Amino Acids And Proteins Flashcards Preview

A2 Chemistry Unit 2 > Amino Acids And Proteins > Flashcards

Flashcards in Amino Acids And Proteins Deck (47)
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1

What is an amino acid

A compound whose molecules contain bird an amino and a carboxyl group

2

How many amino acids occur naturally and in what form

20 occur naturally and they combine to form proteins
All naturally occurring amino acids are a amino acids

3

What does alpha amino acid mean

NH2 and COOH are bonded to same C atom

4

What is the definition of a zwitterion

Ions which have a permanent positive and negative charge but which are neutral overall

5

Why do amino acids exist as zwitterions

- they all contain a basic group and an acidic carboxyl group
- undergo internal acid-base reaction
- forms a dipolar ion

6

Draw the diagram of a zwitterion amino acid

See page 22

7

State the physical properties of amino acids

⭕️ High mp - dipolar ions - strong forces of attraction - lot of energy
⭕️ water soluble - dipolar ions - interact w polar water molecules
⭕️ white crystalline solids
⭕️ insoluble in organic solvents

8

What group is involved in the reaction when an amino acid reacts with sodium carbonate

The COOH group

9

What are the products for the reaction of an amino acid with sodium carbonate

Metal salt
Water
Carbon dioxide

10

What are he observations for amino acid reaction with sodium carbonate

Bubbles of colourless has evolved
Solid disappears

11

What group is reacted when amino acids react with nitrous acid

The NH2 group is replaced by an OH

12

What are the products when amino acid is reacted with nitrous acid

N2
H2O
Hydroxycarboxylic acid

13

How is nitrous acid produced

In situ
NaNO2 and HCl
Below 5°C

14

What is formed when amino acids react with copper (II) sulfate

A complex

15

What are the observations when amino acid is reacted with nitrous acid

Bubbles of colourless has given off (N2)

16

What are the observations when amino acid reacts with copper (II) sulfate

Dark blue solution formed

17

Write the structural equation of amino acid reaction with copper (II) sulfate

See notes

18

Draw the structure of an amino acid in acid conditions and alkaline conditions

See notes

19

Describe the structure of a neutral amino acid

Contains one amine and one carboxyl group

20

Describe an acidic amino acid

Contains additional carboxyl group

21

Describe a basic amino acid

Contains additional amine group

22

What kind of reaction forms a peptide (polyamide)

Condensation polymerisation of amino acids

23

What is a peptide link

Link between -NH2 of one amino acid and -COOH of another

24

What is a condensation reaction

When two molecules combine to form one single molecule. Resulting in the loss of a small molecule eg water

25

Draw the peptide group

See notes

26

What happens during acid hydrolysis of protein

- acids formed are protonated
- NH2 ➡️ NH3+
- positive amino acid ions
- COOH stays same

27

What happens during alkaline hydrolysis of a proteins

- acids formed are deprotonated
- COOH ➡️ COO-
- negative amino acid ions
- NH2 stays the same

28

What is the definition of primary structure of proteins

Sequence of amino acids joined by peptide links in the chain

29

What is the definition of secondary structure

Twisting/coiling of the chain to form a B-pleated sheet/a helix by intramolecular hydrogen bonding

30

Between which parts of the molecule does H bonding occur in the secondary structure

NH and C=O