living things consist with cell.

Allele

 The variant of nucleotide sequence of a DNA is called allele. 

Allele differs from each other in a single position nucleotide polymorphism. But it also can differ in thousand of base pair deletion and insertion.

Most of the allele differs among them in a results as phenotype change,  but not in gene coding.  For example, white and purple colour of pea plant flower is results of different allele,  but not in gene difference.

Laws of independent assortment

 Laws of independent assortment is an inheritance theory. It is known as the third law of inheritance.

According to laws of independent assortment different allele of different gene assorted independently during gamete formation. 

Laws of segregation

 How the property of ancestors pass through the offspring explained by laws of inheritance. This law is a combined law of three inheritance law, 

Law of dominance 

Law of segregation 

Laws of independent assortment 

Laws of segregation is the second law of inheritance.

According to laws of segregation, Each diploid individual will possess a pair of allele for a particular trait.  During reproduction each parents will pass only one allele randomly to diploid offspring.

In F1 generation only dominant allele will appeared and recessive allele is hidden. But in F2 generation both allele will expressed.

Laws of dominance

 Laws of dominance is one of the law of out of three laws of inheritance.

Three laws of inheritance is

Laws of dominance 

Laws of segregation 

Laws of independent assortment 

During crossing of two contrasting trait, only a one trait will be appeared and others will be suppressed. 

The appeared trait is dominant trait and other is ressesive trait. Though, both will be inherit,  but one will be hiden and another will be appeared. 

Dominance trait will suppress the ressesive trait.  

In monohybrid crossing,  in first generation monohybrid trait will be appeared. But,  in second generation both trait will be appeared at a ratio of 3:1.

Inheritence

 Inheritance is passing of genetic information from parent to offspring. 

Gregor Johannes Mendel in his theory shows that Most of the allele is inherit in offspring from its parents. 

Mendel done experiment in pea plant and found the assumption of inheritance. He shows how seed shape and colour of flowers inherits. 

Mendel develops two theory of inheritance is known as

Laws of segregation 

Laws of independent assortment

Types of inheritance 

There have five types of inheritance

AD Autosomal Dominant

AR Autosomal ressesive

XD X linked Dominant 

XR X linked Recessive 

Y-linked inheritance 

DNA

 DNA is dioxyribonucleic acid.  It is a single helix model of encoded gene. 

DNA is a polymer and it consists two polynucleotide chain.  Each polynucleotide chain consists with monomar called nucleotide. 

Each nucleotide consists with nitrogen containing nucleobase, dioxyribose and phosphate. Nucleobases are cystne, thymin, Adenine,  guanine. 

Nucleotide are joint to each other by a bond is called phosphodiester linkage.  It is a covalent bond. 

Again, Hydrogen bond connect two polynucleotides and forms double strand DNA. 

Nitrogen bases are divided into two groups. Single ringed pyrimidine and double ringed Purin.

Function of DNA

DNA carries genetic information and performs the functional work like development, growth, functioning and reproduction.