Biochemistry : Identifying Specific Carbohydrate Functions
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Example Question #1 : Identifying Specific Carbohydrate Functions
Upon examination, a patient is found to have low levels of glucose in his blood. Which of the following observation(s) might be found in this patient?
I. The patient is lethargic
II. Decreased levels of glycogen
III. Decreased levels of fatty acids
I and III
I and II
I, II, and III
II only
I, II, and III
Glucose is a monosaccharide that is utilized for energy production in cells. Decrease in glucose levels in blood and tissues will lead to decreased production of energy (ATP) and, subsequently, will cause the person to be lethargic. Recall that glucose undergoes glycolysis to create products that will eventually undergo Krebs cycle and/or oxidative phosphorylation to generate ATP.
Glycogen is a storage molecule found typically in liver. It is made up of numerous glucose molecules bonded together by glycosidic bonds. If there is a decrease in blood glucose levels, liver initiates the breakdown of glycogen to individual glucose molecules and deposits these molecules in the blood; therefore, this patient’s liver will break down glycogen and create individual glucose molecules.
Fatty acid is another type of macromolecule used to synthesize energy. If there is a decrease in levels of glucose, fatty acids from adipose tissue and muscle will be mobilized and released into the blood. These fatty acids will now travel to tissues and supply energy (by generating ATP).
Example Question #2 : Identification By Function
Atkins diet is a special diet that involves low intake of carbohydrates. Which of the following molecules might be elevated in a person following the Atkins diet?
More than one of these
Ketone bodies in blood
Blood glucose
Glycogen stores in liver
Ketone bodies in blood
Carbohydrates are first lines of energy source for tissues. If there is a decrease in the amount of carbohydrates, then other energy sources such as fatty acids and proteins are mobilized and undergo metabolism to produce energy. One of the byproducts of fatty acid metabolism are ketone bodies; therefore, a decrease in carbohydrates will lead to an increase in fatty acid metabolism and, subsequently, an increase in ketone bodies.
Glycogen stores will be depleted because liver will respond to the decreased glucose levels and break down glycogen to component glucose molecules. Low carbohydrate concentration will decrease blood glucose levels.
Example Question #1 : Identifying Specific Carbohydrate Functions
In which cellular compartment is pyruvate carboxylase found?
Golgi apparatus
Endoplasmic reticulum
Mitochondria
Nucleus
Mitochondria
Pyruvate carboxylase is an enzyme involved in gluconeogenesis, which is the generation of glucose from non-carbohydrate carbon substrates. This enzyme aids in the formation of PEP (phosphoenolpyruvate) from pyruvate. It converts pyruvate to oxaloacetate in the mitochondrion, requiring the hydrolysis of one molecule of ATP.
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