General Science – Amino acids

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Biomolecules — Amino Acids
Amino Acids
➧ Amino acids are organic compounds containing two common functional groups …
☛ Amino group (–NH2)
☛ Carboxyl group (–COOH)

➧ These two funtional groups combines with the same Carbon.
➧ When two reactive / funtional groups combines with the same carbon , then the carbon is called – α carbon.
➧ For the α-Carbon , Amino acids also called α Amino Acids.
➧ Only α-amino acids are obtained on hydrolysis of proteins.

Structure of Amino Acids
➧ Amino acids are actually substituted methanes (CH4).
➧ Besides Amino , Carboxyl groups and Hydrogen they may contain another functional groups also.
➧ This another functional groups called R group or Alkyl group.
➧ Based on the nature of R group there are many Amino acids.
➧ But the number of Proteinogenic amino acids is 20.
➧ Amino acids which are takes part in protein synthesis called Proteinogenic amino acids.
➧ The word “proteinogenic” means “protein creating”.


Note :-
✔ Amino acids contain only the two functional groups namely Amino and Carboxyl groups are called Simplest Amino Acids.
✔ Glycine is the Simplest Amino Acids
✔ Each name of the amino acids given according to their property or nature of the compound
✔ Here Glycine is so named since it has sweet taste.
✔ In Greek glykos means sweet.
✔ Like Glycine , Tyrosine was first obtained from cheese (in Greek, tyros means cheese.)


➧ Amino acids are generally represented by a three letter symbol
➧ sometimes one letter Code is also used.
➧ Example :- Glycine – Gly or G, Alanine – Ala or A.

Classification of Amino Acids based on position of amino group
➧ Depending upon the relative position of amino group with respect to carboxyl group, the amino acids can be classified as ….
☛ α Amino Acid
☛ β Amino Acids
☛ γ Amino Acids
☛ δ Amino Acids

➧ Only α-amino acids are obtained on hydrolysis of proteins.
➧ For formation of Protein chains the amino acids are join togather by forming Peptide Bond (CO – NH)


Note :-
✔ In Methane (CH4) – 4 H
✔ One H replaced by – Carboxilic grop (COOH)
✔ One H replaced by – Amino group (NH2)
✔ One H – Remain as it is
✔ Last H – Remain or / replace by Alkyl group
✔ If last H – remain same in the position – It formed the Simplest amino acid – that is Glysine.


• 20 types of amino acids (Magic 20) found in Nature.
• Amino group , Carboxilic group and one H remain as it is present in all the above 20 amino acids
• But what makes different is that Alkyl group.
• Simplest amino acids — Glycine.
• Only Symmetrical amino acids –Glycine
• Amino acids have Acidic property due to – COOH group
• Amino acids have Basic property due to – NH2 group

Types of Amino Acids Based on the R group or the Alkyl group.
✪ Neutral amino acids
➠ Glycine
➠ Alanine
➠ Valine
➠ Leucine
➠ Isoleucine

✪ Acidic Amino Acids
➠ Aspartic acid
➠ Asparagine
➠ Glutamic acid
➠ Glutamine

✪ Basic Amino Acids
➠ Arginine ➠ Lysine

✪ Sulpher Containing amino acids
➠ Cysteine
➠ Methionine

✪ Alcoholic amino acids
➠ Serine

✪ Arometic amino acids
➠ Phenyl Alanine
➠ Tyrosine
➠ Tryptophan

List of Essential Amino Acids
➧ Animal cannot synthesize 7 amino acids out of 20. ➧ These 7 amino acids are called ESSENTIAL AMINO ACIDS. ➧ List of these 7 amino acids
• 1. Leucine
• 2. Isoleusine
• 3. Valine
• 4. Tryptophan
• 5. Phenyl alanine
• 6. Lysine
• 7. Methionine

➧ In Human the amino acid THREONINE is also not synthesized.
➧ So for Human the essential amino acids are — 8 (Above 7 + Threonine)

➧ In Childrens amino acid ARGININE and HISTIDINE is also not synthesized. ➧ So for Children the essential amino acids are — 10 (Above 7 + Threonine + Arginine + Histidine)

➧ Arginine and Histidine are Semi essential amino acids.

Use of Amino Acids
➧ Amino Acids are the building block of Proteins.
➧ For the formation of Protein chains, the Amino acids are join togather by forming Peptide bond(CO-NH)
➧ Aspartame is Synthetic Polypeptide used as Artificial Sweetener.
➧ Amino acid Dihydroxy Phenylalanine is used in the treatment for — Parkinsonism.
➧ Monosodium glutamate (MSG) amino acid — used as food additive that enanches flavour.


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