Unit 4: Carbohydrates

Question 1

What is the chemical formula for photosynthesis?

Answer 1

6CO2 + 6H2O + Energy —> C6H12O6 + 6O2

Question 2

How many types of dietary CHO are there and what are they?

Answer 2

Three types:

1. Sugars
2. Starch
3. Fibre

Question 3

What’s the difference between monosaccharides and disaccharides?

Answer 3

Mono: simplest CHO, 3-9
Disac: 2 monos, like sucrose, lactose, maltose

Question 4

What are sugar alcohols derived from and used as?

Answer 4

• derived from monosaccharides

- used as sweetener e.g. sugarless gum

Question 5

How is glucose stored in animals compared to plants?

Answer 5

Animals: stored as glycogen
Plants: stored as starch (amylopectin and amylose) and fibre

Question 6

Explain briefly the structural differences in glycogen and the different starch components

Answer 6

Glycogen: highly branched
Amylopectin: branching every 25-30 glucose units, 3/4 starch, more bioavailable
Amylose: loopy, 1/4 starch, less bioavailable

Question 7

Briefly describe soluble fibre and provide examples that contain it

Answer 7

• dissolves in hot water
• forms gel in GI system, slowing motility
• absorbs FA, fuller feeling
• decreases risk of CV disease, cholesterol
  e. g. oat, bran, dried beans, nuts

Question 8

Briefly describe insoluble fibre and provide examples that contain it

Answer 8

• doesn’t dissolve in hot water
• absorbs water into GI system, speeds motility, decreases absorption time
• decreases risk of Type II DM, can lead to nutrient deficiencies
  e. g. veggies, fruit skins

Question 9

In the ___, galactose and ____ are converted to glucose

Answer 9

1. liver

2. fructose

Question 10

What’s the importance of CHO in the body?

Answer 10

• neurons and RBC exclusively use glucose (can use ketones in neurons during starvation)
• need to metabolize other fuels
• pregnancy
• spares using muscle protein for energy

Question 11

The liver has a higher glucose content/energy than ___, but ___ has even more than the liver

Answer 11

1. blood

2. muscle

Question 12

What’s the minimum intake of CHO in a diet?

Answer 12

130g/day for NS function

Question 13

Briefly explain how blood sugar is regulated by the pancreas

Answer 13

• blood glucose high, causes pancreas to release insulin
• insulin promotes uptake of glucose into cells and storage of glycogen, plus converts excess into fat
• lowers blood sugar, causes pancreas to release glucagon to promote liver cells breaking down glycogen stores

Question 14

What is the glycemic index (GI)?

Answer 14

• unitless measure of potential of food to increase blood glucose
• two standards: white bread and pure glucose

Question 15

What factors can affect the GI of foods?

Answer 15

• amount of CHO content in the food (higher CHO means higher GI)
• type of CHO (simple increases GI, complex decreases)
• cooking (longer cooking time increases GI, faster digestion)

Question 16

What’s the eq’n for glycemic load?

Answer 16

(GI x available CHO in g)/100

Question 17

Briefly describe the structure and function of insulin

Answer 17

Structure: produced by pancreas beta cells, 51 AA, 2 chains, disulfide brides between cysteines
Function: increase glucose uptake and glycogen storage, decreases blood sugar

Question 18

Briefly describe the structure and function of glucagon

Answer 18

Structure: produced by pancreas alpha cells, 29AA
Function: signals starved state, stimulates breakdown of glucose and gluconeogenesis, increases blood sugar

Question 19

Which type of diabetes is more common?

Answer 19

Type II NIDDM: non-insulin-dependent diabetes mellitus

Question 20

What’s a brief description of what happens in Type I DM

Answer 20

• beta cells ingested by immune system=no insulin
• leads to hyperglycemia (high blood glucose)
• glucose not taken into cells
• liver doesn’t see glucose being brought into cells so increases glycogenolysis, increasing blood sugar more

Question 21

What’s a big concern with Type I DM and how does it occur?

Answer 21

• frequent thirst, excessive urination, glucose in urine
• when renal threshold is exceeded and glucose not reabsorbed from kidneys
• glucose attracts water molecules (hence thirst and pee)

Question 22

What are some potential complications from Type 1 DM?

Answer 22

• ^ metabolism (catecholamines), ^ muscle breakdown (cortisol), worsened hyperglycemia (glucagon)
• ^ lipolysis, ^ keto acids=decreased pH
• ^ respiration rate, ^ blood pressure
• kidney disease, vascular disease, blindness
• diabetic ketoacidosis

Question 23

How is Type 1 DM managed?

Answer 23

• insulin -> short or long term (release), biosynthetic

- eating habits, exercise

Question 24

Explain briefly what Type II DM is

Answer 24

• chronically high blood glucose

- insulin supply good, but glucose-using cells are insulin resistant

Question 25

How can Type II DM be managed?

Answer 25

• monitoring diet, decreasing simple CHO

- increase physical activity, improves glucose uptake

Question 26

What are the different risk factors associated with each type of DM?

Answer 26

Type I: family history, genetics

Type II: family history, lack of exercise, overweight, gestational diabetes, high triglycerides