Keeping an Eye on Your Blood Sugar Quiz

Answer: Hyperglycemia

Carbohydrates are long chains of sugar units linked by glycosidic bonds. They are broken down by enzymes such as amylase to ultimately yield glucose - the primary fuel unit for most of our tissues.

Answer: Beta cells

The pancreas is a multi-functional organ, releasing hormones and enzymes which generally influence metabolism. Glucose enters the pancreatic beta cells and is metabolised, releasing ATP. This ATP actually acts as a signal and causes an influx of calcium into the cell, inducing it to secrete insulin.

Answer: Glycolysis

Glycolysis can be boiled down to ten distinct steps, which involves phosphorylation, cleavage and isomerisation, which ultimately converts one molecule of glucose into two molecules of pyruvate. There is a net yield of 2 ATP (energy) molecules per glucose, as well as two molecules of NADH, which can be used to generate yet more ATP in later stages of metabolism.

Answer: Glycogen

Glycogen synthesis mainly occurs in the liver, but can also occur in skeletal muscle. Glucose in liver cells is converted into glycogen by an enzyme called glycogen synthase. Another enzyme called glycogen phosphorylase is responsible for the opposite reaction, and this is inhibited by insulin signalling.

Answer: They increase the rate of glucose uptake into the cell

GLUT4 proteins are glucose transporters that are found in muscle and adipose cells. They usually exist in the cytoplasm, but are recruited to the cell membrane following insulin activation. At the membrane, they are able to increase the rate of uptake of glucose into the cell and therefore reduce the amount of glucose circulating in the blood.

It also provides the glucose for cellular processes such as glycolysis and glycogen synthesis (as discussed in the previous two questions).

Answer: The inability to sense and respond to insulin signalling

Insulin resistance has essentially the same effect as having little/no insulin, meaning that glycolysis, glycogen synthesis and glucose uptake are impaired and so blood glucose remains high.

Answer: Type 2 diabetes

High levels of circulating nutrients (such as glucose) indicates to the pancreas that other tissues have become insulin resistant and so the beta cells try and produce more insulin. This is called beta cell compensation. This may work for a short period of time, but the stress placed on these beta cells to produce vast amounts of insulin results in oxidative stress and eventual beta cell failure.

Answer: Secretion of glucagon

Glucagon can be seen in many ways as the opposite of insulin. It activates the enzyme responsible for glycogen breakdown and inhibits glycolysis. Glucagon controls this via binding to a receptor at the plasma membrane and inducing a signalling cascade. The ultimate outcome is the preservation of glucose for vital organs.

Answer: Gluconeogenesis

Gluconeogenesis occurs in the liver. Most amino acids can be converted into glucose precursors. Essentially, any amino acid capable of being converted into a component of the citric acid cycle is a glucose precursor. For example, glutamate can be converted into alpha-ketoglutarate, and aspartate can be converted into oxaloacetate.

Answer: Because the brain is almost entirely dependent on glucose for its energy

The fatty acids of lipids yield energy by undergoing a process known as beta oxidation, which yields plenty of ATP. However, the brain depends almost entirely on glucose for its metabolism and so in times of low blood glucose the body will promote gluconeogenesis and will divert glucose supply away from tissues other than the brain.