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Oct
22
comment Is there any possible way to take a DNA test without using blood in humans?
en.wikipedia.org/wiki/Blood_residue nejm.org/doi/pdf/10.1056/NEJM194910062411414
Oct
20
comment Is there any possible way to take a DNA test without using blood in humans?
For a cheap and fast test of blood groups, you need blood. Unless your fingerprint has it's owner's blood, this gets more difficult. In principle, you could extract DNA (caligari2005 already explained that is bothersome) and then check the DNA sequence for the blood group alleles. But if you did extract the DNA from a fingerprint, you would have much better individuation chances with standard forensic tests than looking for a blood group allele.
Oct
19
comment How many people are required to maintain genetic diversity?
Dan Horvat's scenario is only theoretically feasible. People have, on average, 15 damaged genes that may lead to a deadly disease. The first couple (and next generations, too) would have to produce lots of children in order to give them a good chance of findinf couples who can have healthy children. Much more likely this scenario would result in a population with uncommon genetic diseases being common, like in Finland (which artificially created a series of bottlenecks from the 17th century, a fascinating story), read more here: cs.sjsu.edu/~khuri/Aalto_2010/Norio_2003.pdf
Oct
19
comment How many people are required to maintain genetic diversity?
Actually, that's a much more complicated case. The short answer is: you can't be completely certain you've culled the recessive allele. You can diminish it's frequency and this has been done in a neat way in the Mediterranean with thalassaemias (a group of diseases related to sickle cell anemia) - young couples with non-negligible risk were tested and if both carried the gene, they were advised against having children or given access to abortion if the fetus turned to be sick. Given stricter control, reduction could be achieved fasted, but when the allele becomes rare, it gets more difficult.
Oct
19
comment How many people are required to maintain genetic diversity?
Have you considered women's point of view? That in this scenario somebody decides to use a woman's body to generate some number of children and you cannot decline, you are literally forced into pregnancy? Pregnancy and childbirth, which, even with modern medical advancements, are an important cause of death for women? I guess the people who board such a ship can make this kind of a decision, but their children would not be given any choice with regard to bearing a second generation.
Feb
15
comment Dinuclei cellular mechanism
I hope it's better now.
Jan
31
comment Question about Autosomal Recessive Alleles
I would also add "human error" to the list, a person changing the outcome, e.g. by contaminating the sample or a spelling error while transcribing the result. This might be surprisingly likely - somebody overly tired, or having a bad day.
Dec
4
comment How many people are required to maintain genetic diversity?
It's just mathematics. If you pick two outbred mice/rats etc. and mate them, the offspring is about 0,5-1% more inbred than their parents (meaning both their copies of any gene are a tiny bit more likely to be inherited from one ancestor mouse). If you have enough animals, this effect is smaller than the effect of other phenomena, such as genetic drift (compare with the assumptions behind Hardy-Weinberg equilibrium). I don't know the exact equasions behind those numbers, I just know, that this was calculated and such-and-such numbers are used.
Sep
18
comment Do spouses begin to share genes over time?
I get that this is a legit question, but you are so sexist in formulating it I hope you never write again.
Aug
3
comment Botulinum Toxin
Yes, I doubt that. I think there might be very old studies showing the principle - how it was discovered, or studies pinpointing the exact curve in order to formulate those recommendations that I quoted.
May
25
comment Hardy-Weinberg applied to three alleles and stimation of allele frequencies
So you omitted some data of this question? The thing is, you can substitute whatever you want, e.g. 1-p=q+r or p=1-q-r, but that leads you nowhere if you don't have any more data. Something like p^2+q^2+r^2=3pq+3pr+3rq is crucial to solving this problem. Anyway - these are two equasions, you still need a third to ba able to assign specific numbers to p, q and r.
May
24
comment Hardy-Weinberg applied to three alleles and stimation of allele frequencies
Why do you need to separate homozygotes from heterozygotes?
Apr
22
comment Two brown-haired people have two children, P and Q. P has blond hair. Q has brown hair. What is the probability that Q is heterozygous?
Then you have one more argument: this was probably a high school homework, so it has to use what kids learn about Mendelian heredity, not something deeper and more elaborate.
Jan
26
comment What prevents a pregnant woman's immune system from recognizing her fetus as nonself (and attacking)?
Right now I don't remember the full story, but part of it is that pregnant women are somewhat immunosupressed and there is something like a layer of NK cells around the placenta making sure nothing attacks it. Not very practical to adapt to organ transplants.
Jan
22
comment Why is the Hydra Biologically Immortal?
@shigeta now I have to search those sharks!
Jan
7
comment Can positive and negative blood type of a couple lead to miscarriage?
I would add one more thing - generally the longer they wait before trying again, the better chances fo a Rh+ foetus. Memory cells slowly die and in my country 5 years after last pregnancy with problems a Rh- woman's pregnancy is considered normal risk. Still - a specialist will tell you more and help your sister.
Dec
24
comment Chromosome 2 fusion?
I'd really like to give you more than just one upvote.
Dec
22
comment Chromosome 2 fusion?
You are describing two processes - one of general fusion happening now and then throughout history (which is common) and one of specific fusion, that was supposed to happen at a certain time in human evolution history (which is not sure, but possible).
Dec
19
comment How many people are required to maintain genetic diversity?
I am no expert on dogs, but did learn a bit about in- and outreeding. Each dog breed is either open or closed. In a closed breed, only offspring of animals already belonging to this race belong to the race. In an open breed any animal that looks similar enough (or has other important traits, characteristic for the breed) can be a parent of a "breed" litter. Under certain circumstances (e.g. too few animals in the breed, too bad overall health of the breed) a closed breed can be opened and after the problem is solved, closed again.
Dec
3
comment How much weight/volume do microbes occupy within the human body?
Just human intestines have over a kilogram of bacteria! A good enema will leave you 2kg lighter and that's mostly bacteria.