Tuesday, January 8, 2008

8 - biochemistry mcqs - 54 to 64 - glycolysis

54- in glycolysis ?

ans- glucose is converted inot 2 molecules of pyruvate by the synthesis of two NADH and 2 ATP molecules and utilisation of 2ATP molecules too .

- i dont wanna give u choices in this question because it confuses u a lot , so stick to the above statement .

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55 - the compound which reduces the affinity of pyruvate kinase for its substrate ?

a- phosphoenol pyruvate
b- pyruvate
c- NADH
d- ATP

answer is ATP .

The pyruvate kinase converts phosphoenol pyruvate to pyruvate and in this reaction ATP is synthesized .

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56 - in muscle , glycolytic flux is subject to regulation by substrate cycling .

the above statement is true .

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57 - a deficiency of type B aldolase , results in __________ intolerance , a self limiting genetic disease ?

a- fructose intolerance
b- glucose intolerance
c- galactose intolerance
d- ribose intolerance

the answer is a .

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58 - the isomerisation of glucose-6-phosphate to fructose-6-phosphate is catalysed by which enzyme ?

a- hexokinase
b- glucokinase
c- phosphoglucose isomerase
d- phosphofructo kinase

answer is c . phosphoglucose isomerase.

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59 - the glyceraldehyde 3 phosphate dehydrogenase reaction is exergonic and will therefore proceed in the forward direction ?

the above statement is false . the glyceraldehyde 3 phosphate dehydrogenase reaction is slightly endergonic , but is pulled forward by the subsequent reaction of phosphoglycerate kinase . phosphoglycerate kinase converts 1 , 3 bisphosphoglycerate to 3 phosphoglycerate .

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60 - the rate of NADPH production is controlled by the rate of glucose-6-phosphate dehydrogenase reaction .

the above statement is true .

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61 - the exclusion of water from the active site of hexokinase is responsible for preventing the hydrolysis of ATP from being the dominant reaction during catalysis .

the above statement is true .

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62 - phosphoglycerate kinase catalyses a step in glycolysis , which results in the formation of ATP .

the above statement is true . the enzyme phosphoglycerate kinase catalyses the conversion of 1 , 3 bisphosphoglycerate to 3 phosphoglycerate to produce one ATP .

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63 - The hexokinase has very low affinity for hexoses .

the statement is true .

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64 - in two steps mannose is converted to ______, to enter into the glycolytic pathway ?

a- fructose 6 phosphate
b- glucose 6 phosphate
c- fructose
d- glucose

answer is a .


TO READ COMPLETELY ABOUT GLYCOLYSIS CLICK HERE

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