Question

5. How efficient is the conversion from glucose to ATP? 6. How many ATP molecules are made from one molecule of glucose? 7. In general, what are NAP+ and FAD? 8. Define anaerobic: Aerobic: 9. Summarize the 4 phases (used to be considered 3) of Cellular Respiration: a) Glycolysis b) Prep reaction - c) Citric Acid Cycle - d) ETC-

Answer 1

Question no.5

It is considered that about 40% of the energy from glucose is obtained in the form of ATP (in case of aerobic respiration). Rest 60% is lost in the form of heat.

Question no.6: the answer depends on whether we are considering aerobic respiration or anaerobic respiration.

(Considering that 1NADH produces 2.5 ATP and 1 FADH2 produces 1.5 ATP). So, for 1 molecule of glucose,

In case of aerobic respiration- During glycolysis 2 ATP and 2 NADH are produced. Pyruvate Decarboxylase complex yeilds 2 NADH and 2 acetyl coa. TCA cycle produces 6 NADH, 2FADH2 and 2 ATP. NADH and FADH2 produced during the overall process enters ETC to give 2.5 and 1.5 ATP respectively. Thus, number of ATPs produced during COMPLETE OXIDATION OF GLUCOSE=2+(2x2.5)+(2x2.5)+(6x2.5)+(2x1.5)+2 = 32ATP. (This is only when we consider 1NADH = 2.5 ATP and 1FADH2=1.5 ATP).

For anaerobic respiration, only 2 ATP will be produced during glycolysis. (NADH and FADH2 are not utilized to produce ATP and pyruvate is utilized to produce lactic acid or alcohol.)

Question no. 7

(In the question, NAP+ is mentioned; it should be NAD+)

NAD+ (Nicotinamide Adenine Dinucleotide) act as an electron carrier in metabolism. The cofactor cycles between oxidized form NAD+ and reduced form NADH and carries electron from one molecule to another.

FAD (Flavin Adenine Dinucleotide) function as an electron acceptor and is mainly involved in Citric Acid Cycle.

Question no.8

Aerobic respiration occurs when glucose is completely oxidized in presence of oxygen. Here oxygen acts as the final electron acceptor and a large amount of energy is produced as compared to anaerobic respiration.

Anaerobic respiration occurs in absence of oxygen (the process do not require oxygen) and a small amount of energy in the form of ATP is produced (2ATP per molecule of glucose). It is also known as incomplete oxidation of glucose.

Question no. 9

A. Glycolysis is the 1st step of glucose metabolism, where it is converted to Pyruvate. It is divided into 2 phases- preparatory and Pay-off. Energy produced during glycolysis is stored in the form of ATP and NADH.

B. Prep reaction or preparatory phase of glycolysis includes the 1st five steps during which ATP is utilized to convert glucose into 3 carbon compound Glyceraldehyde 3-phosphate.

C. Citric acid cycle or Krebs cycle occurs in mitochondria and is seen in aerobic respiration during which acetyl coa is oxidized, and energy is produced in the form of ATP, fadh2 and NADH.

D. ETC is the final step of glucose oxidation, occuring in the inner mitochondrial membrane of eukaryotes, during which NADH and FADH2 donate electrons to oxygen through a series of electron carriers, and ATP is produced.