Carbohydrates Review

Carbohydrates1. What is a Carbohydrate?

A carbohydrate is any of the group of organic compounds consisting carbon, hydrogen, and oxygen, usually in the ratio of 1:2:1. Examples include sugar, starch, cellulose, and gums.

CarbohydratesThis structure represents a polymer.

2. What are the individual units called?

They are called monomers

Carbohydrates3. What does poly mean?

4. What does mono mean?Mono means ‘one’ and monomer means ‘one piece.’

Poly means ‘many’ and polymer means ‘many pieces.’

Carbohydrates5. Saccharide comes from the Greek word ‘sakkaron.’ What do you think the word means?

6. What does monosaccharide mean?Monosaccharide means one sugar.

Saccharide means sugar.

Carbohydrates7. Monosaccharides are also known as ‘simple sugars.’ Name at least three monosaccharides.

Glucose (also known as blood sugar)

Fructose (also known as fruit sugar)

Galactose (also known as brain sugar)

Ribose (a sugar found in RNA)

Deoxyribose (a sugar found in DNA)

Gl

Fr

Ga

R

D

Carbohydrates

9. Name three common disaccharides.

Sucrose (also known as table sugar)

Maltose (also known as malt sugar)

Lactose (also known as milk sugar)

8. What does disaccharide mean?Disaccharide means two sugars.

Carbohydrates10. Disaccharides are made up of two monosaccharides. What monosaccharides make up the following disaccharides?

Sucrose:

Maltose:

Lactose:

Glucose + Fructose

Glucose + Glucose

Glucose + Galactose

Gl Fr

Gl Ga

Gl Gl

Carbohydrates11. Name four common polysaccharides and the role each plays in living organisms.

Glycogen

Starch

Cellulose

Made of glucose monomers; how animals store excess sugar.

Made of glucose monomers; how plants store excess sugar.Made of glucose monomers; main component of cell walls in plants.

Chitin Made of modified glucose monomers; main component in cell walls of fungi and exoskeletons of arthropods

Carbohydrates12. Where is glycogen found in animals?

Glycogen is mainly stored as granules in liver and muscle cells.

13. Where is starch found in plants?Starch is mainly stored as starch grains inside plant cells.

Carbohydrates14. List some ways that starch differs from cellulose?

CelluloseStarch

a. The glucose monomers in starch are aligned in the same direction, while in cellulose every other glucose is inverted.

Every other glucose is inverted (flip-flopped)

Carbohydrates15. List some ways that starch differs from cellulose?

a. The glucose monomers in starch are aligned in the same direction, while in cellulose every other glucose is inverted.

Starch Cellulose

b. The flip-flopping of glucose monomers in cellulose allow hydrogen bonds to form between strands

Hydrogen bonds

Carbohydrates16. Describe a simple test for detecting monosaccharides (simple sugars) in food.

a. Put blended samples of the food in a test tube filled with blue Benedict’s reagent.

b. Place the test tube in a hot water bath for 5 minutes.

If monosaccharides (like glucose) are present, the blue color will turn an orange/red color.

Carbohydrates17. Describe a simple test for detecting starch in food.

a. Put blended samples of the food in a test tube.b. Pour some yellow Lugol’s reagent (also known

as iodine-potassium iodide solution or IKI) in the test tube.

If starches are present, the yellow color will turn a dark blue to black.

Carbohydrates

18. What sugar makes up its monomers?

Glucose

This structure represents starch.

CarbohydratesThis structure represents starch.

19. What are the bonds that link the glucose monomers called?

The bonds are glycosidic linkages

CarbohydratesThis structure represents starch.

20. What molecule is released when a glucose monomer is added to the starch polymer?

A water molecule is released

(Click once to see animation)

CarbohydratesThis structure represents starch.

21. What molecule must be added in order to remove a glucose monomer from the starch polymer?

A water molecule is added

(Click once to see animation)

Carbohydrates22. Name a food or object that contains the following carbohydrates.

Sucrose:

Lactose:

Starch:

Cellulose:

Table sugar, syrup, honey, candy

Milk, ice cream, cheeseBread, potatoes, pasta

Seeds, vegetables, fruit, wood, cotton