9 - biochemistry mcqs - 65 to 75 - glycolysis

65 - which enzyme is the major control point for glycolysis in muscle under most conditions .

a- glucokinase
b- hexokinase
c- phosphofructokinase
d- pyruvate kinase

answer is c .

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66 - ATP in fast twitch muscle fibres is supplied predominantly by which type of glycolysis

a- aerobic
b- anaerobic

answer is b . anaerobic glycolysis .

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67 - the rate of ATP production by anaerobic glycolysis can be upto 100 times faster than that of oxidative phosphorylation .

the above statement is true .

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68 - under which conditions is the complete oxidation of pyruvate mediated by citric acid cycle ?

a- aerobic
b- anaerobic

answer is a .

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69 - impaired substrate cycling may lead to a lack of nonshivering thermogenesis and result in cold sensitivity in obese individuals .

the above statement is true .

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70 - which molecule acts as a signal amplifier when concentrations of ATP are low to increase the phosphofructokinase activity ?

a- ADP
b- ATP
c- AMP
d- NADH

answer is c . AMP .

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71 - Ribulose 5 phosphate ( RU5P ) is converted to ribose 5 phosphate ( R5P ) by the enzyme ?

a- ribulose 5 phosphate dehydrogenase
b- ribose 5 phosphate dehydrogenase
c- RU5P ISOMERASE
d- R5P ISOMERASE

the answer is C .

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72 - which aminoacid side chain forms the schiff base with the substrate in the aldolase reaction ?

a- arginine
b- serine
c- tyrosine
d- lysine

answer is d.

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73 - lactate formed in skeletal muscle cells during anaerobic glycolysis is carried back to the liver , where it is used to synthesize

a- glucose
b- fructose
c- fatty acids
d- amino acids

answer is a .

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74 - flouride ion inhibits glycolysis by inhibiting the action of which enzyme ?

answer - enolase
aldolase

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75 - what is the enzyme which catalyses the formation of glyceraldehyde 3 phosphate and dihydroxy acetone phosphate ?

a- aldolase
b- enolase
c- kinase
d- mutase

answer is a . aldolase .


TO READ COMPLETELY ABOUT GLYCOLYSIS CLICK HERE

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7 - glycolysis

Glycolysis is the sequence of reactions that converts glucose into pyruvate with the concomitant production of a relatively small amount of adenosine triphosphate (ATP). The word is derived from Greek γλυκύς (sweet) and λύσις (letting loose).

It is the initial process of most carbohydrate catabolism, and it serves three principal functions:

1. The generation of high-energy molecules (ATP and NADH) as cellular energy sources as part of aerobic respiration and anaerobic respiration; that is, in the former process, oxygen is present, and, in the latter, oxygen is not present
2. Production of pyruvate for the citric acid cycle as part of aerobic respiration
3. The production of a variety of six- and three-carbon intermediate compounds, which may be removed at various steps in the process for other cellular purposes.

As the foundation of both aerobic and anaerobic respiration, glycolysis is the archetype of universal metabolic processes known and occurring (with variations) in many types of cells in nearly all organisms. Glycolysis, through anaerobic respiration, is the main energy source in many prokaryotes, eukaryotic cells devoid of mitochondria (e.g., mature erythrocytes) and eukaryotic cells under low-oxygen conditions (e.g., heavily-exercising muscle or fermenting yeast).

In eukaryotes and prokaryotes, glycolysis takes place within the cytosol of the cell. In plant cells, some of the glycolytic reactions are also found in the Calvin-Benson cycle, which functions inside the chloroplasts. The wide conservation includes the most phylogenetically deep-rooted extant organisms, and thus it is considered to be one of the most ancient metabolic pathways.

The most common and well-known type of glycolysis is the Embden-Meyerhof pathway, initially explained by Gustav Embden and Otto Meyerhof. The term can be taken to include alternative pathways, such as the Entner-Doudoroff Pathway. However, glycolysis will be used here as a synonym for the Embden-Meyerhof pathway.