Genome sequences of extinct hominins Flashcards
what are some of the problems in the study of ancient DNA
not always presereved - depends on conditions
DNA mol highly fragemented
contaminatinom
miscoding lesions
what are process which result in highly fragmented DNA
heat induced hydrolysis of B-N glycosidic bonds- removes bases the structure then left unstable
how does the strucute left by heat induced hydrolysis of B-N glycosidic bonds then become highly fragmented
hydrolysis of double strand DNA - results in gaps which when denature in PCR results in lots of sgl strand fragments
give an example of the process that results in miscoding lesion
deamination of cytosine to uracil
- amino groupp replace with oxygen , in pcr turns C to T
v common in ancient DNA
what is the problem with deamination of cytosine to uracil in ancient DNA
v common
v difficult to interpret
some studies remove uracil residues using enz
why is hish sequence overage needed
to distinguish miscoding lesions from genuine SNP
norm want x50
what is a miscoding lesion
change in nucleotide occuring during degradation that alters th eseq that is read after PCR
how can modern contamination be reduced
wear gloves
most of th econtamination on outside so scrae off
work done under high contaniment
what revealed from seq analysis of N from Denisova caves
38kya DNA from 3 inds mtDNA suggets highly related 52% coverage 70% DNA frag aligned to human genome long runs homozygosity - inbreed suggest
what does comparison of the N D HS genomes suggest about divergence
HS and (N+D) = 553-589kya N and D =38kya
what pop of N are non afr HS more close rel to
Mezaamaiskayathan more than Altai
what is the first fossil of denisovans found
75kya fingerbone and two teeth from altai mountains siberia mtDNA rev a unknown hominin but nuclear DNA suggest sister group of N genome 30 coverage teeth sim to australopithecus low gen div
what region of genome has strong N to D gene flow
human leukocyte antigen
what has genome seq of N and D revealed about oofa hypo
arent direct descendents of H.erectus
discredit the prev model of two migr oofa first by erectus then sap
what is the current model for oofa suggested by D and N
at least 3 migr oofa first H.erectus then N/D ancestor the H,sap = although argued still too simple probs more waves