Question

Which of the following hormones promotes the conversion of glucose into glycogen?
A. Glucagon
B. Adrenaline
C. Insulin
D. Progesterone

Answer 1

Hint: Glycogen is a polysaccharide of glucose that acts as energy storage in animals and few other organisms. Whenever the blood glucose level is reduced or the body is lacking energy the stored glycogen is converted into glucose to fulfil the glucose requirement.

Complete answer: Glucose serves as an energy-providing molecule in our body. This glucose is used by many cells and tissues to perform certain biological functions. Some amount of glucose is stored in the liver in the form of glycogen as a reservoir. This process of conversion of glucose into glycogen is known as glycogenesis. The reaction for the synthesis of glycogen is;
$\text{Glucose }\xrightarrow[\text{ATP}]{\text{Hexokinase}}\text{ Glucose-6-phosphate + ADP}$
$\text{Glucose-6-phosphate}\xrightarrow{\text{Mutase}}\text{Glucose-1-phosphate}$
Glycogen synthesis is initiated from Glucose-1-phosphate,
$\text{Glucose-1-phosphate + UTP + (Glucose}{{\text{)}}_{\text{n}}}\xrightarrow{\text{Glycogen synthase}}{{\text{(Glucose)}}_{\text{n+1}}}\text{+ UDP + pyrophosphate}$
Here, ${{\text{(Glucose)}}_{\text{n+1}}}$ is glycogen, as it is a polysaccharide of glucose.
Glycogenesis is performed depending on the level of glucose and ATP, i.e. energy present in the body. If the body or a cell has a sufficient amount of glucose and energy, the liver initiates the conversion of glucose into glycogen with the help of the insulin hormone. Insulin is produced by beta-cells of islets of Langerhans in the pancreas. The release of insulin stimulates the liver to convert excess glucose into glycogen, which can be used further as an immediate energy supply.
Hence, the correct answer is option C.

Note: Initially, when the level of glucose is high in the blood (hyperglycemia), insulin binds to cells increasing the uptake of glucose by cells and other tissues, resulting in a decrease in glucose level in the blood. However, there are few organs like kidney, liver and brain cells that take up glucose via diffusion. If the liver is saturated with glycogen, then the glucose is taken up by adipose tissues which synthesizes lipoprotein with the help of insulin.