Genes & Genomes Flashcards
Define genomics
sequencing genomes of cultured organisms
Define transcriptomics
sequencings expressed sequence tags - cDNAs
now is RNA-seq
Define metagenomics
culture-independent sequencing from a community of organisms
Define proteomics
large-scale analysis of proteins in mixtures
What does proteomics require?
a reference genome
Define metabolomics
study of small-molecule profiles
What factors contributes the the RNA world theory?
- DNA is modified RNA
- RNA can store information
- RNA is inherently more reactive than DNA and capable of 2ndary structure
Why is RNA inherently more reactive than DNA?
2’-OH group on ribose sugar
What are ribozymes?
naturally occuring RNA molecules capable of catalyzing reactions without protein presence
The spliceosomes - complex can perform what reaction? What ribozyme does it share characteristics with?
u2-u6
splicing
GII introns
Where do snRNAs originate from?
GII introns
Homologs are genes/proteins that….
share common ancestry
orthologs are genes/proteins that
evolve via speciation from a common ancestral gene
paralogs are genes/proteins that
are related within a genome and evolve via duplication
What are the four methods of gene duplication?
- Tandem DNA-based duplication
- Retroposition
- DNA-based gene fusion
- Tc-mediated gene fusion
What is the mechanism of tandem gene duplication?
Unequal cross-over of transposable elements and produces a tandem gene by recombination
What is the mechanism of retroposition?
mRNA is reverse transcribed and integrated into the genome as a retrogene
What is the mechanism of DNA-based gene fusion?
juxtapositin of partial duplicates produce chimeric genes with fused sequences
What is the mechanism of Tc-based gene fusion?
Different genes acquire intergenic Tc and splicing signals and produce a chimeric RNA which is then RT and intergrated into the genome
What are orphan genes a.k.a. ORFans
genes without obvious homologs
How do orphan genes arise?
- gene duplication coupled with extreme divergence
2. from non-coding DNA
What is the mechanism of orphan genes arising from non-coding DNA?
- Mutations abolish a Proto-ORF’s frame disruptions
2. Proto-ORF acquires promoter and is transcriptionally active
How are duplicated genes relatively similar in sequence and function?
via concerted evolution
What factors influence the rate and fate of duplicated genes?
- Rate of duplication
- DNA recombination machinery
- Gene structure
- Population Size
- Impact of new duplicate