Carbodydrates

Question 1

What is monosaccharide?

Answer 1

A single sugar unit, which joins to form a polysaccharide.

Question 2

What is a disaccharide?

Answer 2

When ONLY two monosaccharides join together.

Question 3

What is the bond that joins monosaccharides together?

Answer 3

Glycosidic bond

Question 4

What type of bond are glycosidic bonds?

Answer 4

Covalent

Question 5

How are the glycosidic bonds formed between the monosaccharides?

Answer 5

Condensation reaction, produces water molecules.

Question 6

What is the difference between alpha and beta glucose?

Answer 6

The hydroxyl group is attached differently on carbon 1 of each.

Question 7

Why is the solubility of glucose important?

Answer 7

It can be dissolved in the cytosol.

Question 8

Similarity and difference between constitutional (structural) isomers and stereoisomers?

Answer 8

Same chemical formula.
In constitutional isomers the atoms are attached differently whereas in stereoisomers the atoms are geometrically orientated differently.

Question 9

Define isomer

Answer 9

Compounds with the same chemical formula but different chemical structure e.g. alpha beta glucose

Question 10

Two types of isomers?

Answer 10

Constitutional and stereoisomers

Question 11

Why is glucose soluble in water?

Answer 11

Because of the hydrogen bonds that can form between the hydroxyl group and the water molecules.

Question 12

What is ribose present in?

What is deoxyribose present in?

Answer 12

RNA nucleotides

DNA nucleotides

Question 13

Monosaccharides with

• 3 carbons?
• 4 carbons?
• 5 carbons?
• 6 carbons?

Answer 13

3- triose
4- tetrose
5- pentose
6- hexose

Question 14

Name two pentose carbohydrates.

Answer 14

Ribose

Deoxyribose

Question 15

What do two alpha glucose molecules react to make?

Answer 15

Maltose

Question 16

How is sucrose formed?

Answer 16

alpha glucose + fructose

Question 17

How is lactose formed?

Answer 17

alpha/beta glucose + galactose

Question 18

What is lactose?

Answer 18

The sugar found in milk

Question 19

What is sucrose?

Answer 19

Found mainly in plants and in sugar canes and used to make ‘table sugar’.

Question 20

What is maltose?

Answer 20

The sugar found in large concentrations in germinating seeds, first product of starch digestion

Question 21

What two starch polysaccharides can alpha glucose form?

Answer 21

amylose
AND
amylopectin

Question 22

What are amylose and amylopectin collectively known as?

Answer 22

Starch

Question 23

Bonds in amylose?

Answer 23

Amylose - 1,4 glycosidic bonds

Question 24

Bonds in amylopectin?

Answer 24

Amylopectin - 1,4 and 1,6 glycosidic bonds every 25 subunits

Question 25

Where and how is starch used?

Answer 25

In plants, it is the product of photosynthesis and is an energy story.

Question 26

What is the structure of amylose and how does it help it’s function?

Answer 26

The angle formed by the 1,4 glycosidic bonds means that the chain twists to form a helix, which is further stabilised by hydrogen bonding within the molecule. This makes the molecule compact and much more insoluble than the glucose that made it.

Question 27

What is the structure of amylopectin and how does it help it’s function?

Answer 27

Branched due to 1,6 glycosidic bonds, and so much more compact than amylose. Makes it good for storage.

Question 28

What is the animal and fungi equivalent to starch?

Answer 28

Glycogen

Question 29

What is the structure of glycogen?

Answer 29

Very similar to amylopectin, 1,4 and 1,6 glycosidic bonds every 10 subunits, very very branched and very very compact.

Question 30

How does the structure of glycogen aid it’s function? | animals, branch, compact, energy

Answer 30

Glycogen is very branched and compact so more energy storage and this helps as glycogen is an energy store in ANIMALS, and animals are much more mobile than plants so need more energy. The branching means that there are many free ends where glucose molecules can be added or removed EFFICIENTLY.

Question 31

What happens when starch or glycogen are needed to release glucose for respiration?

Answer 31

They undergo HYDROLYSIS reactions.

Question 32

Why is branching useful?

Answer 32

Glucose molecules can be added do removed quickly via HYDROLYSIS.

Question 33

Why is compactness useful?

Answer 33

Much more energy can be stored.

Question 34

Why is being insoluble useful?

Answer 34

Can be used for long term storage.

Question 35

What is cellulose?

Answer 35

Key component of plant cell walls, composed of monomers of beta glucose.

Question 36

What is the molecular structure (arrangement) of cellulose?

Answer 36

- beta glucose cannot react the same way that alpha glucose does due to the positioning of the hydroxyl groups on its carbon 1 and 4. - thus EVERY ALTERNATE beta glucose must flip over to get the hydroxyl groups close enough to react - this way, the a 1,4 glycosidic bond is formed.

Question 37

What is the overall structure of cellulose?

Answer 37

-due to the way in which beta glucose joins up to form bonds, cellulose does NOT coil up or branch like alpha glucose polysaccharides, instead it forms a STRAIGHT chain molecule.

Question 38

What is the further structure of cellulose?

Answer 38

Cellulose chains form hydrogen bonds with each other to form MICROFIBRILS. Microfibrils join together to make MACROFIBRILES. Macrofibrils join to make fibres.

Question 39

How does the structure of beta glucose aid it’s function?

Answer 39

The fibres are STRONG and INSOLUBLE , and this is helpful as cellulose helps make cell walls in plant cells

Question 40

What is cellulose in our diet?

Answer 40

Cellulose forms the ‘fibre’ and roughage required for a healthy digestive system.