Lessons 4, 5, and 6 - Chapter 3 Flashcards
What are many cellular activities devoted to?
Obtaining energy from the environment and using it to drive energy-requiring reactions.
Many reactions are energetically unfavorable, and can only proceed with what?
Additional energy input
A -> B
If 🔺G < 0, this reaction will proceed in what direction?
The forward direction.
If 🔺G > 0, this reaction will proceed in what direction?
The reverse direction.
True/False: Many biological reactions are thermodynamically unfavorable 🔺G > 0.
True
What does ATP stand for?
Adenosine 5’-triphosphate
What is ATp’s central role?
Stores free energy in the cell
True/False: The bonds between the phosphates in ATP are low energy bonds?
False.
They are high energy bonds. Their hydrolysis is accompanied by a large decrease in free energy.
ATP can be hydrolyzed to…
AMP plus pyrophosphate (PPi)
PPi is rapidly hydrolyzed and the total free-energy change is twice that form hydrolysis of ATP to ADP.
True/False: ATP hydrolysis can drive other reactions.
True
Energy-yielding reactions within the cell are coupled to…
ATP synthesis
Energy-requiring reactions are coupled to….
ATP hydrolysis
How much free energy is yield by the complete oxidative breakdown of glucose to CO2 and H2O?
🔺G’ = -686 kcal/mol
+ means they consume
- means they generate
*Study the reactions of glycolysis picture.
It generates how many ATP’s and NADH’s?
2 ATP’s and 2 NADH’s
True/ False: Glucose is oxidized in a series of steps coupled to ATP synthesis in order to harness free energy?
True, the steps are:
- Glycolysis
- Conversion of NAD+ to NADH
- Depending if anaerobic or aerobic conditions, NADh can reoxidize to NAD+ or donate electrons.
Glycolysis:
Happens in all cells that don’t have oxygen.
-Can provide all the metabollic energy of anaerobic organisms.
Results in the breakdown of glucose into pyruvate.
-Has a net gain of 2 ATP’s.
The first part of the pathwayconsumes energy.
When their is enough ATP supply glycolysis is inhibited.
True/False: Glycolysis converts two molecules of the coenzyme NAD+ to NADH.
True.
NAD+ acts as an oxidizing agent that accepts electrons.
NADH must be recycled by serving as an electron donor for other oxidation-reduction reactions.
In anaerobic conditions NADH…
Is reoxidized to NAD+ by the conversion of pyruvate to lactate or ethanol.
In aerobic conditions NADH…
Donates electrons to the electron transport chain.
Where does glycolysis take place?
In the cytosol.
In eukaryotic cells, _____ is transported into the ______ where it is completely oxidized.
Pyruvate and the mitochondria.
Pyruvate undergoes oxidative decarboxylationin the presence of coenzyme A (CoA-SH), forming what?
Acetyl CoA
- generation of 2NADH.
What cycle does Acetyl CoA enter?
The Citric Acid Cycle (The Krebs Cycle)
When the 2-carbon acetyl group combines with oxaloacetate (4 carbons) what do they yield?
Citrate - 6 carbons
In the last two reaction in the kreb’s cycle , ___ carbons of citrate are completely oxidized to _____ and ______ is regenerated.
2
CO2
Oxaloacetate
2 Carbons of citrate:
Give? Take? - Look at power point
2 CO2 1 Oxaloacetate 1 GTP - converted directly to ATP, so it counts as 1 ATP 3 NADH and 1 FADH2
Oxidation of glucose:
Look at power point
6 Molecules of CO2
4 ATP
10 NADH
2 FADH2
What is the total number of ATP yield the from oxidation of glucose?
36 - 38
Glycolysis Formula:
2 ATP + 2 NADH
Citric Acid Cycle (Krebs Cycle) Formula:
2 ATP + 8 NADH + 2 FADH2
Oxidative Phophorylation Formula:
Each NADH yields 3 ATP
Each FADH2 yields 2 ATP
What is the formula to get the total number of ATP yielded from the oxidation of glucose?
Glycolysis: 2 ATP + 2 NADH
Citric Acid Cycle: 2 ATP + 8 NADH + 2 FADH2
Oxidative Phophorylation:
-Each NADH yields 3 ATP
-Each FADH2 yields 2 ATP
Total: 2 ATP + 2 ATP + 103(NADH) + 22(FADH) = 38 ATP
True/False: The breakdown of other organic molecules can also yield energy.
True
