Metabolism, Fuels, Uptake Of Carbohydrate- Leture 9/14/21

Question 1

Brain fuel

Answer 1

Glucose

Question 2

Pathway

Answer 2

A series of enzyme assisted reactions that do chemistry proteins are capable of

Question 3

Types of pathway (examples (3)

Answer 3

Linear (glycolysis)
Cycles (urea cycle)
Spirals (fatty acid synthesis)

Question 4

Where does regulation occur in pathways

Answer 4

The steps furthest from equilibrium in the cell (the most negative delta G)

Question 5

Regulation of enzyme (4)

Answer 5

1. Inhibition or stimulation by small molecules
2. Covalent modification
3. Regulation of amount of enzyme
4. Compartmental separation

Question 6

Role of phosphorylation (rough rule)

Answer 6

Phosphorylation tends to promote breakdown

Question 7

Insulin

Answer 7

Hormone of the well fed state, promotes oxidation of glucose

Question 8

Epinephrine

Answer 8

Hormone of acute stress, tends to promote oxidation of glucose

Question 9

Glucagon

Answer 9

Hormone of the starved state, tends to promote glucose synthesis

Question 10

Cortisol

Answer 10

Hormone for long term stress response, tends to promote the synthesis of glucose

Question 11

Examples of disaccharides (3)

Answer 11

Maltose, sucrose, lactose

Question 12

Maltose

Answer 12

Glucose-glucose

Question 13

Lactose

Answer 13

Galactose-glucose

Question 14

Sucrose

Answer 14

Fructose (glucose

Question 15

Polysaccharides example (2)

Answer 15

Amylose

Amylopectin

Question 16

Starch

Answer 16

Polyglucose

Question 17

Amylose

Answer 17

Linear polyglucose

Question 18

Amylopectin

Answer 18

Branched poly glucose

Question 19

Glycemic index

Answer 19

Area under the blood glucose curve, the higher the glycemic index, the more insulin response

Question 20

Factors influencing glycemic index (8)

Answer 20

Sugar content
Type of starch
Physical barriers
Viscosity of soluble fiber
Fat and protein content
Acid content
Food processing
Cooking

Question 21

Carbohydrate digestion

Answer 21

Starts in mouth, continues in intestine and colon

Question 22

Salivary alpha amylase

Answer 22

Cleaves 1->4 glucose, cannot cleave the 1->6 bonds

Question 23

Limit dextrins

Answer 23

Smaller polyglucose with branches

Question 24

Pancreas amylase

Answer 24

Continued digestion after passing through stomach

Question 25

CCK

Answer 25

Cholecystokinin, food reaching the intestine stimulates I-cells to produce CCK that stimulates pancreas enzymes to release digestive enzymes

Question 26

Sucrase-isomaltase

Answer 26

Breaks down sucrose and dextrins

Question 27

Maltose-glucoamylase

Answer 27

Breaks down maltose and amylase to glucose compenents

Question 28

Lactase

Answer 28

Breaks down lactose

Question 29

Glut 5

Answer 29

Facilitated diffusion, moves fructose into cell from intestinal lumen

Question 30

Glut 2

Answer 30

Moves glucose to the blood from the intestinal epithelium, liver from portal system

Question 31

SGLT1

Answer 31

Moves glucose and galactose into intestinal epithelial against concentration gradient by coupling with sodium transport

Question 32

SGLT locations

Answer 32

Intestinal mucosa, kidney brush border

Question 33

Glut4

Answer 33

Moves glucose into skeletal muscle, fat, and white blood cells, INSULIN DEPENDENT

Question 34

Fanconi-Bickel Syndrome

Answer 34

It is a glut2 deficiency, glucose can’t be filtered by the liver and leads to post-prandial hyperglycemia

Question 35

Insulin mechanism of actio

Answer 35

Moves GLut4 from intracellular vesicles to cell surface, effectively increasing Vmax

Question 36

Lactose intolerance

Answer 36

Lack of lactase, creates osmotic effect in lower GI tract to pull water out of cells and also bacterial actions create dissension cramps

Question 37

Benefits of malabsorption

Answer 37

Undigested polysaccharides important in gastric emptying, stool bulk, lower cholesterol, may absorb carcinogens

Question 38

Reasons carbs may not be absorbed

Answer 38

• Not digestible by our enzymes
• Insufficient enzyme levels
• Transporter insufficiency or defect
• Lack of sufficient intestinal surface (celiac)