Quiz on Amino Acids and Proteins

1) Glutamic acid is one of the two acidic amino acids. What is the other?

a) Methionine

b) Aspartate

c) Arginine

d) Histidine

e) Threonine

2) Which amino acid differs from Alanine in that one of the methylenic hydrogens is replaced by a hydroxyl group?

a) Cysteine

b) Threonine

c) Serine

d) Methionine

e) Isoleucine

3) Isoleucine is one of the two amino acids that have two chiral centers. What is the other?

a) Aspartate

b) Fructose

c) Threonine

d) Glycine

e) Alanine

4) Leucine and Valine are two of the three amino acids having branched hydrocarbon side chains. What is the third?

a) Lysine

b) Isoleucine

c) Serine

d) Glycine

e) Threonine

5) What amino acid has a secondary amino group, rather than a primary α-amino group?

a) Phenylalanine

b) Serine

c) Glycine

d) Proline

e) Alanine

Why do we need the 20 essential amino acids?

We have been taught about the 20 essential amino acids, but do we know why they are essential to our bodies? Below is a list of their responsibilities and functions.
Alanine:
It is one of the most significant among the 20 common amino acids. It offers energy to your system. It releases into the blood stream during exercise time and induces carbohydrate-consuming effect to the health system. It promotes enhancement in the area of protein synthesis and nitrogen balance.Arginine:
Synthesized normally in the body, arginine is known to be a semi-essential amino acid. Sometimes more is required than normal production. Deficiencies may include poor wound healing, weakness in muscles, hair loss, irritations in skin, and constipation. 

Asparagine:
It is needed to maintain homeostatic balance in the nervous system. Amino acid transformation and ammonia synthesis are largely dependent on asparagine.

Aspartic Acid:
Aspartic acid is one of two acidic amino acids belonging to the group of 20 common amino acids. It promotes enzyme activity, maintenance of solubility in the body, as well as homeostasis in ionic characters of proteins.

Cysteine:
It is present only at the rate of 2.8% into proteins but it provides the 3-dimensional stability of the protein molecule. It also plays a crucial role in the metabolic process of many important enzymes. 

Glutamic Acid:
It is responsible for transportation of glutamate and other amino acids to the blood barrier. 

Glutamine:
Glutamine is able to eliminate excess ammonia from the body system. It enhances immune system. Apart from that, glutamine possesses anti-anxiety property that permits the mind to be relaxed.

Glycine:
It helps in the transformation of harmful toxic substances within the body to a non-toxic form. 

Histidine:
Histidine is required for infant development. Histidine deficiency may result in eczema, a kind of skin disease. There are few genetic disorders that promote non-metabolic state for histidine. This results in speech disorders and mental retardations among infants and toddlers. 

Isoleucine:
This amino acid is particularly important for stimulating the brain in order to produce mental alertness.

Leucine:
It is particularly effective for producing other essential biochemical compounds in the body. These chemicals are important for producing bodily energy and mental alertness. 

Lysine:

Lysine is important for proper growth, and it plays an essential role in the production of carnitine, a nutrient responsible for converting fatty acids into energy and helping to lower cholesterol. Lysine appears to help the body absorb calcium, and it plays an important role in the formation of collagen. It functions against the 
herpes virus in particular by providing body required nutritional supplements. 

Methionine:
It functions at initiating the translation of messenger RNA.Phenylalaine:
This amino acid profoundly affects brain cells at biochemical level.

Proline:
It significantly affects human nutrition. It is believed to act as a source of nitrogen. 

Serine:
Serine is intimately related to various bodily functions such as fat metabolism, tissue growth, enhancement of immune system and many more. It is an essential ingredient of brain protein. 

Threonine:
It helps in the maintenance of protein balance and also in assisting collagen formation. 

Tryptophan: 
This is particularly needed in the body for the production of vitamin B3. 

Tyrosine:
This is crucial in building link between dopamine and norepinephrine. It also reduces fat by suppressing appetite. 

Valine:
It is effective in promoting tissue growth and maintaining nitrogen balance in the health system.

Identifying the polarity of amino acid bonds.

A bond is said to be polar when there is a large amount of electronegativity difference between the atoms in a bond. Partial negative charges are found on the most electronegative atoms and the others are deemed partially positive.

Here are a few tips to aid in identifying the polarity and charges of amino acids.

1) If the amino acid side chain is a hydrocarbon, the amino acid is non-polar. There are 2 exceptions to this: Proline and Tryptophan. These exceptions however can easily be seen due to their steric hindrance.

2) If the amino acid chain has an atom that possesses electronegativity or polarity, but no charge, then the amino acid is polar uncharged.

3) If the amino acid has a charge on the side chain, it is polar.

Below is a table of standard amino acid abbreviations and their side chain properties.

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