Carbohydrates

Question 1

How do we store sugar in out body?

Answer 1

As glycogen

Question 2

What are the 3 important hexoses in human biochemistry?

Answer 2

Glucose
Galactose
Fructose

Question 3

What is a monosaccharide?

Answer 3

A one sugar monomer

Question 4

What is disaccharide?

Answer 4

A two sugar polymer

Question 5

Monomers in sugar are linked by what kind of bonds?

Answer 5

Glycosidic

Question 6

How is a covalent bond formed between sugar monomers?

Answer 6

When the hydroxyl group of one of the monomers reacts with the anomeric carbon of another sugar monomer

Question 7

What are the 3 important disaccharides in human biochemistry?

Answer 7

Maltose
Lactose
Sucrose

Question 8

What is maltose a breakdown product of?

Answer 8

Starch

Question 9

Why is maltose termed a reducing sugar?

Answer 9

As it itself is oxidised

Question 10

What is lactose the main sugar in?

Answer 10

Milk

Question 11

How is lactose formed?

Answer 11

Glycosidic bond between galactose and glucose

Question 12

On lactose there is an anomeric carbon available for oxidation so it therefore known as what?

Answer 12

A reducing sugar

Question 13

What is sucrose made by?

Answer 13

Plants

Question 14

What is the sweetener sugar in most processed food?

Answer 14

Sucrose

Question 15

What is a polysaccharide?

Answer 15

A polymer of sugarnmonomers ranging from medium to high molecular weight

Question 16

What is a homopolysaccharide?

Answer 16

A sugar polymer of a single monomeric species

Question 17

What is a heteropolysaccharide?

Answer 17

A sugar polymer that has two or more monomer species

Question 18

What two polymers of glucose does starch contain?

Answer 18

Amylose

Amylopectin

Question 19

What bonds form the backbone of starch?

Answer 19

The a1-a4 bonds

Question 20

What bonds form the branches of starch?

Answer 20

The a1-a16 bonds

Question 21

What bonds form the backbone of glycogen?

Answer 21

The a1-a4 bonds

Question 22

What bonds from the branches in glycogen?

Answer 22

The a1-a6 bond

Question 23

Which is more extensively branched glycogen or starch?

Answer 23

Glycogen

Question 24

Where is 90% of glycogen stored in the body?

Answer 24

The liver and in skeletal muscle

Question 25

What is glycogen rapidly broken down to yield?

Answer 25

Glucose

Question 26

Why are the polymers of glucose osmotically inactive?

Answer 26

So that energy is not wasted on maintaining correct conc. gradients

Question 27

What is a glycoprotein?

Answer 27

A protein that has carbohydrate COVALENTLY linked to it

Question 28

Why do carbohydrate bind to proteins?

Answer 28

To increase their solubility To influence the proteins folding and conformation To protect the protein from degradation To act as communication between cells (extra signalling)

Question 29

What content is higher in proteoglycans: protein or carbohydrate?

Answer 29

Carbohydrate

Question 30

How are proteoglycans formed?

Answer 30

Form GAGs covalently attaching to proteins

Question 31

What do proteoglycans from pars of?

Answer 31

The connective tissues in the body

Question 32

Where are proteoglycans found?

Answer 32

On the surface of cells or in between cells in the extracellular matrix

Question 33

What is mucopolysaccharidoses caused by?

Answer 33

The absence of malfunction of enzymes that are required for the breakdown of glycosaminoglycans

Question 34

Where in the body does carbohydrate digestion begin?

Answer 34

The mouth

Question 35

What in the mouth breakdowns carbohydrates?

Answer 35

Salivary amylase

Question 36

Does any carbohydrate digestion occur in the stomach?

Answer 36

No

Question 37

What does hydrolysing mean?

Answer 37

Breaking down the covalent link between monomers

Question 38

What are the main products of carbohydrate digestion?

Answer 38

Glucose, galactate and fructose

Question 39

What concentration gradients drives the glucose molecules through the membrane?

Answer 39

Na+ gradients

Question 40

How is glucose transported into epithelial cells?

Answer 40

Sodium flows down its concentration gradient into epithelial cells and takes glucose with it

Question 41

When the sodium gradient takes glucose with it what type of transport is this?

Answer 41

Facilitated transport

Question 42

Why after facilitated transport does Na+have to be pumped back out of the cell?

Answer 42

To maintain the high Na+ on the outside to keep the process going

Question 43

What does the process of the absorption of glucose require?

Answer 43

ATP

Question 44

Does the absorption of glucose continue even if blood glucose is high?

Answer 44

Yes - even though it is working against its concentration gradient

Question 45

How is galactose absorbed?

Answer 45

Through a similar mode of transport as glucose - utilising gradients

Question 46

How is fructose absorbed?

Answer 46

It binds to GLUT5 and moves down its concentration gradient

Question 47

How are cellulose and hemicellulose broken down?

Answer 47

The polymers are broken down by gut bacteria

Question 48

When gut bacteria break down cellulose an hemicellulose what do they yield?

Answer 48

CH4 and H2

Question 49

How is absorbed glucose prevented from being re released back out of the cell?

Answer 49

It is converted to G-6-P which cannot diffuse back out of the cell

Question 50

Why can't G-6-P diffuse back out of the cell?

Answer 50

Because GLUT transporters wont recognise it

Question 51

Once glucose diffuses through the intestinal epithelium cells where does it go?

Answer 51

Into the portal blood and on to the liver

Question 52

Where is glucokinase found?

Answer 52

Liver

Question 53

Where is hexokinase found?

Answer 53

In the other tissues of the body

Question 54

What enzyme breaks down glucose-6-phosphate to yield free glucose?

Answer 54

Glucose-6-phosphatase

Question 55

In skeletal muscle what is glycogen broken down into?

Answer 55

Lactate

Question 56

From what ends is glycogen broken down- glucose is removed one monomer at a time?

Answer 56

Non-reducing ends