Biochemistry Solutions



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1) why amino acids are called. Zwitter ions? What is essential and non-essential Amino acids? Write the physiological important of Amino acids? 


   There is an internal transfer of a hydrogen ion from the -COOH group to the -NH2 group to leave an ion with both a negative charge and a positive charge.This is called a zwitterion.

     An amino acid has both a basic amine group and an acidic carboxylic acid group. So amion acid called a zwitterion.

Essential Amino Acids: Amino acids which can't be created in our body but can only be received from proper food or diet are called Essential Amino Acids. Ex- Histidine, Isoleucine, Lysine.

Non- essential amino acids: Amino acids which can be created in our body itself are Non- essential amino acids.

Ex -alanine, arginine, asparagine, aspartic acid.

    The essential amino acid are the amino acid which body donot able to make on its own,but it can be obtained by taking food .There are 8 essential amino acid present like mithonine ,valixe,tryptophan, inoleunine, lysine, threonine, and phenyl alenine. Histidine is the 9 th amino acid which is necessary for the babies. These amino acids are use to create new protin in the body and it helps to keep body healthy. The non essential amino acid are synthesized by the body itself. There are 11 amino acids it also helps to build the protin.

2) write down the mechanism of enzyme action? 

   Enzymes are very specific and it's was suggested by Fischer that this was because the enzyme has a particular shape into which substrate fits properly. This is often referred as lock and key hypothesis. 

  1. According to these model the safe of the active site of an enzyme is complementary to the shape of substrate. i.e, the substrate is like a key whose shape is complementary to the enzyme which is supposed to be lock and they fil perfectly. 

2. Enzyme catalysed only those substrate which fit perfectly on the active site of the enzyme

3. Most enzyme are larger then the substrate molecule . The active site is usually a very small portion of the enzyme , 3-12 amino acid. The remaining amino acids which make the bulk of the enzyme, function to maintain the correct globular shape of the enzyme. 

4. Once the product is formed , they no longer fit into the active site and escape into surrounding medium. 

5. According to the lock and key model enzyme behaves as rigid molecule , however most enzyme are globular and flexible. 

      The lock and key model of enzyme action was further modified by Henri as enzyme substrate complex theory . He suggest they:- 

      1. Substrate molecule fit into the active sites located on the surface of the enzyme like one particular key fit into one particular type of lock. 

    2. Then the enzyme combines with the substrate and form an unstable intermediate compound termed as enzyme substrate complex. 

    3. This intermediate immediately breaks down into the reaction product and the enzyme. 

    E + S = ES -- E+ P

Induced fit model: in 1959 koshland suggest a modification to the lock and key hypothesis which is known as induced key hypothesis.

Working from evidence then suggested that some enzymes and their activity sides are more flexible. To these he proposed that the active side can modified it's shape as the substrate interact with enzyme.

The amino acid which make up the active side are moulded into precise shape which enable the enzyme to perform it's catalytic function most efficiently.

3) write about different types of DNA & RNA? 

Eukaryotic organisms such as animals, plans and fungi store the majority of their DNA inside the cell molecules and some of their DNA stored organelles such as mitochondria. Each on the location DNA May be

A) Molecular DNA: 

Located within the nucleus of eukaryotic cell Usually has two copies of cell.

The structure of nuclear DNA chromosome is linear with open ends and includes 46 chromosomes containing 3 billion nucleotides.

Nuclear DNA is diploid, ordinarily inheriting from two parents. The mutation rate of nuclear DNA is less than 0.3%

B) Mitochondrial DNA:

Mitochondrial DNA is located in the mitochondria Contains 100-1000 copies per cell Mitochondrial DNA chromosomes usually have closed, circular structure. Mitochondrial DNA is haploid coming only from the mother.

Formed of DNA: Most of the DNA is in the classic Watson crick model simply called as B-DNA or B form DNA. In certain conditions, different forms of DNA are found to be appeared like A-DNA, Z-DNA, D-D A, C-DNA, and B-DNA.This decision in forms are based on their structural diversity.

Different types of RNA are discussed below:

mRNA/ Messenger RNA/ coding RNA: mRNA carries the genetic information from DNA in a form that can be recognised to make protein.Once transcripted from DNA, eukaryotic mRNA body exist in a form called precursor mRNA or pre- mRNA.

Non coding mRNA:

Ribosome RNA is the catalytic component of the Ribosomes. In the cytoplasm rRNA and protein component combine to form a molecular complex called the Ribosome which bind with mRNA and synthesis protein.


4) Classification of carbohydrates? 

 Carbohydrates can be divided into 4 groups, monosaccharides, disaccharides, oligosaccharides and polysaccharide.

1) Monosaccharides: They are the simplest carbohydrates and can't be hydrolysed further into smaller carbohydrate molecule. They are also known as simple sugar. Monosaccharides related to animals usually have 3-7 carbon. They can be subdivided further_

A) Depending upon the no of c-atoms.

They maybe trioses (C3H6O3)

Tetroses (C4H8O4)

Penrose (C5H10O5)

Hexoses (C6H12O6)

B) Depending upon functional groups they maybe aldoses (-CHO).

For ex. Glucose, ribose, ketose, fructose, Ribulose.


The carbohydrates which produced two molecules of same or different Monosaccharides on hydrolysis are called disaccharides. Which means disaccharides are composed of two same or different Monosaccharides molecules. The general formula of disaccharides is Cn(H2O)n-1

Some common ex. Of disaccharides are- meltose(Glu.+Glu)

Lactose (Glu+gelectose)

Sucrose (Glu+fructose) some times disaccharides are consider under oligosaccharides.

3) Oligosaccharides:

The carbohydrates molecules which produced 3-10monosaccharide units on hydrolysis are called oligosaccharides where the Greek word oligo means few.

    Based on the no. Of monosac. Units the oligosaccharides can be trisaccharides, tetrasacc. Pentasacc. Etc.

4) Polysaccharide: The carbohydrates which are composed of more than 10 monosac. Units linked by glycositic bond are called polysaccharide or glycanes. Their general formula is (C6H10O5)n, n>10. They are considered as macro molecule, relatively or totally water insoluble, amorphous and devoid of sweetness.They are decided into 2 groups.

a)Homo polysaccharide: They hv many molecules of same monosacc. Molecule.

Eg. Starch, glycogen, insulin.

b)Hetero polysaccharide: They are made up of more than one type of monosaccharides unit or their derivatives.

Eg. Mucopolysaccharides, hyaluronic acid.

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