CHAPTER THIRTEEN: CARBOHYDRATES

Question 1

What is RESPIRATION?

What does it require?

What is produced and returned to the atmosphere?

Answer 1

A series of metabolic reactions which release chemical energy to do work in the cells. It requires O2 from the air and glucose from our foods. Carbon dioxide and water are produced and returned to the atmosphere.

Question 2

What is PHOTOSYNTHESIS?

Answer 2

A series of reactions in which energy from the Sun is used to combine the carbon atoms from CO2 and the hydrogen and oxygen atoms of water (H20) into the carbohydrate glucose.

Question 3

What is the CARBON CYCLE?

Answer 3

The combination of photosynthesis and respiration, in which energy from the Sound is stored in plants by photosynthesis and made available to us when the carbohydrates in our diets are metabolized.

Question 4

The simplest carbohydrates are the ____.

Answer 4

MONOSACCHARIDES

Question 5

What are DISACCHARIDES?

Answer 5

consist of two monosaccharide until joined together (can be split)

Question 6

What are POLYSACCHARIDES?

In the presence of an _____ or an ______, a polysaccharide can be completely hydrolyzed to yield many molecules of monosaccharides.

Answer 6

Carbohydrates that are naturally occurring polymers containing many monosaccharide units.

In the presence of an acid or an enzyme, a polysaccharide can be completely hydrolyzed to yield many molecules of monosaccharides.

Question 7

MONOSACCHARIDES are sugars that have a chain of ___ to ___ carbon atoms, one in a ____________ group and the rest attached to ________ groups.

Answer 7

3-8

carbonyl group
hydroxyl groups.

Question 8

What are the two types of monosaccharide structures?

Answer 8

1. ALDOSE- the carbonyl group is on the first carbon (-CHO), an aldehyde.
2. KETOSE- contains the carbonyl group on the second carbon atom as a ketone (C=O)

Question 9

What is a TRIOSE?

What is a TETROSE?

What is a PENTOSE?

What is a HEXOSE?

Answer 9

TRIOSE- 3 carbon atoms

TETROSE- 4

PENTOSE- 5

HEXOSE- 6

Question 10

We can use both classification systems to indicate the type of carbonyl group and the number of carbon atoms. Examples:

• what is an ALDOPENTOSE?
• what is a KETOHEXOSE?

Answer 10

ALDOPENTOSE: a five-carbon monosaccharide that is an aldehyde.

KETOHEXOSE- a six-carbon monosaccharide that is a ketone.

Question 11

When the monosaccharide have 5 or 6 carbon atoms with more than one chiral carbon, what is used to determinate D or L isomer?

Answer 11

the -OH group on the chiral carbon farthest from the carbonyl group

Question 12

When drawing Fischer projections with vertical and horizontal lines (with the aldehyde group at the top and -H and -OH groups on the intersecting line):
* when is the letter L assigned?

Answer 12

L=left

D= right

Question 13

The ____ isomers are more commonly found in nature and used in the cells of the body.

Answer 13

D

Question 14

GLUCOSE… know the Fisher projection diagrams on page 457!!

Answer 14

page 457

Question 15

What are HAWORTH STRUCTURES?

Answer 15

Molecules of monosaccharides normally exist in a cyclic structure formed when a CARBONYL group and a HYDROXYL group in the SAME molecule react to give these ring structures.

Question 16

What is MUTAROTATION?

Answer 16

In an aqueous solution, the Haworth structure of alpha-D-glucose opens to give the open chain of D-glucose with an aldehyde group. At any given time, there is only a trace amount of the open chain (closes quickly to form stable ring structure).

When open chain closes again it can form beta-D-glucose. This process is called MUTAROTATION…each isomer converts to the open chain and back again.

As the ring opens and closes, the -OH group on carbon 1 can form either the alpha or beta isomer. An aqueous glucose solution contains a mixture of 36% alpha and 64% beta-D-glucose.

Question 17

In an alpha isomer, the -OH is drawn ___.

In an beta isomer, the -OH is drawn ___.

Answer 17

down

up

Question 18

Know the Haworth structures of GLUCOSE, GALACTOSE and FRUCTOSE

Answer 18

Glucose- see diagram on page 460
Galactose- page 460
Fructose- page 461

Question 19

What is a REDUCING SUGAR?

Answer 19

A carbohydrate that reduces another substance.

Question 20

D- glucose is a reducing sugar: it reduces to __________

Answer 20

D-gluconic acid (brick-red) Cu2O(s)

Question 21

Fructose is a reducing sugar: it reduces to _______.

Answer 21

Glucose

Question 22

What is HYDROLYSIS?

Answer 22

split by water

Ex: a disaccharide split by water in the presence of an acid or an enzyme- the products are two monosaccharides.

Question 23

What is a GLYCOSIDIC BOND?

Answer 23

In the Haworth structure of a disaccharide, a GLYCOSIDIC BOND is an ETHER bond that connects two monosaccharides.

Question 24

What is MALTOSE?

What is LACTOSE?

What is SUCROSE?

Answer 24

Malt sugar

Milk sugar

Sucrose consists of an alpha-D-glucose and a beta-D-fructose molecule joined by an alpha-beta-1.2 glycosidic bond (which is between carbon 1 of glucose and carbon 2 of fructose)… thus sucrose cannot be oxidized and is not a reducing sugar.

Question 25

What is a POLYSACCHARIDE?

Name four important polysaccharides.

Answer 25

A polymer of many monosaccharides joined together.

amylose, amylopectin, cellulose, glycogen

Question 26

What are the structural features of AMYLOSE?

Answer 26

makes up 20% of starch; continuous, coiled chain.

Question 27

What are the structural features of AMYLOPECTIN?

Answer 27

makes up 80% of starch; a branched-chain polysaccharide. Hydrolyzes easily in water and acid to give DEXTRINS, which then hydrolyze to MALTOSE and finally GLUCOSE.

In our bodies, these complex carbohydrates are digested by the enzymes AMYLASE in saliva and MALTASE in the intestines. The glucose obtained provides about 50% of our nutritional calories.

Question 28

What are the structural features of GLYCOGEN?

Answer 28

animal starch, is alpine of glucose that is stored in the liver and muscle of animals. More highly branched than amylopectin found in plants.

Question 29

What are the structural features of CELLULOSE?

Answer 29

the major structural material of wood and plants. Long unbranched chain similar to that of amylose. Aligned in parallel rows that are held in place by hydrogen bonds between hydroxl groups in adjacent chains, making cellulose insoluble in water.

Question 30

what is a starch containing alpha-1,4 and alpha 1,6 glycosidic bonds?

Answer 30

amylopectin and glycogen