TCA & Some Thermodynamics Flashcards
ATP is
Energy storage molecule
Why is ATP such a good energy storage molecule?
Due to the phosphate groups.
Why do reactions occur in small controlled steps to transfer energy to carrier molecule?
so we dont lose energy as heat
Hydrolysis reactions are used when
you break phosphate bonds
Catabolic Pathways
breaking bonds
Anabolic Pathways
make bonds
How does the cell store energy?
Chemical bonds, chemical concentration gradient, electrical concentration gradient and electrochemical gradients
Thermodynamics
study of the relationship between free energy, heat and disorder in a system
1st Law of Thermodynamics
energy cannot be created or destroyed, just converted from one form to another
2nd Law of Thermodynamics
Within an isolated system disorder is always increasing
Entropy (S)
amount of disorder in the system
T/F: Energy is not required to restore order in a system
False, energy IS required
Increasing Disorder has a _____ delta S and decreasing disorder has a ____ delta S
+;-
Free energy
amount of energy available to do work; G
T/F: All reactions have a change in free energy
TRUE
When energy is consumed there is a _____ delta G.
Positive
Endergonic Rxn
energy consumed; +delta G
Exergonic Rxn
energy released; - delta G
Enthalpy
heat content of a reacting system
Exothermic Rxn
releases heat and has a negative delta G
Endothermic Rxn
Put in or consume heat; positive delta G
dG= dH-TdS
relationship between G, H, S
When are reactions favorable?
when they are spontaneous; delta G is negative
When delta G is positive a reaction is or is not spontaneous
is not
If enthalpy is decreasing and entropy is increasing the reaction will be:
favorable
Condensation Rxn are energetically_______
un-favorable
Hydrolysis Rxn are energetically ______
favorable
Overall, you always want delta G to be?
negative
Why might carbs be a better fuel than lipids?
Body can breakdown carbs faster
RNA is more/less reactive
more
RNA is produced
when conditions require them to be produced
Energy from ________ reactions is used for _______ reactions
catabolic; anabolic
Are our bodies an isolated system?
No
Which is more disordered?10 nucleotides or 10 nucleotides assembled into DNA?
10 nucleotides
Combining 10 nucleotides into a polymer is spontaneous or nonspontaneous
nonspontaneous
Are reactions involving the assembly of polymers usually condensation rxn or hydrolysis rxn?
condensation
In some reactions, the standard free energy is positive, but the reaction is favorable in the cell. How could this occur?
Concentrations can vary.
What characteristics are true of a reaction at equilibrium?
Delta G=0Rate of forward reaction=rate of backward reactionratio of reactants to products is constant
Triagylcerol is made of:
1 glycerol and 3 fatty acids
Triacygycerol is mainly used for:
energy storage
Is Triacylglycerol unsaturated or saturated?
Both
How can we determine delta G:
dG=dGnot + RTlog(products/reactants)
Delta G not is:
the change in free energy under specific conditions in the cell
Is equilibrium the same in the presence and absence of an enzyme?
Yes!
Metabolic Pathways are composed of:
molecules and enzymes that are involved in a series of chemical reactions required for the cell to grow, survive, and reproduce.
Enzymes _______ reactions.
Catalyze or accelerate
How does enzymes catalyze reactions?
by lowering the activation energy of a reaction. they dont change the overall delta G
What needs to be overcome to proceed?
activation energy
In catalysis, are both reactions accelerated to the same degree?
Yes.
Oxidation is the ______ of electrons. Reduction is the ______ of electrons.
Loss; Gain
NAD+/NADHwhich is oxidized?
NAD
FAD/FADH2which is reduced?
FADH2
Out of the following, which would be considered the most oxidized? 1. CH42. CO23. CH3OH4. C2H4
CO2
What do activated carriers do?
store energy until it is ready to be used
What is the most abundant activated carrier?
ATP, because of phophoanhydride bonds
Breakage of phosphanhydride bonds eliminates what?
Repulsion between negative charges
Acetyl CoA
high energy bond is present that can be broken to provide energy for another reaction
Thioester bond is between
CH3CO–S
Amino acids, fatty acids, and sugars are processed through a number of steps to yeild the energy storage molecule:
ATP
Citric acid cycle is also called
krebs cycle
where does the citric acid cycle occur in eukaryotes?
mitochondria
In the citric acid cycle, what must first happen to the pyruvate from glycolysis?
It has to be made into acetyl-CoA
Pyruvate Dehydrogenase happens in
mitochondrial nucleus
Pyruvate Dehydrogenase Complex
Complex of 3 enzymes that catalyze 5 reactions, located in mitochondrial matrix
Complex 1 in Pyruvate Dehydrogenase:
remove one carbon from pyruvate
Complex 2 in Pyruvate Dehydrogenase:
transfer of two carbons to CoA
Complex 3 in Pyruvate Dehydrogenase:
making sure reaction can continue to occur
Overall Energy Carrier Production from 1 acetyl-CoA (x2 for each glucose)
3 NADH, 1 FADH2, 1 GTP
What is Step 1 in the Citric Acid Cycle?
Name: Citrate SynthaseWhat Happens: Hydrolysis of high energy thioester bond in Acetyl-CoA, making reaction favorable
What is Step 2 in the Citric Acid Cycle?
Name: AconitaseWhat Happens: Isomerization of citrate
What is Step 3 in the Citric Acid Cycle?
Name: Isocitrate dehydrogenaseWhat Happens: first of four oxidation stepsYields: CO2 and NADH
What is Step 4 in the Citric Acid Cycle?
Name: alpha-ketoglutarate dehydrogenase complexWhat Happens: second of four oxidation stepsYields: NADH, CO2, and compound with high energy thioester bond
What is Step 5 in the Citric Acid Cycle?
Name: Succinyl-CoA synthetaseWhat Happens: phosphate displaces CoA to make high energy intermediate. Phosphate is passed to GDP to make GTP
What is Step 6 in the Citric Acid Cycle?
Name: Succinate dehydrogenaseWhat Happens: third of four oxidation stepsYields: FADH2
What is Step 7 in the Citric Acid Cycle?
Name: FumaraseWhat Happens: hydration reaction (add H2O)
What is Step 8 in the Citric Acid Cycle?
Name: Malate dehydrogenaseWhat Happens: fourth oxidation rxn; oxalacetate regenerationYield: oxaloacetate
Citric Acid Cycle
Series of Eight Rxn; regenerates oxaloacetate, releases 2 CO2, requires O2 for regeneration of NAD+ and FAD
Where does lactate excretion occur?
Skeletal muscle
How do products from glycolysis enter the citric acid cycle?
Pyruvate must be processed to acetyl-CoA by the pyruvate dehydrogenase complex in the mitochondrial matrix in order for products to enter the citric acid cycle
Where does the citric acid cycle occur?
Mitochondrial Matrix
Which steps are redox in the Krebs cycle?
3, 4, 6, & 8
What are the net products of the citric acid cycle?
For each acetyl-CoA that enters the cycle, 3 NADH, 3H+, 1 FADH2, 1 GTP, 2 CO2.
What is regenerated in the final step of the citric acid cycle that keeps the cycle going?
Oxaloacetate