2) In terms of evolution, why are we told to keep taking antibiotics for the full course of treatment? What is the potential evolutionary outcome in the infective bacterial population if you stop antibiotic treatment early?
3) Normally, the chromosomal pair XX will produce a female offspring, while the chromosomal pair XY will produce a male offspring. Is this always true? Describe two different cases in which the sex determining chromosomes might deviate from this pattern and the consequences of this deviation.
4)This week we're going to talk about an oddly specific case of inheritance and survival: altruism. For the purposes of this discussion board, let's define altruism as acting in a way that helps someone else at your own expense. When a mother rushes into a burning building to save her child, she's risking her own life (and health, and potential to further reproduce) to help another individual: her child. Why do instinctively know that this will happen? Why is this a natural process, to save the life of a child? Does that natural instinct extend to other family members, like a brother or a sister? What about a distant cousin? What about a casual acquaintance? A stranger? How well do you have to know someone to risk your own evolutionary "fitness" (your ability to survive and pass your own genes down) for them?
Let's think about lifespans. How long do you expect to live, as a human being? 80 years? 100 years? Now think about your genes - the ones you inherited from your parents: how long do you expect your genes to live? Well, you got them from your parents, so maybe 140 years, your combined life spans between two generations? But wait, your parents got those same genes from their parents - who got them from their own parents - who got them from your distant ancestors, who got them at some point from our primitive ancestors to all humans, who got them from an apelike ancestor--- you get the picture. Your genes have been alive for about 3.8 billion years. Your genes are for all intents and purposes "immortal".
A scientist Richard Dawkins proposed a theory known as the Selfish Gene Hypothesis. Here's a quick youtube video of Dawkins himself explaining his theory. In a nutshell, it proposes that our genes are nearly immortal and they are essentially the masters driving the vehicle of our body, making us behave in certain ways and look certain ways in order to attract mates and reproduce, reproduction simply being a way to make more copies of those genes and let them survive another generation. If this view of life, our genes are controlling us like puppet masters, and we're the puppets getting yanked around on the strings of genetic control. If we feel attracted to someone, that's our genes telling us to pass them on via reproduction and make babies who will grow into adults who will feel the same things, and pass those same genes on into the next generation, and on and on it goes, with all living things acting as giant survival and reproductive machines for the things driving us: our genes.
Now let's get back to thinking about the subject of altruism, which we'll define here as an individual reducing their own fitness, maybe even giving up their own chance of having offspring, for the sake of another individual.
We can certainly understand altruism as humans. In the first week we talked about human emotions we experience: love, commitment, empathy, friendship and connection, and those emotions make some amount of sacrifice feel good, and even necessary. But what is the real biological and evolutionary reason behind altruism?
A lot of scientists debate this question. They even have an equation that predicts how likely you are to behave altruistically towards another person. It looks like this:
rB > C also known as the "inclusive fitness" equation.
Pretty much it says that we'll be more prone to altruism toward another individual if the benefit (B) of our action exceeded the cost (C), after factoring in how many genes we shared with the other lucky guy (r). In other words, we're more likely to sacrifice ourselves for another person if we share a lot of genes with them. If we're more genetically related to them. Is this a totally crazy idea??
Now think about it from the Selfish Gene Hypothesis standpoint. Our genes, this theory says, are trying to make copies of themselves, AND they are controlling our impulses and behaviors. Our genes (according to this theory) don't really care whether Dr. Elizabeth McCliment makes copies of them by having offspring or if Elizabeth McCliment's sister is the one to make copies of them, right? Because we share more of our DNA than I do with a random stranger. So I would be more likely to behave in a way that keeps my sister alive (so the theory says) than a random stranger.
Do you buy this? Are we more likely to behave altruistically and selflessly toward someone who is more biologically and genetically related to us?
If so, how do we KNOW that someone is more or less biologically/genetically related to us than any other person?
Do humans rise above this simple rB>C equation and act altruistically for no other reason than what we call basic humanity? Ignoring the finer distinctions of our similarities and differences?
5) For this LMA write about your scientific/academic thoughts about genetic drift and/or the invasion of new species. I think most people have heard about one type of invasive species or another coming along and ruining a crop, or eating a native flower, or having some kind of harmful traits that are passed on to previously harmless species.
I was born in Chicago and our own 'invasive species' story centers on the zebra mussels that came into Lake Michigan and cleared out all the algae that used to feed native fish species, along with clogging up our drinking water filtration plants. Another example: some of you saw pictures of my albino Burmese Python snake - the state of Florida has been struggling with the invasion of these exact types of pythons into their waterways as people who own these snakes release them into the wild, and Florida happens to be an environment that has everything the pythons need to thrive. Only the snakes can outcompete and sometimes kill alligators (as well as small pets, birds and other native species) and are therefore considered something of an environmental nightmare.
Considering the subject of genetic drift, and also the subject of invasive species, give your thoughts on how natural the invasion of species into new territory actually is. Should we fight against invasive species, or is it a natural process that results in a strong gene pool? Is there a species that is considered invasive either in your own home environment or in a place you've lived, worked, visited or read about? What are your thoughts about how natural (or unnatural) this process is, and what (if anything) our response should be in light of that?
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Emerging viruses cause many deadly endemics or pandemics such as SARS, West Nile Fever and Influenza (Bird flu and Swine flu). Flu is caused by Influenza viruses that are member of orthomyxoviridae family, having segmented genome (typically 8 segments of RNA (-) strand). These are enveloped viruses and depending upon the antigenic Hem-agglutinin (HA) and neuraminidase (NA) gene variants, they are divided into various strains notable among which are H5N1 (Bird Flu) and H1N1 (Swine flu)
In 1918 a variant of Influenza A virus (natural parasite of birds) crossed its host barrier and infected humans causing a pandemic. This strain was termed H1N1. Replacement of various genes from bird strains lead to the emergence of new strains and thus pandemic in 1968 and 1977. Further in 2009 as new strain from pigs infected humans. This strain contained five genes from pigs, two from birds and one from humans. This caused a worldwide pandemic.
Since, the genome is segmented these segments of RNA can combine with the one from different sources if a host is infected from one or more strains, because during viral particle assembly any combination of these segments can be assembled. This leads to the variability and evolution of new strains. The strains are classified based on the antigenicity of surface glycoproteins hemagglutinin (HA) and neuraminidase (NA). Sixteen HA and 9 NA subtypes have so far been identified.
Mechanism of Action of Influenza A viruses:
Influenza A virus is an enveloped virus. Through direct contact (sneezing, coughing etc) the virus gains entry into human body via airway passages (lungs). It infects tracheal and alveolar...
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