google "blood group diet" and you will get more information on your question than you really wanted (it originated in Norway I think)! Is any of it evidence based - not so far!

David

See Mike's response to your other question

Big whales mostly eat plankton or krill (very tiny sea creatures) and sometimes small fish for food, as far as I am aware. There are many stories and myths about huge wales eating people or even boats but they are untrue. The largest whales are filter feeders; that is they filter large volumes of sea water and eat the animals in it.

In contrast, the orcas or "killer whales" do eat mammals eg seals, sea lions, porpoises and dolphins but are not known to eat humans.

Difficult question to answer! For sure there are a number of chemicals which if you breathe them in will kill you (poisons, biological weapons etc)  and some of those have a very nasty smell. However what I think you are asking is can a non-toxic chemical kill a person purely because the smell is very unpleasant. If so I think on balance the answer is no, and what will probably happen is that the body will "get used" to the smell so it no longer bothers the person.

I have never heard of that idea and searching all the published papers on AD and using google turns up nothing of note. Sound waves are however used for dissolving kidney stones!

My worry would be that the intensity of the sound waves, if sufficient to break up the A-beta deposits, would also damage the surrounding normal brain tissue.

David

maybe in the wild (ie before hens were domesticated) the majority of the eggs did get fertilised but many were eaten by predators, hence the high volume of eggs laid.

I hasten to add that is mere speculation on my part and is backed up by no evidence at all!

David

see

http://en.wikipedia.org/wiki/Cholera

You are asking two separate questions!

Yes the seasons (which are in part determined by the sun and surrounding planets) and especially the phases of the moon have an enormous impact on very many species in terms of the regulation of migration and reproduction etc. Whether the same can be said of humans is debatable.

In contrast, there is no scientific evidence I am aware of that astrology (which I take to mean as the belief that you can predict the future of human beings by knowing when and where they were born) works!

just like any other infectious disease a person can only be infected by somone else who has HIV, or if they are in contact with bodily fluids from a person with HIV.

men and women both have 24 ribs - 12 on each side.  The first seven pairs of ribs are connected to the sternum (breast bone). Rarely, some pople have one more or less pairs of ribs due to various genetic mutations.

(posted in Mammals)

this seems to be an oft repeated myth, including Bill Bryson's recent autobiography (and he should know better) - see

http://www.ccmr.cornell.edu/education/a … l?quid=165

and lots of others

The simple answer is no one knows, but current thinking is that it is a mixture of nature and nurture. By that I mean that there are likely to be a very large number of genes and thus proteins that are important for "intelligence" (and let us not forget that intelligence itself is not an entity but a whole range of skills and tools including memory, understanding and handling mathematical concepts, intuition, and creativity in science and the arts etc). The identity of these very many genes and how they work in concert to determine the above qualities is still in its infancy and very poorly understood. One thing is for sure there is no one gene for intelligence!

Then on top of genetics comes nurture, in other words our upbringing and education. The relative importance of genes and upbringing is hotly debated and some think one or other are the major determinants. Personally, I think both are bound to have an important role and since each person is different, the relative importance of genes and environment will vary hugely between individuals, races, countries etc.

(posted in Evolution)

The idea that humans are a superior species is rather subjective and not necessarily supported by existing evidence.  Yes humans have complex brains and are capable of speech, but that does not necessarily make them superior. Almost every other species is capable of doing something amazing that humans can't do!

I assume you asking why sometimes when one star fish leg is damaged or cut off then the animal grows back two legs rather than one.

Assuming yes then no one knows for sure but I would think that the answer lies in the mechanisms and genes the star fish has for growing back limbs. When damage occurs to a leg, that triggers a whole load of genes to be activated, that make loads of new proteins whose job it is to grow back a leg. Ocassionally when the damage is severe and right at the part where the star fish leg joins the body, then the signals get a bit confused and the star fish "thinks" it has lost 2 legs rather than one, which is why two legs grow back.

What you may also be interested to know is that the genes in the star fish that do this are very similar to those in mammals (including humans). However in mammals the function of those genes is to tell the developing embryo how and where to grow limbs whilst the foteus is developing. Sadly, they do not do the same thing in adults when the limb is damaged!

Hope that helps

I am not at all sure I know the answer but will "have a go" and rely on my colleagues who are experts in this area to correct my mistakes! I will leave my answer to your previous questions on the website since it makes a usefull point regarding genome and gene sizes.

Evolution states that all animals evolved at some point from prior less complex species. Thus if you go back far enough logic would tell us that humans apes and rodents must have had a common ancestor. BUT.... that in no way means that because of that we should have similar numbers of genes. As I have said previously numbers of genes do not equate to numbers of proteins, and the absolute numbers of genes and proteins will not explain the complexity or differences between various species. Look at arabadopsis it has nearly the same numbers of genes as a human and it is a plant!

In summary, yes mice monkeys and humans have similar numbers of genes and yes they had a common ancestor. Whether that common ancestor had 30,000 genes I VERY much doubt, I would not focus too much on just gene number. As I said above, it is only one of very many variables that makes each species what it is.

David

see
http://www.ornl.gov/sci/techresources/H … genomesize

you will see that there are radically different numbers of genes and genome sizes between different organisms (including bacteria). So if I understand your question correctly, no there is no absolute relationship between the numbers of genes and the complexity of the organism. If I have (again) misunderstood your question, then please do post again

David

the 2 DNA chains are mirror images of each other. One of the reasons we have two chains is that when a cell divides each daughter cell gets one strand and then makes a second one from that. In that way all the genetic information from the parental cell is faithfully copied to both daughter cells. The first step is the DNA unwinding.

When Watson and Crick first described the structure of DNA in 1953 and reported it in the journal "Nature" with the picture of the double helix, the final line in the paper was "it has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material".  Possibly the most understated sentence in any scientific paper written in the last 60 years!

hope that helps

David

Great Question!

We do all have roughly the same number of genes give or take 5000! But clearly no one would mistake a chimp for their friend or a fly for their brother so what you are, I think, asking is what accounts for the obvious differences between species. The answer is not fully known but the following points are probably responsible for much if not most of the differences.

1.    Some fly genes are similar to chimps/human but some are not. In contrast, almost all chimp genes are very very similar (and in many cases identical) to humans. So gene differences are clearly not the major answer!
2.    Genes code for proteins, and each cell (irrespective of its function) will make hundreds of thousands of different proteins (one gene can code for a number of subtly different proteins).  Now imagine that there are very small differences in which cell makes which protein and at which time that protein is switched on (and in many cases off again) in the life of that cell. Now multiply that up by ten of thousands. Now you can start to see how two species such as human and chimp that apparently are 99.7% identical can be so very different! Put simplistically the answer is NOT in the genes, but in the proteins they encode.

I hope that helps

David

I think the simple answer is almost anyone you want to be! To go to university and study most science subjects (including medicine, dentistry or to be a vet) you need at least biology and chemistry to A-level. I would guess if you wanted to study maths or physics then you would need that subject at A-level as well.

Of course doing those subjects to GCSE and/or A-level would also allow you to study many other things at university eg English, law, accountancy etc, in combination with other relevant subjects.

My advice is study what you enjoy and what you are good at!

Good luck

David

I did not know the answer but one of the senior electrophysiologists in our department has provided the following:-

The repolarization of the action potential results from inactivation of sodium channels and activation of delayed rectifier potassium channels. Delayed rectifier channels are so named because there is a delay before they open, which allows the upstroke of the action potential to occur. These potassium channels are also quite slow to close, so the 'overshoot' is caused by the persistent opening of delayed rectifier potassium channels after the action potential has been repolarized.  This period of 'overshoot' is essential to speed up the switch of sodium channels from inactivated to closed, to allow them to reopen for a subsequent action potential.  Therefore, the amplitude and duration of the 'overshoot' will determine the refractory period, the time after an action potential when another cannot be evoked.

That’s an excellent question and there is no easy or short answer, so bear with me! It really depends upon the situation you are thinking of. Let me give you some background and an example or two. A gene is a stretch of DNA that codes for a protein and there are many thousands if not hundreds of thousands of proteins (one gene can give rise to many slightly different proteins or variants). A single cell and indeed a tissue or organ therefore contains a huge number of proteins that will act together and sometime oppose each other in terms of function. Thus no one gene can really be “dominant” over another. Having said that some proteins (and thus genes) are certainly critical to normal cellular function and if that protein malfunctions (due to mutations that occurs in the womb or in the adult eg in cancer) then the loss- or gain-of function may be so important that it can appear “dominant”. Further, many geneticists will use the term to mean that just one mutated/altered copy of the gene is enough to cause the observed change in function (which may be inherited and thus passed on to the next generation, hence called a dominant allele).

I suspect what you are thinking of is the common thought that brown eye colour is dominant over blue which in many cases is true. What most people do not realise is that eye colour is not determined by just one gene (ie if you have it then the eyes are brown and if you don’t then they are blue). In fact eye colour is very complex and is specified by a whole cascade of genes, so again it’s incorrect to say that one gene or protein is dominant. Another example of this is the gene/protein cascade that determines arms/legs and digits. This is another critically precise series of events that if its goes wrong can end up with very weird or misshaped appendages (or even a missing limb or even more rarely a duplication). Once again an alteration in a single gene can appear “dominant”. I am sure others on the site will be able to give additional examples of this.

Hope that helps

They are very similar and many would use the terms interchangeably. From a physician’s perspective if a disease (eg cancer) went away completely and then comes back we tend to call that relapse. If the disease is still there but not a problem and then "flares up" again (eg an attack of arthritis or a bout of malaria) then often times people would tend to call that a recurrence.

you are right that hyperbaric oxygen therapy is contraversial, though there is not much else that is proven to work for people with severe monoxide poisoning. When I was a junior doctor we tried free radical scavenger therapy to see if that would reduce the brain damage and thus the functional outocme, but we never got a large enough group of patients to make the results statistically significant and thus never wrote the study up!

regards

David

I also like Bill Bryson's a short history of nearly everything very much - his ability to effortlessly make complex issues simple to understand is a gift I wish I had!

David

with regard to embryology - try this!

http://cna.uc.edu/embryology/

regards


David

Theoretically it might be possible but in practise occurs rarely. As you rightly say, if that did occur there would be a high likelihood that the foetus would be damaged and/or malformed. If that was the case then the likely outcome would be a miscarriage. So the short answer to your question is yes it is possible that a damaged sperm might result in a baby with abnormalities, but thankfully it is rare. Nature is very good at minimising these situations – another good example of “the survival of the fittest”.

If you take shallow breaths then your diaphragm does not press so much
on your tummy so it hurts less. Similarly, if you curl up then the
muscles in your abdomen are not as tightly strethched and that again
puts less pressure on the tummy.

David