In the Classroom
Krebs Cycle Wordsearch Terry Helser Department of Chemistry, SUNY College at Oneonta, Oneonta, NY 13820-4015;
[email protected] This puzzle contains 46 names, terms, abbreviations and acronyms that describe the citric acid (Krebs) cycle. Find them by filling the blanks in the description beside the matrix. Then, find and highlight these terms in the letter matrix below. “KREBS CYCLE” is already done for you. Afterward, use the 24 letters remaining in the matrix to complete the sentence describing this pathway. Your success will be rewarded. The answers to Krebs Cycle Wordsearch are on page 550. Good hunting!
A M A L O N A T E C E L L U L A R
N A L A N I N E E T S W E D T R E
O L C I T R I C K G A M I N O P S
I A O S L F A D R T N R P X P Y P
R T A O C C H E E I E T A H Y T I
D E S C I U C R B E G L C M R T R
N L H I B E E S S T O N E E U A A
O K E T O G L U T A R A T E V F T
H I A R R L E C C N D O Y H A S I
C N T A E U C E Y I Y C L D T D O
O A E T A R T I C C H O H A E I N
T S C E E A R A L C E 2 N N P C E
I E M I T L O B E U D X I R T A M
How many other words of ≥ 3 letters can you find? Use the remaining letters to fill in the sentence:
M L O E D A N C A S P A R T A T E _ _ _
The K R E B S C Y C L E, also called the C _ _ _ _ _ _ _ _ _ C _ _ _ _, is a major part of C _ _ _ _ _ _ _ or A _ _ _ _ _ _ R _ _ _ _ _ _ _ _ _ _ occurring in the M _ _ _ _ _ _ _ _ _ _ _ _. To begin, P _ _ _ _ _ _ _ made from glucose or _ _ _ _ _ _ _ (Ala) enters the M _ _ _ _ _. There it is oxidized to A _ _ _ _ _-_ _ _ and _ _ _, and produces _ _ _ _ in a D _ _ _ _ _ _ _ _ _ _ _ _ complex. You need thiamine to make one of its cofactors, _ _ _. F _ _ _ _ A _ _ _ _ and A _ _ _ _ _ _ _ _s also form acetyl-_ _ _. It combines with O _ _ _ _ _ _ _ _ _ _ _ (OAA) to make C _ _ _ _ _ _, then I _ _ _ _ _ _ _ _ _ and eventually α-K _ _ _ _ _ _ _ _ _ _ _ _, a product of glutamate ( _ _ _ ), too. α-KG is oxidized, then linked to C _ _ _ _ producing succinyl-_ _ _ , which thio_ _ _ _ _ _ in turn uses to generate _ _ _ and S _ _ _ _ _ _ _ _. That is oxidized to F _ _ _ _ _ _ _ making _ _ _ _2 in a step showing competitive inhibition by M _ _ _ _ _ _ _. W _ _ _ _ is added to fumarate making M _ _ _ _ _, which is oxidized back to OAA to start the cycle again. OAA can also come from A _ _ _ _ _ _ _ _ (Asp). Finally, the E _ _ _ _ _ _ _ transport C _ _ _ _ ( _ _ _ ) regenerates _ _ _+ and _ _ _ while producing _ _ _, water, and H _ _ _.
_ _ _ _ _ _ _ _ _
_ _ _ _ _ and _ _ _
_ _ _ _.
JChemEd.chem.wisc.edu • Vol. 78 No. 4 April 2001 • Journal of Chemical Education
515
In the Laboratory
Answers to the Krebs Cycle Wordsearch on page 515
A M A L O N A T E C E L L U L A R
N A L A N I N E E T S W E D T R E
O L C I T R I C K G A M I N O P S
I A O S L F A D R T N R P X P Y P
R T A O C C H E E I E T A H Y T I
D E S C I U C R B E G L C M R T R
N L H I B E E S S T O N E E U A A
O K E T O G L U T A R A T E V F T
H I A R R L E C C N D O Y H A S I
C N T A E U C E Y I Y C L D T D O
O A E T A R T I C C H O H A E I N
T S C E E A R A L C E 2 N N P C E
I E M I T L O B E U D X I R T A M
M L O E D A N C A S P A R T A T E
The KREBS CYCLE, also called the CITRIC ACID CYCLE, is a major part of CELLULAR or AEROBIC RESPIRATION occurring in the MITOCHONDRION. To begin, PYRUVATE made from glucose or ALANINE (Ala) enters the MATRIX. There it is oxidized to ACETYL-COA and CO2, and produces NADH in a DEHYDROGENASE complex. You need thiamine to make one of its cofactors, TPP. FATTY ACIDS and AMINO ACIDs also form acetyl-COA. It combines with OXALOACETATE (OAA) to make CITRATE, then ISOCITRATE and eventually α KETOGLUTARATE, a product of glutamate (GLU), too. αKG is oxidized, then linked to COASH producing succinylCOA, which thioKINASE in turn uses to generate GTP and SUCCINATE. That is oxidized to FUMARATE making FADH 2 in a step showing competitive inhibition by MALONATE. WATER is added to fumarate making MALATE, which is oxidized back to OAA to start the cycle again. OAA can also come from ASPARTATE (Asp). Finally, the ELECTRON transport CHAIN (ETC) regenerates NAD+ and FAD while producing ATP, water, and HEAT. ALL MOLECULES BEGIN and END HERE.
550
Journal of Chemical Education • Vol. 78 No. 4 April 2001 • JChemEd.chem.wisc.edu
