19A.5

Question 1

what are amino acid

Answer 1

they are compounds with both a amino group and a carboxylic group but are separated by a carbon

Question 2

what are the known amino acids and there sructures

Answer 2

alanine - the carbon is attached to a methyl group

cysteine - the carbon is attached to a CH2 which is attached to SH

Glutamic acid - the carbon is attached to propanoic acid

glycine - carbon is only attached to h making it the simplest one

lysine - the carbon is attached to butlyamine

Question 3

what are amino acids often called and why

Answer 3

2 amino acids since the NH2 group is attached to the second carbon counting from the COOH

Question 4

proteins are made from

Answer 4

amino acids

Question 5

how do we name amino acids by there UPAC name

Answer 5

They are amine derivatives of carboxylic acid, with the prefix of amino to indicate the amino group and the locant for which carbon atom its attached to and then the rest is following the normal structure

Question 6

amino acids are not

Answer 6

naturally occurring

Question 7

what does the structural formula, displayed formula, skeletal formula of amino acids look like

Answer 7

page 250

Question 8

what does isoelectric points mean

Answer 8

The PH of an aq solution (of amino acids) in which it is neutral i.e the PH of a aq zwitter amino acid

Question 9

what is the solubility of amino acids

Answer 9

they are all soluble in water

Question 10

amino acids can act as both

Answer 10

acid and base as they have the acid-base character

Question 11

what is the chemical reaction when amino acids react with water leaving an alkaline solution

Answer 11

N2H - R - COOH + H20 —> N3H^+1- R - COOH + OH^-

Question 12

what is the chemical reaction for when amino acids react with water leaving an alkaline solution

Answer 12

N2H - R - COOH + H2O —-> N2H - R -COOH^- + H3O^+

Question 13

what is the chemical reaction for when an amino acids functional groups (react)

Answer 13

it is a H+ transfer

reaction:
H2N - R - COOH ⇌ H3N^+ - R - COO^- (this is a zwitterion)

Question 14

What is a zwitterion

Answer 14

a molecule containing a positive and a negative charges but has no overall charge

Question 15

what does the number of isoelectric point tell us about the amino acids properties

Answer 15

if the isoelectric point is low it indicates that the amino acid is predominantly acidic, and is the isoelectric point is high then the amino acid is predominantly a base

Question 16

the isoelectric point is linked with the amino groups and acid groups in what way?

Answer 16

if there is more amino groups in the molecules then the isoelectric point is higher, and if there is more carboxylic groups in the molecules then the isoelectric point is lower

Question 17

why are proteins used involved in buffering solutions

Answer 17

because they contain an amino acid which has both an acid and base character following there two groups of NH2 and COOH (also we need a isoelectric point in the middle yk)

Question 18

all amino acids can form salts with

Answer 18

acids and bases

Question 19

what is the structure of the salt when alanine reacts with acid

Answer 19

the protonated structure is page 251

Question 20

how many salts can glutamic acid form and why

Answer 20

it can form 3 salts since they have 2 COOH groups so either one can react or both

Question 21

what is the structure and use of monosodium glutamate and how is it made

Answer 21

structure page 251

use - flavour enhancer in food

made - reaction of glutamic acid with a base where the main COOH only reacts

Question 22

most 2-amino acids contain

Answer 22

a chiral center, so they are optically active, the excepion is glycine

Question 23

aq enantiomers of amino acids do what

Answer 23

rotate the plane of polarization of plane polarized light. some are dextrorotatory (clockwise) and some are laevorotatory (anti clockwise)

Question 24

if an amino acid is synthesised in a laboratory then

Answer 24

a racemic mixture is formed