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FYI: This is Option Number Twenty-Five. Isn't this being a bit, uh, mean on the hamsters?This thread is now fab (ha!).....koth, thanks for the great questions!
It just seemed like a wasted opportunity if I didn't throw questions to the folk that seem to have a good understanding of biology and evolution.
At least they're receptive to answer questions and providing evidence/links to support what they post.If you can read this, you're too close!
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with regards to the 4/128 being deleterious or harmful, can the harmful mutations accumulate with each generation? I.e. generationA = 4 harmful, generationB =6, generationC =9? Or are there corrective traits that remove some of the traits before passing on mutations to the next generation?
I think there are two different questions at play here.
Can the deleterious mutations accumulate? Certainly.
Do they accumulate? Not really.
To determine whether deleterious mutations will accumulate, a number of factors have to be considered.
The first factor is artificial selection. In humans this typically presents as consanguineous relationships or inbreeding. Where you have a close degree of consanguinity maintained for a number of generations, the deleterious mutations have no escape route, no way to be weeded out of the genome.
We also see this kind of mutation accumulation in dogs. Repeated artificial selection of traits which are harmful to the animal itself are quite common in dogs, King Charles spaniels for example.
The second factor to consider is the degree of detriment that a mutation may cause to the parent organism.
Take the gene responsible for your blood type. The gene responsible lies near the end of the long arm of chromosome 9. (Long arm by the way refers to the physical structure of the chromosome as seen below)
The blood type system as we know involves four blood types, A,B,AB and O. The A and B versions of the gene are co-dominant and one copy of each gene will result in blood type AB. Blood type O, however, is the recessive form of the gene and results from a frameshift mutation caused by the deletion of a single base. This single mutation results in the O version of the gene coding for an entirely different protein. The consequences of this in terms of the parent organism is that people with the AB version of the gene have a high resistance to cholera. People with A and B, slightly less resistance and people with O are susceptible. You would imagine, therefore that O would have disappeared from the genome long ago. However, it isn't that straightforward. As it turns out, people with the O version of the gene have a higher resistance to malaria than the others.
Molecular genetic basis of the histo-blood ABO system
Of course, current medical technology and other cultural factors must also be taken into account. Take something like haemophilia for example. While this may have contributed to a negative impact on survivability throughout history, such a mutation now would not necessarily affect the lifespan of an affected individual. Similarly, with the decline in large families advantages or disadvantages in fecundity are unlikely to have any actual impact on the number of descendants.
If you would like a pop-sci primer on the topic I would recommend this:
Genome: The autobiography of a species in 23 chapters0 -
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You're full of infection-causing bacteria right now. To cause infection requires the right circumstances, like being in the 'right' part of the body. If you swallowed a pill containing concentrated cold viruses, you wouldn't get a cold because they need to be in the sinuses/airways for that. Same with bacteria.
So they're still in you, and they'll be affected by antibiotics wherever they are, so the risk of making them resistant remains. Don't take antibiotics unless you have a bacterial infection, and then finish the damn course, and you won't send us back to the hellish age before penicillin was discovered.
You mean I shouldn't take them for my virus 0 -
For those that signed up for it, a reminder that the Coursera Introduction to Genetics and Evolution course starts this week. Week 1 materials are already up on the site with the first assignment coming on Monday.
Really don't like the lack of immediate feedback on the problem set. How can you actually learn something if you don't know if you're right or wrong? I always it found it best to make errors and learn from why I was making them. Here, I'm left completely in the dark over whether any errors have been made or not.
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Really don't like the lack of immediate feedback on the problem set. How can you actually learn something if you don't know if you're right or wrong? I always it found it best to make errors and learn from why I was making them. Here, I'm left completely in the dark over whether any errors have been made or not.
You'll know tomorrow;) I like the fact that you can take the problem sets multiple times, and compare your answers as you go along. I've taken the first set 3 times and the current answers are only the same as the first for 2 problems!
What I have found so far is you can't rely solely on the lectures, as they are very short and basically an overview. The additional materials, youtube videos etc. are really helpful, and I have also been consulting my daughter's AP Biology textbook (to her endless amusement).0 -
Different strokes for different folks I guess. I prefer the problems having instant feedback a limited number of tries and changing between each iteration of a try. So that way you don't even get asked the same question twice. The variant of each question changes in a way to ensure you understand the concepts. 0
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TheChizler wrote: »Same. Aced the first test, figure I can flunk the rest!
Misread one question entirely. Thought it was asking which are not possible. Instead it was asking which were possible. In any case, I would have answered it correctly so not too fussed. Worse thing is, now we're basically in the boat the Week 1 has to be identical to week 2 time wise. Which may not be the case. It may require double the amount of time. Considering that I started week 1 when it began. This doesn't bode well.
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Misread one question entirely. Thought it was asking which are not possible. Instead it was asking which were possible. In any case, I would have answered it correctly so not too fussed. Worse thing is, now we're basically in the boat the Week 1 has to be identical to week 2 time wise. Which may not be the case. It may require double the amount of time. Considering that I started week 1 when it began. This doesn't bode well.
Week 2 is a considerable step up from week 1:(. I would say I have put in more than double the time to get to a point where I am satisfied with the problem set, and the problem set is 10 questions this time rather than 6.
What I have found of great value is the discussion forum and specifically the dialog on the problem sets. If you are stuck for time it is a good source to get an overview of the topics. There are a few posters who pose excellent questions and hints without giving away the answers (and a few others who just give the answers which isn't really helpful).0 -
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