Carbs

Question 1

Polysaccharides subgroups (2)

Answer 1

Starch (a-glucans)
Non starch (non a-glucans)

Question 2

Examples of monosaccharides (3)

Answer 2

Glucose
Fructose
Galactose

Question 3

How are monosaccharides linked together?

Answer 3

Glycosidic bonds

Question 4

What are the subgroups of sugar?(3)

Answer 4

Monosaccharides 
Disaccharides 
Polyols (sugar alcohols)

Question 5

Oligosaccharides subgroups (2)

Answer 5

Malto-oligos

Non digestible-oligos

Question 5

Explain the structure of starch (4)

Answer 5

Consists of linear amylose and branched amylopectin

Linear amylose - chain of glucose linked together by 1,4 bonds

Branched amylopectin - glucose also linked by 1,4 however branch points are 1,6 bonds

Question 6

Which bonds cannot be broken down by the small intestine?

Answer 6

B- bonds

Question 7

What determines whether a carb is digestible by enzymes?

Answer 7

Type of bond

Question 8

Disaccharides examples (3)

Answer 8

Lactose
Maltose
Sucrose

Question 9

What determines the nutritional properties of a carb?(2)

Answer 9

Monosaccharide composition

Type of bond

Question 10

What are glycaemic carbs?(2)

Answer 10

They provide glucose for metabolism

As a result of digestion in absorption in small intestine

Question 11

What are non glycaemic carbs?(2)

Answer 11

Not absorbed in small intestine

Fermented in large intestine

Question 12

What are carbs composed of?(3)

Answer 12

Carbon, hydrogen, oxygen

Question 13

What is the enzyme that hydrolyses glycaemic carbs?

Answer 13

a-amylase

Question 14

How are monosaccharides aborted across the basolateral membrane?(2)

Answer 14

Facilitated diffusion

GLUT2

Question 15

What is the brush border?

Answer 15

Microvilli on the small intestine wall

Question 16

Name the brush border enzymes involved in digestion (3)

Answer 16

Glucosidases (Maltase)
Disaccharidases
Oligosaccharidases

Question 17

Explain the digestion process in the stomach (3)

Answer 17

Chewing and salivary a-amylase partially breakdown starch
Starch enters the stomach
Salivary amylase is inactivated by stomach acid

Question 18

Explain digestion in the small intestine (3)

Answer 18

Food reaches the lumen of the small intestine
Pancreatic a-amylase further breaks down starch
Brush border/enterocyte enzymes breaks down starch to monosaccharides

Question 19

What do the a-amylase enzymes do?(2)

Answer 19

Break down alpha 1-4 glycosidic bonds of starch

Question 20

Which microvilli enzyme hydrolyses both 1,4 and 1,6 glycosidic bonds?

Answer 20

Sucrase-isomaltase

Question 21

Explain the absorption of fructose process within the intestine (3)

Answer 21

Fructose crosses enterocyte apical membrane via facilitated diffusion
Using GLUT5

Fructose then crosses the the basolateral membrane into the blood via GLUT2

Question 22

What are some of the reasons why some carbs enter the large intestine (colon) (6)

Answer 22

Enzymes required are not present within the small intestine
Cant gain access to carb
Does not hydrolyses carb fast enough
Monosaccharide transporters not available or do not function at a high enough rate
Beta bonds

Question 23

Fermentation process (3)

Answer 23

Bacteria produces hydrolytic enzymes
Carbs are broken down into monosaccharides
Monosaccharides are used as energy for growth by bacteria

Question 24

What are the products of fermentation (2)

Answer 24

Short chain fatty acids | Gases

Question 25

Name the SCFA products of fermentation (3)

Answer 25

Acetate Propionate Butyrate

Question 26

What is the fate of each SCFA (3)

Answer 26

Butyrate - used as predominant energy source by colon cells Propionate - absorbed and transported to liver Acetate - absorbed and metabolised by peripheral tissues

Question 27

What is the range of blood glucose?

Answer 27

3-5.5 mmol/l

Question 28

Glycogenesis process (6)

Answer 28

``` G6P converted to G1P Using phosphoglucomutase G1P converted to UDP-glucose Using G1P uridyltranferase Glucose from UDP-glucose added to glycogen chain Using glycogen synthase UDP is released ```

Question 29

Glycogenolysis initial process (4)

Answer 29

Glycogen to G1P By glycogen phosphorylase G1P to G6P By phosphoglyceromutase

Question 30

Glycogenolysis process in liver (3)

Answer 30

G6P converted to glucose Via G6 phosphatase Glucose then enters blood

Question 31

Glycogenolysis in muscle (3)

Answer 31

G6P to pyruvate Via glycolysis Pyruvate is transaminated to alanine

Question 32

What are low carb diets associated with?(3)

Answer 32

High concentrations of ketone bodies Depleted glycogen stores Hypercholesterolaemia

Question 33

What are intrinsic sugars?

Answer 33

Naturally incorporated into cellular structure of food

Question 34

What are extrinsic sugars?

Answer 34

Not contained within cellular structure of foods

Question 35

What are free sugars?(4)

Answer 35

Sugar added to food

Question 36

Explain the absorption of glucose and galactose across apical membrane (4)

Answer 36

Decreased sodium within cell draws sodium across apical membrane with glucose This occurs via active transport Using sodium-glucose transport protein 1 Sugar then crosses the the basolateral membrane into the blood via GLUT2 (facilitated diffusion)

Question 37

What determines the rate of glucose uptake from the intestine?(2)

Answer 37

Rate of hydrolysis of oligosaccharides and polysaccharides

Question 38

Glucose formula

Answer 38

C2H12O6

Question 39

Degree of polymerisation for each class of carbs (3)

Answer 39

Sugars 1-2 Oligo 3-9 Poly 9+

Question 40

Example of malto-oligosaccharides

Answer 40

Maltodextrins

Question 41

Examples of starch (3)

Answer 41

Amylose Amylopectin Modified starches

Question 42

Examples of non digestible oligosaccharides (3)

Answer 42

Ruffinose Fructo-oligo Galacto-oligo

Question 43

Examples of non starch polysaccharides (4)

Answer 43

Cellulose Hemicellulose Pectin Hydrocolloids

Question 44

Where is glucose found?(3)

Answer 44

Fruits Plant juices Honey

Question 45

Where is fructose found?(3)

Answer 45

Free state alongside glucose in: Ripening fruits Honey

Question 46

Where is galactose found?(2)

Answer 46

In combination with glucose as lactose | In milk

Question 47

Composition of sucrose (2)

Answer 47

Alpha 1, 2 linked | Glucose-fructose

Question 48

Composition of lactose (2)

Answer 48

Beta 1, 4 linked | Galactose-glucose

Question 49

Maltose composition (2)

Answer 49

Alpha 1, 4 linked | Glucose-glucose

Question 50

Sucrose sources (3)

Answer 50

Sugar cane Sugar beet Fruit

Question 51

Lactose sources

Answer 51

Milk and dairy produce

Question 52

Maltose sources (2)

Answer 52

Spotted grain | Malt beverages

Question 53

What is the most common natural sweetener?

Answer 53

Sucrose

Question 54

_______ is produced during the digestion of starch

Answer 54

Maltose

Question 55

Sources of starch (3)

Answer 55

Cereals Root veg Legumes

Question 56

Glycogen is a form of ______

Answer 56

Starch

Question 57

What is the optimal pH range for alpha amylase?

Answer 57

6.6-6.8

Question 58

Where is alpha amylase produced?

Answer 58

Acinar cells in the pancreas

Question 59

Define glycogenesis

Answer 59

Synthesis of glycogen from glucose

Question 60

Define glycogenolysis

Answer 60

Stored glycogen is converted to glucose

Question 61

Define gluconeogenesis

Answer 61

Synthesis of glucose from non-carb sources

Question 62

Main substrates involves in gluconeogenesis (3)

Answer 62

Lactate Glycerol Alanine

Question 63

How many molecules of ATP per glucose is produced?

Answer 63

38

Question 64

DRV for free sugars

Answer 64

5% of energy intake

Question 65

DRV for total carbs

Answer 65

50%

Question 66

Non starch polysaccharide RDA

Answer 66

30 g/day

Question 67

Why is it recommended that 50% of energy intake comes from carbs?(2)

Answer 67

Too much may be associated with inadequate intakes of essential nutrients Too little may be associated with excess intake of sat fats

Question 68

How can extrinsic sugars cause dental carries?

Answer 68

Fermented in mouth to yield acidic products

Question 69

Lactose is an example of an _____ sugar

Answer 69

Extrinsic

Question 70

Where are free sugars found?(3)

Answer 70

Honey, syrups and unsweetened fruit juices