1.2.1/.2 - Carbohydrates 1 and 2

Question 1

How many bonds can each carbon atom make?

Answer 1

can make up to 4 bonds

Question 2

define a monomer

Answer 2

small molecule (single unit of a polymer)

Question 3

define a polymer

Answer 3

a long chain of molecules made of of smaller, repeating monomers joined together by chemical bonds

Question 4

what is an organic compound?

Answer 4

biological molecules that contain carbon,hydrogen or oxygen atoms (less frequently nitrogen, sulfur and phosphorus)

Question 5

What are carbohydrates used for?

Answer 5

they are used as an energy source and for storing energy

(also part of the cell wall in plant, fungi and bacteria cells).

Question 6

What is the basic structure of all carbohydrates?

Answer 6

They are all made up of carbon, hydrogen and oxygen

Question 7

What are the three main groups of carbohydrates?

Answer 7

Monosaccharides
Disaccharides
Polysaccharides

Question 8

What is a monosaccharide?

Answer 8

a simple sugar

the general formula = (CH2O)n

Question 9

Give examples of carbohydrates.

Answer 9

Examples of carbohydrates include: 
sugars 
starch 
sucrose 
glucose

Question 10

What is a triose sugar?

Answer 10

They have 3 carbon atoms –> therefore n = 3 in the general formula
they are important in the mitochondria (where glucose is broken down into triose sugars during respiration)

Question 11

What is a pentose sugar?

Answer 11

they have 5 carbon atoms —> therefore n = 5 in the general formula
Ribose and deoxyribose are important in the nucleic acids DNA and RNA (which make up the genetic material)

Question 12

What is a hexose sugar?

Answer 12

they have 6 carbon atoms —> therefore n = 6 in the general formula
they are the best known monosaccharides
often taste sweet
and include glucose, fructose and galactose

Question 13

What is ribose?

Draw it’s displayed formulae

Answer 13

• a pentose sugar
• used in RNA backbone
• deoxyribose is used in the DNA backbone
• chemical formula = C5 H10 O5

Question 14

What is Alpha - glucose?

Draw it’s displayed formulae

Answer 14

• hexose sugar
• an isomer (different form of the same molecule) of glucose
• chemical formula = C6 H12 O6

Question 15

What is Beta - glucose?
Include its chemical formula
Draw it’s displayed formulae

Answer 15

• hexose sugar
• isomer of glucose
• chemical formula = C6 H12 O6

Question 16

What is a disaccharide?

Answer 16

two monosaccharides joined together (a double sugar)

Question 17

How do two monosaccharides join together?

Answer 17

Through a condensation reaction

• removes a molecule of water
• forms a disaccharide
• bond formed between them is a glycosidic bond
  (e. g 1,4 glycosidic bond)

Question 18

Where is sucrose found and what monosaccharides join together?

Answer 18

• stored in plants (e.g sugar cane)

- Alpha glucose and fructose

Question 19

Where is lactose found and what monosaccharides join together?

Answer 19

• milk sugar (main carbohydrate found in milk)

- alpha glucose and beta glucose

Question 20

Where is maltose found and what monosaccharides join together?

Answer 20

• malt sugar (found in germinating seeds e.g barley)

- a and a glucose

Question 21

What is a polysaccharide?

Answer 21

11+ monosaccharides joined by condensation reactions to form glycosidic bonds

Question 22

What is a oligosaccharide?

Answer 22

3-10 monosaccharides joined together

Question 23

Draw the hydrolysis of maltose

Answer 23

(maltose drawn + water —> two a-glucose molecules)

Question 24

Why are polysaccharides such good storage molecules?

Answer 24

1. very compact, large numbers can be stored in a cell
2. glycosidic bonds are easily broken allowing for the rapid release of monosaccharides
3. not very soluble in water, therefore little effect on water potential within a cell

Question 25

How are glycosidic bonds broken?

Answer 25

Through hydrolysis
- water is added to the bond
- disaccharides are broken into two monosaccharides
- polysaccharides are broken down into shorter chains until eventually they are single sugars
This takes place: during digestion in the gut, in muscle and liver cells

Question 26

What are the two compounds that make up starch?

Answer 26

Amylose

Amylopectin

Question 27

What is amylose?

Answer 27

• chain of a-glucose (an A 1,4 glycosidic bond)
• helical structure
• unbranched polymer
• releases glucose more slowly and is a form of energy storage
• used in plants

Question 28

What is amylopectin?

Answer 28

• chain of a- glucose (in an A 1,4 glycosidic bond and an A 1,6 glycosidic bond)
• highly branched
• releases glucose rapidly as its highly branched (more spaces for amylase to break down)
• used as plant storage

Question 29

What is glycogen?

Answer 29

• only carbohydrate energy store found in animals
• highly branched
• made of a-glucose (A1,4 and A1,6 glycosidic bonds)
• can be broken down extremely quickly due to having more 1,6 bonds - more branched - therefore is very useful in places such as muscle and liver tissue
• insoluble (more soluble than starch)

Question 30

What is cellulose?

Answer 30

• insoluble
• made up of b-glucose in a B1,4 glycosidic bond
• one of the monomer units in this needs to turned around 180 so bonding can take place
• means hydroxyl group (-OH) sticks out of both sides and causes a hydrogen bond to form between each layer
• this gives cellulose great strength and support, making it an important structural material in plants (cell walls)
• NO spirals, just long straight layered unbranched chains