Synthesis, Structure and Function of Genetic Material - Agriculture Optional

Genetic material refers to the hereditary information that is passed from one generation to the next in living organisms.

Genetic material is those materials of the cell determines the structure and functions of the cell.

Found in the nucleus (eukaryotes) and cytoplasm (prokaryotes) and mitochondria and chloroplast of some organisms.

Meischer in 1871 discovered the nucleic acid called nuclein.

DNA as genetic first time identified by Griffith in 1928 in Diplococcus pneumoniae and concluded with the experiment of Harshey and Chase in 1952 in E Coli.

RNA as genetic material in 1957 demonstrated by Frankel-Conrat and Singer in TMV.

 

Nucleic Acid is the carrier of genetic information which includes DNA and RNA.

 

DNA (Deoxyribonucleic Acid) –

DNA is a genetic material that carries genetic information and transmits to offspring.

 

Features of genetic material –

Location –

It located in both the nucleus and cytoplasm.

A chromosome is the main source of DNA in the nucleus and mitochondria and chloroplast are the main source of DNA in the cytoplasm but DNA remain free in the cytoplasm of prokaryotic cells.

In prokaryotes, it is in free condition due to unbounded nucleus.

 

Structure –

Generally, it is a double-stranded structure but in some virus have a single-stranded DNA structure.

DNA made up of purine (adenine, guanine), pyrimidine (cytosine, thiamine), phosphate group, pentose sugar (Deoxyribose sugar) with a hydrogen bond (double and triple).

 

Shape –

Linear shape in eukaryotes but the circular shape in prokaryotes.

 

Types –

DNA – A =

DNA - B =

DNA - C =

DNA - D =

DNA - Z =

 

Self-Replication –

It has self-replication capacity during the synthesis phase of cell division as discussed earlier in the cell cycle.

 

Structure of DNA –

Before structure let us try to understand the component of DNA.

Bases –

DNA forms by 4 types of nitrogen bases – Adenine (A), Guanine (G), Cytosine (S) and Thiamine (T).

Adenine –

 

Guanine –

Cytosine –

Thymine –

Sugar –

DNA contains 2’-deoxy – D-ribose (deoxyribose) type of pentose sugars.

Based on sugar it called deoxyribose nucleic acid (DNA).

 

Phosphoric acid – H₃PO₄

It has three hydroxyls reactive group of which two involve in sugar-phosphate backbone formation of DNA.

It works as joining of two sugar at 5’ and 3’ end.

Nucleosides –

Deoxyriboside nucleoside present in DNA.

In the nucleic acid linkage -H  molecule of 1^st position carbon attached to -N molecule of 1^st and 9^th position of pyrimidine and purine respectively and forms covalent bond between C-N.

Nucleoside = Base + Deoxyribose

Four nucleoside –

Deoxyadenosine

Deoxyguanosine

Deoxycytidine

Thymidine