Questions:
a) What is the chemical structure of glycogen and what is its biological function?
Glycogen chemical structure has got a long polymer chain of glucose units that are configured by an alpha acetal linkage. The linkages are formed through the combination of alcohol and carbonyl group. In instances that the carbonyl group also forms the aldehyde group (-CHO), then it is referred to as hemiacetal, and if ketonic group exist, then hemiketal linkage is formed.Glycogen plays a key role as one of the long term energy reserves in the human body after undergoing the process of conversion into glucose and is majorly stored and made in the muscles, liver, and liver.
b) Glycogen stored in muscles and liver has quite different physiological functions. Explain.
First, the liver cell is responsible for regulating the glucose level in the blood since they can break up glycogen in a process known as glycogenolysis. Glucose is not a significant energy source for liver, which mainly uses keto acids. Hence, the liver cells initiate glucose storage and release mainly for the efficient functioning of other organs. Therefore, this reveals the concept of dual functionality. On the other hand, in the muscle glycogen acts asan energy reserve that can be generated in the process of exercise. Therefore, the muscle cells are capable of realizing glucose in the blood, so the glycogen is stored for the main purpose of internal use during strenuous activity
c) What is the function of glycogen phosphorylase and how is its activity different from that of amylase?
The main function of glycogen phosphate is to provide phosphorylated glucose molecules commonly abbreviated as (G-1-P) through the process of metabolism and glycolysis to generate ATP for the cell. In general, it catalyzes the rate-limiting step in the process of glycogenolysis. The phosphorylated glucose originates from cellular and glycogen phosphate. Its activity is distinct from amylase since it cannot break down starch in the form of amylose and amylopectin. Therefore, phosphorylase uses the process of phosphorolysis to split linkages alpha (1->4) while amylase uses the process of hydrolysis to split linkages alpha (1->4)
d) What is the function of the de-branching enzyme and why is it required for complete glycogen breakdown?
The de-branching enzyme helps in the facilitation of the breakdown of glycogen, which forms the glucose storage site in the body through glucosidase and glucosyltransferase activities. Moreover, in conjunction with phosphorylases, this enzyme mobilizes glucose reserves from glycogen deposits in the liver and muscle. The de-branching enzyme plays an integral role in complete glycogen break downsince the breakdown involves a high regulation from the blood, particularly in the liver by hormones such as glucagon and insulin to stabilize the homeostatic balance of the blood and glucose level. The de-branching enzyme can only undertake this function
e) What is the function of phosphoglucomutase in glycogen metabolism? Phosphoglucomutase aids the process of glycogen synthesis and transports a phosphate group on a glucose form monomer from position 1-6 in a forward direction or position 6-1 one in a reverse direction. Generally, Phosphoglucomutase aids the process of glycogen metabolism by aiding the conversion of glucose 6-phosphate and glucose 1-phosphate.
f) What is the function of glucose-6-phosphatase?
Glucose-6 phosphatase is an enzyme majorly found in the kidney and the liver. This enzyme plays the role of providing glucose when the body is undergoing starvation. It hydrolyzes glucose six phosphates which result in the development of a phosphate group and free glucose. In contrast with other phosphatases acting on water-soluble compounds, glucose-6-phosphatase is a membrane-based enzyme which is associated with the endoplasmic reticulum
g) What are the biochemical basis and consequences of von Gierke’s disease and what is the incidence of this disorder?
Von Gierke’s also referred to as Glycogenosis I is the most common type of glycogen storage disorders. The disease is inherited through autosomal-recessive characteristic. This disease makes the body’s metabolism of glycogen is restricted by the inactiveness of enzyme six phosphatases which plays a role of realizing the simple glucose sugar from glycogen stored in the liver. The consequences will be an abnormal accumulation of glycogen in the liver, making the liver to enlarge and produce symptoms of gout and low blood sugar
h) What causes Pompe’s disease?
Pompe’s disease occurs when an individual’s body cannot generate enough protein to break down the complex sugars of glycogen for energy purposes. Therefore, the disease is caused by too much sugar build up which eventually damages an individual’s muscles and organs. Moreover, this disease is mostly acquired from one’s parents where the inheritance of two flawed genes from each parent is involved. The effects of Pompe’s diseases are too much weakness all over the body and difficulty during breathing.
i) The deficiency of what enzyme causes Cori’s disease?
Glycogen debranching enzyme
j) What disease is caused by lack of muscle phosphorylase and what are its symptoms?
The disease is McArdle which also has another name of glycogen storage disease V (GSDV). The symptoms of this disease are evident in the muscles. First, it will make it difficult for an individual to carry out exercise activity without getting tired, and this does not take place with gentle walking. However, an individual will experience difficulty with strenuous exercise for a few minutes. Generally, the common and most frequent symptoms of this disease are;muscle cramping, red urine particularly after an activity, permanent weakness on the thigh, conducting an aerobic exercise for about 10 minutes only, muscle pain and ease of tiring during activities