Genomic DNA from a mouse is isolated, fragmented, and denatured into single strands. It is then mixed with mRNA isolated from the cytoplasm of mouse cells. The image represents an electron micrograph result showing the hybridization of single-stranded DNA and mRNA.

Which nucleic acid is indicated by the 'a' pointer? Justify your answer. 

Key Concepts

Hybridization

Hybridization refers to the process where complementary nucleic acid strands bind together to form a double-stranded structure. In this context, single-stranded DNA from the mouse genome can hybridize with mRNA, which is complementary to the DNA sequence that was transcribed. This process is crucial for understanding how genetic information is expressed and can be visualized in experiments like the one described.

Nucleic Acids

Nucleic acids, including DNA and RNA, are biopolymers essential for all forms of life. DNA (deoxyribonucleic acid) carries the genetic blueprint, while RNA (ribonucleic acid) plays various roles, including acting as a messenger between DNA and protein synthesis. In the question, the distinction between mRNA and genomic DNA is vital for identifying which nucleic acid is indicated by the pointer in the electron micrograph.

mRNA Function

Messenger RNA (mRNA) is a type of RNA that conveys genetic information from DNA to the ribosome, where proteins are synthesized. It is transcribed from DNA and carries the code for protein synthesis. In the context of the question, understanding the role of mRNA in gene expression helps in determining which nucleic acid is represented by the pointer, as it hybridizes with the complementary DNA strand.