Transport Proteins

Question 1

In the digestion and absorption of carbohydrates what occurs after hydrolysis?

Answer 1

Carbohydrates are transported across the membrane of the intestine

Question 2

What are transporters?

Answer 2

A type of enzyme that relocates substrates instead of converting them

Question 3

What happens to the carbohydrates in the intestine?

Answer 3

They are initially moved against the concentration gradient into the cells and are subsequently released downhill into the bloodstream

Question 4

What is the uphill movement of carbohydrates facilitated by?

Answer 4

The concomitant movement of Na+ downhill (Na+ gradient hypothesis)

Question 5

What is the energy for transport derived from?

Answer 5

The hydrolysis of ATP (primary active transport) or from substrate and ion gradients (secondary active transport

Question 6

What is glucose-galactose malabsorption and what is it caused by/ what does it cause (why)

Answer 6

A rare genetic disorder

• Caused by a mutation in the intestinal glucose transporter SGLT1
• Causes severe diarrhea because glucose is not removed from the intestine and subsequently metabolized by the intestinal microflora, forming fermentation products
• This causes reverse osmosis similar to the situation in lactose intolerance