Amino Acids

Question 1

Glycine

Answer 1

building block for protein
not considered an “essential amino acid” because the body can make it from other chemicals
in protein-rich foods including meat, fish, dairy, and legumes

Question 2

Alanine

Answer 2

important source of energy for
muscles and the central nervous system
strengthens the immune system
helps in the metabolism of sugars and organic acids
displays a cholesterol-reducing effect in animals

Question 3

Serine

Answer 3

non-essential amino acid in humans (synthesized by the body)
present and functionally important in many proteins
With an alcohol group, serine is needed for the metabolism of fats, fatty acids, and cell membranes; muscle growth; and a healthy immune system

Question 4

Phenylalanine

Answer 4

building blocks of proteins in
your body
exists in two forms or arrangements: L-phenylalanine and D-phenylalanine

Question 5

Cysteine

Answer 5

non-essential sulfur-containing amino acid in humans, related to cystine
important for protein synthesis, detoxification, and diverse metabolic functions

Question 6

peptide bond

Answer 6

chemical bond formed between two molecules when the carboxyl group of one molecule reacts with the amino group of the other
molecule, releasing a molecule of water (H2O).
This is a dehydration synthesis reaction (also known as a condensation reaction), and usually occurs between amino acids,

Question 7

dipeptide, tripeptide, polypeptide

Answer 7

two amino acids form
join a third amino acid
This reaction occurs naturally within cells, in ribosomes

Question 8

Hydrogen bonding

Answer 8

present abundantly in the secondary structure of proteins, and also sparingly in tertiary conformation

Question 9

secondary structure of a protein

Answer 9

involves interactions (mainly hydrogen bonds) between neighboring polypeptide backbones which contain Nitrogen- Hydrogen bonded pairs and oxygen atoms. Since both N and O are strongly electronegative, the hydrogen atoms bonded to nitrogen in one polypeptide backbone can hydrogen bond to the oxygen atoms in another chain and visa-versa. Though they are relatively weak, these bonds offer substantial stability to secondary protein structure because they repeat many times and work collectively.

Question 10

tertiary protein structure

Answer 10

interactions are primarily between functional R groups of a polypeptide chain; one such interaction is called a hydrophobic interaction. These interactions occur because of hydrogen bonding between water molecules around the hydrophobe that further reinforces protein conformation.

Question 11

Solubility

Answer 11

Most of the amino acids are usually soluble in water and insoluble in organic solvents

Question 12

Melting Point

Answer 12

generally melted at a higher temperature of ten above 2000C

Question 13

Taste

Answer 13

sweet (Gly, Ala & Val), tasteless (Leu) or Bitter (Arg & Ile)

Question 14

Optical Properties

Answer 14

due to the presence of asymmetric α-carbon atoms

Question 15

ZwitterIon And Isoelectric Point

Answer 15

zwitter is derived from the German word which means “hybrid”
hybrid molecule containing positive & negative ionic groups
proton shifts from the carboxyl group to the amino group of the self molecule at normal pH cellular levels

Question 16

amino acids used as precursors for chemicals

Answer 16

used in various industries, such as pesticides and herbicides
threonine can be used to produce herbicide aztreonam and glycine can be used to produce glyphosate, another herbicide

Question 17

Chemical reactions of amino acids due to carboxyl group

Answer 17

Decarboxylation
Reaction with Alkalis (Salt formation)
Reaction with Alcohols (Esterification)
Reaction with Amines
Amino Acid Reaction with Ninhydrin Reagent

Question 18

Decarboxylation

Answer 18

The amino acids will undergo alpha decarboxylation to form the corresponding “amines”. Thus important amines are produced from amino
acids.
● Histidine → Histamine + CO2
● Tyrosine →Tyramine + CO2
● Tryptophan →Tryptamine + CO2
● Lysine →Cadaverine + CO2
● Glutamic acid → Gamma Amino Butyric Acid (GABA) +
CO2

Question 19

Reaction with Alkalis (Salt formation)

Answer 19

The carboxyl group of amino acids can release an H+ ion with the formation of Carboxylate (COO–) ions. These may be neutralized by cations like Na+ and Ca+2 to form Salts. Thus amino acids react with alkalies to form “Salts”.

Question 20

Reaction with Alcohols (Esterification)

Answer 20

When the amino acids are reacted with an alcohol to form, “Ester”.
The esters are volatile in contrast to the form of amino acids.

Question 21

Reaction with Amines

Answer 21

Amino acid reacts with Amines to form “Amides”.

Question 22

Amino Acid Reaction with Ninhydrin Reagent

Answer 22

used to detect primary and secondary amines
excess of ninhydrin, which is originally yellow in colour, reacts with a free α-amino acid group, a purple coloured dye known as Ruhemann’s purple is formed along with an aldehyde and liberation of CO2 gas(primary amines does not liberate CO2). The presence of Ruhemann’s purple imparts purple colour to the product which forms the basis of the Ninhydrin test in order to detect amino acids.

Question 23

Ninhydrin

Answer 23

tricyclic 1,2,3-trione
functions as an amino acid reagent
vital organic building block, which exposes latent fingerprints on porous surfaces like paper, cardboard and raw wood

Question 24

Porphyrins + Heme

Answer 24

Glycine + Succinyl-CoA (animals)
Glutamate (bacteria + plants)

Question 25

Non-ribosomal peptide synthesis

Answer 25

peptidoglycan, antibiotics
glutathione (glutamate+ cysteine + glycine)

Question 26

Modified amino acids

Answer 26

plant compounds
neurotransmitters
polyamines

Question 27

Nucleotide heterocyclic bases

Answer 27

purines and pyrimidines