Tag: carbohydrate metabolism

Questions Related to carbohydrate metabolism

Which one of the following equations represents the Aerobic respiration?

bio-chemistry carbohydrate metabolism energy output living organisms and energy production respiration in cell

  1. $6CO _2\,+\,6H _2O\,\rightarrow \,C _6H _{12}O _6\,+\,6O _2$

  2. $C _6H _{10}O _2\,+\,6O _2\,\rightarrow\,6CO _2\,+\,5H _2O\,+\,674Kcal$

  3. $C _6H _{12}O _6\,+\,6O _2\,\rightarrow\,6CO _2\,+\,6H _2O\,+\,674Kcal$

  4. $C _6H _{12}O _2\,+\,6O _2\,\rightarrow\,6H _2CO _3$

Show answer
Correct Option: C

The net yield of ATP, except substrate-level phosphorylation, from Krebs cycle per glucose molecule is

bio-chemistry carbohydrate metabolism energy output living organisms and energy production respiration in cell

  1. $12$

  2. $24$

  3. $22$

  4. $36$

Show answer
Correct Option: C
Explanation:

From one molecule of glucose, 38 ATP molecules can be produced during cellular respiration. Glycolysis produces net 2 ATP molecules by substrate level phosphorylation. Kreb cycle produces 2 ATP molecules by substrate level phosphorylation. About 34 ATP are produced from oxidative Phosphorylation. During Kreb cycle, 6 molecules of NAD$^+$ are reduced to NADH and 2 molecules of FAD are reduced to FADH$ _2$. Now 6 NADH produce 6 x 3 = 18 ATP molecules. Similarly, 2 FADH$ _2$ produce 2 x 2 = 4 ATP molecules. Hence, total 18 + 4 = 22 molecules of ATP are produced per glucose molecule from Kreb cycle except substrate level phosphorylation.

Thus, the correct answer is '22.'

If one triose phosphate completely oxidized inside prokaryotic cell than gain of ATP of energy equal to?

bio-chemistry carbohydrate metabolism energy output living organisms and energy production respiration in cell

  1. $5$ ATP

  2. $4$ ATP

  3. $20$ ATP

  4. $19$ ATP

Show answer
Correct Option: D
Explanation:

Triose phosphate is another name of glyceraldehyde 3- phosphate

Total NADH and ATP are produced in the cycle are as follows as -

 Name of process  Gain of ATP
 Glycolysis: glyceraldehyde 3- phosphate $\rightarrow$pyruvate  1 NADH ( each NADH is equal to 3 ATP) + 1 ATP3ATP+ 1ATP = 4ATP
 Oxidative decarboxylation pyruvate $\rightarrow$acetyl CoA  1 NADH = 3 ATP
 Tricarboxylic acid cycle  3NADH +1 FADH (each FADH is equal to 2ATP) + 1 GTP(equivalent to ATP) =  12 ATP

Total gain of ATP, when one triose phosphate is completely oxidised =  4 ATP =3 ATP =12 ATP $\rightarrow$  19 ATP

So, the correct answer is ' 19 ATP '

Mark the incorrect statement

bio-chemistry carbohydrate metabolism energy output living organisms and energy production respiration in cell

  1. The breaking of c-c bonds of complex organic molecules by oxidation cells leading to the release of a lot of energy is called cellular respiration

  2. Initial stage of cellular respiration takes place in cytoplasm

  3. Incomplete oxidation of pyruvate by stepwise removal of all the hydrogen atoms leaving 3 molecules of CO2

  4. TCA cycle starts with condensation of acetyl group with OAA and water to yield citric acid

Show answer
Correct Option: A
Explanation:

Aerobic respiration is comprised by

1) The complete oxidation of pyruvate by stepwise removal of all hydrogen atoms leaving 3 molecules of CO$ _2$. 
2) The passing of the electrons removed as apart of the hydrogen atoms to molecular O$ _2$with the simultaneous synthesis of ATP.
So, the incorrect statement is ' Incomplete oxidation of pyruvate by stepwise removal of all hydrogen atoms leaving 3 molecules of CO$ _2$'.
rest all are correct statements w.r.t. Respiration. 

Out of $36$ ATP molecules produced per glucose molecule during respiration.

bio-chemistry carbohydrate metabolism energy output living organisms and energy production respiration in cell

  1. $2$ are produced outside glycolysis and $34$ during respiratory chain

  2. $2$ are produced outside mitochondria and $34$ inside mitochondria

  3. $2$ during glycolysis and $34$ during Krebs cycle

  4. All are formed inside mitochondria

Show answer
Correct Option: B
Explanation:

Cellular respiration is a set of metabolic reactions and processes that take place in the cells of organisms to convert biochemical energy from nutrients into adenosine triphosphate (ATP), and then release waste products. The reactions involved in respiration are catabolic reactions, which break large molecules into smaller ones, releasing energy in the process, as weak so-called "high-energy" bonds are replaced by stronger bonds in the products. Respiration is one of the key ways a cell releases chemical energy to fuel cellular activity.  The chemical energy stored in ATP (its third phosphate group is weakly bonded to the rest of the molecule and is cheaply broken allowing stronger bonds to form, thereby transferring energy for use by the cell) can then be used to drive processes requiring energy. Since the cellular respiration happens inside mitochondria, and glucose being given out as a by-product, glucose is produced inside and outside mitochondria.

So the correct option is '2 are produced outside mitochondria and 34 inside mitochondria'.

Complete oxidation of a molecule of glucose yields?

bio-chemistry carbohydrate metabolism energy output living organisms and energy production respiration in cell

  1. $15$ ATP molecules

  2. $2$ ATP molecules

  3. $36$ ATP molecules

  4. $8$ ATP molecules

Show answer
Correct Option: C
Explanation:

Oxidation is a chemical process that, loosely defined, involves removing electrons from particular areas of a molecule. In biochemical processes, oxidation generally results in the release of energy. The glucose molecule contains stored energy in its bonds, just as other nutrient molecules do, including starch, proteins and fats. When you consume food that contains glucose, you digest the food and absorb the glucose into your bloodstream. From there, cells take up the glucose and either store it for later use or chemically burn it to provide energy. Oxidation of glucose is analogous to burning wood in many ways: It releases chemical energy. The complete aerobic oxidation of glucose is coupled to the synthesis of as many as 36 molecules of ATP.

So the correct option is '36 ATP molecules'.

Number of ATP obtained at the end of Kreb's cycle?

bio-chemistry carbohydrate metabolism energy output living organisms and energy production respiration in cell

  1. $2$ ATP

  2. $4$ ATP

  3. $36$ ATP

  4. $38$ ATP

Show answer
Correct Option: D

How many ATP molecules will be produced when one molecule of $3$-phosphophoglyceric acid is completely oxidised?

bio-chemistry carbohydrate metabolism energy output living organisms and energy production respiration in cell

  1. $16$

  2. $17$

  3. $32$

  4. $20$

Show answer
Correct Option: A

The incremental oxidation of 1 molecule of glucose during cellular respiration produces 30 molecules of ATP according to the balanced equation:
$C _6H _{12}O _6+6O _2+30ADP+30P _i\rightarrow 6H _2O+6CO _2+30ATP$
ATP is then hydrolyzed by cells for a variety of biochemical processes.
Changes in free energy between glucose oxidation and ATP hydrolysis were compared. The table below illustrates the data collected:

Reaction Change in Free Energy ($\triangle G$)
Glucose Oxidation -686 kcal/mol
ATP Hydrolysis -13 kcal/mol

Which statement best explains the data?

bio-chemistry carbohydrate metabolism energy output living organisms and energy production respiration in cell

  1. Both glucose oxidation and ATP hydrolysis, are exergonic because they have negative $\triangle G$ values.

  2. Both glucose oxidation and ATP hydrolysis, are exergonic because their products have more free energy than their reactants.

  3. Both glucose oxidation and ATP hydrolysis, are endergonic because they have negative $\triangle G$ values.

  4. Both glucose oxidation and ATP hydrolysis, are endergonic because their products have less free energy than their reactants.

Show answer
Correct Option: A
Explanation:

Both ATP and Glucose oxidation are energy releasing or exergonic processes as the value of $\delta$G is negative

So, the correct answer is 'Both glucose oxidation and ATP hydrolysis, are exergonic because they have negative △G△G values'

Respiratory substrate yielding maximum number of ATP molecules is

bio-chemistry carbohydrate metabolism energy output living organisms and energy production respiration in cell

  1. Ketogenic amino acids

  2. Glucose

  3. Amylose

  4. Glycogen

Show answer
Correct Option: B
Explanation:

The process of glycolysis in respiration requires glucose as the primary substrate to be oxidised. Any other substrate is first converted to glucose before it can enter glycolysis. Certain substrates like ketogenic amino acids, amylose, glycogen need to be converted to glucose first at a cost of some energy in the form of ATP. Hence their net yield of ATP is less than that of glucose as a substrate.

So the answer is 'Glucose'.