Digestion and absorption of carbohydrates, cellular glucose uptake, glucose transport

Question 1

What is Anabolism?

Answer 1

Precursor molecules like amino acids, sugar, fatty acids and nitrogenous bases become

• proteins
• polysaccharides
• Lipids
• Nucleic acids

Through uptaking of ATP, NADH, NADPH, FADH (chemical energy) and giving: ADP + HPO2-4,NAD+, NaDP+, FAD

Question 2

Give examples of derivatives of carbohydrates

Answer 2

Phosphate groups
Amino groups
Sulfate groups

Question 3

What is catabolism?

Answer 3

Making energy depleted end products like CO2, H2O and NH3 out of Energycontaining nutrients; Carbohydrates, Fats, proteins

Question 4

Shortly describe the catabolism

Answer 4

Carbohydrates -> Glucose -> Glycolysis -> Pyruvate -> Acetyl CoA -> Citric acid cycle -> CO2-> Oxidative phosphorylation = ATP

Question 5

What are carbohydrates in the diet?

Answer 5

Starch, disaccharides (sucrose and lactose) and glucose

Question 6

Where are Carbohydrates absorbed?

Answer 6

Only in the small intestine

Question 7

What happens when starch enters the mouth?

Answer 7

Alpha-amylase acts on starch cleaving alpha 1,4 linkages

Question 8

What happens in the intestine?

Answer 8

Enzymes digest sucrose, lactose and the products generated form starch by amylase

Question 9

What is starch?

Answer 9

The storage form of carbohydrate in plants. Contains amylose and amylopectin.

Question 10

What is sucrose?

Answer 10

A component of table sugar and fruit, contains galactose and fructose residues linked via their anomeric carbons

Question 11

What is Lactose?

Answer 11

Milk sugar, contains galactose linked beta 1-4 to glucose

Question 12

Which enzymes are located at the brush border of the small intestine?

Answer 12

Glycosidases, sucrase, lactases, galactose ++

Question 13

What is SGLT1 and SGLT2?

Answer 13

Sodium dependent glucose cotransporter. Sodium-glucose linked transporter, SGLT) are a family of glucose transporter found in the small intestine (SGLT1) and the proximal tubule of the nephron (SGLT2 in PCT and SGLT1 in PST). They contribute to renal glucose reabsorption.

Question 14

What is the function of SGLT1?

Answer 14

Normal people: No production of glucose
Diabetes: Increased glucose excretion
Diabetes and SGLT2-inhibition: Increased glucose excretion

Question 15

Why do we need Glucose transporters?

Answer 15

They are uniports = involves the movement of a single molecule at the time, lowering the concentration gradient

Question 16

Which glucose transporters do we have in humans?

Answer 16

GLUT1 (erythrocytes, blood brain barrier, placenta, most tissue at low level)
GLUT 2 ( liver, pancreatic islands, intestine, kidney)
GLUT 3 (Brain, testis)
GLU4 (muscle, fat)
GLUT5 ( intestine)
GLUT 6, GLUT 7, GLUT 8, GLUT 9, GLUT 10, GLUT 11, GLUT12

Question 17

What are the symptoms of intestinal lactase deficiency?

Answer 17

Lactose cannot be digested = production of gass bc of oxidation. Floating and watery diarrhea.

Question 18

Mention a secondary active transport way of glucose

Answer 18

Transport proteins that carries sodium ions in addition to the monosaccharide