Chem Lec (Dash 3) Flashcards
Building units of proteins
Amino Acids
There are about — amino acids occur in nature.
and only – of them enter in proteins synthesis.
300
20
Structure of amino acids:
Four different groups are attached to α- carbon:
Amino Group
COOH Group
Hydrogen atom
And Side Chain (R)
At physiological pH (7.4), -COOH group is
dissociated forming a negatively charged —– and amino group is protonated forming positively charged ion forming ——-
Carboxylate ion (COO-)
Zwitter Ion
Proline is an —— —- not amino acid.
Imino Acid
Classification according to polarity of side chain (R):
In Polar amino acids: in which R contains —— ——- —— so can forms hydrogen bond with H2O.
polar hydrophilic group
Classification according to polarity of side
chain (R):
OH Group: as in —-, ——, and ——-
- SH Group: as in ——
Amide group: as in ——, and ——-
NH2 group or nitrogen act as a base (basic amino acids): as ——, ——, and ——
COOH group (acidic amino acids): as —— and ——-
OH group : as in serine, threonine and tyrosine
- SH group : as in cysteine
amide group: as in glutamine and aspargine
NH2 group or nitrogen act as a base (basic amino
acids ): as lysine, arginine and histidine
COOH group (acidic amino acids): as aspartic and
glutamic .
Polar, uncharged R groups
Serine, Threonine, Cysteine, Asparagine, and Glutamine
Positively Charged R groups
Lysine, Arginine, and Histidine
Negatively charged R groups
Aspartate and Glutamate
In Non polar amino acids: R is —– ——- group which can’t enter in hydrogen bond formation.
Alkyl hydrophobic group
9 amino acids are non polar
glycine, alanine,
valine, leucine, isoleucine, phenyl alanine,
tryptophan, proline and methionine).
Nonpolar, Aliphatic
Glycine, Alanine, Valine, Proline Lecuine, Isoleucine
Aromatic R Groups
Phenylalanine
Tyrosine and Trptophan
Can’t be synthesized in the body, essential to be taken in
diet. Their deficiency affects growth, health and
protein synthesis
Essential Amino Acids
How many Essential amino acids can’t be synthesized by our body
10
formed in the body but not in
sufficient amount for body requirements especially in children.
Semi Essential
What are the 2 examples of Semi essential amino acids?
Arginine and histidine
This amino acid can be synthesized by our body
Non essential amino acid
How many non standard amino acids have been detected in living organisms. Many are metabolic intermediates.
700
are intermediates in urea biosynthesis
ornithine and
citrulline
Chemical derivatives of amino acids also have i m p o r t a n t b i o l o g i c a l f u n c t i o n s , e g .
————- lack the a-carboxylate
of amino acids
Catecholamines
——— and ——- are neurotransmitters.
——– mediates parts of the immune
response.
GABA & Dopamine
Histamine
Functions of Amino Acids
Apart from being the monomeric constituents
of proteins and peptides, amino acids serve
variety of functions.
(a) Some amino acids are converted to carbohydrates and are called as
Glucogenic amino acids
Specific amino acids give rise to specialised products, e.g.
• Tyrosine forms hormones such as —– hormones, (T3, T4), ———- and ——– and a pigment called ——.
Thyroid
epinephrine and
norepinephrine
Melanin
Tryptophan can synthesise a vitamin called
Niacin
• Glycine, arginine and methionine synthesise
Creatine
help in synthesis of Bile
salts.
Glycine and cysteine
•Glutamate, cysteine and glycine synthesis
Glutathione
Histidine changes to ——- on
decarboxylation.
Histamine
Is formed from tryptophan
Serotonin
Glycine is used for the synthesis of
Haem
Pyrimidines and purines use several amino acids for their synthesis such as ——–, ——– for pyrimidines and glycine,
——-, ——-, ——- for purine synthesis
aspartate and
glutamine
aspartic
acid, Glutamine and serine
Some amino acids such as —— and —– are used as detoxicants of specific substances.
glycine and cysteine
Are sources or sulphur
Cystine and methionine
Methionine acts as “active” methionine (S-adenosylmethionine) and transfers methyl group to various substances by : ——-
transmethylation
