Lecture 7 DA

Question 1

What are carbohydrates made from?

Answer 1

Ketone or aldehyde bodies with multiple hydroxyl groups.

Question 2

What is the biggest use of carbohydrates in the body?

Answer 2

Fuel source and metabolic intermediates.

Question 3

What iss the difference between simple and complex sugars in digestion, and how does this affect how they release energy?

Answer 3

Simple sugars get converted directly into glucose and release their energy quickly.
Complex sugars take longer to break down, and release their energy more slowly.

Question 4

What kind of structure does a starch granule have?

Answer 4

They can form different structures depending on the plant.
Some are pitted, which gives greater surface area for enzymes.
Some are unpitted and smooth, and take longer to break down.

Question 5

What is the formula for an aldehyde?

Answer 5

R-CHO

Question 6

What is the formula for a ketone?

Answer 6

R-C-(=O)R’

Question 7

Which form of sugar is more stable, ring form or linear form?

Answer 7

The ring form.

Question 8

What is found in every di- and polysaccharide?

Answer 8

Glucose.

Question 9

What are the compositions of maltose, sucrose and lactose?

Answer 9

Maltose - glucose x2
Sucrose - glucose + fructose
Lactose - glucose + galactose

Question 10

What are the causes of lactose intolerance (5)?

Answer 10

Age, damage, medication, diarrhoea, and malnutrition.

Question 11

Are oligosaccharides water-soluble? What about polysaccharides? What is an advantage of this?

Answer 11

Oligosaccharides are typically soluble while polysaccharides aren’t, making it good for storage.

Question 12

What is a fischer projection, vs a haworth projection?

Answer 12

Fischer - straight chain representation

Haworth - cyclic representation, with thick lines to represent a 3D image.

Question 13

True or false

D and L conformations are not mirror images.

Answer 13

False, they are mirror images.

Question 14

What number of stereoisomers are possible given a number of asymmetrical carbons?

Answer 14

2^n

where n is the number of asymmetrical carbons.

Question 15

Which configuration od D or L do most naturally occurring sugars occur?

Answer 15

The D configuration.

Question 16

How are hemiacetals formed?

Answer 16

By reacting an alcohol and an aldehyde or ketone, giving a carbon with an ether and hydroxyl group.

Question 17

What are the D and L configruations based on? What about d and l? What is another way od representing d and l?

Answer 17

D and L are based on configurations of enantiomers.
d and l are based on properties of polarised light rotation, dextrorotary and levorotary.
d is usually (+)- and l is (-)-

Question 18

What is produced following the cyclisation of glucose?

Answer 18

A new asymmetrical carbon at C1.

Question 19

What are stereoisomers of glucose called? How many are there?

Answer 19

Anomers, there are two, α and β.

Question 20

What is found at the C! of glucose, and what is the difference between α and β glucose anomers?

Answer 20

An OH group is found at C1.
In the α anomer, it is below the ring.
In the β anomer, it is above the ring.

Question 21

What is the glycosidic bond of sucrose, and what is its anomer?

Answer 21

Sucrose has a 1,4-α glycosidic bond.

Its anomer is cellobiose, which has a 1,4-β glycosidic bond.

Question 22

What is cellobiose?

Answer 22

Product of cellulose breakdown.

Question 23

What form is glucose stored in and why?

Answer 23

Glucose is stored in the polymeric form, to minimise osmotic effects.

Question 24

What molecule is glucose stored in plants?

Answer 24

Amylose or amylopectin, collectively called starch.

Question 25

What is a reducing end?

Answer 25

The end of a polysaccharide with an anomeric C1 that isn’t involved in a glycosidic bond.

Question 26

What glycosidic bonds are found in amylose? What about cellulose?

Answer 26

Amylose - 1,4-α glycosidic bonds.

Cellulose is the anomer, with 1,4-β gylcosidic bonds.

Question 27

What glycosidic bonds does amylopectin have? What about glycogen?

Answer 27

Amylopectin - mainly 1,4-α bonds, but has 1,6-α branches coming off some of them.
Glycogen is similar, but has much more 1,6-α branches.

Question 28

Why is glycogen more branched than amylopectin?

Answer 28

More branches allow for faster energy release, due to higher surface area, and allow for more energy storage, which animals need more over plants.

Question 29

What is it about cellulose binding that gives it its structural strength?

Answer 29

Every second glucose is flipped due to the 1,4-β gylcosidic bonds, promoting interlinkage.

Question 30

What charge does chitin have, and what does this confer?

Answer 30

A strong positive charge, allowing it to bind to negatively charged surfaces, such as metals, proteins etc.

Question 31

What are glycosaminoglycans? What charge do they tend to have?

Answer 31

Linear polymers made of repeating disaccharides, which are usually modified. Typically negative.

Question 32

What is a sugar alcohol?

Answer 32

They lack ketones and aldehydes.

Question 33

What is a sugar acid?

Answer 33

The aldehyde at C1 or the OH at C6 is oxidised to a carboxylic acid.

Question 34

What is an amino sugar?

Answer 34

Amino group substitution for an OH group. The amino group is typically acetylated.

Question 35

What are the types of fibre (3)?

Answer 35

Cellulose
Lignin
Pectin

Question 36

What is pectin?

Answer 36

Important cell wall polysaccharide, allowing primary cell wall expansion and growth.

Question 37

What is lignin made of (3)?

Answer 37

Made of 3 monolignol monomers:
-p-coumaryl alcohol
-coniferyl alcohol
-sinaperyl alcohol
-

Question 38

Are soluble fibres easily fermented? What viscosity do they have?

Answer 38

They are viscous and fermentable. Easily digestible.

Question 39

What are soluble fibres found in?

Answer 39

Fruits and legumes.

Question 40

What are insoluble fibres found in?

Answer 40

Grains and vegetables.

Question 41

Are insoluble fibres fermentable?

Answer 41

Not easily.

Question 42

What are the effects of eating soluble and insolbule fibres (2,2)?

Answer 42

Soluble
Lowers cholesterol and glucose levels.
Insoluble
Promotes bowel movement and alleviates constipation.