(1) Chapter 3: Cell Metabolism Flashcards
Thermodynamically unfavorable biological reaction
Change in G > 0. these reactions use energy to generate an end product
Thermodynamically favorable biological reaction
Change in G
Thermodynamically favorable and unfavorable reactions can combine to form _____reactions?
very efficient.
Main function of ATP
(adenosine 5’-triphosphate) ATP.
-stores free energy in the cell
What occurs as bonds between phosphates of ATP break?
-bonds are broken by hydrolysis and release a large amount of free energy
Hydrolysis of ATP to AMP and PPi
-ATP can be hydrolyzed to AMP & Pyrophosphate (PPi), then PPi is rapidly hydrolyzed and the total free-energy change is double than the hydrolysis from ATP to ADP
Energy yielding reactions within the cell are coupled to _____
ATP synthesis
Energy-requiring reactions are coupled to _____
ATP hydrolysis
The complete breakdown of glucose to CO2 and H2O yields how much free energy?
-686 kcal/mol
Glycolysis
- 1st stage of ATP synthesis
- takes place in cytosol
- inhibited if there is an adequate supply of ATP
- provides all metabolic energy of anaerobic organisms
- occurs in all cells in the absence of oxygen.
What is the result of Glycolysis?
- breakdown of glucose into pyruvate
- net gain of 2 ATP
- Gain 2NADH from NAD+
- uses 2ATP to start process
In Anaerobic glycolysis conditions what happens to NADH?
NADH is reoxidized to NAD+ by conversion of pyruvate to lactate/ ethanol/ or Acetaldehyde
In aerobic glycolysis conditions, what happens to NADH?
NADH donates electrons to the electron transport chain
What happens to pyruvate after aerobic glycolysis?
Pyruvate enters mitochondria and is converted to acetyl CoA
How is Acetyl CoA formed? What is a byproduct?
- pyruvate enters mitochodria and undergoes oxidative decarboxylation when coenzyme A & NAD+ is present
- Generates acetyl CoA, 2NADH, and CO2
What happens to Acetyl CoA after it is synthesized?
- enters citric acid cycle (Kreb’s cycle)
- Citrate (6C) is formed after Acetyl CoA binds with oxaloacetate.
What happens to Citrate in the Kreb’s cycle?
2 C’s of Citrate are oxidized to CO2 and Oxaloacetate is regenerated
Where does the citric acid cycle take place?
mitochondria
What are the products of the Kreb’s cycle?
after one turn:
- 2 CO2, 1 oxaloacetate, 1 GTP, 3NADH, 1 FADH2
- products double after the 2nd turn
FADH2
- Flavin adenine dinucloetide
- an electron carrier
List products after oxidation of glucose and name what process they are from
- Total ATP: 36-38
- GLycolysis: 2 ATP and 2 NADH
- Citric Acid Cycle: 2 ATP, 6 NADH, 2 FADH
- Oxidative phosphorylation: 30 ATP from NADH, 4 ATP from FADH
In oxidative phosphorylation which electron carriers produce ATP and what amount to they produce?
NADH yields 3 ATP: so produces 30
FADH2 yields 2 ATP: so produces 4
What other molecules besides glucose can break down to yield energy?
- polysaccharides can be broken down to sugars in order to metabolized by glycolysis and the krebs cycle.
- lipids can be oxidized to yield a whole lot of energy
Describe the process of triacylglycerol break down to produce ATP
- Fats are broken down into glycerol and free fatty acids
- fatty acids bind to coenzyme A
- Acyl-CoA is formed using 1 ATP
- Fatty acids are degraded in stepwise oxidative process, 2 carbons at a time.
- each round of oxidation yields 1 NADH and one FADH2
- acetylCoA then enters citric Acid cycle.
- net gain is 130 ATP per 16 C fatty acid
What processes derive the most energy from the breakdown of macromolecules?
- electron transport
- oxidative phosphorylation
In general, what happens to electrons carried by electron transporters during oxidative phosphorylation?
-Electrons from NADH and FADH2 are transferred to O2, which is coupled to the formation of 34 ATP
How are the components of the etc organized?
-four complexes in the inner mitochondrial membrane
Describe process of ETS for transport of e- from NADH
- e- from NADH enter ETC @ complex 1, NAD left
- e- transferred to complex 3 by coenzyme Q
- Cytochrome C carries e- from complex 3 to complex 4
- e- transferred to O2 and 2H+ from mitochodrial matrix is added to form water
Describe Process of ETS for transport of e- from FADH2
- e- from Krebs cycle are transferred to complex 2 by the intermediate Succinate
- In complex 2, e- transferred to FADH2
- e- transferred to complex 3 by coenzyme Q
- Cytochrome C carries e- from complex 3 to 4
- e- transferred to O2 and 2H+ from mitochondrial matrix is added to form water.
Which ET complexes are coupled to the transport of protons across mitochondrial membranes?
1, 3, 4. They establish a proton gradient across the mitrochondrial membrane
At each proton transfer complex in the ETS, how many protons are transported per pair of electrons?
4
What kind of gradient is formed across the inner membrane of the mitochondria? describe components
An Electrochemical gradient is formed by both a pH and electric potential gradient. In the matrix, pH is higher, and there is a (-) charge. In the intermembrane space, pH is lower and there is a (+) charge