3.1.2 carbohydrates

Question 1

What is the structure of amylose?

Answer 1

• Formed from alpha glucose
• Straight chain
• Only 1-4 glycosidic bonds
• Often forms a spiral held together by hydrogen bonds

Question 2

What bonds join monosaccharides?

Answer 2

Glycosidic

Question 3

Are disaccharides soluble? Are disaccharides reducing sugars?

Answer 3

Are soluble- dissolve to form sweet tasting solutions
Some are reducing sugars like maltose and lactose

Question 4

What are maltose, sucrose and lactose? How is each formed?

Answer 4

Disaccharides formed in condensation reactions of…
* Glucose and glucose = maltose
* Glucose and galactose = lactose
* Glucose and fructose = sucrose
Forming a glycosidic bond

Question 5

What are the polymers present in starch?

Answer 5

Amylose and amylopectin

Question 6

Monosaccharides with 6 carbon atoms are called…

Answer 6

Hexoses

Question 7

What are 3 examples of hexoses? What are they used for?

Answer 7

Glucose, fructose and galactose. Used as a source of energy in respiration and to form larger molecules.

Question 8

Monosaccharides are s______ , w_____ c_________ solids.

Answer 8

Monosaccharides are soluble, white crystalline solids.

Question 9

What is the general formula of carbohydrates?

Answer 9

Cx(H20)y

Question 10

What are 3 common groups of monomers? MOVE

Answer 10

Monosaccharides
Amino acids
Nucleotides

Question 11

Describe the structure and function of cellulose

Answer 11

• Long straight beta glucose chains joined by 1-4 glycosidic bonds in condensation reactions
• Become linked together by many hydrogen bonds to form (micro)fibrils
• Provide strength to cell wall

Question 12

What are the 2 main roles of carbohydrates?

Answer 12

• Structural
• Energy sources

Question 13

What specific glycosidic bonds can form in the condensation of monosaccharides?

Answer 13

• 1 - 4 glycosidic bond or 1-6 glycosidic bond
• Hydrogen from carbon 1 reacts with hydroxyl group from carbon 4/6

Question 14

What are the 3 main groups of carbohydrates?

Answer 14

Monosaccharides
Disaccharides
Polysaccharides

Question 15

Monosaccharides are __________ sugars

Answer 15

Reducing (donate electrons)

Question 16

How do beta glucose molecules form cellulose?

Answer 16

Due to different position of C1 OH group, molecules rotate 180* when they condense to form a chain.
Hydrogen bonds between chains.

Question 17

What are the isomers of glucose? What’s the difference between them?

Answer 17

ABBA
Alpha (OH on C1 is) Below ring
Beta (OH on C1 is) Above ring

Question 18

What is the structure and function of glycogen

Answer 18

• lots of branching (bc 1-6 glycosidic bonds) –> large SA for quick and easy hydrolysis into a glucose by enzymes for respiration
• Large but compact –> maximises amount of energy stored
• Insoluble–> WP not affected, can’t leave cells, easy storage
• polysaccharide of alpha glucose joined by 1-4 and 1-6 glycosidic bonds
• Main storage compound in animals
• Stored in liver (released into blood for widespread use) and muscle cells (for muscles)

Question 19

What isomers of glucose form a. Starch b. Glycogen c. Cellulose

Answer 19

A. a glucose
B. a glucose
C. B glucose

Question 20

What is the structure and function of starch?

Answer 20

• Coiled/helical - so it’s compact, can store a lot in a small space
• Insoluble - so there is no osmotic effect/ doesn’t affect water potential, doesn’t diffuse out of cells
• (Amylopectin) is branched - so it’s easy and faster to hydrolyse into alpha glucose for use in respiration
• Large molecule - so can’t leave cell, large number of glucose molecules provides respiratory substrate for energy release

Question 21

What’s the general formula of monosaccharides? What is n between?

Answer 21

CnH2nOn
(CH2O)n

3 and 7

Question 22

Which enzymes hydrolyse a. Maltose, b. Sucrose, c. Lactose? Where are they produced?

Answer 22

A. Maltase
B. Sucrase
C. Lactase

Epithelial cells that line the small intestine (ileum)

Question 23

How is the structure of glycogen adapted for its function?

Answer 23

• coiled so compact
• polymer of glucose so easily hydrolysed
• branched so many ends for faster hydrolysis
• polymer of glucose so provides respiratory substrate for energy release
• Insoluble so doesn’t affect water potential or osmosis/ not easily lost from cell

Question 24

Describe the role of enzymes in the digestion of starch

Answer 24

• Amylase
• starch to maltose
• maltase
• maltose to glucose
• hydrolysis
• of glycosidic bond