Staining of Nucleic Acid by Acetocarmine

Our Objective

Staining of nucleic acid by acetocarmine.


The Theory 

Nucleic Acid  

Nucleic acids are a naturally occurring chemical compound that serves as the primary information carrying molecules in cells and make up the genetic material.  They are mostly found in all living things. Their function is to transmit and express that information in living cells. 

Nucleic acids are genetic material of cells, including DNA and the various types of RNA.   

There are two types of nucleic acids within cells, the single-stranded Ribonucleic acid (RNA) and the Double-stranded DNA. Both DNA and RNA are long-chained polymers made up of nucleotides. 


DNA can be a long molecule that is tightly wound within the nuclei of eukaryotic cells and within the cytoplasm of prokaryotic cells. In eukaryotic cells, DNA is present in the chromosomes of the nucleus and within the mitochondria and chloroplasts. 


Three different types of RNA are produced using DNA as a template: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). Each type of RNA serves a distinct purpose. Ribonucleic acid functions in converting genetic information from genes into the amino acid sequences of proteins.  

Onion cell

Staining of nucleic acid can be done in onion peel using acetocarmine stain. The cell of an onion peel consists of a cell wall, cell membrane, cytoplasm, nucleus and a large vacuole. The nucleus is present at the periphery of the cytoplasm. The vacuole is prominent and present at the center of the cell. The presence of a cell wall and a large vacuole are indicators that help identify plant cells, such as seen in the onion peel. 

Acetocarmine stain  

Acetocarmine, a saturated carmine solution in 45% acetic acid, is employed in particularly to rapidly stain newly formed, unfixed chromosomes. Carmine is obtained from insects. It is used to study the stages of cell division. Acetocarmine is a non-specific nuclear stain which simply binds the chromosomes and gives color to them. Acetocarmine combines with nucleic acid present in the nuclei of cells to form a deep red conjugate.  


Learning Outcomes

  • Students can understand the terms Nucleic acid, DNA and RNA.
  • Students can learn about the action of Acetocarmine with Nucleic acid.
  • Students can learn to do the experiment in a real lab using onion peel.