lec 35- evolutionary medicine Flashcards
what has caused the evolution of antibiotic resistance in bacteria?
the overuse of antibiotics
does reducing the amount of antibiotics reduce the amount of bacterial antibiotic resistance?
yes, feeding pigs antibiotics reduces the resistance of bacteria
what is antigenic drift?
mutations in viral RNA or DNA of parasites causing the old antibodies of hosts to not recognize the antigens on the mutated viruses anymore, causing them to by pass
e.g. annual flu viruses and COVID
what is antigenic shift?
sudden change in a virus caused by viral reassortment and horizontal transfer, making the virus dangerous and can cause a pandemic
where did the influenza virus originate?
in birds, but then spread to mammals through reassortment
what is the origin of the SARS (sudden acute respiratory syndrome)?
it came from the horseshoe bat, then with reassortment it entered the civet, which is used in the Chinese market and then spread to humans
what is the origin of MERS (middle eastern respiratory syndrome)?
came from bats that infected camels, which then spread the virus to humans
what are zoonotic strains?
strains of viruses and bacteria than can spread between animals and humans
what is used to find the source material for infections like SARS, AIDS, etc.?
phylogenetic trees and other genetic tools
why do pathogens have very rapid evolution?
-high mutation rate
-high reproductive rate
-horizontal transmission and reassortment of genetic components
what has long periods of co-evolution between viruses and humans caused?
reduced the virulence of most flue viruses due to the immune systems defense responses (Red Queen Effect)
how do pathogens compete for evolutionary fitness?
-within a host, the fittest viruses are those that replicate quickly, but have high virulence that can kill the host and them
-across a population of hosts, selection should ultimately favor viruses with reduced virulence, which allows hosts to survive and pass the virus on to new populations
why did the 1918 influenza, which was a variant of SARS, have a higher virulence then the seasonal flu?
-due to crowded conditions causing selection for higher virulence
-the flue had high virulence and can find another host easily to replace dead hosts
what helps reduce viral transmission rates?
social distancing and isolation
if there is no coevolutionary history, are hosts defenseless and very prone to death from viruses?
yes, e.g. Europeans brought measles, TB, and smallpox which wiped 70% of the indigenous of Haida
can population bottlenecks increase frequency of genetic diseases?
yes
what evolutionary trade offs cause aging, give an example?
-selection in early years favours genes for maintenance (survival and reproduction) but in later years a pleiotropic effect causes the same genes to reduce health in the post reproductive period
-e.g. P53 tumor suppressor gene also can damage normal cells in later years
how does cancer occur?
-it occurs when cells divide uncontrollably, leading to a population of cells that gain higher fitness than normal ones
what genes cause cancer?
-p53 tumor suppressor gene when mutated
-proto-oncogenes: normal genes involved in cell division, cause cancer when mutated
-oncogenes: mutated proto-oncogenes
can environment cause cancer?
yes, radiation, pesticides and more
what tissues are most vulnerable to cancer?
rapidly dividing cells, hence why children are more prone due to the cells growing
if children are more prone to cancer, why is it more common in adults?
because it takes time for the mutations in a tissue type to accumulate and initiate cancer
are humans more prone to diseases in this day and age compared to the oldern days?
yes, our immune systems are undergoing many disorders and we need allele combinations to catch up to the changing environment and diets due to our genetic heritage only being suited for the old days
