Chapter 27.2

Question 1

General formula of an α amino acid

Answer 1

RCH(NH2)COOH

Question 2

How many amino acids are there

Answer 2

20

Question 3

State what is meant by the term zwitterion.

Answer 3

Ion which has both + & - charges

Question 4

The no charge form of an amino acid never occurs.
The amino acid exists as a

Answer 4

dipolar zwitterion.

Question 5

amino acids are often in what state

Answer 5

Amino acids are often solids

Question 6

how can the relatively high melting point of amino acids be explained

Answer 6

The ionic interaction between zwitterions

Question 7

what is the name of the ph point where an amino acid exists as a zwitterion

Answer 7

isoelectric point

Question 8

Some amino acids have an extra
carboxylic acid or an amine
group on the R group. These are
classed as

Answer 8

acidic or basic (respectively) amino acids

Question 9

effect of an acidic or basic group in the side R group on the isoelectric point

Answer 9

ph value of isoelectric point will be different

Question 10

esterification

Answer 10

amino acid heated with alcohol in the presence of concentrated sulfuric acid forming ester and water

Question 11

under acidic conditions of esterification the amine is

Answer 11

protonated

Question 12

amino acid + acid

Answer 12

salt
amine group acts as a base
N atom accepts proton to form ammonium ion

Question 13

amino acid+ alkali

Answer 13

salt + water
cooh acts as an acid and donates proton to form carboxylate ion

Question 14

amide

Answer 14

carboxylic acid derivative, oh replaced with nh2 or nhr

Question 15

suffix of amides

Answer 15

amide

Question 16

in amide formation, ammonia and amines act as nucleophiles by

Answer 16

donating lone pair of electrons on n to electron deficient carbon

Question 17

propanoyl chloride + nh3

Answer 17

propanamide + nh4-+cl-

Question 18

propanoyl chloride + primary amine(methylamine)

Answer 18

n-methylpropanamide + ch3nh3+cl-(primary amine hcl salt)
a secondary amide

Question 19

Hydrolysis of di-peptides/proteins

Answer 19

If proteins are heated with concentrated acid or alkali they can
be hydrolysed and split back in to their constituent amino acids.

Question 20

acid hydrolysis of ester

Answer 20

reflux, dilute aq acid
forms carboxylic acid + alcohol

Question 21

alkaline hydrolysis ester

Answer 21

reflux, aqueous hydroxide ions
forms carboxylate ion and alcohol

Question 22

hydrolysis of polyesters

Answer 22

base: salt + alcohol
acid: carboxylic acid + alcohol

Question 23

condensation polymerisation

Answer 23

joining of molecules via a condensation reaction. ie elimination of a small molecule like water or hcl

Question 24

ester linkage

Answer 24

r- coo- r’

Question 25

dicarboxylic acid + diol

Answer 25

poly(ester) + water

Question 26

diacyl dichloride + diol

Answer 26

poly(ester) + HCl

Question 27

dicarboxylic acid + diamine

Answer 27

poly(amide) + water

Question 28

diacyl dichloride + diamine

Answer 28

poly(amide) + HCl

Question 29

number of h2o's in condensation reaction expression

Answer 29

2n-1 H2O

Question 30

polyamides and polyesters to form from one monomer

Answer 30

IF monomer contains both functional groups

Question 31

amide hydrolysis acid

Answer 31

amide + h2o -> carboxylic acid + ammonium ion

Question 32

amide hydrolysis alkaline

Answer 32

amino acid -> carboxylate ion + ammonia

Question 33

polyamide hydrolysis in base and acid

Answer 33

base: salt of (cooh)2 + diamine acid: dioic acid + diamine salt

Question 34

cyclisation

Answer 34

some of these compounds can form various cyclic esters under different conditions from forming the polymer.

Question 35

Optical isomerism

Answer 35

occurs in carbon compounds with 4 different groups of atoms attached to a carbon (called an asymmetric carbon). forming non superimposable isomers

Question 36

chiral (asymmetric) carbon atom

Answer 36

A carbon atom that has four different groups attached

Question 37

amino acid chirality

Answer 37

All amino acids, except glycine, are chiral because there are four different groups around the C

Question 38

Two compounds that are optical isomers of each other are called

Answer 38

enantiomers

Question 39

Optical isomers have similar physical and chemical properties, but they rotate....

Answer 39

plane polarised light in different directions One enantiomer rotates it in one direction and the other enantiomer rotates it by the same amount in the opposite direction

Question 40

optical isomer rotates light clockwise, called

Answer 40

dextrorotatory

Question 41

optical isomer rotates light anti-clockwise, called

Answer 41

laevorotatory