A Level Biology Revision "Structure and Function of Glycogen"

Summary

This video explains the structure and function of glycogen, the primary glucose storage molecule in animals. Glycogen consists of alpha glucose units linked by 1-4 and 1-6 glycosidic bonds, with numerous branches that allow for rapid breakdown and energy release. The branched structure makes glycogen compact and efficient, supporting quick glucose mobilization during increased energy demand, such as physical activity or stress. Unlike glucose, glycogen is insoluble in water, preventing osmotic issues within cells. This design makes glycogen ideal for storing energy in animal tissues, especially in the liver and muscles.

Takeaways

• 😀 Glycogen is a polysaccharide made of alpha glucose, used by animals to store glucose.
• 😀 Glycogen's structure is similar to amylopectin but more highly branched, making it more compact.
• 😀 The glucose molecules in glycogen are connected by 1-4 glycosidic bonds, with branches connected by 1-6 glycosidic bonds.
• 😀 The high branching in glycogen creates numerous free ends, allowing for rapid glucose release when needed.
• 😀 Glycogen's compact structure helps optimize space for storage in cells like the liver and muscles.
• 😀 Glycogen provides a fast source of glucose for energy, which is especially important during periods of high activity or stress, such as escaping from predators.
• 😀 Because glycogen is insoluble in water, it does not cause cells to swell by osmosis, unlike glucose.
• 😀 Glycogen's large size prevents it from diffusing out of cells, ensuring it remains stored in the cell for later use.
• 😀 Starch in plants and glycogen in animals both store glucose, but glycogen has more branches and is more compact than starch.
• 😀 The ability to rapidly convert glycogen into glucose supports high energy demands in animals, particularly in muscle cells during physical exertion.

Q & A

What is glycogen and what is its primary function in animals?

Glycogen is a polysaccharide composed of alpha glucose molecules, and its primary function is to store glucose in animals, particularly in the liver and muscle cells, for energy use during periods of high demand.

How does the structure of glycogen relate to its function?

The structure of glycogen, with its highly branched chains, allows for rapid glucose release from the many free ends. This enables quick conversion of glycogen into glucose, which is essential for meeting the energy needs of animals.

What are the main differences between glycogen and amylopectin?

Both glycogen and amylopectin are polymers of alpha glucose, but glycogen is more highly branched than amylopectin. This additional branching makes glycogen a more compact molecule and allows it to be more rapidly converted into glucose.

What types of glycosidic bonds are found in glycogen?

Glycogen contains 1-4 glycosidic bonds connecting the glucose molecules in the main chain and 1-6 glycosidic bonds at the branching points.

Why is the branching of glycogen important for its function?

The branching of glycogen creates many free ends, where enzymes can act quickly to break glycogen down into glucose, making it an efficient source of energy during times of increased activity or stress.

How does glycogen’s solubility affect its function in animal cells?

Glycogen is insoluble in water, which prevents it from causing water to enter cells by osmosis. This ensures that glycogen remains in the cells without disrupting their water balance.

What role does glycogen play during periods of high respiration or physical activity?

During high respiration or physical activity, glycogen stored in muscle cells is rapidly broken down into glucose to provide quick energy for the body’s increased metabolic demands.

Why is glycogen an ideal storage molecule for glucose in animals?

Glycogen is an ideal storage molecule because it is insoluble in water, does not draw water into cells, and is large enough to stay within cells while being easily converted back into glucose when needed.

What is the significance of glycogen being insoluble in water?

The insolubility of glycogen in water ensures that it does not cause osmosis and water influx into cells, which would be detrimental to cell function. It also allows glycogen to remain stored in the cells without diffusing out.

Where in the body is glycogen primarily stored?

Glycogen is primarily stored in the liver and muscle cells of animals.