June 3, 2026 - THE SCIENCE NOTES

The diagram shows three sequential test tubes illustrating the qualitative analysis of proteins containing aromatic amino acids. Step 1 shows a test tube labeled "NITRATION" where concentrated nitric acid ($HNO_3$) is added to a protein sample, beginning to form a light yellow color representing nitrated aromatic amino acids. Step 2 shows the test tube being gently heated over a small burner flame, producing a distinct yellow substance labeled "Xanthoproteic Acid" to ensure reaction completion. Step 3 shows sodium hydroxide ($NaOH$) alkali being added via a dropper, resulting in a dark yellow-orange positive result due to the intensification into an orange salt.

June 3, 2026 Biochemistry Protocols and Techniques

Xanthoproteic Test: Qualitative Protein Analysis Using Nitric Acid

Learn how the xanthoproteic test uses nitric acid to detect aromatic amino acids in proteins, including principle, procedure, results, uses, and limitations. Read more

Labeled diagram of a eukaryotic cell nucleus showing the nuclear envelope, outer nuclear membrane, inner nuclear membrane, perinuclear space, nuclear pore complexes, nucleoplasm, nucleolus, chromatin, chromosomes, ribosomal subunits exiting through nuclear pores, and the endoplasmic reticulum connected to the outer nuclear membrane.

June 3, 2026 Biology

Nucleus: Definition, Structure, Functions, DNA Organization, and Diagram

The nucleus is a membrane-bound organelle that stores DNA and controls gene expression in eukaryotic cells. Learn its structure, nucleolus, chromatin, chromosomes, nuclear pores, and functions. Read more

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