Biological Molecules

Question 1

What is a hydrogen bond?

Answer 1

A weak interaction that can occur whenever molecules contain a slightly positive charged atom bonded to a slightly negative charged atom.

Question 2

What is a hydrolysis reaction?

Answer 2

A reaction that occurs when a molecule is split into two smaller molecules with the addition of water.

Question 3

What is a monomer?

Answer 3

A small molecule which binds to many other identical molecules to form a polymer.

Question 4

What is a polymer?

Answer 4

A large molecule made up of monomers.

Question 5

Why is a water molecule polar?

Answer 5

oxygen has a greater number of positive protons in its nucleus so that it exerts a greater attraction for shared electrons making it slightly negative and the hydrogen atoms become slightly positive

Question 6

Why is a hydrogen bond weaker than a covalent bond?

Answer 6

A hydrogen bond is a weak interaction between slightly positive and slightly negative molecules whereas covalent bonds are the sharing of electrons to gain a full outer shell.

Question 7

What are carbohydrates?

Answer 7

A group of molecules containing carbon, hydrogen and oxygen.

Question 8

What is a condensation reaction?

Answer 8

A reaction that occurs when two molecules join together with the removal of water.

Question 9

What is a glycosidic bond?

Answer 9

A bond formed between two monosaccharides by a hydrolysis reaction.

Question 10

What is the function of carbohydrates?

Answer 10

To act as a source of energy(glucose), a store of energy(starch and glycogen), and as structural units(cellulose in plants).

Question 11

What are the three main groups of carbohydrates?

Answer 11

Monosaccharides, disaccharides and polysaccharides.

Question 12

What are monosaccharides?

Answer 12

The simplest carbohydrates. Good source of energy because of large number a carbon to hydrogen bonds. Soluble in water and insoluble in non- polar solvents.

Question 13

What are disaccharides?

Answer 13

Sweet and soluble.

Most common is maltose.

Question 14

Give an example of a reducing sugar?

Answer 14

Maltose and lactose.

Question 15

Give an example of a non-reducing sugar?

Answer 15

Sucrose.

Question 16

How are disaccharides made?

Answer 16

When two monosaccharides join.

Question 17

What makes maltose?

Answer 17

Alpha-glucose + alpha-glucose.

Question 18

What makes sucrose?

Answer 18

Alpha-glucose + fructose.

Question 19

What makes lactose?

Answer 19

Beta-galactose + alpha-glucose.

Question 20

What makes cellobiose?

Answer 20

Beta-glucose + beta-glucose.

Question 21

What happens when monosaccharides join.

Answer 21

A condensation reaction and a glycosidic reaction.

Question 22

What does a hydrolysis reaction do?

Answer 22

Breaks disaccharides into monosaccharides.

Question 23

What is the bond joined to the top carbon bond in glucose?

Answer 23

CH2OH

Question 24

What is the molecular formula of sugars?

Answer 24

CnH2nCn

Question 25

Difference between alpha glucose and beta glucose

Answer 25

The OH and H are swapped round

Question 26

Molecular formula of Ribose

Answer 26

C5 H10 O5

Question 27

Molecular formula of deoxyribose

Answer 27

C5 H10 O4

Question 28

Carbohydrate monomer?

Answer 28

Monosaccharides- glucose

Question 29

Carbohydrate polymer?

Answer 29

Polysaccharides- starch

Question 30

Difference between alpha and beta glucose?

Answer 30

In Alpha glucose the H is above the OH

Question 31

Difference between ribose and deoxyribose?

Answer 31

Ribose is bonded down to two OH's

Question 32

Molecular formula of glucose?

Answer 32

C6H12O6

Question 33

Alpha glucose role in the body?

Answer 33

Energy source Component of starch and glycogen Energy stores

Question 34

Role in the body of beta glucose?

Answer 34

Energy source | Component of cellulose

Question 35

Role in the body of ribose?

Answer 35

Component of RNA and ATP

Question 36

Role in the body of deoxyribose?

Answer 36

Component of DNA

Question 37

Example of non-reducing sugar?

Answer 37

Sucrose

Question 38

How to calculate Rf value?

Answer 38

Distance travelled by dye over distance travelled by solvent

Question 39

What are the main polysaccharides?

Answer 39

Glycogen, starch and cellulose

Question 40

Describe glycogen?

Answer 40

``` Compact- doesn't occupy a large space In animals Branched- 1,4 and 1,6 glycosidic bond Occur in dense granules Less soluble in water ```

Question 41

Describe starch?

Answer 41

Compact | Occurs in granules within a cell

Question 42

Describe amylose?

Answer 42

``` Unbranched chain Alpha glucose molecules (chain) 1/4 glycosidic bonds Spiral shape held with H bonds Less soluble ```

Question 43

Amylopectin description?

Answer 43

Branched chain More compact- hydrolysed more easily Spiral shape held by hydrogen bonds 1,4 and 1,6 glycosidic bonds

Question 44

Describe cellulose?

Answer 44

Found in plant cell walls Tough, insoluble and fibrous Made form long chains of beta glucose molecules Chains lie straight rather than spiralling

Question 45

How are the cellulose chains straight?

Answer 45

Hydrogen and hydroxyl groups on carbon 1 are inverted | The beta glucose molecules in the chain are rotated by 180 degrees. The beta 1,4 glycosidic bond prevent spiralling.

Question 46

Describe microfibrils?

Answer 46

``` 60-70 cellulose chains bonded together. 10-30 nm in diameter Bundle together to form macrofibrils Run in all directions and criss-cross Numerous hydrogen bonds between chains ```

Question 47

Properties of cellulose?

Answer 47

High tensile strength Difficult to digest Permeable for water molecules and ions

Question 48

Roles of calcium?

Answer 48

``` Bone and teeth rigidity Blood clotting and muscle contraction Activator for enzymes Regulates permeability of cell membranes Cell wall development ```

Question 49

Functions of hydrogen?

Answer 49

Involved in photosynthesis and respiration | Involved in transport of co2 in the blood

Question 50

Reducing sugars test?

Answer 50

Heat with Benedicts solution- copper sulphate Blue- green- yellow- orange/red Forms a precipitate

Question 51

Non- reducing sugar test?

Answer 51

First test for reducing sugars Separate sample- boil with hydrochloric acid Cool and neutralise with hydrogencarbonate Test for reducing sugar again Green- yellow- orange- red

Question 52

Apparatus to be used in qualitative tests?

Answer 52

Spotting tile Calibration chart Colorimeter Biosensors

Question 53

Test for starch?

Answer 53

Spotting tile Add iodine Yellow/brown to blue/black