Lect. 3 Carbohydrates

Question 1

Glucose

Answer 1

Used in polymer synthesis

(monosaccharide)

Question 2

Fructose

Answer 2

Component of table sugar

(monosaccharide)

Question 3

Galactose

Answer 3

Component of milk sugar

(monosaccharide)

Question 4

Ribose (Type)

Answer 4

Used in RNA nucleotides

Component of RNA

Question 5

Deoxyribose (Type)

Answer 5

Used in DNA nucleotides

Component of DNA

Question 6

Sucrose

Answer 6

In plants, table sugar

di-saccharide

glu + fru

Question 7

Lactose

Answer 7

Milk sugar

di-saccharide

glu + gal

Question 8

Maltose

Answer 8

Brewing sugar

di-saccharide

glu + glu

Question 9

Starch

Answer 9

Storage in plants

polysaccharide

Question 10

Glycogen

Answer 10

Storage in animals

polysaccharide

Question 11

Cellulose

Answer 11

Structural in plants

polysaccharide

Question 12

Chitin

Answer 12

Structural in animals in fungi

polysaccharide

Question 13

Peptidoglycan

Answer 13

Structural in bateria

polysaccharide

Question 14

2 types of sugar

Answer 14

aldoses and ketoses

difference lies in the location of the carbonyl gr. (-C=O)

Question 15

Monosaccharide molecular formulas

Answer 15

multiple of CH2O

(1:2:1 ratio)

[CH2O]n where n is a nber between 3 and 7

Question 16

3 most common sugars

Answer 16

• Trioses (smallest sugars)
• Pentoses (in DNA)
• Hexoses (common sugars)

Question 17

3 common monosaccharides

(all hexoses)

Answer 17

• glucose
• galactose
• fructose

all 3 have chemical formula: C6H12O6

they are structural isomers of one another

Question 18

most common monosaccharide

Answer 18

glucose

its open chain forms of glucose form ring structures in solutions

ring form is the most common form in living organisms

Question 19

How does glucose form rings?

What is the ring called?

Answer 19

C1 aldehyde reacts with C5 hydroxyl gr. to form a ring called a pyranose ring

Question 20

2 isomers of glucose ring structure

Answer 20

• α-glucose, OH gr. at C1 is on the opp. side of CH2OH
• β-glucose, OH gr. at C1 is on the same side as CH2OH

these isomeric forms differ in the orientation of the OH gr. at C1

Question 21

Glucose in Biology

Glucose is the end product of what process? What is it used for?

Answer 21

• Photosynthesis in plants
• Glucose is used as an energy source in most organisms

During cellular respiration, cells oxidize glucose molecules converting the stored energy to a form that can be readily used for cell work.

Question 22

Homeostasis of Blood Glucose

What regulates the concentration of glucose in the blood?

Where is it produced?

Answer 22

Hormones insulin and glucagon which are produced by the pancreas

transported thoughout the body via blood vessels

Question 23

Almost all mechanism to maintain homeostasis:

Answer 23

negative feedback mechanisms

return a variable to its set point

loop: set point, stimulus -> detected by a sensor -> triggers response to return to the set point (effector)

Question 24

What does insulin do?

Answer 24

Insulin decreases blood glucose.
Insulin can bind to receptors on surface of fat, muscle, and liver cells and promote the transport of glucose inside cells.

Glucose Transporter 4 triggered by insulin

Question 25

Insulin decreases blood glucose levels by:

Answer 25

• Stimulating uptake of glucose in muscle
• Preventing breakdownof glycogen to glucose in the liver
• Stimulates adipose cells to store glucose as fat

Question 26

What does glucagon do?

Answer 26

Glucagon increases blood glucose levels.

the pancreas is stimulated to secrete glucagon

Question 27

Glucagon increases blood glucose levels by:

Answer 27

• Stimulating conversion of glycogen to glucose in the liver
• Breakdown of proteins into amino acids in muscle cells
• Breakdown of fats in adipose tissue and release of fatty acids

Question 28

Sugars in food

Glucose is rarely found in its monosaccharide form in food. It’s often found as part of:

Answer 28

a disaccharide or starch

Question 29

Sugars in Food

What is more commonly found in foods as it’s the primary sugar in foods such as fruits, vegetables, and honey?

Answer 29

Fructose

Question 30

Disaccharides

How is a dissacharide formed?

Answer 30

A dissacharide is formed when a dehydration reaction joins 2 monosaccharides.

water is a product from the reaction

Question 31

Lactose Intolerance

How is the digestion of disacharides and other carbs mediated?

Answer 31

It is mediated by enzymes synthesized by cells lining the small intestine.

Question 32

Lactose Intolerance

What is Lactose Intolerance the result of?

Answer 32

A drop in lactase production

often following childhood