2.1.2 Biological Molecules - Carbohydrates

Question 1

What elements are found in carbohydrates?

Answer 1

Carbon, Hydrogen, Oxygen

Question 2

How much of cells organic matter is carbohydrates?

Answer 2

10%

Question 3

What is the chemical formula for Carbohydrates?

Answer 3

Cx(H20)y

Question 4

What are carbohydrates also known as?

Answer 4

Saccharides or sugars

Question 5

What is a single sugar unit known as? - Examples?

Answer 5

A monosaccharide
- Glucose
- Fructose
- Galactose

Question 6

When two monosaccharides link together they form a…?
Examples?

Answer 6

Disaccharide
- Maltose - Glucose + Glucose
- Sucrose - Glucose + Fructose
- Lactose - Glucose + Galactose

Question 7

When three monosaccharides or more are joined together. It is called a…? Examples?

Answer 7

Polysaccharide
- Starch
- Cellulose
- Glycogen

Question 8

What monosaccharide is Glucose?

Answer 8

Hexose sugar ( as it has 6 carbons )

Question 9

Why are glucose molecules soluble in water and why is this important?

Answer 9

They are polar molecules, due to the hydrogen bonds between the hydroxyl groups and water molecules
- Important as it means glucose can dissolve in the cytosol of the cell

Question 10

What reaction joins glucose molecules together and what product is formed?

Answer 10

Condensation and water is produced

Question 11

What bond is it when two glucose molecules are joined

Answer 11

Glycosidic bond

Question 12

What are the two types of glucose, what is the difference between them and what are they to each other?

Answer 12

Alpha glucose - OH at Carbon 1 is below the plane
Beta Glucose - OH at Carbon 1 is above the plane
- They are isomers of each other

Question 13

Properties of Fructose

Answer 13

• Hexose sugar
• Naturally occurs in fruit
• Sweeter than glucose

Question 14

Properties of Galactose

Answer 14

• Hexose sugar
• Found in milk
• Less sweet than glucose

Question 15

What are pentose monosaccharides and what are two examples?

Answer 15

5 Carbon atoms
- Ribose - DNA and RNA
- Deoxyribose - Ribose that has lost one oxygen - DNA

Question 16

How many polysaccharides in Starch and what are they?

Answer 16

Two
- Amylose
- Amylopectin

Question 17

Properties of Amylose

Answer 17

• Alpha glucose joined together by only glycosidic 1-4 bonds
• Forms a helix due to the angle of the bond, stabilised by hydrogen bonding
• Polysaccharide is much more compact and much less soluble than the glucose that made it

Question 18

Properties of Amylopectin

Answer 18

• Made by Alpha 1 - 4 glycosidic bonds
• Also has Alpha 1 - 6 glycosidic bonds every 25 subunits
• Branched and coiled structure
• Because of its branches it is a good storage molecule

Question 19

Storage molecule in Plants

Answer 19

Starch

Question 20

Storage molecule in animals

Answer 20

Glycogen

Question 21

Glycogen properties

Answer 21

• More branched than amylopectin and therefore more compact and needs less space to be stored which is important as animals are more mobile than plants

Question 22

Properties of amylopectin and starch

Answer 22

• compact due to the coiled and branched chains, ideal for storage
• branching means many molecules of glucose can be broken off or added
• insoluble so don’t affect water potential of the cell

Question 23

Reaction that breaks down the polysaccharides

Answer 23

Hydrolysis reaction, need to add water

Question 24

What glucose is used to form cellulose?

Answer 24

Beta glucose

Question 25

Why is cellulose a long straight chain?

Answer 25

• The only way beta glucose molecules can join together and form a polymer is if each alternating beta molecule is turned upside down
• This way it can not coil or branch only form a straight chain

Question 26

What is a microfibril?

Answer 26

When cellulose molecules made hydrogen bonds with eachother

Question 27

What is a macrofibril

Answer 27

Microfibrils that have joined together

Question 28

Cellulose fibres

Answer 28

Macrofibrils that have been joined together

Question 29

Cellulose properties

Answer 29

• strong
• insoluble
• used to make cell walls