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 'b' pointer? Justify your answer. 

Verified step by step guidance

1. Analyze the context of the problem: The question involves hybridization of single-stranded DNA (ssDNA) and mRNA. Hybridization occurs when complementary nucleic acid sequences bind to each other, forming a DNA-RNA hybrid.
2. Understand the experimental setup: Genomic DNA is fragmented and denatured into single strands, while mRNA is isolated from the cytoplasm. The hybridization process allows mRNA to bind to complementary sequences in the ssDNA.
3. Interpret the electron micrograph: The image likely shows regions where mRNA has hybridized with ssDNA, as well as regions where ssDNA remains unbound. The 'b' pointer in the image is likely pointing to a specific nucleic acid structure.
4. Determine the identity of the nucleic acid at 'b': If the 'b' pointer indicates a region where no hybridization has occurred, it is likely single-stranded DNA (ssDNA). This is because mRNA only hybridizes with complementary sequences, leaving non-complementary regions of ssDNA unbound.
5. Justify the answer: The 'b' pointer likely indicates ssDNA because it represents a region of the genomic DNA that does not have a complementary sequence in the mRNA. This could correspond to introns or non-coding regions of the DNA, which are not transcribed into mRNA.

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 serves as a template for protein synthesis. This interaction is crucial for understanding the relationship between DNA and RNA in gene expression.

mRNA (Messenger RNA)

mRNA, or messenger RNA, is a type of RNA that carries genetic information from DNA to the ribosome, where proteins are synthesized. It is transcribed from DNA and serves as a template for translation, allowing the genetic code to be expressed as proteins. In the experiment, mRNA is isolated from mouse cells and is essential for understanding the hybridization process.

Electron Micrography

Electron micrography is a technique that uses electron beams to visualize samples at a very high resolution, allowing for detailed imaging of cellular structures and molecular interactions. In this scenario, the electron micrograph shows the hybridization of DNA and mRNA, providing visual evidence of their interaction and helping to identify the nucleic acids involved.