Introduction To Carbohydrates

Question 1

How are carbohydrates produced ?

Answer 1

They are produced by photosynthesis in plants.
32ATP per glucose

Question 1

What are the different types of carbohydrates ?

Answer 1

Monosaccharides
Disaccharides
Polysaccharides

Question 2

Monosaccharides

Answer 2

The simplest carbohydrates

Question 3

Disaccharides

Answer 3

Consists of 2 monosaccharides

Question 4

Polysaccharides

Answer 4

Consists of many monosaccharides

Question 5

How do monosaccharides react ?

Answer 5

Hydrolysis

Question 6

What do monosaccharides consist of ?

Answer 6

3-6 carbon atoms
A carbonyl group
Several Hydroxyl groups

Question 7

What are 3 functions of carbohydrates ?

Answer 7

Energy storage
Components of complex molecules
Recognition of events in protein folding

Question 8

Aldose

Answer 8

Monosaccharide with an aldehyde group (C=O at the end of a carbon chain) and many hydroxyl groups (-OH)

Question 9

Ketose

Answer 9

Monosaccharide with a ketone group (C=O between 2 carbons) and many hydroxyl groups (-OH)

Question 10

Chiral molecules

Answer 10

Non-superimposable mirror images
A carbon with 4 substituent groups that can be mirrored

Question 11

Fischer projection

Answer 11

Used to represent carbohydrates

The most oxidised group is at the top
Chiral carbons are represented at intersections between vertical and horizontal lines.

Question 12

L-form isomer

Answer 12

The -OH group on the chiral carbon FARTHEST from the carbonyl group is on the LHS

Question 13

D-form isomer

Answer 13

The -OH group on the chiral carbon FARTHEST from the carbonyl group is on the RHS

Question 14

What are form are naturally occurring amino acids ?

Answer 14

L-form isomers

Question 15

What are form are naturally occurring carbohydrates ?

Answer 15

D-form isomers

Question 16

Where is D-glucose found ?

Answer 16

Found in fruits and honey
Blood Sugar

Question 17

What is the name of a D-glucose ?

Answer 17

Aldohexose

Question 18

What is the difference between D-glucose and D-galactose ?

Answer 18

The body cannot digest galactose.
It must be converted into glucose first.
-OH group attached to C4 is on different sides
D-glucose RHS
D-galactose LHS

Question 19

Can the body digest galactose ?

Answer 19

NO ! It must be converted into glucose first.

Question 20

Galactosemia cause

Answer 20

Lack of enzymes required for galactose metabolism

Question 21

Effects of galactosemia

Answer 21

Accumulation of galactose intermediates
Toxic effects in liver, brain, kidneys and eyes.

Question 22

What are cyclic structures ?

Answer 22

More prevalent form of monosaccharides with 5/6 carbon atoms.

Question 23

When do cyclic structures form ?

Answer 23

When the hydroxyl group on C5 reacts with the aldehyde or ketone group.

Question 24

3 steps of cyclic structure formation of glucose

Answer 24

1. Number the carbon chain 2. Turn the chain clockwise to form a linear open chain 3. Fold the linear chain into a hexagon - C5 bonds to C1 - C6 group is placed above the ring - Add the -OH groups - C1 receives new -OH (down = Alpha form) (up=Beta form)

Question 25

What happens when alpha/beta glucose is placed in solution ?

Answer 25

The cyclic structure opens and closes. Glucose is converted between alpha and beta forms through a DYNAMIC FLOW.

Question 26

What is a reducing sugar ?

Answer 26

A sugar that will reduce inorganic ions e.g. Cu++ (Fehling's reagent)

Question 27

What are examples of reducing sugars ?

Answer 27

All monosaccharides are reducing sugars.

Question 28

What is a reducing agent ?

Answer 28

One which donates electrons and gains protons.

Question 29

Function of Fehling's reagent

Answer 29

Determines the levels of glucose in the blood

Question 30

What are the 3 main steps in Fehling's reaction ?

Answer 30

1. Glucose is oxidised 2. Copper is reduced 3. Colour change occurs in the presence of a reducing sugar. blue ------> orange

Question 31

How do you determine the amount of reducing sugar in a persons blood ?

Answer 31

The amount of colour is directly proportional to the concentration.

Question 32

What is the glucose oxidase test ?

Answer 32

More practical application of glucose level testing. Used in clinical settings.

Question 33

Disadvantage of Fehling's test

Answer 33

It requires boiling, and so isn't very practical. It is not specific for glucose.

Question 34

How does glucose enter red blood cells ?

Answer 34

In a non-insulin dependent manner.

Question 35

What are the results of uncontrolled hyperglycemia ?

Answer 35

Uncontrolled hyperglycemia results in a covalent linkage between glucose and the NH2 terminal amino acid of the hemoglobin β chain. The resulting adduct is designated as HbA1c.

Question 36

Glycation

Answer 36

Non-enzymatic natural addition of sugar

Question 37

What is lactose ?

Answer 37

Disaccharide of beta-D-galactose or beta/alpha-D-glucose.

Question 38

Sucrose

Answer 38

Glucose + fructose

Question 39

Maltose

Answer 39

Glucose + glucose

Question 40

Galactose

Answer 40

Glucose + lactose

Question 41

What causes a lactose intolerance ?

Answer 41

Lack of lactase enzyme in SMALL INTESTINES.

Question 42

Results of Lactose intolerance

Answer 42

Lack of lactase in small intestine Lactose passes into colon Bacteria start to ferment lactose Stomach cramps, bloating, flatulence

Question 43

Function of lactase enzyme

Answer 43

Splits lactose into glucose and galactose.

Question 44

What is the most common polysaccharide in animal cells ?

Answer 44

Glycogen

Question 45

What is the function of glycogen ?

Answer 45

The storage form of glucose

Question 46

Where is glycogen found ?

Answer 46

In the liver and muscle

Question 47

Structure of glycogen

Answer 47

Highly branched polysaccharide made of multiple glucose units linked by alpha-1,4 and alpha-1,6-glycosidic bonds.

Question 48

What is an advantage of the branched structure in glycogen ?

Answer 48

Lots of ends so can release lots of glucose easily. So, this makes it an efficient store.

Question 49

What is starch ?

Answer 49

The plant form of carbohydrate ingested by humans.

Question 50

What are the 2 forms of starch ?

Answer 50

Amylose Amylopectin

Question 51

Amylose structure

Answer 51

Unbranched starch comprised of glucose units

Question 52

Amylopectin structure

Answer 52

Branched form of starch

Question 53

Which enzyme hydrolyses amylose and amylopectin ?

Answer 53

alpha- amylase secreted by the salivary glands and the pancreas.

Question 54

Function of cellulose

Answer 54

Storage in plants

Question 55

What is an important source of diversity ?

Answer 55

Blood groups Viral protein coats

Question 56

Is cellulose digestible by humans ?

Answer 56

NO ! Humans don't have cellulases to recognise the inverted/flipped structure of cellulose.