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Physics, Astronomy & Cosmology / Does time slow down for a person spinning in a centrifuge?

« on: 15/07/2009 07:19:00 »

Thanks LeeE, BC, & Sophie,
 I think I understand now (at least relatively so).

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Physics, Astronomy & Cosmology / Does time slow down for a person spinning in a centrifuge?

« on: 30/06/2009 03:59:32 »

Hi Sophie,
 Will you elaborate on that? 
At first glance it seems like the person up high would be traveling faster ... maybe I am thinking about it backwards?

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Plant Sciences, Zoology & Evolution / Where do the Parakeets go?

« on: 26/06/2009 09:07:33 »

Maybe Here?
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Photo from pubsgalore.co.uk

Or maybe they're trying to get away from the Old Fat Cat in Southampton
http://www.beerintheevening.com/pubs/s/18/18313/Old_Fat_Cat/Southampton

That must be very neat to see such beautiful birds fly over in large groups.  Are they noisy?

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Plant Sciences, Zoology & Evolution / What Is This Yellow Stuff I Saw On This Tree Today ?

« on: 24/06/2009 10:43:52 »

Chicken of the woods?  Jessica Simpson would be REALLY confused.

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Cells, Microbes & Viruses / Few Questions About Cell Biology

« on: 24/06/2009 05:03:47 »

Hi,
 I'll give question 1 a shot.

 I'll give a brief description of Two dimensional gel electrophoresis (I'll abbreviate it 2D-GE) first then explain how it fits to answer the question.  2D-GE is used to separate out proteins by their physical structure.  With 2D-GE proteins can be separated by two properties, the idea is that most proteins should have an individual "signature" when you compare them by two criteria. 

A simple comparison would be if you are having a party with 100 people and you'd like to take a picture from above with everyone in their own spot in a reproducible manner. If everyone was lined up along a wall by height. You might have 5 people that are 5'11" so if you asked them to line up again later the 5 people would be in the same general spot, but they might not be in the exact same order.  However, if you also separated each of these height groups by how much each person weighed, by having the people move away from the wall a certain distance based on their weight, you could now take a picture from above with most people would be in their own spot in the room and you could get them back to the same spot again later.

  The same applies to proteins.  All the proteins from a sample are collected, and then these are separated in one dimension.  Commonly, this is by isoelectric point - but other measures could be used to separate the proteins (just like you could use other measures to separate the people, hair color, salary etc.).  Then the gel is turned 90 degrees and the proteins are separated by size.  This should give most proteins their own unique spot on the gel.

Now suppose at your party someone has taken advantage of your hospitality and has eaten all of your lasagna before you put it out for everyone else (pretend lasagna is really, really heavy).  If you lined everyone up again and took a second picture you could compare this to the first and see who moved relative to their original position.

So for RAS, an amino acid change can change the isoelectric point, how RAS interacts with other proteins, or other physical properties.  If you compare a control sample to the 5 patients you could look and see if the position of RAS moved relative to its position in the control sample.

All that said however, I think it might be cheaper and easier to amplify RAS DNA from each of the samples and sequence it to answer this question.  I guess the advantage of the 2D gel is that if RAS wasn't what changed, you might be able to identify other proteins that did change.  But if you really wanted to just know if RAS changed, I don't see how a 2D-GE would be better than sequencing the DNA.

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The Environment / Do sounds get louder just before a storm?

« on: 24/06/2009 02:58:54 »

I used to live close (too close) to a train track and there was a big change in the sound of the train whistle depending on how humid it was.  I can't say if it was louder or not, but very distinct, less "tinny" and more fluid sounding on a humid day than a cold, dry day  (the only time it was not humid was when it was cold). 

There was also a change between winter (in Michigan, so below freezing) and summer.  I love the above freezing train sound because it means summer is coming.

Of course it was always louder in summer, I had my windows open  []

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Plant Sciences, Zoology & Evolution / what happens when you add giberellin to a flower ?

« on: 24/06/2009 02:41:13 »

Hi Paul,
 5000+ Posts!  You've been busy!

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Question of the Week / QotW - 09.05.31 - How do sunflowers follow the sun?

« on: 24/06/2009 02:40:01 »

Thanks!
It's good to be back, I missed y'all!

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Plant Sciences, Zoology & Evolution / what happens when you add giberellin to a flower ?

« on: 23/06/2009 09:13:12 »

If you give giberellin to a plant that is already flowering the flowers look fine, they don't seem to look much different. 

 However, there are some studies that show that giving giberellin to cut flowers (through the stem or by brushing it on them) will make them last longer.  Just looking quickly at some of these papers it looks like that really depends on the type of flower.  In one paper they show that it makes one type of rose last longer, but has no effect on another type of rose.   

I hope this answers your question this time,
Colleen

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Question of the Week / QotW - 09.05.31 - How do sunflowers follow the sun?

« on: 23/06/2009 09:01:51 »

As to if they would follow the moonlight, I would suspect not.   The circadian clock in plants works to "gate" most light responses.  That is, if you shine light on a plant when it expects it to be night (as determined by its internal clock), it won't be fooled into turning on its photosynthetic machinery.  So it is probably likely that this response is also gated.  There is some evidence that hormones, such as auxin, are also regulated by the circadian clock. 

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Plant Sciences, Zoology & Evolution / The evolution of toolmaking

« on: 05/12/2007 07:27:09 »

Yes, in this situation the Keas are not making a toy- but I wonder if there are animals that do that.

Cool about the elephants!  I didn't know they drank

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Plant Sciences, Zoology & Evolution / The evolution of toolmaking

« on: 05/12/2007 02:56:21 »

Hi George,
 Right, I think it would be really hard to differentiate between whether modern chimps learned from us or on their own.  Interesting about the crows, that's pretty cool.  And yeah, it certainly seems like nests would be a "modification of the environment"  also with beaver dams, fox dens, etc.

  The story of the crows reminds me of two things-

1.  Where I used to live there was a Mulberry tree and after the berries had been on there for a long time they would ferment in the sun.  Then a flock of crows would come and spend a few days there eating the mulberries.  They would fall out of the trees, roll around on the ground and basically spend the few days there drunk.  They did this every year that I lived there for 5 years- one big crow party.  I know, it's not tool related, but it did amaze me that somehow they remembered to check this tree every year- and I never saw them eating the mulberries when they were ripe (of course I wasn't watching all the time).  From this behavior of the crows it is not hard to imagine how the first humans discovered alcohol.   

2. The Kea, a parrot from New Zealand, loves to play with "toys" especially any rubber on cars parked near their territory.  They love to tear it off and play with it.  If one took a broader meaning of tools- I wonder if there are animals that modify items for play.

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Plant Sciences, Zoology & Evolution / Seed or spore?

« on: 05/12/2007 00:36:02 »

I don't know if this is the good animation or not - I don't have flash on this computer so I can't tell: I hope it's good!

http://academic.kellogg.cc.mi.us/herbrandsonc/bio111/animations/0124.swf

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Plant Sciences, Zoology & Evolution / Seed or spore?

« on: 05/12/2007 00:33:47 »

Hi Opus!

  Well, on a fern if you are looking at the spores inside a sporangium they would be haploid cells.  The sporangium itself and the "leaf" it was on would be diploid.  The spores inside are haploid they get distributed and if they find a nice moist place to land will grow into a prothallus- a tiny little structure.  Then they produce sperm and eggs and the fertilized egg (zygote) is now diploid and this grows into the diploid fern.  When it is time to reproduce the fern goes through meiosis to produce haploid spores and the whole thing start again- here's a picture - and I know I've seen a good animation of this, but I can't find it just now, I'll keep looking.

Colleen

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Plant Sciences, Zoology & Evolution / The evolution of toolmaking

« on: 05/12/2007 00:13:09 »

Hi Carol,

There are several documented cases of chimps actually adapting what is available to make better tools.  An example would be Jane Goodall's famous observation that chimps prepare the grass and sticks they use for fishing out termites.

This is my favorite example- Chimps use two different tools, one to puncture the termite mound, then a second (That they modify by chewing on) to fish out the termites.

For subterranean nests the chimps use their feet to force a larger "puncturing stick" into the earth, drilling holes into termite chambers, and then a separate fishing probe to harvest the insects. Often the chimps modified the fishing probe, pulling it through their teeth to fray the end like a paintbrush. The frayed edge was better for collecting the insects.

The rest of the article is very interesting and has some great videos to watch also:
http://news.nationalgeographic.com/news/2004/10/1006_041006_chimps.html

Colleen

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Plant Sciences, Zoology & Evolution / The evolution of toolmaking

« on: 04/12/2007 06:39:40 »

 

my questions tend to be met with a deafening silence, but here goes, we'll see if anyone has any ideas on this.

Well, I don't know the answer to your question, but just to prevent the deafening silence I'll post my two cents worth.

There have been many recent "discoveries" that chimps and other animals are using tools in ways we had not expected, in fact, in ways we had quite clearly thought they were incapable of doing.  My guess is that this is one of those cases that if you aren't looking for it you won't see it.  I highly doubt that chimps suddenly in the last 20 years started this behavior.  They have probably been doing it all along, we just either never noticed, didn't believe it, or didn't consider it toolmaking. 

In the defense of the scientist studying them early on - it took the patience and approaches of people like Jane Goodall, and the advantage of excellent lenses and video equipment to make these types of discoveries.  The first part allowed the subjects to be comfortable enough around the observers to relax and "act normally."  The latter was important for convincing the rest of the world.  I would bet that 100 years ago there were people who saw chimps using tools and they probably came back and told others. . but how seriously would these reports have been taken without pictures or some hard proof.  It is easier to accept these ideas now, that a few cases have been documented well.

OK- that's it for my speculation. . .

The only thing I could find on real evolution of tools in primates is that they have been doing it for a long, long time. . . .
http://www.sciencedaily.com/releases/2007/02/070213142924.htm
 

Before this study, chimpanzees were first observed using stone tools in the 19th century. Now, thanks to this new archaeological find, tool use by chimpanzees has been pushed back thousands of years. The authors suggest this type of tool use could have originated with our common ancestor, instead of arising independently among hominins and chimpanzees or through imitation of humans by chimpanzees.

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Plant Sciences, Zoology & Evolution / Can someone help?

« on: 04/12/2007 06:23:19 »

I did- It's FREEZING here (at ground level even)

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Plant Sciences, Zoology & Evolution / Seed or spore?

« on: 04/12/2007 06:21:56 »

Hi Opus,

  I think this is one of those pairs of words that are very commonly confused.

Spores come from non-flowering plants (mosses and ferns) and fungi.   Seeds come from flowering plants.  Seeds come from the ovules of the flower. 


http://www.ou.edu/cas/botany-micro/ben/ben122.html

A spore consists of a single cell and contains no preformed embryonic parts. In contrast, a seed (typically) consists of hundreds or thousands of cells and contains stored food (the endosperm) and an embryo. Moreover, spores and seeds differ in what they give rise to. A fern spore gives rise to the prothallus of the gametophyte generation; a seed, to the baby plant of the new sporophyte generation.

What the last line means is that spores are haploid and when these spores divide they give rise to haploid cells or the reproductive generation of the organism- in the case of the ferns the tiny prothallus that then through sexual reproduction produces the zygote that creates the diploid sporophyte generation- the fern that you see.

 Seeds are formed from the union of two haploid cells (the pollen and the ovule) and the cells of the embryo divide to give rise directly to the diploid (or more) sporophyte generation of the plant. 

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Physiology & Medicine / Clever chimp, dump human.

« on: 04/12/2007 05:55:04 »

Wow, Interesting!

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Plant Sciences, Zoology & Evolution / Can someone help?

« on: 02/12/2007 04:56:38 »

Wow That is really high!..What if they were higher what risks would they begin to encouter at that pont... would lungs collapse or what..The air gets thinner so would that be the first effect on the lungs..

Well, even if I could breathe up there, say with an oxygen tank, I'd be really, really cold.