Molecular 18-19 Flashcards
Why cant genomes be 100% functional ?
It would require huge Ne and really short generation times
What is the C-value a good measure of ?
The haploid genome in bp
What are the 3 things that effect genome size ?
Genome duplications
Transposable elements
Deletions
What can have a profound effect on the C-value
transposable elements
What is literal DNA ?
Functional DNA that the order of nucleotides is constrained
What is indifferent DNA ?
Functional DNA but order of nucleotides is not constrained
What is garbage DNA ?
DNA that is selected against
What is junk DNA ?
DNA that is not useful but doesnt have deleterious effects so isnt selected against.
Why does the neutralist theory believe that most of the genome is non functional ?
Because cost of replication is negligible
Are large or small genomes more evolutionary successful
small
What is the c-value paradox ?
The lack of correlation between genome size and complexity
What is the G-value paradox ?
The lack of correlation between the number of protein coding genes and the complexity of an organism
Why do apes and humans have a different number of chromosomes ?
telomere-telomere fusion event between 2 ancestor chromosomes
What is molecular tinkering ?
A combination and modification of pre-existing functional and non functional genetic elements.
What is the protein domain ?
A well defined region in the protein that is stable and independently folding unit with a 3d structure
Has a distinct function
How many domains do function proteins have ?
2 or more
What does internal duplication cause ?
Tandem repeats
Why is internal duplication a particular problem for eukaryotes ?
Introns can replace exons which will effect splicing resulting in the loss of info
What causes domain reshuffling ?
When exons correspond to more than one protein domain or when multiple exons correspond to the small domain
What does domain reshuffling cause ?
Mosaic chimeric proteins: The gene contains sequences that are found in nonhomologous genes
What is gene fission ?
A multidomain gene that is split into 2 or more transcriptional units
What is the problem with gene fusion ?
One gene ends up being under control by the other promoter
What is domain accretion ?
Domains can be added to existing domains to add complexity and alter function
What is exonization and pseudoexonization ?
exonization: introns become exons this is generally deleterious
pseudoexonization: When exons become non functional
What does alternative splicing of the primary RNA transcript result in ?
The production of different mRNAs from the same DNA fragment which will be translated into different polypeptides
Why can genetic elements alter phenotype ?
They can jump to different places in the genome
What is the difference between mobile and transposable elements ?
Mobile elements can be integrated into genomes where as transposable elements can only move intragenomically
What type of transposable element has code for reverse transcriptase ?
Retroelements
What are retrosequences ?
Accidental retro elements that exhibit no adaptation for retroposition
What are retrogenes ? and what can they cause ?
They are functional retrosequences that produce a protein that is identical to the one produced by that gene that the retrogene is derived from.
Give 2 examples of retroelements ?
long interspersed repetitive elements (LINEs)-pseudogenes
Short interspersed repetitive elements (SINEs)- do not contain ORF and need help replicating and moving
