Lecture 23

Question 1

What is glucose?

Answer 1

A hexose simple sugar monosaccharide

Question 2

What is a hexose?

Answer 2

6 Carbon ring

Question 3

What is the chemical structure of glucose?

Answer 3

C6H12O6

Question 4

What is a carbohydrate?

Answer 4

A large macromolecule / polysaccharide

Question 5

What are sources of glucose from carbohydrates?

Answer 5

Starch from plants and glycogen from meat

Question 6

What is starch?

Answer 6

A polymer made up of up to 1 million glucose units joined by glycosidic bonds

Question 7

What are the two forms of starch?

Answer 7

Amylose and amylopectin

Question 8

What is the structure of amylose?

Answer 8

A liner polymer of glucose units

Question 9

What is the structure of amylopectin?

Answer 9

A branched polymer of glucose units

Question 10

What is glycogen?

Answer 10

A branched polymer of glucose units

Question 11

What is a disaccharide?

Answer 11

two sugars joined by a glycosidic bond

Question 12

What are the examples of disaccharides?

Answer 12

Sucrose, lactose and maltose

Question 13

What is the structure of sucrose?

Answer 13

A glucose bound to a fructose by a glycosidic bond

Question 14

Where are disaccharides found in the diet?

Answer 14

Fruit and raw sugar

Question 15

What enzyme cleaves glycosidic bonds from polysaccharides to disaccharides?

Answer 15

Amylase hydrolase

Question 16

What enzymes cleave the glycosidic bonds from disaccharides to monosaccharides?

Answer 16

Specific enzymes e.g. sucrase for sucrose

Question 17

What is the end result of digestion of carbohydrates?

Answer 17

Glucose in the GI tract

Question 18

Are sugars polar or non polar?

Answer 18

Highly polar

Question 19

Are sugars water or lipid soluble?

Answer 19

Water soluble

Question 20

How do glucose molecules cross the lipid membrane?

Answer 20

Through specific transporter proteins anchored in the membrane

Question 21

What are the two types of transpot?

Answer 21

Active and facilitated transport

Question 22

What is active transport?

Answer 22

The movement molecules against a concentration gradient, requiring energy input

Question 23

What transporter protein transports glucose via active transport across the membrane in the GI tract?

Answer 23

The sodium-glucose linked transporter

Question 24

What is facilitated transport?

Answer 24

The movement of molecules down a concentration gradient, not requiring energy input

Question 25

What transporter protein transports glucose via facilitated transport across the membrane in the GI tract?

Answer 25

GLUT2

Question 26

How is glucose used as a fuel molecule?

Answer 26

It is oxidised in glycolysis (in all organisms) which usually occurs in the cytoplasm in eukaryotes

Question 27

Why is glucose essential as fuel for red blood cells?

Answer 27

RBCS do not have mitochondria and can therefore not utilise other pathways

Question 28

What is the energy requirement in the brain?

Answer 28

120g of glucose per day

Question 29

Do brain cells have mitochondria?

Answer 29

Yes

Question 30

What is the traditional view on why the brain favours glucose?

Answer 30

Glucose easily crosses the blood-brain barrier and fats do not

Question 31

What is the modern hypothesis as to why the brain prefers glucose?

Answer 31

It is safer, providing a quicker source of ATP without the risk of damage

Question 32

Why is glucose favoured as a energy molecule in the eye cells?

Answer 32

High amounts of blood vessels and mitochondria would refract the light, so these are limited and glucose does not require either

Question 33

Which muscle cells use fats as fuel?

Answer 33

Red muscle cells, for endurance

Question 34

Which muscle cells use glucose as fuel?

Answer 34

White muscle cells, for sprinting