Carbohydrates: monosaccharides & disaccharides

Question 1

Macromolecules

Answer 1

A macromolecule is a giant molecule made up of many repeating units (containing c). Such molecules are called as polymers & the individual units are called monomers.

Question 2

Monomers

Answer 2

The monomers are covalently linked to make a polymer by removing water; chemical process called condensation.

Question 3

Polymer

Answer 3

The polymers could be broken down by the addition of water; process called hydrolysis

Question 4

Four major classes are:

Answer 4

Carbohydrates
Lipids
Protein
Nucleic acid

Question 5

Monomers and their polymers

Answer 5

Monosaccharides to carbohydrates
Fatty acids & glycerol to lipids
Amino acids to proteins
Nucleotides to nucleic acid

Question 6

Carbohydrates

Answer 6

They are compounds containing carbon, hydrogen & oxygen
The ratio of hydrogen to oxygen is usually 2:1
They have general formula (CH2O)n

Question 7

Types of carbohydrates

Answer 7

Monosaccharides
Disaccharides
Polysaccharides

Question 8

Carbohydrates: sugar

Answer 8

Monosaccharides and disaccharides

Question 9

Monosaccharides (monomers) example

Answer 9

Glucose
Fructose
Ribose

Question 10

Disaccharides (dimers) example

Answer 10

Sucrose
Maltose
Lactose

Question 11

Polysaccharides (polymers) example

Answer 11

Starch
Cellulose
Glycogen

Question 12

Types of carbohydrates: monosaccharides

Answer 12

Single, simple sugar

Question 13

Types of carbohydrates: disaccharides

Answer 13

Consist of two monosaccharides joined by a condensation reaction ie glycosidic bond

Question 14

Types of carbohydrates: polysaccharides

Answer 14

Polymers of many sugars joined by more than two condensation reactions ie glycosidic bonds

Question 15

Monosaccharides

Answer 15

Simple sugar units which make up all other carbohydrates which cannot be further hydrolysed into smaller units

Question 16

α-glucose: OH above or below

Answer 16

Hydroxyl (OH-) group of 1c projects below the plane of ring.

Question 17

α-glucose

Answer 17

It is a primary substrate in cellular respiration & provides energy for most metabolic reactions

Question 18

β- glucose: OH above or below

Answer 18

Hydroxyl (OH-) group of 1c projects upwards the plane of ring.

Question 19

β- glucose

Answer 19

Is a component of the cellulose micro fibrils that are found in the cell wall of plants

Question 20

Disaccharides

Answer 20

Two monosaccharides can be linked by glycosidic bonds to form disaccharides
2[(CH20)n]-H20

Question 21

Condensation reaction: monosaccharides

Answer 21

During condensation reaction, 2 monosaccharides are joined by the removal of water molecules to form a covalent bond known as a glycosidic bond

Question 22

Hydrolysis reaction

Answer 22

Hydrolysis is the splitting of a disaccharides into its monosaccharides by the addition of water molecules this process breaks glycosidic bonds

Question 23

Condensation vs hydrolysis

Answer 23

Monosaccharides forms condensation reactions which forms disaccharides.
Disaccharides forms hydrolysis reactions which forms monosaccharides.

Question 24

Condensation of monosaccharides

Answer 24

Glucose and glucose forms maltose and water
Glucose and fructose forms sucrose and water
Glucose and galactose forms lactose and water

Question 25

Hydrolysis of monosaccharides

Answer 25

Maltose and water forms glucose and glucose Sucrose and water forms glucose and fructose Lactose and water forms glucose and galactose

Question 26

There are three disaccharides

Answer 26

Maltose Sucrose Lactose

Question 27

Carbohydrates & energy: monosaccharides & disaccharides

Question 28

Monosaccharides & energy: polar utility

Answer 28

It can easily enter cells & get metabolised or stored as starch or glycogen

Question 29

Monosaccharides & energy: smaller & more reactive when compared to disaccharides & polysaccharides

Answer 29

They can easily enter the cells & be broken down by respiration to provide energy for metabolic processes

Question 30

Monosaccharides & energy: ability to undergo condensation reactions & form glycosidic bonds

Answer 30

Monosaccharides are used as bulging blocks for larger & more complex carbohydrates like starch , glycogen & cellulose

Question 31

Disaccharides & energy: polar & solubility

Answer 31

Since disaccharides are polar they can dissolve in water. This is particularly useful for the transport of carbohydrates as sucrose in the phloem sap of plants

Question 32

Disaccharides & energy: ability to be hydrolysed

Answer 32

Sucrose is hydrolysed in the gut of mammals to form glucose & fructose. The glucose is then absorbed into the cell & used as a respiratory substrate

Question 33

Disaccharides & energy: less permeable to cell membrane

Answer 33

Cannot easily pass across the cell membrane