DNA replication, repair, transcription, translation

Question 1

Why are nucleoli prominent in malignant cells?

Answer 1

Nucleoli are responsible for making RNA polymerase 1 making rRNA or for Ribosomal assembly—-> which is increased in neoplastic cells.

Question 2

which enzyme is only found in the nucleolus?

Answer 2

RNA polymerase 1 which makes ribosomal RNA.

Question 3

The story for mRNA production, transciption?

Answer 3

Imagine/Draw the same 2 DNA strands as you made in DNA replication story, but the below one will be the template strand, and the above one will be the coding strand. Start from where we start writing.
Promoter region (CAAT/TATA region)
Start Codon
(Promotor Region and Start codon are also called UTR/untranslated region and are not the part of mRNA)
Introns exons.
Enhancer/Suppressor regions can be anywhere along the gene, before/after or nearby.

Once the mRNA has been transcribed it is immature/Pre-mRNA/hnRNA.
Post transcription modifications include:
1. Addition of Guanosine to 5’ end.
2. Methylation of Guanosine added to 5’ end.
3. Multiple Adenine added to 3’ end.–> Called poly-A tail. Question that asked about it said that deoxythymine is added to latex beads, which molecule will most likely bind strongest to the latex beads in this experiment? And the answer was MatureRNA because the deoxythymine will pair up with Adenine. (AT)
4. Splicing is done in the nucleus. Exons EXIT the nucleus. Splicing occurs due to snRNP.
(RNA type 2 include—->RNA polymerase 2, snRNP, and miRNA)
Clinical significance of snRNP—-> SMN gene defect causing floppy baby syndrome, or spinal muscular atrophy is basically defective snRNPs. The anti-smith antibodies seen in SLE are basically antibodies against snRNPS.
5. Posttrascriptional degradation of mRNA. THIS IS THE ONLY POST-TRANSCRIPTIONAL MODIFICATION THAT OCCURS IN THE CYTOSOL. It has been asked.
In cytosol, we have P-bodies. P-bodies contain exonucleases, decapping enzymes, and
microRNAs which can degrade mRNA in the cytoplasm.
MicroRNA/miRNA mimicing molecules are also used as chemotherapeutic agents to kill mRNA produced by neoplastic cells.