02.15 - Eukaryotic Transcriptional Processing Flashcards
This refers to all the RNAs synthesised by a cell or organism.
Transcriptome
It is the set of protein sequences that can be derived by translation of all protein-coding genes of a completely sequenced genome.
Proteome
True or False: mRNA levels are not well-correlated with protein levels.
True
True or False: Epigenetic changes involve changes in the underlying DNA sequence of the organism.
False
Which chromatin structure is actively transcribed? Transcriptionally silenced?
Euchromatin, heterochromatin
It refers to the number of copies of a certain gene present within an individual cell of an organism.
Gene dosage
Which of the following is incorrect?
a. Genes for rRNA, which are expressed at high levels, must have multiple copies.
b. In human cells, 5 rDNA clusters are found in chromosomes 13, 14, 15, 21 and 22.
c. Gene amplification is always beneficial for an organism
d. Multiple drug resistance may be caused by amplification of genes that code for pumps.
c. Gene amplification is always beneficial for an organism
It is the selective increase in number of a certain gene without affecting the quantity of the other genes.
Gene amplification
What gene is amplified in breast cancer?
HER-2/neu or erbB-2
What is the protein product of HER-2/neu?
Epidermal growth factor receptor-2
Which of the following does not lead to breast cancer?
a. Increase in epidermal growth factor receptors in the cells
b. HER dimerization
c. Binding of herceptin to EGFR-2
d. Cross-phosphorylation of HER2-HER3 heterodimers
c. Binding of herceptin to EGFR-2
In eukaryotes, in which part of the cell does transcription happens? Translation?
Nucleus, cytosol
Enumerate the basic post-transcriptional modifications that are performed on the primary mRNA transcripts
5’ capping
3’ polyadenylation
Intron removal
Alternative splicing
These are consensus sequences that serves as the binding site for RNA polymerase and general transcription factors.
Promoters
These are transcription factor binding sites that are located anywhere in the gene and serves to increase promoter effectiveness and stimulate transcription.
Enhancers
These are DNA sequences that binds with transcription regulation factors that prevents RNA polymerase from binding to the promoter.
Silencers
Which of the following statements is incorrect?
a. Enhancer sequences can stimulate transcription at start sites thousands of bases away.
b. Chromosomal translocation of the proto-oncgene myc near the immunoglobulin enhancer may cause lymphoma or leukaemia.
c. Pax6 is a transcription factor that exhibits high specificity for a single enhancer sequence.
d. Promoters and enhancers are cis-acting elements, while RNA and proteins are trans-acting elements.
c. Pax6 is a transcription factor that exhibits high specificity for a single enhancer sequence.
True or False: Trans-acting factors control gene expression by binding to cis-acting factors.
True
Which of the following is incorrect?
a. 5’ cap enhances translation of mRNAs by eukaryotic translation machinery.
b. The 5’ cap is characterised by a unique 5’-5’ triphosphate linkage.
c. The stop codon serves as a signal for polyadenylation.
d. The spliceosome is composed of snRNA and proteins.
c. The stop codon serves as a signal for polyadenylation. (The polyadenylation signal sequence is AAUAAA.)
What are the three general mechanisms for localisation of mRNAs?
Directed transport via cytoskeleton
Random diffusion and trapping
Generalized degradation + local protection
Which of the following statements is incorrect?
a. mRNA translation should be silenced as it travels from the nucleus to the cytoplasm.
b. Oocytes store some mRNAs in inactivated form, which are only activated after fertilisation.
c. The poly A tail are the target binding sites of miRNAs.
d. Translation of cytoskeleton-attached bicoid mRNA leads to bicoid protein gradient in the fertilised egg of Drosophila.
c. The poly A tail are the target binding sites of miRNAs. (The 3’ UTR is the target binding site of miRNAs.)
Arrange the steps of RNA interference in order:
I - Formation of siRNA-RISC complex
II - Cleavage of dsRNA into siRNA
III - Formation of single stranded RNA (ssRNA) + RISC complex
IV - Complementary binding of ssRNA-RISC to mRNA
V - Cleavage of target mRNA
a. II-III-I-IV-V
b. II-I-III-IV-V
c. II-III-I-V-IV
d. I-II-III-V-IV
b. II-I-III-IV-V
