Unit 1 (Chapter 3 Part 2) Carbs

Question 1

What are carbon-containing organic molecules often represented by the general formula, Cn(H2O)n?

Answer 1

Carbohydrates.

Carbohydrates include starches, sugars, and cellulose.

Question 2

What are most carbohydrates linked to?

Answer 2

Contain water, a hydrogen atom, and a hydroxyl functional group.

Remember: A hydroxyl functional group is polar and forms hydrogen bonds with water. -OH (Hydroxyl)

Question 3

What are simple sugars (usually sweet tasting) such as pentose or hexose called?

Answer 3

Monomers called Monosaccharides (very water soluble because of the large number of OH or hydroxyl groups).

Question 4

How many carbons do the most common types of monosaccharides contain? (2)

Answer 4

Pentose (5 carbons)

Hexoses (6 carbons)

Hence, pent and hex prefix.

Question 5

What are the important pentoses? (2)

And what is their chemical formula?

Answer 5

Ribose (C5H10O5)

Deoxyribose (C5H12O4)

Part of RNA/DNA

Question 6

What is the most important hexose and its chemical formula?

Answer 6

Glucose (C6H12O6)

Question 7

What happens when sugar is transported across the cell membrane?

Answer 7

Enzymes break it down into smaller groups.

Releases energy that was stored in the chemical bonds.

The energy is then stored in other bonds of another molecule, ATP or adenosine triphosphate.

It then powers a variety of cell processes.

Question 8

What is the predominant structure found within living organisms?

Answer 8

The ring structure.

Question 9

What common type of glucose is found within living cells?

Answer 9

D-Glucose… an enantiomer (mirror image) of L-Glucose (both are considered isomers of glucose)

Question 10

Why do enantiomers such as D- and L-glucose differ their ability to bind to enzymes?

Answer 10

One reason is that the binding of a molecule to an enzyme depends on the spatial arrangements of the atoms in that molecule. Enantiomers have different spatial relationships and are mirror images of each other. Therefore, one may bind very tightly to an enzyme and the other may not be recognized at all.

Question 11

How are the isomers formed of glucose based on its ring structure?

Answer 11

The changing of spatial positions of the hydroxyl groups.

For example, the a form of glucose happens when the hydroxyl group attached to the number 1 carbon atom is below the plane of the ring.

b form happens when the hydroxyl group attached to number 1 carbon atom is above the plane of the ring.

IF the hydroxyl group on carbon atom number 4 AND 1 of glucose is above the plane instead of below it, it becomes a sugar called galactose.

Question 12

What is created when two monosaccharides are linked through a dehydration reaction?

Answer 12

A Disaccharide is created

Question 13

What is a common disaccharide and what two monomers is it composed of?

Answer 13

Sucrose, or table sugar, and it is composed of monomers glucose and fructose

Remember: Small molecules or monomers of sugar are sweet!

Question 14

What is the major transport form of sugar in plants?

Answer 14

Sucrose

Question 15

What happens when the most of these monosaccharides link together chemically?

Answer 15

One hydroxyl group is removed from a monosaccharide while a hydrogen atom from another monosaccharide.

This in turn creates a water molecule, and the two monosaccharides are covalently bonded to an oxygen atom.

Question 16

What is the covalent bond formed between two sugar molecules via a dehydration reaction called?

Answer 16

Glycosidic bond

Question 17

What common disaccharide is found and formed in animals during the digestion of large carbohydrates in the intestinal tract?

What common disaccharide is found in the milk of mammals?

Answer 17

Maltose and Lactose

Question 18

What type of reaction is the reverse of the one shown here, in which a disaccharide is broken down into two monosaccharides?

Answer 18

A hydrolysis reaction

Question 19

What do you call a long carbohydrate polymer formed of many monosaccharides linked together?

Answer 19

A polysaccharide (meaning many sugars).

Question 20

What are two very common polysaccharides that are found within plants and one that is found in animals which is used for storage?

Answer 20

Starch and glycogen

Question 21

What is starch?

Answer 21

A polysaccharide composed of repeating glucose units that is produced by the cells of plants and some algal protists.

Question 22

What is glycogen?

Answer 22

A polysaccharide found in animal cells (especially the liver and skeletal muscle) and sometimes called animal starch; also, the major carbohydrate storage of fungi.

Question 23

What molecule are both starch and glycogen comprised of?

Answer 23

Thousands of a-D-glucose molecules linked together in long, branched chains, differing only in the extent of the branching along the chain.

Question 24

In starch and glycogen, where do the bonds form between? This is very specific.

Answer 24

Carbons 1 and 4 and between carbons 1 and 6.

Question 25

What contributes to the solubility of glycogen in animal tissue like muscle tissue?

Answer 25

Since it has a high degree of branching, it creates a more open structure in which many hydrophilic hydroxyl (-OH) side groups have access to water in which it hydrogen bonds.

Starch is less branched and less soluble, which contributes to the properties of plant structures (like a potato or a kernel of corn)

Question 26

Which glycosidic linkages form chains and which form branches?

Answer 26

a-1,4-Glycosidic linkages form chains (Carbons 1 and 4)

a-1,6-Glycosidic linkages form branches (Carbons 1 and 6)

Question 27

What is the main macromolecule of the cell wall of plants and many algae; a linear polymer made of thousands of glucose (B-D-glucose) monomers?

Answer 27

Cellulose (believed to be the most abundant molecule on Earth)

Each monomer is flipped over, forming chains of thousands of monomers.

Question 28

What makes linear chains of cellulose arrange themselves in parallel patterns?

Answer 28

The hydrogen bonds between them.

Question 29

Why are plant cells able to break the bonds between monomers of a-D-glucose in starch without breaking the bonds between b-D-glucose in the cell walls?

Answer 29

Enzymes within the plant do not recognize the shape of b-D-glucose monomers in cellulose.

Question 30

Since some animals do have the enzyme to breakdown b-D-glucose into monomers, what do humans call this insoluble material?

Answer 30

Referred to as fiber.

Question 31

What is a tough, nitrogen containing, polysaccharide polymer that forms the external skeleton of many insects and crustaceans and is found in the walls of fungi?

Answer 31

Chitin

In this case, the nitrogen containing groups have sugar monomers attached to them.

Question 32

What is the most abundant type of polysaccharide in the extracellular matrix (ECM) of animals, consisting of repeating disaccharide units that give a gel-like character to the ECM?

Answer 32

Glycosaminoglycans

These are large polysaccharides.