Unit 2 - Proteins

Question 1

Where can proteins be found?

Answer 1

Meat, fish, eggs, wool, silk, muscle tissue, skin, hormones such as insulin, hair and nails.

Question 2

What does the body use proteins for?

Answer 2

Needed in diet for: growth and repair of body tissue and biological processes.

Question 3

What elements do proteins ALWAYS contain?

Answer 3

Hydrogen
Oxygen
Nitrogen
Carbon

Question 4

What are proteins?

Answer 4

Natural polymers made of amino acids.

Question 5

What functional groups are in amino acids?

Answer 5

An amino group (NH2)
A carboxyl group (-COOH)

Question 6

What is an essential amino acid?

Answer 6

Amino acids that must be obtained through diet.

Question 7

How do you test that a protein is present in human hair?

Answer 7

Heat a test tube. In the test tube is protein, soda lime and mineral wool. Put wet pH paper in the gas leaving the test tube, it should turn blue.

Question 8

How are proteins made?

Answer 8

When amino acid units join together through the elimination of water in a condensation reaction. The amino and carboxylic groups join to form an amide link.

Question 9

How can proteins be hydrolysed in a laboratory?

Answer 9

Using a suitable enzyme such as pepsin. Pepsin breaks down proteins to amino acids and is most active in acid conditions.

Question 10

What are enzymes?

Answer 10

Protein molecules that act as biological catalysts.

Question 11

How are spirals/helix and sheet structures made?

Answer 11

Hydrogen bonds forming between the N—H bonds and the C=O bonds in a protein. The helix then twists and folds into the characteristic shape of the protein.

Question 12

Describe the structure of an aldehyde.

Answer 12

A carbonyl group (C=O) which is at the end of the carbon chain.

Question 13

What do aldehydes’ names end in?

Answer 13

-al

Question 14

Describe the structure of a ketone.

Answer 14

Carbonyl group (C=O) in the middle (ketOne oxygen in middle).

Question 15

What do ketones’ names end in?

Answer 15

-one

Question 16

What is the general formula of aldehydes?

Answer 16

Cn H2n O

Question 17

What is the general formula of ketones?

Answer 17

Cn H2n O

Question 18

What ketones CAN’T you get?

Answer 18

Methanone and ethanone.

Question 19

What is organic oxidation?

Answer 19

An increase in the oxygen to hydrogen ratio.

Question 20

What is the symbol that means that an oxidising agent has been added?

Answer 20

[O]

Question 21

What do you use to indicate that an oxidation reaction occurs?

Answer 21

Oxidizing agents

Question 22

What 3 oxidizing agents can be used to oxidize an aldehyde and distinguish it from a ketone?

Answer 22

Fehlings solution, Tollens reagent, Acidified potassium dichromate solution

Question 23

What is the colour change of fehlings solution?

Answer 23

Blue to orange

Question 24

What is the colour change of tollens reagent?

Answer 24

Silver mirror effect

Question 25

What is the colour change or acidified potassium dichromate solution?

Answer 25

Orange to green

Question 26

What does volatile mean?

Answer 26

Easily releases gaseous molecules.

Question 27

How does volatility work?

Answer 27

Stronger intermolecular forces = less volatile

Question 28

Do compounds with low boiling points have high or low volatility?

Answer 28

High

Question 29

In general, with a formula mass under ___ are likely to be volatile.

Answer 29

300

Question 30

Polar molecules will be soluble in water since polar substances dissolve in ___ solvents.

Answer 30

Polar (like dissolves like)

Question 31

Non-polar molecules will dissolve in ____ solvents such as _____.

Answer 31

1. non polar 2. oil/butter (like dissolves like)

Question 32

If you want to keep flavour when cooking a polar molecule, what should you cook it in?

Answer 32

Non-polar oil/butter. (Non-polar molecules should be cooked in polar and water)

Question 33

How does denaturing work?

Answer 33

Chains of proteins are held together in a particular shape by **hydrogen bonds.** The **heat breaks the hydrogen bonds** and the **protein loses it’s shape.**

Question 34

What temperature will proteins normally denature at?

Answer 34

Around 60 degrees celsius.

Question 35

What is the ‘“lock and key theory’?

Answer 35

Enzyme catalyse specific reactions in the body. Substrates go into the active site and take out products.

Question 36

What happens when enzymes are heated?

Answer 36

The substrate molecule becomes denatured and is no longer suitable for the specific reaction, thus won’t work efficiently.

Question 37

What is a primary alcohol?

Answer 37

1 C attached to the C—OH.

Question 38

What is a secondary alcohol?

Answer 38

2 C attached to the C—OH.

Question 39

What is a tertiary alcohol?

Answer 39

3 C attached to the C—OH.

Question 40

What do you put in the name of an alcohol with 2 hydroxyl groups?

Answer 40

-diol (3 = triol)

Question 41

What is the colour change of hot copper (II) oxide?

Answer 41

Black to brown.

Question 42

What oxidising agents can be used to oxidise a secondary alcohol?

Answer 42

Hot copper (II) oxide and Acidified potassium dichromate solution.

Question 43

What is the process of the oxidation of a primary alcohol?

Answer 43

Primary alcohol ➡️ Aldehyde ➡️ Carboxylic acid

Question 44

What oxidising agents are used for 1st step oxidation of a primary alcohol?

Answer 44

Hot copper (II) oxide or acidified potassium dichromate solution.

Question 45

What oxidising agents are used for 2nd step oxidation of a primary alcohol?

Answer 45

Acidified potassium dichromate solution, fehlings solution or tollen’s reagent.

Question 46

What is the process of the oxidation of a secondary alcohol?

Answer 46

Secondary alcohol ➡️ Ketone ➡️ ❌

Question 47

Can you oxidise an tertiary alcohol?

Answer 47

No

Question 48

Many foods are packaged in an __ atmosphere of ____ ____ to prevent ___.

Answer 48

1. Inert 2. Nitrogen gas 3. Oxidation

Question 49

What’s an antioxidant?

Answer 49

A compound that easily oxidises itself so that it protects other compounds from oxidation.