1. Biological Molecules - glucose, starch Monosaccharides

Question 1

Define monomer

Answer 1

Monomers are the smaller units from which larger molecules are
made.

Question 2

Define polymers

Answer 2

Polymers are molecules made from a large number of monomers
joined together.

Question 3

Examples of monomers

Answer 3

Monosaccharides, amino acids and nucleotides are examples of
monomers

Question 4

what is a condensation reaction

Answer 4

A condensation reaction joins two molecules together with the
formation of a chemical bond and involves the elimination of a
molecule of water.

Question 5

what is a hydrolysis reaction

Answer 5

A hydrolysis reaction breaks a chemical bond between two
molecules and involves the use of a water molecule.

Question 6

what is a monosaccharide

Answer 6

Monosaccharides are the monomers from which larger
carbohydrates are made

single sugar units

Question 7

examples of carbohydrates

Answer 7

sugars and starch

Question 8

where are sugars found e.g. sucrose

Answer 8

sucrose is found in cakes and biscuits

Question 9

where is starch found

Answer 9

starch is found in foods such as pasta and rice

Question 10

Describe the structure of glucose

Answer 10

Glucose has a ring shape
Glucose contains 6 carbon atoms

Question 11

What do all carbohydrates contain

Answer 11

All carbohydrates including glucose contain only the elements carbon, hydrogen and oxygen

Question 12

What are sugars /monosaccharides with six carbon atoms called

Answer 12

Sugars with six carbon atoms are called hexose sugars/monosaccharides

Question 13

What type of sugar is glucose and why?

Answer 13

Glucose is a hexose sugar/monosaccharide because it contains six carbon atoms

A single sugar molecules (a monosaccharide)

Question 14

Draw the structure of glucose

Answer 14

https://static.aqa.org.uk/assets/image/0018/235440/00055366-DA00046397-DB.png

write 1 - 6 on the inside of the hexagon
then 6 on the left of the stick

Question 15

Give examples of a monosaccharide

Answer 15

glucose, galactose, fructose

Question 16

describe a key feature of monosaccharides - explain using the structure of glucose

Answer 16

Monosaccharides are soluble in water
Monosaccharides including glucose have a large number of OH groups.
OH groups are called hydroxyl groups

Hydroxyl groups are polar due to the small negative charge in the oxygen atom and the small positive charge on the hydrogen atom.
This means that Hydroxyl groups can form hydrogen bonds with water molecules
Due to this, monosaccharides are soluble in water

These molecules are hydrophilic

Question 17

What are hydrophilic molecules

Answer 17

Hydrophilic (water loving)
Hydrophilic molecules all dissolve in water

Question 18

Monosaccharides are ______ molecules

Answer 18

Monosaccharides are hydrophilic molecules

Question 19

State the two forms of glucose

Answer 19

Alpha glucose
Beta glucose

Question 20

The two different forms of glucose can also be called ______ of glucose

Answer 20

The two different forms of glucose can also be called ISOMERS of glucose

Question 21

Draw the structures of alpha and beta glucose

Answer 21

https://static.aqa.org.uk/assets/image/0018/235440/00055366-DA00046397-DB.png

https://static.aqa.org.uk/assets/image/0008/235439/00055366-DA00046396-DB.png

Question 22

Describe the similarity between alpha and beta glucose

Answer 22

In both isomers of glucose, carbon 1 is bonded to a hydrogen atom and also to an OH (hydroxyl) group.

Question 23

Describe the difference between alpha and beta glucose

Answer 23

The key difference between the two isomers of glucose is the position of the hydroxyl group on carbon 1

If the carbon 1 hydroxyl group
points below the plane of the ring, then this isomer is called alpha glucose

If the carbon 1 hydroxyl points above the plane of the ring, this this isomer is called beta glucose

https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcQtVcnkOpYu6-eFvrKkMGS7Zeacf_nG260b7BNijnErTnPs5fFs - beta glucose

https://www.youtube.com/watch?v=8GDXf2LrrUg&list=PL9IouNCPbCxVF0IVlwiILW-TmAMYX5OO7&index=4 at 1:43

Question 24

Describe how disaccharides are formed from monosaccharides

Answer 24

Disaccharides are formed by the condensation of two
monosaccharides:

Question 25

Describe what happens when two molecules of alpha glucose react together

Answer 25

When two molecules of alpha glucose react together, the disaccharide maltose is made. Also when the disaccharide is made, a molecule of water is also produced The water molecules is formed from a hydrogen atom from one of the monosaccharides and a hydroxyl group from the other This reaction is called a condensation reaction since the reaction forms a water molecule The glycosidic bond is formed between carbon 1 on one alpha glucose and carbon 4 on the other alpha glucose

Question 26

When a disaccharide is made from two monosaccharide was is also produced and how?

Answer 26

Also when the disaccharide is made, a molecule of water is also produced The water molecules is formed from a hydrogen atom from one of the monosaccharides hydroxyl group and a hydroxyl group from the other This reaction is called a condensation reaction since the reaction forms a water molecule

Question 27

a disaccharide is formed from two monosaccharides. What type of reaction is this and why?

Answer 27

This reaction is called a condensation reaction since the reaction forms a water molecule

Question 28

What is a glycosidic bond

Answer 28

The chemical bond formed between the two molecules of alpha glucose

Question 29

A condensation reaction between two monosaccharides forms a _____________

Answer 29

A condensation reaction between two monosaccharides forms a glycosidic bond.

Question 30

Draw the reaction for the formation of maltose

Answer 30

https://o.quizlet.com/pVG3e0ugJZiYwjQlseKHVw.jpg

Question 31

How are the two alpha glucose molecules bonded together What type of glycosidic bond is in the disaccharide maltose

Answer 31

Maltose has a 1,4 glycosidic bond

Question 32

Explain how maltose has a 1,4 glycosidic bond Why it is called a 1,4 glycosidic bond

Answer 32

The glycosidic bond is between carbon 1 on one alpha glucose and carbon 4 on the other alpha glucose

Question 33

What type of reaction a disaccharides formed in

Answer 33

Disaccharides are formed in a condensation reaction (water molecule is also produced)

Question 34

Describe what happens when you add water to a disaccharide

Answer 34

If water is added to the disaccharide, the glycosidic bond breaks. This converts the disaccharide back to the original monosaccharides This is called a hydrolysis reaction

Question 35

What is a hydrolysis reaction

Answer 35

A reaction where water is added to the disaccharide which breaks the glycosidic bond This converts the disaccharide back to the original monosaccharides

Question 36

Where are hydrolysis reactions normally carried out and by what

Answer 36

In cells this reaction is normally carried out by enzymes

Question 37

State some disaccharides

Answer 37

Maltose Sucrose Lactose Are examples of disaccharides.

Question 38

How is sucrose made

Answer 38

Glucose (alpha) + fructose = sucrose The disaccharide sucrose is formed from the monosaccharides glucose and fructose

Question 39

How is lactose made

Answer 39

Glucose (alpha) + galactose = lactose The disaccharide lactose is formed from the monosaccharides glucose and galactose

Question 40

Why is glucose being extremely soluble in water a problem

Answer 40

If a cell contains a large amount/(high conc. of in cell) dissolved glucose, this can cause water to move into the cell by osmosis

Question 41

How do plant cells solve the problem of water moving into cells by osmosis (due to glucose’s solubility) and why?

Answer 41

To solve this problem, plant cells store glucose as starch - because starch is insoluble

Question 42

What is a polysaccharide

Answer 42

Polysaccharides are formed by the condensation of many glucose units. Polysaccharides are formed when more than two monosaccharides are joined together by condensation reactions

Question 43

What two molecules/polysaccharides does starch consist of

Answer 43

Amylose Amylopectin

Question 44

Describe the structure of amylose

Answer 44

Amylose is an unbranched polymer of alpha glucose molecules (joined by 1,4 glycosidic bonds) If a large number of alpha glucose molecules are joined together, then the polysaccharide amylose is made. The alpha glucose molecules are joined by 1,4 glycosidic bonds Each bond forms in a condensation reaction producing a molecule of water The amylose molecule then twists into a compact helix with hydrogen bonds forming between glucose molecules along the chain Amylose forms a helix which is held in place by hydrogen bonds between glucose molecules This helical shape helps to make starch a very compact molecule

Question 45

In amylose how does each bond form

Answer 45

Each bond forms in a condensation reaction producing a molecule of water

Question 46

What is starch

Answer 46

Starch is a store of glucose

Question 47

If a cell needs glucose, what happens

Answer 47

If a cell needs glucose, water is used to break the glycosidic bonds This converts the polysaccharide back to the original monosaccharides (glucose) This is called a hydrolysis reaction When the cell needs glucose, enzymes are used to break the glycosidic bonds in starch This is a hydrolysis reaction and requires water The enzymes that break down starch act at the ends of the molecules Because amylopectin has a large number of branches, this means that it has a large number of ends. Because of this the enzymes can break down starch rapidly

Question 48

Draw the structure of amylose

Answer 48

https://o.quizlet.com/pVG3e0ugJZiYwjQlseKHVw.jpg but many

Question 49

Where do we find starch

Answer 49

We find starch in starch grains. /plants

Question 50

State the advantage of the structure of amylose in starch / structure relate to function

Answer 50

Amylose twists into a helix This helical shape helps to make starch a very compact molecule SO A lot of it can be stored in a small space

Question 51

Describe the structure of amylopectin

Answer 51

Amylopectin is a polymer of alpha glucose molecules joined by 1,4 glycosidic bonds Amylopectin chains have a branch every 25-30 glucose molecules A branch is another chain of alpha glucose molecules joined by 1,4 glycosidic bonds The branch is connected to the main chain by a glycosidic bond. The glycosidic bond is between carbon 1 of one of the alpha glucose molecules and carbon 6 of the other alpha glucose molecules. This is called a 1,6 glycosidic bond The glucose molecules at the branch points are joined by 1,6 glycosidic bonds. Amylopectin is a heavily branched molecule

Question 52

Regarding amylopectin, what is a branch

Answer 52

A branch is another chain of alpha glucose molecules joined by 1,4 glycosidic bonds

Question 53

In amylopectin, how is the branch connected to the main chain

Answer 53

The branch is connected to the main chain by a glycosidic bond.

Question 54

Describe the glycosidic bond between the branch and main chain in amylopectin

Answer 54

The branch is connected to the main chain by a glycosidic bond. The glycosidic bond is between carbon 1 of one of the alpha glucose molecules and carbon 6 of the other alpha glucose molecules. This is called a 1,6 glycosidic bond

Question 55

Draw the structure of amylopectin Draw a simplified structure of amylopectin

Question 56

Which polysaccharide is unbranched and which polysaccharide is branched

Answer 56

Amylose - unbranched polysaccharide Amylopectin - branched polysaccharide

Question 57

How is the structure of starch related to its function in cells

Answer 57

Amylose forms a tight helix. This makes starch compact This means/allows for starch can store a large amount of glucose molecules for its size Starch is insoluble in water This means that starch does not cause water to enter the cell by osmosis Because amylose and amylopectin are polymers, they are two large to diffuse through the cell membrane and pass out of the cell When the cell needs glucose, enzymes are used to break the glycosidic bonds in starch This is a hydrolysis reaction and requires water The enzymes that break down starch act at the ends of the molecules Because amylopectin has a large number of branches, this means that it has a large number of ends. Because of this the enzymes can break down starch rapidly insoluble - therefore doesnt affect water potential - so water is not drawn into cells by osmosis - means cell does not cell - makes it good for storage being large and insoluble - does not diffuse out of cells compact - a lot of it can be stored in a small placed when hydrolysed forms alpha glycose - which is easily transported and readily used in resp. branched form has many ends, each of which can be acted on by enzymes simultaneously meaning that glucose monomers are released very rapidly has lots of branches (more than starch), so has more ends that can be acted on simultaneously by enzymes. it is therefore more rapidly broken down to form glucose molecules, which are used in respiration