Question

Question: You buy a sample of glucose that has the radioactive carbon-14 (C) isotope at the second position (Carbon #2). All other carbon positions in the glucose molecules have the "C isotope. "C is only a label and does not alter the biochemical behavior of the molecules in which it is found. This glucose sample is mixed with all the enzymes derived from liver cells, which initially contain no other C-labeled chemicals. A) Draw the Haworth structure of glucose and indicate which carbon is Carbon #2 using a different color. B) In order, draw every metabolic step involved in converting the 'C-labeled glucose molecule into 'C-labeled Pyruvate. See the instructions below. C) Convert 'C-labeled Pyruvate into C-labeled Acetyl-CoA. Show the product of each of the three steps catalyzed by the pyruvate dehydrogenase complex. See the instructions below. D) Assuming that all the 14C-labeled Acetyl-CoA formed enters the citric acid cycle at the same time, draw the citric acid cycle intermediates up to and including malate, and indicate the position of the 'C-label in each intermediate. See the instructions below. E) Continue to draw citric acid cycle intermediates up until a 'C-labeled CO2 molecule is generated by the cycle. How many turns of the citric acid cycle must be made before CO2 is released? Which enzymatic reaction in the citric acid cycle first catalyzes the release of 14 CO2? See the instructions below. F) Can CO2 be released at a different step in the citric acid cycle? Explain your answer. In sections B, C, D and E: Draw the chemical structure of the final molecule(s) that is formed by each enzyme in the catabolic pathway and includes the "C-label. To follow the 'C-atom through the pathways, clearly label the C-labeled carbon atom in each molecule in a different color. Be sure to include all carbon (C), oxygen (O) and hydrogen (H) atoms in your chemical structures. Also include the names of the enzyme and coenzymes (if applicable) that are involved in the catalysis of each reaction, the name of each molecule produced in the process, and indicate if the reaction is reversible or not using arrows.

Answer 1

A.
staat ㅐ 은 야 | 1 / | 12 1 ㅐ매 - Gluese
B.
C olt te Gheose 1 a-oro ATP F-er-z Нехо - ADP kinase Grease -6- Phosphate o scure É elan on Phosphoghnesse coomerane - 20,80 the one слъ, т %, Рос Fonelose-6- Phosphate nell lofa ンさ — АТР H. Phosphofneto kinase - ADP PO-2 to -o, Row p. I-lea Emelose-1, 6- Bisphesphate Aldolane ③ Dihydroxy enthate autone phosphale. Glycasal dehyde . 3. Phezphate H et ou CHOPO 2 Glyceraldehizde NADT 3-P02

- autone pour Glycanal dehyde . 3. Phezphate . ! 4 out CHOPO-2 NADT Glyceraldehyde 3-004 dehydrogenase ( 6 NADHTHT "o, r eco #-4-04 1,3-Bisphosphoglycerate. Phosphoglycenate e ADP muce дуу оро, - Kinase . — АТР. ont 3- Phosphoglycerate. CH2O PO 2 Phosphoglycenate Mutane. ose to 2-phosphoglyaraté .2 H-chopo Enolase Chaolt Phosphoenolpyamate leh, 0802 Ryourale kinase ATP

Phosphoenolpysmate let 8802 ETH Ryourale kinase ATP. Pyarate . 14 o CAR
C.
or oxidation Utz Here Decarboard? 436- → He ce - be toca e 40 o cation. cota I | Transfer 8 o C. H₂66) S-CoA
D.
Citrate Coo- COA - . 14 synthene Hool e O=C + - I > - 07- Cocos Cho atz COA СА, / ooo Acelial lot too Ć citric acid oxaloacetate § 1 oo- coo Hoc Hoover Hal-H I Iord-- T 9 - C - ceo 0o C - Q - H joc I Aconitase. - con СУО Clba CAR 1 ooc -ooc con ceo . Iso citrate eis-aconitate citrate Coo e oo &x ср. Coo NADHA' Ooo NADT if- crot @ro c= 0 ooc-c-H CHR Isocitrale ooo-e-H dehydrogenase che Clth city ceo con con X-KG. Isocitrate Oxalosuccinale

e oo CoA-s C20 c - cito INADTA COA A cont Naphttp? Olbo - > L-kG Dehydrogenase ch CHAR 1 - co L-kg Succinyl - LOA COAS 2 ہے | co im Pit ADP - an ATP tcoA. Clth Sweeingl con Saniñelase I ata 'ceo co Succinate. Smeinal LoA

FAD PADA H. i co ca cool 1 0 - C-H H S Cator Succinaté Delmessgenane en fumarase Deam H- 6-H H con Suecinate fumarate ant Malale 1 Malaté I Dehydrogenase, NADHTHE u H -6-H о . ОҲАШофее
E. The TCA cycle will take a single turn to release the C14 molecule as carbon di oxide. The reaction involving isocitrate dehydrogenase to produce oxalosuccinate and alpha ketoglutarate from iso citrate produce the first carbon di oxide molecule.

F. No. Carbon di oxide can not be release at a different step.