Cellular Respiration Flashcards
Energy
the ability to do work
First Law of Thermodynamics
- energy can not be created or destroyed, only changed into different forms
- total amount of energy in universe remains constant
- during conversion, some energy is lost as heat
Second Law of Thermodynamics
- entropy (disorder) is continuosly increasing as it is spontaneous
- energy transformations spontaneously to convert from more order to less order
- diffusion increases entropy as molecules becomes more spread out
_________ happens spontaneously
Disorder happens spontaneously
________ requires energy
Organization requires energy
Free energy
energy of system available to do work
∆G = ∆H -TS
G: gibbs free energy
H: total energy of system, enthalpy
T: absolute temperature
S: degree of disorder/entropy
+ ∆G
- products have more free energy than reactant
- H is higher or S is lower
- NOT SPONTANEOUS
- requires energy input
- Endergonic/Anabolic
-∆G
- products have less free energy than reactant
- H is lower or S is higher
- SPONTANEOUS
- Exergonic/Catabolic
Catabolism + Anabolism =
Metabolism
Metabolism
- sum of all chemical reactions in a living system
Catabolism
- all destructive reactions that release energy
- exergonic reactions
- digestion and respiration
Anabolism
- all constructive reactions that require input of free energy and decrease entropy of body
- endergonic reaction
- protein synthesis and photosynthesis
Coupled Anabolic Reaction
couple exergonic and endergonic reaction where net energy of reaction is negative
Coupled Catabolic Reaction
couple exergonic and endergonic reaction where net energy of reaction is positive
Since _____ reactions that build the complex of living systems are _____, a continuos intake of energy that can be _____ in _______ reactions to do work is needed
Since anabolic/contructive reactions that build the complex of living systems are endergonic, a continuos intake of energy that can be released in exergonic/catabolic reactions to do work is needed
Chemosynthesis
inorganic exergonic reactions coupled with endergonic synthesis reaction to produce food molecules
Where does the energy come from?
- living things can only do work by harnessing and converting energy sources
- GLUCOSE is universal source of energetic electrons because the C-H and C-C are energetic enough to yield energy if electrons are transferred to more electronegative source
Cellular Respiration
- aerobic respiration, exergonic with series of coupled reactions
- breakdown of glucose to synthesize ATP
- rearranging molecules in small steps using enzymes, until bonds become unstable and release phosphate to form ATP, or electrons stored for later reaction
Oxidation
losing an electron to oxygen or more electronegative molecule, exergonic reaction
Reduction
reducing charge, gaining an electron, endergonic reaction
Redox Reaction
one substance gaining electron and one loses electron
LEO says GER
loss of electron=oxidation
gain of electron=reduction
Activation Energy
energy required to initiate a CR
3 steps of Cellular Respiration
- Glycolysis
- Krebs Cycle
- Electron Transport Chain
Where does glycolysis occur?
In the cytoplasm of the cell
Glucose Priming
1st step of Glycolysis
- 6 Carbon Glucose with rearranged into Fructose iwth 2 phosphates from ATP (energy investment)
- phosphate makes 6-carbon molecule unstable and lower activation energy
- rearranged into Fructose 1 6-Biphosphate
- has inhibitor of phosphofruktokinase
Cleavage/Breakdown of Glucose
2nd Step of Glycolysis
- 6 carbon molecule with 2 phosphate splits as 2 isomers of 3-Carbon sugar phosphate aldehydes
Energy Yielding (Glycolysis)
3rd step of Glycolysis
- inorganic phosphate joins and catylized by enzyme, NAD+ gains 2 electrons in redox reaction
- one of the 2 phosphates binds to ADP to form ATP and leaves behind 3-Carbon sugar + 1 phosphate
- A few chemical rearrangements
- Substrate level phosphorolation of PEP into 3-Carbon Pyruvate resulting in another ATP
Glycolysis
- product is 2 pyruvate
- a net 2ATP and 2NADH+ H+ are produced after input of 2ATP
Substrate Level Phosphorolation
metabollic process that results in formation of ATP from a direct transfer of phosphate group
Krebs Cycle
- takes place in the mitochondrion
- a net of 8NADH+H+ , 2FADH2 and 2ATP formed
(6 NADH+H+ formed from oxidate decarboxylation, 2 formed by redox reaction)
- 6CO2 released
Pyruvate Oxidation/ Link reaction
(Krebs Step 1)
- Pyruvate is transported into mitrochondrial matrix where it loses one carbon that oxidizes and forms CO2
- molecule becomes acetate which is joined by CoA by the pyruvate dehydrogenase complex by oxidative decarboxylation and NAD+ takes 2 hydrogens creating NADH+H+
oxidative decarboxylation
oxidation reactions in which a carboxylate group is removed, forming carbon dioxide
What happens to the 2NADH+H+ from glycolysis?
- 2NADH+H+ from glycolysis are oxidized at the membranes of the mitochindria, converting it back to NAD+
- the hydrogens/electrons are dropped off at membrane
- weaker cousin FAD recieves the electrons and becomes FADH2
- NAD+ can not accept electrons on other side of membrane because CR release heat energy
Krebs Step 2
4-carbon acid oxaloacetate joins 2-Carbon AcetylCoA to form 6-Carbon acid citrate (the product of last reaction on cycle is the first reactant)
Krebs Step 3
Rearranged Citrate has oxidative decarboxylation, CO2 leaves substrate and NADH+H+ is formed leaving a 5-Carbon molecule
Krebs Step 4
5-molecule alpha keto-glutarate has oxidative decarboxylation, CO2 leaves substrate and NADH+H+ is formed
Krebs Step 5
4- Carbon succinyl CoA hydrolases CoA and uses the output energy to allow for synthesis of GTP be substrate level phorphorolation
- phosphate from GDP goes to ADP -> ATP
Krebs Step 6
4-Carbon acid succinate is oxidized and forms FADH2 and then is rearranged to form oxalo-acetate with another oxidation to form NADH+H+
Electron Transport Chain
- electrons from electron carriers reduce substances in ETC
- occurs on folded inner membrane cristae that increases rate of reaction because of SA
- proteins and enzymes found in membrane (1-3 in sequence)
-because of the electrons in the ETC that were oxidized by NADH+H+, as they pass through the ETC the proteins pump protons into the intermembrane space. This creates and electrochemical gradient. Protons will then flow through ATP synthase down the electrochemical gradient by chemiosmosis. When they do so they exert a proton motive force that allows the enzyme to rotate and provide the activation energy for synthsis of ATP
Electron Carriers
molecule that transports electrons during cellular respiration
(NADH+H+ , FADH2)
1st Protein in ETC
NADH dehydrogenase
- take away hydrogen from substrate NADH+H+
- redox reaction that eill use the energy to pump a proton into intermembrane space
- like an active transport mechanism
Coenzyme Q
- non polar protein that shuttles electrons back and forth between NADH dehydrogenase and Cyctochrome BC1 Complex
- sits in membrane
- where FADH2 oxidizes in the chain
2nd Protein in ETC
Cytochrome BC1 Complex
- reduce electrons and oxidizes to pass along to other proteins, H+ pumped into intermembrane space
- Electrical potential energy building ip
- next electron carrier protein is cytochrome- c
3rd protein in ETC
Cytochrome Ocidase Complex
- receives electrons and becomes reduced, oxidizes them and pumps more H+ into space
- last protein in chain and binds oxygen
- low energy electrons combine with Oxygen and H+ to form water
Why is oxygen important?
- it is the final electron acceptor in the ETC because of its electronegativity
-
4th Protein in ETC
ATP Synthase
- activation energy comes from Ep of protons is used to make ATP
- protons flow through channel of ATP synthase enzyme into mitochondrial matrix through chemiosmosis
Chemiosmosis
flow of electrons through ATP synthase
- as protons flow through the might repel ‘R’ groups of enzymes rotating the ATP synthase that forces ADP and P together
Proton Motive Force
movement of protons and exerting a force
Electrochemical Gradient
Ep of hydrogens in intermembrane space
Why does this process need to be regulated?
- to maintain current state, as molecules are unstable and can break down
- if needed to adjust to environment, change amount of energy
- can be done by inhibitors
Inhibitor
is a molecule that binds to an enzyme and decreases its activity.
Allosteric Inhibition
- any form of regulation where the regulatory molecule binds to an enzyme someplace other than the active site. The place where the regulator binds is called the allosteric site.
Allosteric Activation
allosteric activators bind to locations on an enzyme other than the active site, causing an increase in the function of the active site
- ADP allosterically activates phosphofructokinase to increase breakdown of gluces
Phosphofruktokinase
- Fructose 6-Phosphate is catylized by phosphofruktokinase to become Fructose 1 6-Biphosphate to make it unstable in an irreversible step
- dont require much energy due to inactivity
- regulates ATP in cytoplasm
- inhibited by ATP allosterically
Pyruvate Dehyrdogenase Complex
- during pyrivate oxidation between glycolysis and krebs
- multienzyme complex that carries out pyruvate to Acetyl CoA
- inhibited by NADH+H+ competitively so that ETC does not get backed up, and so that it can’t accept more electrons since it is already full
Catalyst
a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change
Anaerobic Respiration
- environment without oxygen, only in bacteria
- other molecules accept electrons, less free energy as last acceptor is less elextronegative = less ATP
- if there is nothing to accept electrons from last protein, the ETC will be blocked up, this will increase NADH+H+ and inhibit enzymes
- when O2 is not meeting demands of body
-
Fermentation
- to use organic molecules to accept electrons from glycolysis to recycle oxidized NAD+
- redox reaction where:
organic acid+ NADH -> reduced organic molecule + NAD+
Ethanol Fermentation
done in Fungi (yeasts) and some bacteria
(ethanol is by product alongside CO2)
Lactic Acid Fermentation
mammals and some bacteria
(lactic acid is by product alongside CO2)
Temperature on Enzymes
- As temp increases the rate of reaction increases because more frequent collisions
- enzyme has flexibility to bond that is more rigid at low temp and very high at high temp
- at optimal temp range, there is the most collisions being able to reduce fit without compromising the shape
- the rate goes down afterwards because you can break H bonds (which hold up tertiary structure) and the enzyme will unfold
Warm Blooded Creatures
Mice respire more at lower temperatures because they are endotherms as they use metabolic heat to maintain internal temperature, and as a result increase cellular respiration reactions to warm themselves to keep homeostasis. At higher temperatures mice respire less because they purposely have a lower cellular respiration rate, decreasing the amount of heat energy from the reactions.
Cold Blooded Creatures
Crickets are coldblooded creatures (ectotherms), meaning that they have a body temperature that changes with thetemperature of the environment, do not require as much thermal energy.
How change in CO2 can represent changes in respiration rate
- it is a by product during the krebs cycle
Where is ATP used?
- muscles
- glucose priming
- condensation synthsesis
- active transport
- oxidize fatty acid
Energy systems
cellular processes that produce ATP
Benefits of Physical Training
- greater vascularization of muscle tissue
- more energy capacity
- muscle strength anf lexibility
- heart pumps more blood to muscles quicker
- body can deal with more lactic acid
- decreases dependency on glycogen and increases dependency on fatty acids
3 energy systems that supply ATP to cells
- Creatine Phosphate System
- Glycolytic-Lactic Acid System
- Oxidative System
Creatine Phosphate System
- bond between creatine & phosphate split and energy liberated, catylized by creatine kinase, phosphate gets added onto ADP
- synthesized in liver, pancrease and kidney yhen transported to other parts of body
- 15 seconds energy, no oxygen, maximal exercise
Glycolytic-Lactic Acid System
- moderate-high intensiry of 45 seconds
- initial exercise if more ATP needed, can help body if more ATP needed than can be supplied
- pyruvate accepting NADH+H+ electrons, producing lactic acid
- fructose and galactose and be catabolized for glycolysis
- increase of lactic acid denatures enzymes
- lactic acid fermentation costs 1/6 energy ATP
Gluconeogensis
new glucose creating- glucose made from lactate
Cori Cycle/ Lactic Acid Cycle
when glycolytic cycle exceeds oxidative phosphorlation, the end product lactic acid is passed through blood to live into glucose
- 2 3-Carbon lactace = 1 glucose
Oxidative System
- Nucleic Acid
- least energy favourable, fed into krebs - Proteins
- deamination, removing animo functional group to form urea, and fed into krebs cycle as intermediary depending on the # of carbons or as pyruvate - Lipids
- Beta Oxidation to form AcetylCoA + remaining carbons, fatty acid main fat source of energy
Muscle Contractions & ATP
- motor preoteins actin&myosin shorten cell length, large quantities of ATP used
- active transport to put Ca2+ away
- Ca2+ cofactor open up ion channel that allow to attach and change shape
Glycolysis is limited by
- supply of glucose
- availability of oxidizez NAD+
What effect would cyanide have on the electron transport chain and the production of ATP? Explain your answer
- Cyanide binds to the enzyme and changes shape of active site preventing the oxygen from binding to the enzyme cytochrome c
- Backlog of electrons if ETC is stopping after 3rd protein
- As a result the protons are not being pumped out, so nothing is coming back through ATP synthase through chemiosmosis and there is no concentration gradient
- ATP production = 0
Given what you now know about the action of cyanide on cellular respiration, explain why the patients died of lack of oxygen while their blood oxygen levels were normal?
- There was oxygen initially going in
- Concentration gradient and diffusion at the same rate because the blood is already saturated, no more oxygen would diffuse
- Oxygen is not being used in the ETC, so the concentration would not decrease
- Depending on glycolysis for ATP production, so there is a buildup of lactic acid that denature the enzymes, glycolysis produces a small amount of ATP that would be used faster than it is produced, so the patient could go into cardiac arrest if depending solely of glycolysis due to a lack of ATP
Which of the following has more potential energy?
A the same molecule when oxidized
B a reduced molecule
C the same molecule when it is neither oxidized nor reduced
D There is no way of telling.
a reduced molecule
