Question

1) Based on your own experience (are you lactose tolerant, or intolerant? totally voluntary if you want to include that!) and the assigned reading, describe the process by which some groups of humans evolved the ability to digest milk products well into their adult years.

In your answer I want you to specifically talk about the "evolution" of the ability. Was it gradual? Immediate? And why haven't all humans evolved this ability?

Assigned readings:

When we're babies, we're meant to have our nutrition come from milk products (specifically, from human milk products). Milk contains a protein called lactose, which babies can break down with an enzyme called lactase, which is secreted by little projections inside their intestines. The lactase enzyme splits the lactose sugar into two smaller pieces that can be easily absorbed by the intestines. 

As we get older, a lot of humans (and other mammals) gradually stop producing the lactaseenzyme because we're no longer dependent on milk for our nutritional needs. We'd call those humans "lactose intolerant" because their bodies lack the enzyme that splits the lactose sugar into smaller pieces, and their intestines therefore can't absorb it easily. 

As humans started domesticating animals, we suddenly had access to a rich, nutritious milk supply that we could drink into adulthood. However if we no longer had the lactose enzyme that helped us to digest the milk, then this source of nutrition would have been problematic for us.

For this LMA, we're going to think about the evolution of the human ability to keep our production of lactose well into adulthood, and perhaps for our whole lives. How did this happen? Read on!

http://phenomena.nationalgeographic.com/2007/02/26/in-the-footsteps-of-my-lactose-intolerant-ancestors/

2) Your first discussion will be an open discussion about how the news reports scientific information, and how reliable they are as a source of information for us out here in the general population.

Let's use the example of the recent Ebola outbreak. That was ALL over the news, and for a while, the news articles were pretty scary and panic-inducing. Remember?

Here's an article from just last summer, about the two American medical missionaries who had contracted Ebola and were being flown back to the US for treatment. Read the way the news article handled the story, and how you feel reading it.

By October, the American news was talking about the Dallas nurse who flew on a commercial plane with Ebola. It hinted that this was the first stage of a "widespread outbreak" in the US.

In contrast, here's the Ebola informational page courtesy of the Centers for Disease Control.

And what happened to all the fear - what became of the Ebola epidemic?

-- Keep in mind that while this was happening, an HIV epidemic was quickly growing in a small town in Indiana. We didn't hear very much about that.

So in this week's discussion, I want you all to talk about your thoughts on how the media handles really important scientific information and news, like disease outbreaks, epidemics, vaccinations and the like. Do you feel you're getting good scientific information from the media? Do you feel like you'd know where to turn for good, solid, scientific information in case of an emergency? How reliable would the media be if we did have a widespread epidemic threatening us?

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Ans: Lactose a milk disaccharide cannot directly absorbed by gastrointestinal tract (GIT) into blood stream. It can be hydrolysed by lactase enzyme which breaks lactose in to the monosaccharides like glucose and galatose. Lactose intolerance is the consequence of absence of lactase enzyme and lead to unabsorbance of milk lactose especially in adults. This phenomenon is based on the observation that during childhood the babies are mainly dependent on milk and to digest it enterocytes lining villi in small intestine secrets the lactase enzyme and as baby grows the dependency on milk is reduces and hence production of lactase also goes down, later it stops. This is commonly with non dairy consuming societies, and due to the ‘switching off’ of the lactase gene which present on chromosome 2. ...

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