Question

7. Rat liver can metabolize glucose by both the glycolytic and the pentose phosphate pathways. Indicate in the box if the following are properties of glycolytic (G), pentose phosphate (P), both (G+P), or neither (O): (5 marks) a) NAD+ is involved b) CO2 is liberated c) Phosphate esters are intermediates d) Glyceraldehyde 3-phosphate is an intermediate e) Fructose 6-phosphate is an intermediate

Answer 1

a. NAD+ is involved in Glycolysis (G)

b.  CO2  is liberated in pentose phosphate pathway (P)

c.  Phosphate esters are present both the pathways (G+P)

for example Glucose-6-phosphate and Fructose-6-phosphate in Glycosis and

Fructose-6-phosphate in pentose phospahate pathway

d. Glyceraldehyde 3 phosphate is an intermediate in pentose phospahate pathways (P)

e. Fructose-6-phosphate is an intermediate in both the pathways (G+P)

For reference the glycolytic and pentose phospahate pathways are shown as follows,

figure no. 1 :- Glycolysis
ADP + Pi Glucose (6 carbon compound) ATP Hexo kin ase Gelucose-6-, -Phosphate phospho gluco isomerase fructose -69 Phosphate ATP - phospho fructo kinase fructose 1,6 - Di phosphate ADP + pie V Di hy doo xy acetone phosphate (DHAP) (30) 2 MADH + H2 LATPK Toiose phosphate phosphogly cer ate (30) isomerase phophoglycerodehyde DNAD 2 dehydrogen alse "1,3 diphospho gly ceraldehyde QADP+ piz_ phosphoglycero Rinase H 3 Phosphó glycesate phospho glycerdo mutase p phospho glycerate H₂o Enolase Phospho onol pyruvate pysuvate kinase PYRUVATE (8) 2ADP+ pia 2ATP + -Pooja

figure no. 2 :- pentose phosphate pathway
Glucose-6 - PO4 NADP - Glucose 6 P04 dehydrogenase NADPH 6 phosphoglurono lo cHono H₂O Gluconolactase H+ 6 phosphogluconate - 6 phosphogluconate dehydrogenase Napp+ phospho NADPH + CO2 Ribulose - 5-P04 Ribulose 5 P04 Ribulose 5 P04,3 isomerase - epimedase Ribulase 5 P04 xylulase -5 - P04 -Transaldolase Gly ceo al dehyde 3-P04 + sedoheptulose - 4 -PO4 K Toansgldolase fructose 6 P04 + Erythose 4 P04 xylulose 5-P04 Transa)doloese Glycolysis Glyceraldehy de + fructose-6-po. glycolysis glycolysis -Pooja

f