D2.2 Gene expression (Cells, HL): แบบฝึกหัด

• a.It causes the gene to be transcribed into multiple different mRNA isoforms.
• b.It results in the silencing of the gene, preventing transcription.
• c.It stimulates the removal of introns during post-transcriptional modification.
• d.It increases the rate of transcription by recruiting RNA polymerase.

• a.Differences in the rate of semi-conservative DNA replication in each twin.
• b.Spontaneous mutations occurring at a high frequency in somatic cells.
• c.The random loss of telomeres in different tissues as the twins grow older.
• d.The accumulation of different epigenetic marks on the DNA due to environmental factors.

• a.

  Methylation of histone tails always leads to the immediate degradation of the associated mRNA transcripts.

• b.

  Phosphorylation of the deoxyribose sugars in the DNA backbone causes the nucleosomes to dissociate from the promoter.

• c.

  Acetylation of histone tails neutralizes positive charges, loosening the binding between histones and DNA to allow RNA polymerase access.

• d.

  Nucleosomes move to the distal enhancer regions to block the binding of transcription factors.

• a.

  They identify and degrade mRNA molecules that contain premature stop codons in the cytoplasm.

• b.

  They remove introns from pre-mRNA and join exons together to form a mature mRNA molecule.

• c.

  They bind to the promoter region to initiate the recruitment of RNA polymerase.

• d.

  They add a methylated guanine cap to the 5' end of the transcript to protect it from degradation.

• a.\(3' \rightarrow 5'\) using the antisense strand
• b.\(5' \rightarrow 3'\) using the sense strand
• c.\(3' \rightarrow 5'\) using the sense strand
• d.\(5' \rightarrow 3'\) using the antisense strand

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