G25-26 Flashcards
how many base pairs and genes in the human genome
3.2 x 10^9 bp, 21,000 genes roughly
what is the stanley miller
reproducing environment of early earth
proposed constituents H2O, CH4, NH3, H2
no O2
produced 17/20 of the AA used in protein synthesis and all the purines and pyrimidines used in NA synthesis
what can a purely geochemical process lead to?
the synthesis of polymerase biomolecules
what could have been the first coding RNA
a ribozyme with duel catalytic and coding function.
what are viroids
200bp rna - too simple to be viruses
often complex secondary loops
often non coding
some ribozyme properties - can interact with proteins and replicate
move between plant cellsa nd case disease. through plasmodestmata.
what is the smaulhausen threshold
threshold between life and non life
how many genes are universally present in all organisms? what does this info combined with knockouts suggest
65 genes
knockouts have shown that minimum set of genes is 200, luca genes must have been lost from some organisms
what are COGS
clusters of orthologos genes - subset of COGs probably represent minimum LUCA genome.
what are type of genes are the overlaps between archea and eukaryotes
mostly involved in dna replication
what type of genes are in the overlap between bacteria and archea
those that have been transfered by horizontal transfer (so share more gens that E/A)
what types of genes are shared between eukaryotes and bacteria
endosymbiont genes - chloropast and mitchochondria
What do the number of genes and protein coding genes show in many viruses and bacteria
mosst genes are protein coding.
how many of yeasts genes are protein coding
roughly half.
what was used to analyse how many of yeasts genes were protein coding and what were the resutls
disruption analysis
40% have no phenotype
what is disruption analysis
when a transposon is added to knockout a gene.
what could be the issues with results from disruption analysis
some genes might be required under different growth conditions.
and duplications of genes = redundency
what is the genomic organisation of a typical eukaryotic genome
introns and reg seqs = 24%
repetitive DNA that includes transposable elements - 44%
reperative dna unrelated to transpoable elements - 15%
unique non coding = 15%
exons = 1.5%
where do the highest proportion of new genes arise from?
already exisisting genes (exons)
which type of selfish genetic element is more likely to produce new genes
LINEs
SINES arent that useful for new genes
what are the simplist retroelements
lines with no LTRs or ENV genes (envelope genes)
what is an example of a gene family that is related by sequence but not function
serpins serine protease inhibitors
dont all have serine protease inhibitor function othersa re hormones for example antithrombin. or ovalbumin
* may only need one AA change to dramatically change gene function
how did globin genes evolve?
via unequal crossing over events - occurs when chromosomes misalign at recombination.
- becausse they are simialr they misalign
what do multigene globin allow the production of
different types of heamoglobin embryonic foetal and adult
what is vpr?
an example of a gene in primate lentivirus - in HIV 2 the virus has duplicated and has both the vpr gene and the related vpx gene