Carbohydrates

Question 1

Which two types of sugars are considered “simple”

Answer 1

• monosaccharides
• disaccharides

Question 2

Which two types of sugars are considered complex sugars?

Answer 2

• oligosaccharides
• polysaccharides

Question 3

Disaccharides are two monosaccharides joined by a(n) ________ bond

Answer 3

acetyl (glycosidic)

Question 4

What is the ratio of H:O in CHOs

Answer 4

2:1

Question 5

Which monosaccharide is nutritionally the most important? Trioses, Pentoses or Hexoses

Answer 5

Hexoses

Question 6

What is a chiral carbon?

Answer 6

a carbon with four different groups attached to it

Question 7

What is the difference between D and L sugars

Answer 7

D - last OH is on the right side of the chain
L - last OH is on the left side of the chain

Question 8

Are D or L sugars more nutritionally important? Why?

Answer 8

D because digestive enzymes are stereospecific for D sugars

Question 9

Which of the three common disaccharides is/are reducing sugars? (sucrose, lactose and maltose)

Answer 9

• lactose
• maltose

Question 10

Which of the three common disaccharides is/are non-reducing sugars? (sucrose, lactose and maltose)

Answer 10

sucrose

Question 11

what is the minimum amount of monosaccharides required to be considered a polysaccharide

Answer 11

6

Question 12

are hetero or homopolysaccharides more abundant in food?

Answer 12

homopolysaccharides

Question 13

What are three types of insoluble dietary fibres?

Answer 13

1.Cellulose
2.Hemicellulose
3.Lignin

Question 14

What are three types of soluble dietary fibres

Answer 14

1. Pectin
2. Gums
3. Mucilages

Question 15

This dietary fibre has B-1,4 glucose units

Answer 15

Cellulose

Question 16

This dietary fibre has a mixture of a and b glycosidic linkages

Answer 16

hemicellulose

Question 17

this dietary fibre has a-1,4-linked-D galacturonic acid backbone

Answer 17

Pectin

Question 18

What is the function of insoluble fibre?

Answer 18

• decreases constipation
  
  • stimulates muscle contraction to break down waste
  • decreases risk of bacterial infections

Question 19

What is the function of soluble fibre?

Answer 19

• increase satiety
  
  • delays gastric emptying
  • slows nutrient uptake

Question 20

What types of bonds does salivary a-amylase break down? What is resistant?

Answer 20

• breaks down a-1,4-glycosidic bonds
• cellulose, lactose, and a-1,6-bonds are resistant

Question 21

what does isomaltase do?

Answer 21

breaks a-1,6 glycosidic bonds that are resistant to stomach and salivary digestion. (into 2 glucose)

Question 22

What are most monosaccharides taken up by?

Answer 22

enterocytes

Question 23

What types of sugars enter the blood by basolateral GLUT2?

Answer 23

glucose, galactose and fructose

Question 24

What are the three fates that glucose has in a cell?

Answer 24

1. enter glycogenesis for energy storage
2. enter glycolysis for energy production
3. enter hexose monophosphate shunt to generate precursors for biogenesis

Question 25

What is the function of the Glycogen Synthase enzyme?

Answer 25

- converts glucose 1-phosphate to glycogen

Question 26

what is the function of the glucokinase enzyme in the liver?

Answer 26

- convert blood glucose to glucose 6-phosphate

Question 27

what is the function of the glycogen phosphorylase enzyme?

Answer 27

- break down glycogen to glucose 1-phosphate by breaking a-1,4-glycosidic bonds

Question 28

What is the function of the hexokinase enzyme?

Answer 28

- Converts blood glucose to glucose 6-phosphate in muscle

Question 29

What is the function of the glucose-6-phosphatase enzyme?

Answer 29

- convert glucose 6-phosphate to blood glucose in the liver

Question 30

what does glucagon stimulate??

Answer 30

glycogen breakdown

Question 31

what does insulin do?

Answer 31

- stimulates glycogen formation - stimulates glucose uptake from food into tissue cells

Question 32

What does low blood sugar stimulate?

Answer 32

glucagon release

Question 33

what does high blood sugar stimulate?

Answer 33

insulin release

Question 34

what is the net energy yield from one glucose in glycolysis

Answer 34

- 2 NADH - 2 ATP (8 ATP)

Question 35

What is the Cori cycle?

Answer 35

- occurs under anaerobic conditions in muscle leading to the production of lactate - lactate gets transported back to the liver and converted to pyruvate - gluconeogenesis allows for conversion of pyruvate back to glucose - not sustainable because 6 ATP is required for 2 molecules of lactate to form glucose

Question 36

What does the hexose monophosphate shunt do>

Answer 36

generation of NADPH and precursors for nucleotide synthesis

Question 37

What vitamins are used as cofactors in the pyruvate dehydrogenase complex

Answer 37

- thiamine - niacin - riboflavin - pantothenic acid

Question 38

How much ATP is generated from 1 NADH

Answer 38

3

Question 39

How much ATP is generated from 1 FADH2

Answer 39

2

Question 40

How much ATP is generated from one GTP

Answer 40

1

Question 41

What is the energy yield from one acetyl-coA in the Kreb's cycle

Answer 41

- 3 NADH - 1 FADH2 - 1 GTP (12 ATP)

Question 42

What is the energy yield from pyruvate dehydrogenase?

Answer 42

1 NADH

Question 43

What is the ATP yield from the complete oxidation of 1 mole of glucose?

Answer 43

- 38 ATP - Glycolysis = 2 NADH (6 ATP) + 2 ATP - Pyruvate Dehydrogenase = 1 NADH (3 ATP) - Kreb's cycle = 3 NADH (6 ATP), 1 FADH2 (2 ATP), 1 GTP (1 ATP) x 2 because 2 acetyl coA