Where are group II introns found?
Distribution and phylogeny Group II introns are found in rRNA, tRNA, and mRNA of organelles (chloroplasts and mitochondria) in fungi, plants, and protists, and also in mRNA in bacteria.
What is a difference between group I and group II introns?
The key difference between group I and group II introns is that in group I introns, the splicing reaction is initiated by a guanosine cofactor, while in group II introns, the splicing reaction is initiated by internal adenosine. RNA splicing or pre-mRNA splicing is one such post-transcriptional modification.
Are Group 2 introns ribozymes?
Group II introns are mobile ribozymes that self-splice from precursor RNAs to yield excised intron lariat RNAs, which then invade new genomic DNA sites by reverse splicing.
What are introns in bacteria?
Bacterial group II introns are large RNA enzymes that mostly behave as retromobile elements [1–5]. Following their autocatalytic excision from interrupted RNA transcripts, they can reinsert within identical or similar DNA target sequences by retrohoming or retrotransposition, respectively [6–8].
What do group I and group II introns have in common?
What do group I and group II introns have in common? Both are known to be self-splicing introns. Which of the following correctly describes the concept of alternative splicing? Multiple protein products are often produced from single eukaryotic genes.
What is a difference between group I and group II introns quizlet?
-Group I introns are found across all organisms, including vertebrates. -Group I introns form a lariat structure. -Group II introns use an exogenous guanosine as a cofactor.
Where are introns found in bacteria?
Within bacteria, group I introns are predominately inserted within structural RNA genes such as tRNA and rRNA genes [31-33,101-107].
What is the difference between intron and exon?
Introns and exons are nucleotide sequences within a gene. Introns are removed by RNA splicing as RNA matures, meaning that they are not expressed in the final messenger RNA (mRNA) product, while exons go on to be covalently bonded to one another in order to create mature mRNA.
Do bacteria have introns?
Mobile introns are widespread. They have been identified in bacteria and bacteriophage, archaebacteria, and eukaryotes. The RNA of most of these introns folds into a series of stems and loops.
What is a major function of prokaryotic DNA polymerase I besides replication?
What is a major function of prokaryotic DNA polymerase I besides replication? -decreased ability to repair double-strand DNA breaks. -increased ability to form methylated guanine.
Where are Group II introns found in the genome?
Present in the genomes of bacteria and eukaryotic organelles, group II introns are an ancient class of ribozymes and retroelements that are believed to have been the ancestors of nuclear pre-mRNA introns.
How are eukaryotic introns similar to bacterial introns?
These eukaryotic introns share a common ancestor with bacterial group II introns, which are mobile, scarce and maintained at low copy-levels. Because of this stark contrast, bacterial group II introns are considered as selfish mobile elements with no beneficial function to their hosts.
How are bacterial Group II introns considered selfish Retromobile elements?
In sharp contrast, since bacterial group II introns are scarce, irregularly distributed and frequently spread by lateral transfer, they have mainly been considered as selfish retromobile elements with no beneficial function to their host.
What makes up a group II intron retroelement?
Group II intron retroelements consist of an RNA and a protein component. The RNA is a ribozyme (catalytic RNA) that is capable of self-splicing in vitro, while the intron-encoded protein (IEP)’s open reading frame (ORF) sequence is contained internally within the RNA sequence and encodes a reverse transcriptase (RT) protein [ 1 – 6 ].