BIO 327G EXAM 2 questions well
answered to pass
Role of duplications in eukaryotic genome variation and evolution - correct answer
✔✔- mutations have more impact on the diff b/w individuals (in protein coding
genes -> prob the reason for phenol changes we see)
- amt of change in the genome (copy # dup) contributes more change to the
genomic diff b/w species
Whole genome duplication (autopolyploidization) - correct answer ✔✔-
nondisjunction of all chromosomes; gametes have 2x the ploidy
- most common in organisms capable of self-fertilization b/c of compatibility
Single chr nondisjunction causing aneuploidy - correct answer ✔✔"duplication" of
an entire chromosome
segmental duplications - correct answer ✔✔- mostly occur by uneq crossing over
@ rep seqs; rel small
- results in tandem dup (genes flanking, same dir)
early evidence of WGD - correct answer ✔✔even number of chrs b/c you inc
number by WGD
Wolfe & Shields 1997 WGD in yeast - correct answer ✔✔- duplicated regions
appear as a diagonal series of genes
,- proposed that due to expansiveness of dups, it occ by a single WGD (followed by
translocations and deletions) rather than by successive indep events
How to identify WGD events? - correct answer ✔✔look for large syntenic/dup
regions on diff chrs and/or counting chr #s can provide evidence of WGD
Susumo Ohno hypothesis 1970 - correct answer ✔✔WGD as basis for all
innovation in evolution / 2R hypothesis
gene duplication - correct answer ✔✔predom mech by which genes w/ new
functions and associated pheno novelties arise in euks
duplication - correct answer ✔✔single ancestral copy gives rise to 2 copies w/in a
genome
tandem duplication - correct answer ✔✔new copy flanks old copy on the chr (res
of crossing over)
homologs - correct answer ✔✔2 gene copies that diverged from a single ancestor
paralogs - correct answer ✔✔homologs that initially diverged following a dup;
gene duplicates
orthologs - correct answer ✔✔homologs that initially diverged @ speciation event
,ohnologs - correct answer ✔✔duplicates/paralogs og from WGD
gene family - correct answer ✔✔set of homologous genes diverging due to dup
and speciation (ex: globin gene family)
how to assess age of dup genes (paralogs) - correct answer ✔✔the more identical
the dup genes, the newer the age of these genes
fate of duplicated genes - correct answer ✔✔dup gene is redundant and likely to
be expendable and there are 4 fates: neofunctionalization, subfunctionalization,
gene conservation, nonfunctionalization
neofunctionalization - correct answer ✔✔one copy takes on a new function; the
other maintains its og function (could res in fast seq change, exp for AA
replacements)
subfunctionalization - correct answer ✔✔both copies become partially
compromised by mutations, and both are needed to perform the function as the
single ancestral gene
gene conservation - correct answer ✔✔both copies can perform same function as
og ancestral gene
nonfunctionalization - correct answer ✔✔one copy becomes inact by mutations
b/c there is no selection to maintain it (becomes a pseudogene)
, most common fate of dup gene - correct answer ✔✔nonfunctionalization b/c
most mutations are bad so will knockout copy of that gene and therefore will have
pseudogenes
how to recognize duplications from genome seq - correct answer ✔✔high level of
sim b/w seqs
why have dup genes? - correct answer ✔✔- better to have 2 copies than 1 -> to
inc dosage and supply more of a product, w/ seqs preserved by gene conversion
(concerted evo)
- to attain permanent heterozygosity (heterosis; overdom) by incorporating 2 diff
alleles into the genome (think sickle cell anemia and color vision genes)
- subfunctionalization - maintain multiple copies to help compensate for del
mutations
- to create substrates for new functions from existing genes
how could neofunctionalization ever occur? - correct answer ✔✔- Ohno's
dilemma: maintaining dup copy for its og function would restrict its freedom to
diverge
- soluton: innovation-amplification-divergence model
moonlighting - correct answer ✔✔when a protein can take on another activity
what is neofunc evidence of? - correct answer ✔✔- evidence of pos sel
- how genes w/ new functions og
answered to pass
Role of duplications in eukaryotic genome variation and evolution - correct answer
✔✔- mutations have more impact on the diff b/w individuals (in protein coding
genes -> prob the reason for phenol changes we see)
- amt of change in the genome (copy # dup) contributes more change to the
genomic diff b/w species
Whole genome duplication (autopolyploidization) - correct answer ✔✔-
nondisjunction of all chromosomes; gametes have 2x the ploidy
- most common in organisms capable of self-fertilization b/c of compatibility
Single chr nondisjunction causing aneuploidy - correct answer ✔✔"duplication" of
an entire chromosome
segmental duplications - correct answer ✔✔- mostly occur by uneq crossing over
@ rep seqs; rel small
- results in tandem dup (genes flanking, same dir)
early evidence of WGD - correct answer ✔✔even number of chrs b/c you inc
number by WGD
Wolfe & Shields 1997 WGD in yeast - correct answer ✔✔- duplicated regions
appear as a diagonal series of genes
,- proposed that due to expansiveness of dups, it occ by a single WGD (followed by
translocations and deletions) rather than by successive indep events
How to identify WGD events? - correct answer ✔✔look for large syntenic/dup
regions on diff chrs and/or counting chr #s can provide evidence of WGD
Susumo Ohno hypothesis 1970 - correct answer ✔✔WGD as basis for all
innovation in evolution / 2R hypothesis
gene duplication - correct answer ✔✔predom mech by which genes w/ new
functions and associated pheno novelties arise in euks
duplication - correct answer ✔✔single ancestral copy gives rise to 2 copies w/in a
genome
tandem duplication - correct answer ✔✔new copy flanks old copy on the chr (res
of crossing over)
homologs - correct answer ✔✔2 gene copies that diverged from a single ancestor
paralogs - correct answer ✔✔homologs that initially diverged following a dup;
gene duplicates
orthologs - correct answer ✔✔homologs that initially diverged @ speciation event
,ohnologs - correct answer ✔✔duplicates/paralogs og from WGD
gene family - correct answer ✔✔set of homologous genes diverging due to dup
and speciation (ex: globin gene family)
how to assess age of dup genes (paralogs) - correct answer ✔✔the more identical
the dup genes, the newer the age of these genes
fate of duplicated genes - correct answer ✔✔dup gene is redundant and likely to
be expendable and there are 4 fates: neofunctionalization, subfunctionalization,
gene conservation, nonfunctionalization
neofunctionalization - correct answer ✔✔one copy takes on a new function; the
other maintains its og function (could res in fast seq change, exp for AA
replacements)
subfunctionalization - correct answer ✔✔both copies become partially
compromised by mutations, and both are needed to perform the function as the
single ancestral gene
gene conservation - correct answer ✔✔both copies can perform same function as
og ancestral gene
nonfunctionalization - correct answer ✔✔one copy becomes inact by mutations
b/c there is no selection to maintain it (becomes a pseudogene)
, most common fate of dup gene - correct answer ✔✔nonfunctionalization b/c
most mutations are bad so will knockout copy of that gene and therefore will have
pseudogenes
how to recognize duplications from genome seq - correct answer ✔✔high level of
sim b/w seqs
why have dup genes? - correct answer ✔✔- better to have 2 copies than 1 -> to
inc dosage and supply more of a product, w/ seqs preserved by gene conversion
(concerted evo)
- to attain permanent heterozygosity (heterosis; overdom) by incorporating 2 diff
alleles into the genome (think sickle cell anemia and color vision genes)
- subfunctionalization - maintain multiple copies to help compensate for del
mutations
- to create substrates for new functions from existing genes
how could neofunctionalization ever occur? - correct answer ✔✔- Ohno's
dilemma: maintaining dup copy for its og function would restrict its freedom to
diverge
- soluton: innovation-amplification-divergence model
moonlighting - correct answer ✔✔when a protein can take on another activity
what is neofunc evidence of? - correct answer ✔✔- evidence of pos sel
- how genes w/ new functions og
