Lecture 29 Flashcards
What is comparative genomics? What can it be used to determine? How is it done?
Comparitive genomics refers to the comparison of genomes in order to find out what is common and what is different.
Things which are in common are known as conserved and may encode the biology which is in common between species, things which are different may encode biology specific to an organism. The combination of these two allow us to learn about which bits of the genome do what.
To do this both genomes are lined up next to each other and marked where the sequence is the same (known as aligning).
What makes aligning genomes difficult and what can make it easier?
Aligning genomes is difficult because its hard to know where to start, closely related species are easier because of fewer changes and aligning the coding sequences is much easier than the non coding because more changes tend to occur in non coding sequences.
What allows us to predict the genes from genome aligning? Once these have been found what can be done?
The coding sequences (genes) are more conserved than non coding regions, once these have been found these can be compared between species to let us know where genes come from, what their likely function is and how much genetic information we share with relatives.
What do we find about most of our genes relative to other animals/bacteria?
Genes are remarkably conserved, almost all of our genes can be found in other organisms and many are found in every organism.
What is synteny? What can we do with this? What does it tell us?
Synteny refers to the fact that in many cases the gene order and organisation is often conserved between organisms. We can compare the order of genes on chromosomes in one species with another to identify syntentic ‘blocks’.
Synteny tells us that blocks of chromosomes are conserved through evolution, while chromosomal rearrangements to happen they often arn’t fixed and closely related species have very similar gene order and organisation.
What can we find by comparing genomes between individuals of the same species?
We can find individual differences which might be associated with disease, characteristics of that individual and evolutionary history.
What allows us to sequence extinct animal genomes? What must we be careful of when doing this?
The use of PCR (which is extremely sensitive) allows us to amplify tiny bits of DNA, however contamination and DNA base modification via degradation is a huge problem. With care however ancient DNA can be used to determine relationships of extinct animals or let us understand extinct species better.
Who were the neanderthals? What does comparitive genomics let us do?
Probably the closest relative to modern humans, they lived between 130000 and 30000 years ago in europe and asia and due to their living in caves their remains are well preserved. Comparitive genomics allows us to answer questions like did we interbreed (which some remains of those in europe and asia suggest we did).
What does and doesn’t the human genome sequence allow us to do?
Allows us to: experiments we couldn’t do otherwise (e.g comparisons), provides vital information on our biology.
However it doesn’t tell us the function of genes.
How do we work out the function of genes?
We take them our of an organism and observe the resulting phenotype.
