Define the term glycolysis in terms of its initial substrates and products. Explain why there is a net gain of 2 molecules of ATP in this process.
To review:
The definition of glycolysis in terms of its initial substrates and products along with the reason for the net gain of two molecules of ATP in the process.
Introduction:
Cellular respiration is a process in which energy is released by stepwise break down of glucose and other molecules through which energy is consumed, and some of this energy is used to produce ATP (adenosine triphosphate), that is, the energy currency for every cell. The complete combustion of a glucose molecule requires oxygen and yields about 38 ATP for each molecule of glucose. Some of the energy is produced in the absence of an oxygen requiring pathway that leads to the generation of lactic acid as an end product.
Explanation of Solution
The first cellular respiration process for the breakdown of glucose is glycolysis, which is a process of breakdown of glucose (a 6-carbon compound) into the two molecules of pyruvate or pyruvic acid (a 3-carbon compound). The diagram belowshows the different steps in the breakdown of glucose:
Glycolysis is a 10-step process and in every step, enzymes are required to catalyze the reaction. The 6-carbon molecule is the substrate which results in the production of two molecules of 3-carbon pyruvic acid (pyruvate).
The pathway requires two ATP molecules as a source of energy, one for the conversion of glucose into glucose-6-phosphate and the second for the conversion of fructose-6-phosphate into the fructose-1,6-bisphosphate.
The glycolysis pathway generates 2 molecules of NADH (nicotinamide adenine dinucleotide hydrogen) and 4 molecules of ATP, 2 ATP molecules are expended during the process, so there is a net gain of 2 ATP molecules.
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Chapter 5 Solutions
Human Physiology
- What should be the net yield of ATP in glycolysis when endogenous glycogen is used? Give answer as a numeric value.arrow_forwardIndicate at what step in the glycolysis pathway each of the following events occur 1. First phosphorylation of ADP occurs 2. First “energy rich” compound is produced 3. Second “energy rich” compound undergoes reaction 4. First isomerization reaction occurs 5. Second formation of ATP occurs 6. Second “energy rich” compound is produced 7. ATP is converted to ADP for the second time 8. A dehydration reaction occursarrow_forwardExplain the origin of the word glycolysis and why this is anappropriate name for the function of that reaction pathway.arrow_forward
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- Explain the fate of electrons that are removed during the oxidation of triose phosphates during the glycolysis.Also explain the glucose be "primed" with a high energy phosphate bond before it can be degraded in the glycolytic pathway.arrow_forward*Determine the ATP yield from the metabolism of one molecule of glucose under the following conditions: a) b) c) in a mammalian muscle cell carrying out anaerobic glycolysis. in Escherichia coli, an aerobic prokaryote in a mammalian brown fat cell, in which electron transport occurs without producing ATParrow_forwardIn glycolysis, the KM value of hexoquinase is 0.04 mM. At physiological conditions, the cellular concentration of glucose is between 4 mM to 15 mM. According with this information, which of the following statements is true (Choose all that are correct) The enzyme has a low affinity for its substrate The enzme is working at its maximum velocity The phosphorilation of glucose is very slow The small value of KM assures that glycolysis will continue even when the concentration of glucose drops below 4 mM. The hexoquinase is saturated with glucosearrow_forward
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