Mutation

                                             Mutation 

A sightly change in the sequence of  DNA  which may be transmitted to further generation caused by  the addition  , deletion or alternation of single base of DNA is  known as Mutation .

Classification - Mutation can be classified into two ways

• Acquired Mutation - The mutation which is not occur in our body but it is acquired from other source are known as Acquired Mutation . For example Ultraviolet rays that sometime cause Cancer in body by mutation in DNA . The only advantage in this type of mutation is that it is not transformed to further generation and  limited in some of the cells of  the body .
• Hereditary Mutation-  The mutation which is transformed from parents to offspring are known as Hereditary Mutation . When the egg cell and sperm cell unite they form fertilized egg . This fertilized egg receives DNA from both the parent and  if this DNA have mutation then obviously child that grow have mutation in every cells of the body . This type of mutation remains through out the life in person's body and are not recoverable . 

Factor Responsible For Mutation - There are mainly two factor responsible for Mutation -

•  External Factor - Ultraviolet radiation , Smoking , other radiations are responsible for Mutation .
  
• Internal Factor -    Error in DNA replication can cause Mutation  in a body .

Types Of Mutation -  Mutation have several types . They are described below -

• Deletion - This type of Mutation occur when their is deletion of  one or two nucleotide from a single base of  a chromosome or their is deletion of sequence of DNA in DNA replication .
  
• Insertion - When there is addition of one or more nucleotide in a sequence of DNA are known as Insertion Mutation . 
  
• Frameshift - This type of mutation occur due to insertion or deletion of number of nucleotide in a DNA sequence that are not divisible by three .
  
• Missence -  Missence mutation is that mutation in which a single nucleotide change can result in a different codon which code for different amino acids .
  
• Point - Point mutation  results when there is change in single base pair in DNA Sequence .
  
• Nonsense - When there is single change in the base sequence of DNA that does not code for any amino acids and lead to the protein product that is early truncated .
  

• Silent - Silent mutation do not alter the sequence of amino acids and the resulting protein is remain functional .
  

Example Of Some Genetics Diseases Occur Due To Mutation -

Sickle Cell Anemia - This is the hereditary type of anemia in which the red blood cell become irregular in shape or sickle shape and carry less oxygen to the body . If the both parents have this type of disease then definitely their child suffer from this disease .

Hemophilia -  This is the inherited type of disease in which the blood can't clot properly and their is a excessive bleeding occur when there is a any type of injury . This type of disease can't be cured but some medical treatments helps a lot . The symptoms of this disease are joint pain and swelling , unexplained bleeding and bleeding in the urine .

Enzyme : classification, mechanism , mode of action

                                            Enzyme

Enzymes play a very important role in our life. They are specialized proteins with catalytic activities and a great degree of specificity.  All the living beings need enzymes for their biochemical reaction in which reaction starts with substrate and end in the product . Therefore Enzymes are also called Biocatalyst.

Characteristics Of Enzyme -

• Enzymes are highly specific in nature.
  
• All enzymes are proteinaceous in nature.
  
• Enzymes always catalyze the reaction.
  
• They act actively at optimum temperature.
  
• They are colloidal in nature.
  
• Inhibitor always inhibits the enzymatic reaction.
  
• Enzymes are manufactured in the living cells but they are non-living.

Enzyme  Classification - According to the international union of biochemist (IUB), enzymes can be classified into six classes-

1. Oxidoreductase - It involves oxidation, reduction, and electron transfer. For example, alcohol dehydrogenase.
   
2. Transferase -It involves transfer of functional group. For example, hexokinase.
   
3. Hydrolase - It leads to hydrolysis . For example, pepsin.
   
4. Lyase - It leads to lysis and hence provide additional double bond. For example, aconitase.
   
5. Isomerase - It leads to the isomerization reaction. For example, triose phospho isomerase.
   
6. Ligase - It leads to the joining of a chain .
   
     

Factor affecting enzyme activity -

• Temperature - Initially when we increase the temperature, then the enzyme activity also increase but it increase up to an optimum level and that temperature is known as optimum temperature. Optimum temperature is the temperature in which enzyme activity is maximum. After the optimum temperature if the further temperature rises occur then enzyme activity starts decreasing.
  
• Effect of pH- Increase in pH increases the velocity of the enzyme but it happens up to a certain level. A pH at which the reaction reaches its maximum velocity then it is called Optimum pH.on increasing the temperature beyond the level, then the active site of enzymes starts ionizing and the rate of reaction decreases.
  
• Substrate concentration - Increase in substrate concentration increases the enzyme velocity of the reaction . This velocity increase up to a level or definite range and then remains constant.
  
• Activators - There are certain substances that have capacity to increase enzyme activity after getting introduced. These are called activators. Like, hexokinase enzyme -mg and phosphate enzyme -mn.
  
• Inhibitors - There are certain chemicals which after getting introduced with the enzyme reduces the activity of the enzyme. Such chemicals are known as  Inhibitors. 

Mechanism Of Enzyme Action -  The mechanism of enzyme action was given by Michalitis menten. According to him -

• Most of the chemical reactions do not start until there is a supply of external energy for starting and speed up the reaction. Therefore the energy above the average is required for the reaction to go over its activation Barrier is called Activation Energy. An enzyme lowers the activation energy of a reaction, thereby increasing the fraction of molecules that have enough energy to attain the transition state and making the reaction faster. As the rate of reaction increases, it lowers the activation energy.

• The enzyme also posses some active sites on its surface where the substrate binds with the enzyme.
  
• The enzyme and substrate binds to form an enzyme-substrate complex which further changes into product . after that enzyme released out.
  
  
  
• The enzyme can be used for multiple reactions.

Mode Of Enzyme Action - There are two theories were given by scientist to explain the mode of Enzyme Action.

Lock & Key Model - This theory was given by Emil Fisher in 1894. It is based on the simple concept that there is just one key of particular that opens the lock in a similar way active site here is work as a lock-in which the reactant substance fits in just like a key.  The reaction is as follows -
First of all the enzyme react with the substrate molecule and form the enzyme-substrate complex.
Now, this Enzyme substrate complex converted into the end product.

Induced Fit Theory -This theory was given by D. E . Koshland in 1963 according to which there is a flexibility of the region of the active site, means the enzyme changes its active site when induced by a substrate that is substrate can alter the geometry of the enzyme to get a perfect fitting of the substrate.