GtP Metabolism week 8

Where does protein digestion begin and which enzyme initiates it?

Stomach – Pepsin breaks proteins into polypeptides.

What enzymes continue protein digestion in the small intestine?

Trypsin, Chymotrypsin, Carboxypeptidase

What is the role of the sodium-potassium ATPase in amino acid absorption?

It creates a sodium gradient, powering sodium-amino acid co-transporters.

How are amino acids and peptides absorbed?

By enterocytes using specific amino acid transporters and peptidases at the brush border.

How do sodium-hydrogen exchangers assist peptide absorption?

They exchange sodium for hydrogen ions, helping maintain the gradient needed for transport.

What are some main uses of absorbed amino acids in the body?

For protein synthesis, nucleotide formation, or as an energy source.

What happens to excess amino acids in the body?

They are deaminated, producing toxic ammonia.

How is ammonia detoxified in the body?

The liver converts it into urea via the urea cycle for excretion by the kidneys.

Which key enzymes are involved in the urea cycle?

Carbamoyl phosphate synthetase and ornithine transcarbamylase.

How does the body regulate glycogen storage and breakdown?

Through glycogenesis (storage) and glycogenolysis (release), regulated by insulin and glucagon.

What is glycolysis, and what does it produce?

It's the breakdown of glucose into pyruvate, producing ATP and NADH.

What happens to fatty acids during fasting or energy demand?

They undergo beta-oxidation to produce acetyl-CoA, which enters the Krebs cycle.

When and why are ketone bodies formed?

During fasting or low carbohydrate intake, to provide energy (especially to the brain).

How do amino acids support glucose production during fasting?

Through gluconeogenesis, where they’re converted into glucose in the liver.