Genetic code in the nucleus b. main component in a ribosome c. translated with introns removed d. attached to amino acids e. translated including introns 15. tRNA 16. mRNA 17. DNA 18. pre-mRNA 19. rRNA

a.genetic code in the nucleus- DNA

b. main component in a ribosome- rRNA

c. translated with introns removed- mRNA

d. attached to amino acids -tRNA

e. translated including introns-  pre-mRNA

Explanation:

a. DNA- is a nucleic acid molecule that acts as a genetic material in the organisms. In eukaryotes, the DNA molecule is present in the nucleus of the cell .

b. rRNA- is a molecule formed by the transcription but does not undergo translation and is directly involved in the formation of the ribosome structure which provides the site for the protein synthesis.

c. mRNA- is the RNA formed from the DNA by transcription which contains the message for the formation of the protein molecule. The mRNA is formed after the modification like splicing which removes the non-coding sequence.

d. tRNA-transfer RNA is involved in the translation of mRNA as it brings a specific amino acid to the peptide after it recognizes the codon.

e. pre-mRNA- is the mRNA molecule that has not undergone any modification and thus contains the non-coding sequence also.

during the process of dna replication, brdu can replace thymidine and incorporate into the newly synthesized dna, cell proliferation thus can be reflected in the extent of brdu incorporation.