During fasting, when glycogen stores have been depleted, the body begins to synthesise glucose from

Question

BlackTom AI · Accepted Answer

The question asks: During fasting, when glycogen stores have been depleted, the body begins to synthesise glucose from

Option a: amino acids. This is correct because during prolonged fasting, gluconeogenesis uses non-carbohydrate precursors, primarily amino acids (especially alanine and glutamine) from muscle protein to generate glucose for tissues that depend on it, such as the brain and red blood cells.

Option b: fatty acids. Fatty acids are largely broken down to acetyl-CoA for energy via beta-oxidation and are not a primary substrate for gluconeogenesis. In mammals, acetyl-CoA derived from fatty acid oxidation cannot be converted back to pyruvate or oxaloacetate in sufficient quantities to support significant glucose production, so fatty acids do not serve as gluconeogenic substrates.

Option c: acetyl CoA. While acetyl-CoA enters the citric acid cycle to provide energy, it cannot be used directly to form glucose in gluconeogenesis because the conversion of acetyl-CoA to pyruvate or oxaloacetate is not a reversible step that yields net glucose; thus acetyl-CoA itself is not a gluconeogenic substrate.

Option d: ketone bodies. Ketone bodies are produced during prolonged fasting from acetyl-CoA to supply energy to the brain and other tissues, reducing the need for glucose. They are not substrates for gluconeogenesis; instead, they represent an alternative fuel source when glucose is scarce.

In summary, gluconeogenesis during extended fasting relies on amino acids as the principal gluconeogenic substrates, while fatty acids, acetyl-CoA, and ketone bodies serve other metabolic roles or energy pathways and do not directly supply glucose synthesis.

During fasting, when glycogen stores have been depleted, the body begins to synthesise glucose from单项选择题

类似问题

Provided the diet contains sufficient glucose precursors, most animals can synthesize enough glucose to meet their needs without a dietary source of carbohydrates.

The process of synthesizing glucose from non-carbohydrate sources is called:

In a grazing ruminant, the main source of glucose comes from:

Person X decides to eliminate completely all carbohydrates from their diet, eating only proteins. How is glucose generated?

After 1 day fasting

The synthesis of glucose from lactate, glycerol, or amino acids is called

Gluconeogenesis is

Some glucose can be synthesised from

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单