6- carbohydrates

Question 1

functions of carbohydrates:

Answer 1

Provide energy for plants and animals​ (through carbohydrate oxidation)

Form supportive structures in plants (cellulose), insects and crustaceans (chitin)​

Supply short-term energy storage in plants (starch) and humans (glycogen)​

In plants: provide carbon atoms for the synthesis of other biochemical substances​ (such as proteins, lipids and nucleic acids​)

Form part of the structural framework of DNA and RNA molecules​

Act as structural components of cell membranes (when linked to lipids)

Involved in a variety of cell–cell and cell–molecule recognition processes​ (when linked to proteins)

Question 2

Structure of carbohydrates?

Answer 2

Carbohydrates are polyhydroxy (many hydroxyl (OH) groups) aldehydes or polyhydroxy ketones, or compounds that produce such substances upon hydrolysis.

Question 3

4 classifications of carbohydrates?

Answer 3

Monosaccharides
(Contain a single polyhydroxy aldehyde or ketone unit )

Disaccharides
(Contain 2 monosaccharide units)

Oligosaccharides
(Contains 3-10 monosaccharide units)
usually found associated with proteins and lipids in complex molecules​

Polysaccharides
(a few hundred to a few million monosaccharide units; eg cellulose, starch)

Question 4

the smallest monosaccharides are..?

Answer 4

Trioses

as D-Glyceraldehyde​ (Aldotriose​) or Dihydroxyacetone​ (Ketotriose​)

Question 5

the most abundant monosaccharide in nature and also the most important monosaccharide for human nutrition is..?

Answer 5

D-Glucose

it is an aldohexose

Question 6

The normal range concentration of blood sugar is ..?

Answer 6

3.5 – 5.5 mmol/L of blood

Question 7

What is the difference between D-glucose and D-galactose?

Answer 7

Their atoms are the same but arranged differently in space (at carbon-4)

they are both stereoisomers: have atoms bonded together in the same order

Question 8

D-Galactose is a component of which 3 things?

Answer 8

Glycoproteins in the brain​
Glycoprotein blood group markers of the ABO blood group system​
Lactose

Question 9

what is lactose composed of?

Answer 9

Lactose = D-Galactose + D-Glucose​

disaccharide

Question 10

the difference between d-fructose and d-glucose?

Answer 10

fructose contains a ketone functional group​, whereas glucose contains an aldehyde functional group​

Question 11

what is d-ribose?

Answer 11

D-Ribose​ is an aldopentose​ that functions as a vital component of important biomolecules, including nucleic acids (RNAs) and ATP​. Compared to D-Glucose, D-Ribose contains one less Carbon group.

Question 12

Monosaccharides with 5 or more carbon atoms can exist in which 2 structures?

Answer 12

open-chain or cyclic

Question 13

5 important reactions of monosaccharides?

Answer 13

1- Oxidation to acidic sugars ​
2- Reduction to sugar alcohols ​
3- Glycoside formation​
4- Phosphate ester formation ​
5- Amino sugar formation ​

Question 14

what are glucoside and galactoside?

Answer 14

Glucoside​: A glycoside produced from glucose

Galactoside​: A glycoside produced from galactose

Question 15

what is the structure of a disaccharide?

Answer 15

Disaccharides are crystalline and water-soluble substances​ that contain 2 monosaccharide units joined via a glycosidic linkage​/bond. Hydrolysis of a disaccharide produces two monosaccharides

Question 16

D-maltose = ?​

Answer 16

D-maltose = D-glucose + D-glucose​

Question 17

what is the most abundant disaccharide?

it’s found in plants

Answer 17

D-sucrose

D-Sucrose = D-Fructose + D-Glucose​

Question 18

Oligosaccharides that occur naturally in onions, cabbage, broccoli, all types of beans and whole wheat​ include:

Answer 18

Raffinose: made of one each of galactose, glucose and fructose

Stachyose: made of 2 galactose, 1 glucose and 1 fructose units

Question 19

structure ofpolysaccharides?

Answer 19

polymers of many monosaccharide units bonded via glycosidic linkages

Question 20

Dietary carbohydrates are divided into which 2 groups?

Answer 20

Simple Carbohydrates​: Monosaccharides and disaccharides​. Simple carbohydrates are sweet-tasting and usually referred to as sugars​.

Complex Carbohydrate​: Dietary polysaccharides (starch and cellulose) that do not taste sweet​.