS))
delta G equation
negative delta G
system has given up free energy, energy is released to do work, EXERGONIC
positive delta G
system has gained free energy, energy is absorbed to the system, ENDERGONIC
spontaneity
the tendency of a physical or chemical change to proceed spontaneously, nothing about rate, gravitational motion, diffusion, chemical reaction
metabolism
cells can take the energy from exergonic reactions to drive the energy for endergonic reactions; cells use fuel molecules to perform exergonic reactions to release free energy
cellular respiration
C6H12O6 + ^O2 -> 6COO2 + 6H2O (needed for next lectures!!), non-polar bonds to polar covalent bonds, glucose goes from less stable and more complex (low entropy) to more stable and less complex (higher entropy); energy for other direction comes from sunlight
releasing energy from cells
cells release energy in small packets that re more easily used for other processes with little release of heat; molecule that couples exergonic to endergonic reactions is ATP
ATP structure
3 phosphate groups, ribose sugar, adenine (adenine triphosphate), hydrolyze ATP< break last phosphate group off and energy is released
ATP + H2O ->
ADP + Pi
glutamic acid conversion to glutamine
ammonia added to glutamic acid produces glutamine, endergonic reaction, needs energy
conversion reaction coupled with ATP hydrollysis
glutamic acid + TP -> phosphorylated intermediate + ADP -> glutamine, phosphorylation causes reaction to release energy (now exergonic)
enzymes
lower activation energy of chemical reactions
Think of NAD
As a packaging agent for free energy
Electrón transport chain intro
Each step, energy is pulled off and put into NADH to synthesize ATP
Potential energy in glucose in contained in
Reduced hydrocarbon bonds
Six major steps of glucose oxidation
- Transport of glucose into cell using glucose transporters, glycolysis splits glucose into two private molecules, pyre ate oxidation produced acetyl coA which is metabolized further in, citric acid cycle )Krebs), which oxidizes acetyl coA to produce ATP and reduced electron carriers NADH and FADH2, electron transport chain uses NADH - FADH2 from citric acid cycle and glycolysis to maintain a proton gradient across inner mitochondria membrane, gradient drives ATP synthase to produce ATP
Compartmentalization is important in metabolism
Movement of molecules between different compartments
Step 1. Movement
Transport of glucose between the extra cellular and intracellular compartments
Step 2 movement
Glycolysis requires soluble cytosolic enzymes
Step 3 and 4 movement
Pyruvate moves from cytosol to the mitochondrial matrix, where enzymes required for citric acid cycle are located
Step 5 movement
Molecules required for ETC are located in the inner mitochondrial membrane as is ATP synthase
Step 6 movement
Protón gradient is maintained across the inner mitochondrial membrane y ETC to drive ATP synthase
TIPS,
follow carbon atoms, electrons,and ATP molecules
Glycolysis overview
Metabolic pathway made up of cytosolic enzymes that metabolize glucose (6 carbon compound) int 2 x 3 carbon compounds (pyruvate)
2 phases of glycolysis
- Energy investment phase where kinases use ATP to phosphoryate glucose and some of the molecules that are produced as glucose begins to be broken down
- Energy payoff phase where the energy from some of the first C-H bonds of glucose that are broken own is squinted to ATP and NADH2
Results in ATP; NADH2, 2 pyruvates
Energy investment phase
Glucose uses 2 ATP to produce 2 ADP, then 4ADP used to generate 4 ATP and 2NAD used to form 2NADH (with 2 pyruvate) and 2h2o
Glycolysis
Glucose is first phosphorylated, then goes to fructose w- phosphate, then ATP used (to ADP), fructose molecule into state to do next step (has 2 phosphates), then goes to two molecules (go to energy payoff), allows one of these molecules to go down energy payoff phase (glyceraldehyde 3 phosphate, 2 of them), molecule uses phosphate to produce NADH, use ADP to produce ATP, (now 3 phosphoglycerate), the goes to phospholenol pyruvate by rearranging, then 2 ADP used to produce 2 ATP and 2 pyruvates
Pyruvate kinase (known phosphofructo kinase too), ask which are most mportant
Enzyme that that’s PEP and generates pyruvate through phosphorylation, removal of phosphate group and ATP production
Outcome of glycolysis
2 ATP, 2NADH, 2 pyruvate
Overview of Citric Acid cycle
Metaboli pathway made up of a series’s of enzymes in the mitochondrial matrix that initially conjugates acetyl coA (2 carbons) to oxaloacetate (4 carbons) to form citrate (6 carbons), citrate hen progressively metabolized in a. Series of reaction that remove carbons along the way, produces oxaloacetate (4 carbons) FADH2, NADH, and ATP, and 2 molecules of CO2, in this manner, the potential energy stored in hydrocarbon bonds of glucose is transferred to FADH2, NADH, and ATP, leaving the electrons in the C-O bond closer to the more electronegative O but w less PE
3 phosphoglycerate (glycolysis)
Used in opposite direction in photosynthesis
Location of cellular respiration
Glycolysis in cytoplasm, the rest in mitochondria!
Movement os pyruvate into mitochondrial matrix
Break c-c bond and release CO2, then generate NADH, H from NAD due to energy of electrons captured by bond breaking, put on molecule S-CoA by Coenzyme A, turns to acetyl CoA (prior to citric acid cycle)
Citric acid cycle step 1
Acetyl coA w oxaloaetate, causes coA to be lost and turned into citrate
Citric acid cycle step 2
Citrate to isocitrate
Citric acid cycle step 3
Isocitrate to alpha ketpglutarate, carbon lost and NADH produced
Citric acid cycle step 4
Alpha ketoglutarate ti succinyl coA (CoA added) lost C and NADH produces
Citric acid cycle step 5
Succinyl coA to succincate (CoA-SH leaves), phosphorylation GDP to GTP, ADP to ATP (ATP produced)
Citri acid cycle step 6
Succionaste to fuma rate, production of FADH2
Citric acid cycle step 7
Fumarate ro malate, addition of H2O
Citric acid cycle step 8
Mala te to oxaloacetate, production of NADH, then cycle begins again
Molecules produced during citric acid cycle
4 NADH, 1 FADH2, 1 ATP (per pyruvate) electron carriers (double for one molecule of glucose!)*
ATP synthesized goes where
Used by the cell, immediately hydrolyzed and exits mitochondria
Electrón carriers
NADH, FADH2
Location of electron transport chain and oxidative phosphorylation
Inner membrane space
ETC protein 1
NADH back to reduced form, the H is released and pushed out through proton pump
ETC protein 2
FADH2 to FAD, proton pumped out
ETC protein 3
Pumps H from FADH2 to FAD
ETC protein 4
2H and 1-2 O2 becomes water, H pumped out
ETC electron path
NADH, through 1 to Q (in membrane), electron added by NADH2, through 3, to Cyt c, to 4, electron is accepted by oxygen to form water
Where is water produced in ETC
In mitochondrial matrix
FADH protein sits
on matrix side of membrane, not within membrane
Final e- acceptor
O2
Free energy in ETC from e-
Free energy decreases throughout the ETC, free energy is used to pump protons against concentration gradient into inner membrane
Chemiomosis
Production of ATP using proton gradient and ATP synthase
ATP synthase function-structure
Stator located within membrane , rotor which acts like a water wheel (moves and is driven by protons), internal rod also spins, the energy from rotation drives catalytic knob to produce ATP from ADP and Pi
Amount of ATP produced via ETC and chemiosmosis
26 or 28 ATP
Maximum amount of ATP per glucose
30 or 32 ATPs
How does ATP get out of the mitochondria?
Crosses 2 membranes, ATP gradient across inner membrane, ADP gradient in cytoplasm, ATP and ADP move through poring in outer membrane, (ATP goes out down con. Gradient, ADP moves in down con. Gradient), transport protein ADP-ATP translocase flips over and moves them across inner membrane
ADP-ATP translocase
Transpor protein in inner membrane that gets ATP out of matrix and flip ADP into mitochondrial matrix
Oxidative phosphorylation
ETC, chemosmosis
Not enough oxygen for oxidative phosphorylation, what happens?
Everything is backed up, cell dies
Anaerobic respiration
Continuing glycolysis to produce ATP, ethanol (not animal cells) and lactic acid fermentation
Ethanol fermentation
Yeast cells, glycolysis to pyruvate, with no oxygen, fermentation takes places and produces either ethanol, lactate, or other products
Alcohol fermentation
In plant cells, 2 pyruvate lose 2 carbons (in co2) to produce acetaldehyde which then add 2 H from 2NADH to form ethanol, uses NADH and generates NAD(plus), only produces 2 ATP per glucose
Lactate fermentation
Pyruvate directly converted into lactate using H from 2NADH, turns NADH to NAD(plus), only produces 2 ATP, occurs with exercise (why there is a build up of practice acid in anaerobic activities
Carbohydrates as source of energy
Glycolysis, Kreisler cycle, ETC and oxidative phosphorylation
Fats as source of energy
Glycerols can start in glycolysis as glycerol de rhyme-3-P and through normal cycle, fatty acids go straight to acetyl CoA then through cycle
Amino acids as sources of energy
Either enter as pyruvate, (releases NH3), some go to acetylene CoA, some go to Krebs cycle (protein would be last step if all other sources of energy are gone)
Control of metabolism
Regulated tightly, balance is achieved via allosteric regulation of enzyme activities, control points use both positive and negative feedback mechanisms,
Main control point in glycolysis
Phosphofructokinase
