Carbohydrates in Nutrition

Question 1

Are carbohydrates essential in the diet?

Answer 1

No

Question 2

What is the average persons carbohydrate consumption composed of?

Answer 2

Monosaccharides = glucose and fructose
Disaccharides = sucrose and lactose
Polysaccharides = starch and glycogen

Question 3

What is sucrose composed of?

Answer 3

Glucose and fructose

Question 4

What is lactose composed of?

Answer 4

Glucose and galactose

Question 5

What is maltose composed of?

Answer 5

Glucose and glucose

Question 6

What is the average daily intake of carbohydrates?

Answer 6

300g

Question 7

What is the largest carbohydrate component of the diet?

Answer 7

Starch

Question 8

What two forms is starch found in?

Answer 8

Amylose and amylopection

Question 9

What is the structure of amylose?

Answer 9

Glucose monomers joined by alpha 1,4 glycosidic bonds

Question 10

Can amylose be tightly packed?

Answer 10

Yes

Question 11

Is amylose readily digested?

Answer 11

No

Question 12

What is the structure of amylopectin?

Answer 12

Glucose monomers joined by alpha 1,4 and alpha 1,6 glycosidic bonds

Question 13

Can amylopectin be tightly packed?

Answer 13

No

Question 14

Is amylopectin readily digested and why?

Answer 14

Yes - because enzymes can permeate the molecule easily due to it not being tightly packed

Question 15

What other molecule is the amylopectin structurally similar to?

Answer 15

Glycogen

Question 16

What does the digestion of a carbohydrate by alpha amylase produce?

Answer 16

Short chains of glucose NOT glucose monomers

Question 17

What enzyme is found in the mouth and where is it secreted from?

Answer 17

Amylase

Secreted in saliva from salivary glands

Question 18

What enzyme is found in the duodenum and where is it secreted from?

Answer 18

Secondary alpha amylase

Secreted from the pancrease due to stimulation from absorbed glucose

Question 19

What enzymes are found in the intestine and what do they produce?

Answer 19

Maltase
Sucrase
Lactase
Produce single glucose monomers which can be absorbed into the blood

Question 20

What does maltase break down?

Answer 20

Maltose into glucose and glucose

Question 21

What does sucrase break down?

Answer 21

Sucrose into glucose and fructose

Question 22

What does lactase break down?

Answer 22

Lactose into glucose and galactose

Question 23

Why might a person be intolerant to a certain sugar?

Answer 23

If they do not possess the enzyme required to break down that sugar

Question 24

What sugars can a human body not break down?

Answer 24

Stachyose

Raffinose

Question 25

What is dietary fibre?

Answer 25

The edible part of plants that are not broken down in the small intestine

Question 26

What is crude fibre?

Answer 26

Residues of plant food left after extraction by dilute acid and alkalis

Question 27

What happens when food reaches the colon?

Answer 27

We cannot use it however the bacteria in our colon metabolise it and we can use the byproducts = symbiotic relationship

Question 28

How is glucose transported into our cells?

Answer 28

Sodium glucose linked transporter I - transports sodium and glucose into cells - driven by the high concentration of sodium outside cells (as a result of sodium potassium pumps)

Question 29

How is fructose transported into our cells?

Answer 29

Via facilitated diffusion through the Glut - 5 transporter

Question 30

What molecules does Glut - 2 transport and where does it transport them?

Answer 30

Glucose Galactose Fructose Out of the cell and into the blood

Question 31

What is the glycemic index?

Answer 31

A method of ranking foods based on their predicted blood glucose response compared to the same gram weight of pure glucose

Question 32

How is the glycemic index produced?

Answer 32

Subjects are tested 5 times - Subjects are given 50g of pure glucose three times - Subjects are given 50g of the food containing available carbohydrates twice - Repeated with 10 subjects for every food

Question 33

Why is the glycemic index not definitively correct?

Answer 33

- Foods are tested on their own (other foods in a meal will affect how readily individual foods are digested) - Subjects are always tested in the morning (digestion varies depending on time and a persons fasting state) - Fructose does not count - Other macronutrients are not taken into account - All subjects are young, white, healthy individuals

Question 34

What does a high GI value indicate?

Answer 34

A rapid glucose peak and a high insulin peak

Question 35

How do you calculate glycemic load?

Answer 35

(amount of food carbohydrate x GI) / 100

Question 36

What are the advantages of using the glycemic load?

Answer 36

Takes into account portion size and carbohydrate content