NEET

The helical structure of protein is stabilized by

dipeptide bonds
hydrogen bonds
ether bonds
peptide bonds

Solution

The α-helix structure is formed when the chain of α-amino acids coils as a right handed screw (called α-helix) because of the formation of hydrogen bonds between amide groups of the same peptide chain, i.e.,NH group in one unit is linked to carbonyl oxygen of the third unit by hydrogen bonding. This hydrogen bonding between different units is responsible for holding helix in a position.

Glucose molecule reacts with X number of molecules of phenylhydrazine to yield osazone. The value of X is

three
two
one
four

Solution

A sequence of how many nucleotides in messenger RNA makes a codon for an amino acid?

Three
Four
One
Two

Solution

The sequence of bases in mRNA are read in a serial order in groups of three at a time.Each triplet of nucleotides (having a specific sequence of bases) is known as codon. Each codon specifies one amino acid.Further since, there are four bases. therefore,4³= 64 triplets or codons are possible

a
b
c
d

Solution

The metal present in vitamin B₁₂ is :

cobalt
iron
manganese
magnesium

Solution

Metal present in vitamin B₁₂ is Co (cobalt).

Which is not a true statement?

α-Carbon of α-amino acid is asymmetric
All proteins are found in L-form
Human body can synthesize all proteins they need
At pH = 7 both amino and carboxylic groups exist inionised form

Solution

All proteins are not found in L-form but they may be present in form of D or L.

a
b
c
d

Solution

Number of chiral carbon atoms in glucose and fructose are

4 in each
3 in each
4 in glucose and 3 in fructose
3 in glucose and 4 in fructose

Solution

The number of essential amino acids in man is

8
10
18
20

Solution

There are 20 amino acid in man out of which 10 amino acids are essential amino acids. These essential amino acids are supplied to our bodies by food which we take because they cannot be synthesised in the body. These are (1) Valine (2) Leucine (3) Isoleucine (4) Phenylalanine(5) Threonine (6) Methionine (7) Lysine (8) Tryptophan(9) Arginine (10) Histidine

The highest calorific value is found in

proteins
fats
vitamins
carbohydrates

Solution

1 g fat provide 37 kJ of energy on oxidation while 1 g carbohydrate on oxidation gives 17 kJ of energy. Hence,fat has highest calorific value.

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