30 Questions
What term is used for the coding sequences in eukaryotic genes?
Exons
What are the non-coding sequences that interrupt the coding sequence in eukaryotic genes called?
Introns
In eukaryotic genes, what must be done to the introns and exons post-transcription?
Introns must be removed, and exons must be joined together.
Which term applies to any region retained in a mature RNA, whether or not it is coding?
Exon
What are examples of non-coding exons mentioned in the text?
50 and 30 untranslated regions of an mRNA
How many introns are shown to interrupt the coding region in a typical eukaryotic gene in Figure 14-1?
Three
What is the process that converts pre-mRNA into mature mRNA by removing introns?
Splicing
Why is precision in the splicing process crucial?
To prevent the loss or addition of nucleotides
What consequence could occur if a base is lost or gained at the boundary between two exons during splicing?
Incorrect amino acids incorporated into proteins
Which term describes the phenomenon where some pre-mRNAs can be spliced in more than one way?
Alternative splicing
What would be the consequence of having downstream codons out of register due to lack of precision in splicing?
Incorrect amino acid incorporation
Which process enables a gene to produce more than one polypeptide product?
Alternative splicing
What are the products generated by alternative splicing called?
Isoforms
How many alternative versions can the Slo gene from rat potentially encode?
500
What process can result in one particular Drosophila gene encoding as many as 38,000 possible products?
Alternative splicing
In what organism was splicing discovered during studies of gene expression?
Mammalian adenovirus
What is another way in which initial transcripts can be altered apart from alternative splicing?
RNA editing
What determines where splicing occurs within the RNA molecule?
RNA sequences
What marks the borders between introns and exons in pre-mRNAs?
Specific nucleotide sequences
Which sequence is necessary for splicing and is usually close to the 3' end of the intron?
Branchpoint sequence
What is found at the 5' end of an intron?
5' splice site
What is the conserved base at the branch site during splicing?
Adenine (A)
Which sequence is sometimes referred to as the 3' site in older nomenclature?
3' splice site
What is the function of the 5' and 3' splice sites?
Mark the exon – intron boundary for splicing
What is responsible for generating separate mRNAs for individual virion components?
Alternative splicing
Which non-protein-coding sequences are involved in stitching together the 50 sequence shared by all mRNAs?
Tripartite leader
What experiment involves incubating RNA with double-stranded DNA to observe the formation of loops?
R-loop mapping
What can be observed in the electron microscope following the staining procedure used to visualize nucleic acids?
Thicker RNA – DNA duplexes
Which region of the genome do the late viral mRNAs arise from?
Multiple regions of the genome
What is displaced in the form of a loop during an R-loop mapping experiment?
A stretch of the noncomplementary strand
Test your knowledge on the process of RNA splicing in gene coding sequences, which involves removing introns and joining exons to create a mature mRNA transcript. Explore how eukaryotic genes can produce multiple protein variants through alternative splicing.
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