Topic 1 - Saccharides + Triglycerides 1.12 To 1.16

Question 1

What are monosaccharides

Answer 1

The monomers of carbohydrates (sugars)

They form glycosidic bonds with each other to form polysaccharides

Question 2

What is a hexose monosaccharide

Answer 2

A monosaccharide containing 6 carbons.
It has the formula

C6 H12 O6

Question 3

What is the difference between alpha glucose and beta glucose (structure)

Answer 3

In alpha Glucose the H group is above Carbon 1 and the OH is below C1

In beta glucose the OH group is above C1 and the H group is below C1

Question 4

What is the only structural difference between beta glucose and galactose

Answer 4

In beta glucose the H group is above C4 and the OH group is below

In galactose the OH group is above C4 and the H group is below

Question 5

How is the structure of Fructose different from glucose and galactose

Answer 5

Fructose contains two CH2 OH groups

Because of this it has a pentagonal structure (but is still a hexose sugar)

Question 6

What are glucose, fructose and galactose

Answer 6

They are monosaccharides

They are hexose sugars

Question 7

What is a disaccharide

Answer 7

The molecule formed when two monosaccharides form glycosidic bons with each other

Question 8

What type of reaction makes disaccharides / polysaccharides

Answer 8

Condensation reactions

Question 9

How much water is produced when two hexose monosaccharides form a disaccharide

Answer 9

1 H20

Question 10

What is the formula of a disaccharide formed by hexose monosaccharides

Answer 10

C12 H22 O 11

(C6 H12 O6 ×2) - ( 1 H20)

Question 11

What is maltose

Answer 11

A disaccharide formed when two alpha glucose molecules form an alpha 1-4 glycosidic bond

Question 12

Where is maltose found biologically / used

Answer 12

It is found in germinating seeds and used for brewing

Question 13

What bond is present in maltose (between the monosaccharides)

Answer 13

An alpha 1-4 glycosidic bond

Question 14

What is sucrose

Answer 14

A disaccharide made of alpha glucose and fructose

An alpha 1-2 glycosidic bond is formed

Question 15

What the biological role of sucrose and what do we use it for

Answer 15

It is used to transport energy in plants
We use it in cooking

It is stored in sugar cane

Question 16

What bond is formed between the monosaccharides in sucrose

Answer 16

An alpha 1-2 glycosidic bond

Question 17

What is lactose

Answer 17

A disaccharide formed by alpha glucose and galactose

There is a beta 1-4 glycosidic bond between the monosaccharides

Question 18

What is the biological role of lactose and what do we use it for

Answer 18

It is found in mammalian milk to supply energy

We use it in food (e.g cheese)

Question 19

What bond is formed between the monosaccharides in lactose

Answer 19

A beta 1-4 glycosidic bond

Question 20

How is it determined whether a glycosidic bond is alpha or beta

Answer 20

If the OH groups on C1 and C4 are both below or both above the carbon, and alpha bond will form

If one is above and one is below a beta bond will form

Question 21

How are Disaccharides broken down

Answer 21

In hydrolysis reactions ( 1 H2O is added)

Question 22

When do humans break down disaccharides

Answer 22

They are broken down during digestion
(In reactions catalysed by enzymes)

Question 23

What is glycogen

Answer 23

A highly branched, not coiled polysaccharide found in animals and fungi

It is made by alpha glucose monosaccharides forming 1-4 glycosidic bonds
(And 1-6 glycosidic bonds every 10 units)

Question 24

Why is glycogen highly branched

Answer 24

Having many branches means that there are many terminal ends for enzymes to join to

This means glycogen can be quickly broken down (which is needed to maintain a high metabolic rate)

Question 25

What is glycogen used for

Answer 25

Glycogen is used to store energy As it is compact it can store a lot of energy in a small space

Question 26

What is glycogen used for

Answer 26

Glycogen is used to store energy As it is compact it can store a lot of energy in a small space

Question 27

Where is the energy in polysaccharides (such as glycogen) stored / located

Answer 27

In the glycosidic bonds between monosaccharides

Question 28

What is starch

Answer 28

A polysaccharide found in plants that is used to store energy It is made of two types - amylose and amylopectin

Question 29

What is amylose

Answer 29

A type of starch It is unbranched, linear and coiled in a helix It contains alpha 1-4 glycosidic bonds between alpha glucose molecules

Question 30

What is amylopectin

Answer 30

A type of starch It is branched (every 20 minutes) and not coiled There are alpha 1-4 and 1-6 glycosidic bonds between alpha glucose

Question 31

Why does amylopectin have less branches than glycogen

Answer 31

As plants have a lower metabolic rate

Question 32

Why are starch and glycogen suitable storage molecules

Answer 32

Glycogen + amylopectin are branched, so they can be hydrolysed easily (quick energy release) They are compact → store a lot of energy. They are large → do not cross surface membranes They are insoluble → They do not dissolve in water, so they have no osmotic effect

Question 33

What is cellulose

Answer 33

It is a linear and unbranched polysaccharide used structurally in plants It is made from 1-4 glycosidic bonds between beta glucose Several cellulose fibers form hydrogen bonds between each other

Question 34

What is the purpose of cellulose

Answer 34

Cellulose is used structurally, and it can be found most commonly in plant cell walls.

Question 35

Where are triglycerides found

Answer 35

in fats and oils

Question 36

What is a triglyceride made of

Answer 36

Glycerol and 3 fatty acids There is an ester bond between the glycerol and each fatty acid

Question 37

What reaction forms triglycerides

Answer 37

Condensation reactions - 3 water is produced

Question 38

How are triglycerides broken down

Answer 38

In hydrolysis ( 3 water is added)

Question 39

what are saturated fats

Answer 39

Fats made of triglycerides that contain (saturated) fatty acids with a c-c bonds

Question 40

Why are saturated fats solid at room temperature

Answer 40

The fatty acids are linear and unbranched so the triglycerides can pack closer together This makes the intermolecular forces between the triglycerides harder to break so they are solid at room temperature

Question 41

What are unsaturated fats

Answer 41

Fats which contain unsaturated fatty acids with a C=C double bond This means that they have bends (or kinks) in their Carbon chain

Question 42

Why are unsaturated fatty acids liquid at room temperature

Answer 42

Due to the kinks in the carbon chains the trigkycerides do not pack closely together. This means the intermolecular forces between them are weaker, and require less energy to break

Question 43

Why does the hydrolysis of triglycerides decrease the pH of a solution

Answer 43

As fatty acids are acidic Hydrolysis of triglycerides releases fatty acids into the solution, causing the pH to decreases

Question 44

How do beta glucose molecules form alpha 1-4 glycosidic bonds

Answer 44

The molecules inverts after every bond is formed. This ensures the OH groups are always in the same position

Question 45

Whats the minimum number of monosaccharides needed to make a polysaccharide

Answer 45

10

Question 46

Why is starch made from amylose + amylopectin

Answer 46

Amylose can be less readily hydrolysed, but can be stored more compactly than amylopectin as it has a helical structure

Question 47

Why is cellulose unable to spiralise

Answer 47

As hydrogen bonds hold molecules of cellulose together

Question 49

Why are triglycerides good storage molecules

Answer 49

They contain long carbon chains which store a lot of energy (High energy density) They are abundant (the body stores a lot of them)