3.3 Carbohydrates

Question 1

What is a carbohydrate

General formula?

Answer 1

Compound with carbon hydrogen and oxygen atoms only

2) Cx(H2O)y

Question 2

What is a monosaccharide, di and poly?

Answer 2

Monosaccharides are single units of carbohydrates, di are 2

Polysaccharides are multiple units of monomer monosaccharides

Question 3

What are the properties of glucose in general

Answer 3

• six carbons = a hexose monosaccharide
• variations of it: alpha and beta
• polar due to hydroxyl groups
• soluble in water

Question 4

Why is glucose soluble in water , why important ?

Answer 4

• soluble due to interaction of hydrogen bonds of both polar water and the glucose.
• this important as this means it can dissolve into the cytosol (aqueous part of cell)

Question 5

Alpha glucose structure

Beta glucose structure

Answer 5

Remember alpha don’t follow rules, so don’t follow up down up down

Down up down up

2) beta follows so up down up down

Question 6

What are the different disaccharides and how do you make them.

How many carbons do these have?

Order of sweetness?

Answer 6

1) Maltose = glucose + glucose
2) Sucrose= glucose + FRUCTOSE
3) Galactose = glucose + lactose

• 6, so hexose
  3) =sucrose, fructose, glucose , galactose

Question 7

Which are the pentose monosaccharides

Answer 7

Ribose and deoxyribose, used to make DNA

Question 8

Starch amylose structure

What does this do

Answer 8

• Long chains of alpha glucose bonded , non branched

- forms helix held together by hydrogen bonds = more compact and better for storage

Question 9

Starch properties in general

Answer 9

• compact , chemical energy store, insoluble and easily digestible

Question 10

Amylose properties (3)

Answer 10

• helix = compact and ideal for storage
  -insoluble means it does not create a WATER GRADIENT, so water csn’t enter by osmosis to cause swelling .
  (Converted from soluble to insoluble for storage)
  -metabolically inactive

Question 11

Amylopectin structure

Answer 11

• Long chains of alpha glucose monomers bonded together, but WITH BRANCHES TOO
• branch = 1/25 units
• (More branches = more free ends )
• forms helixes too( thus compact)

Question 12

Amylopectin bonding

Answer 12

1-4 glycosidic

+

1-6 glycosidic 1/25

Question 13

Amylopectin properties

3

Answer 13

• Branching makes Amylopectin MORE COMPACT= ideal for storage
• multiple branches = MULTIPLE FREE ENDS, meaning more enzymes can act on amylopectin at once, so easy adding and removing of glucose
• INSOLUBLE STILL = doesn’t affect water potential

Question 14

Glycogen structure

Answer 14

• short , but BRANCHED chains of alpha glucose monomers bonded together
• More branches than Amylopectin
  (Free ends)

Question 15

Glycogen bonding

Answer 15

1-4 + 1-6 too AS BRANCHES THERE

Question 16

Properties of glycogen
- why is compact storage more important for glycogen ?

What name given to ability for free ends to allow for quick adding of glucose etc

Answer 16

• More branches in glycogen = even MORE compact and less space needed for it to be stored = perfect for storage
  (Needed because animals are mobile)
• free ends = EASILLY HYDROLISED
• insoluble

Question 17

Cellulose structure

Micro etc

Answer 17

• Long, unbranched chains of beta glucose monomers
• straight chain that cannot coil
• chains are linked by HYDROGEN BONDS TOO, to from strong fibres called micro fibrils
• these join to make MACRO FIBRILIS
• which join to make cellulose fibres

Question 18

Cellulose bonding

Answer 18

1- 4 beta glycosidic binds,

- each alternate beta monomer flipped so that condensation can take place

Question 19

Cellulose properties

Why do the micro macro help for a cell wall?

Answer 19

• hydrogen bind linkage between chains making the micro macro fibrils means cellulose is STRONG AND INSOLUBLE , which is needed for cell walls
• compact and better for storage as closed

Question 20

Function of starch / glycogen

Answer 20

Main Energy store in plants and animals
- stores soluble glucose as Insoluble polysaccharides that don’t affect water potential it’s, (meaning water can’t cause cells to burst) until needed for something !!

Question 21

Function of cellulose however

• plants and humans?

Answer 21

• provides structural support for for cells in plants

- very hard to breakdown , forming FIBRE /ROUGHAGE necessary for healthy digestive system

Question 22

Some other functions of glucose

Answer 22

• store energy
• structural
• soluble to insoluble
• deoxyribose ribose
• respiration
• SUCROSE FOR TRANSPORT IN PLANTS
• ANTIGENS (recognition molecules ) (made from glycolipids )

Question 23

How are dissachrides broken down

Answer 23

• hydrolysis reaction
• water added
• reactions catalysed by enzymes
• glycosidic bond broken, now back to useable monomers

Question 24

Why does polysaccharides branch in alpha glucose unit

Answer 24

• when you line them up they have to curve , meaning they branch
• beta glucose doesn’t as they flip meaning they form straight chains