Biochemistry : Anabolic Pathways and Synthesis
Study concepts, example questions & explanations for Biochemistry
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Example Questions
Example Question #5 : Carbohydrate Anabolism
What is the major distinction between NADH and NADPH in biochemistry?
NADH is used primarily by eukaryotes, whereas NADPH is used primarily by prokaryotes
NADH and NADPH serve the same function in all reactions
NADPH is oxidized in catabolic reactions to produce ATP, wheres NADH serves as a reducing agent in anabolic reactions
NADH is oxidized in catabolic reactions to produce ATP, wheres NADPH serves as a reducing agent in anabolic reactions
NADH is used in reactions to create ATP, whereas NADPH is used in reactions to produce ADP
NADH is oxidized in catabolic reactions to produce ATP, wheres NADPH serves as a reducing agent in anabolic reactions
The major distinction between NADH and NADPH is that NADH is generally used in catabolic reactions meant to produce ATP. NADPH, on the other hand, is used primarily in anabolic reactions meant to build macromolecules from their smaller parts.
Example Question #1 : Carbohydrate Anabolism
What is the role of phosphoenolpyruvate carboxykinase in carbohydrate metabolism?
Carbon dioxide is a byproduct of the reaction that it catalyzes
The enzyme converts oxaloacetate to phosphophenolpyruvate
All of these
Guanosine triphosphate (GTP) is converted to guanosine diphosphate (GDP) by the enzyme
The reaction catalyzed by this enzyme is one of the first steps in gluconeogenesis
All of these
Gluconeogenesis is the production of glucose from other sources than carbohydrates, such as from pyruvate, amino acids, lactate and glycerol. Phosphoenolpyruvate carboxykinase converts oxaloacetate to phosphoenolpyruvate and carbon dioxide. It also produces GDP from GTP. It is regulated by hormones, such as glucagon and cortisol.
Example Question #133 : Anabolic Pathways And Synthesis
What two molecules are the links between the urea cycle and gluconeogenesis?
Citrate and aspartate
Fumarate and citrate
Oxaloacetate and fumarate
Fumarate and aspartate
Oxaloacetate and citrate
Fumarate and aspartate
Aspartate can form arginosuccinate, which can then release a fumarate molecule. The fumarate can enter into the Krebs cycle and eventually the pathway can lead to gluconeogenesis. The arginine from the arginosuccinate can continue through the urea cycle.
Example Question #131 : Anabolic Pathways And Synthesis
In order to be added to a growing glycogen chain, glucose must first be activated by which of the following molecules?
UDP
ADP
UTP
ATP
GDP
UDP
UDP-glucose is the activated form of glucose that works to build chains of glycogen. The other listed molecules do not serve this function.
Example Question #134 : Anabolic Pathways And Synthesis
How does ingestion of high amounts of ethanol affect gluconeogenesis?
I. High amounts of ethanol get oxidized producing NADPH.
II. High levels of NADPH inhibit gluconeogenesis.
III. High levels of NADPH stimulate gluconeogenesis.
IV. High amounts of ethanol get oxidized producing NADP.
II and IV
I and IV
III only
I and III
I and II
I and II
Ingestion of high amounts of ethanol leads to increased NADPH. High levels of NADPH inhibit gluconeogenesis followed by low glucose levels in the absence of dietary intake. In acute ingestion of alcohol, hypoglycemia (low levels of glucose in the blood) can follow due to inhibition of gluconeogenesis.
Example Question #131 : Anabolic Pathways And Synthesis
What is the net yield from the pentose phosphate pathway?
I.
II.
III.
IV.
I and II
III only
I only
II only
IV only
I only
The pentose phosphate pathway produces NADPH and five-carbon sugars. The net reaction is:
The pathway is also important in purine precursor synthesis.
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