Gene families, protein isoforms, RNA splicing and editing Flashcards
Provide an example of a gene family.
Myosin heavy chain isoforms.
An ancestral DNA sequence can diverge at two levels to give rise to a new functional gene. What are they?
Mutation in protein-coding sequence (change mechanism)
Mutation in regulatory sequences (change, e.g., site of expression)
What is the difference between orthologues and paralogues?
Orthologues are genes encoded by the same ancestral gene in two species -> new genes being compared are derived from a single gene present in the last common ancestor of the two species being compared
Paralogues are genes encoded by isoforms of a gene ancestrally shared by two species = not the “same” gene -> one species inherited one isoform of the gene while the other species inherited another isoform
What is the DDC model for evolutionary maintenance of duplicates?
Model that attempts at explaining why duplicates of a single gene can be preserved and become necessary.
DDC -> duplication, degeneration, complementation = original gene duplicates, each copy undergoes subfunctionalization through mutations and become complementary (both copies are need to carry out the full functions of the original gene)
Differential expression becomes a key component of function maintenance
True or false: gene families cannot evolve separately in different organismal lineages.
False: they can.
List neurobiologically important gene superfamilies
Ligand-gated ion channels
Voltage-gated ion channels
Neurtransmitter receptors
What components mostly determine alternative splicing?
Regulatory elements by enhancing/inhibiting splicing, or by binding directly to introns and exons
How can transcriptional choice lead to different splice pathways?
By activating different promoters/regulatory elements
From which mechanisms does arise the diversity of K+ channels?
- Alternative RNA splicing
- Several distinct genes involved
- Protein complex assembly -> homo-tetramer and hetero-tetramer channels have different properties
What is RNA editing? What is the most common form in animal proteins?
Post-transcriptional alteration of an RNA sequence -> often the substitution or the insertion of a single nucleotide
For animal proteins, the most significant forms of RNA editing are single-base substitutions due to the deamination of A residues by adenosine deaminase (A changed to I (inosine)), or the deamination of C by cytidine deaminase (C changed to U)
