2
votes
1answer
62 views

Where does the fate map of a human embryo end?

I'm confused about the fate map of a human embryo. Is it just a particular part of the embryo development or does it include everything, from the conception (germinal stage) to the day the baby is ...
4
votes
3answers
132 views

Does the genetic material the sperm carries affect it's physical properties

Basically, what I'm asking is, is the actual sperm cell built from the blueprint in the DNA of the man or is it itself also a consequence of the DNA it carries? I'd like to know a few more things ...
1
vote
1answer
18 views

Is there a Lyme disease vaccine?

Each Spring, our local health unit begins its campaign of Lyme disease and tick-bite awareness. I was wondering if there has ever been a vaccine available, and if so, what antigen does it target?
9
votes
1answer
232 views

If all B cells are present at birth, why should the primary response to an infection take longer than the secondary response?

When learning about the immune response, my teacher mentioned that all the bodies B cells are present at birth, and there is one to counter every disease. But if this is the case, why should the ...
5
votes
3answers
186 views

Does our eyeball increase in size as we grow?

Does the size of the eye increase as we develop from the stage the complete eye first forms to infancy and then to adulthood ?
4
votes
1answer
77 views

Book suggestion on computational molecular evolution

I'm currently reading Computational Molecular Evolution by Yang. Can you recommend alternative books? I am finding it to be lacking on conceptual discussion (it's more focussed on the mathematics and ...
2
votes
1answer
43 views

Number of autoregulation and FFL motifs in a network

Suppose we have a network with N* nodes (N* is the number of internal nodes). Every directed link in this network exists with probability p. What would be the number of: motifs that are ...
6
votes
1answer
73 views

Evolution of Chromosome Numbers

Some species have different numbers of chromosomes, as we all know. Throughout evolution, how was a species able to survive with an extra chromosome? How was this organism able to breed successfully ...
1
vote
2answers
112 views

Which was the last significant event in human evolution? What's next?

At 10.000 BC (12 ka), we became the last of the Homo species on Earth. In evolutionary terms this is a very little time range to something happen, but I'm wondering anyway, in this meantime which are ...
1
vote
1answer
56 views

Earwax versus Mucus

Something I have wondered for a while is why have two different primary defense mediums, ie earwax and mucus, that perform the same function? As far as I know, mucus and earwax are both part of the ...
2
votes
1answer
47 views

For emphysema, which of the respiratory volumes is effected. I have a couple of educated answers

It could be the tidal volume because it effects how a person inhales and exhales normally. It could be the residual volume and functional residual volume, because it increases its amount. Because it ...
6
votes
1answer
153 views

What exactly makes bananas go brown?

I know that often oxidation processes are mentioned when referring to the color change from yellow to brown in bananas (specifically: those that you get everywhere in supermarkets, with no seeds). ...
3
votes
1answer
178 views

What is the beneficial function of IgE antibody?

Dont tell me the "function" of IgE is to cause allergy ! In whatever texts I have seen it is written that IgE is important to cause allergies but what is the beneficial function of IgE ? Why was it ...
0
votes
0answers
17 views

What are the mechanisms of disabling extrinsic control of heart?

I started this thread by thinking this question but I developed it further below What is the mechanism maintaining refractory period of pacemakers? My conjuncture is that the mechanism is the ...
0
votes
0answers
15 views

Distribution of Physarum polycephalum tubes during starvation phase

So I have been trying to find an answer to this question in the literature but to no avail. I am looking at the Tero and other articles on the slime mold Physarum polycephalum. I understand the models ...
5
votes
3answers
135 views

Is it possible to have life in vacuum?

I just got struck by curiosity now: Intuition says no, but I've never had confirmation of it.
0
votes
0answers
26 views

Which reflex arcs work in Heart with extrasystoles?

I am researching what is triggering the extrasystoles - initial idea from this thread about Which ionic channels of Pacemakers can work in very low frequencies in extrasystole? I am interested in the ...
0
votes
1answer
15 views

Which ionic channels of Pacemakers can work in very low frequencies in extrasystole?

At frequency 0-3 Hz. Like computer processors which can work at low frequencies and controlling under- and overvoltage. Normal most significant channels are Ca2+ and K+ that are changing. However, I ...
5
votes
2answers
179 views

Is there a biological reason for spreading food intake into breakfast-lunch-dinner?

I keep hearing over an over how humans can satisfy their entire daily caloric need in one sitting at a fast food restaurant. At the same time I'm looking at the kitchen plates, cups, etc, and they ...
6
votes
1answer
106 views

Task-dependent “reversed” handedness: why use left hand for some tasks? How is it controlled by the brain?

I am right-handed. Which means that when I hammer down a nail, I hold the nail in my left hand, with which I can hold it straight and at a controlled position. This is true in situations where the ...
7
votes
1answer
96 views

What are the costs associated with carrying lots of genetic material

What are the costs (if any) associated with carrying lots of genetic material? energy for copying? raw material for copying? space in the cell? Maintenance cost (matter and energy)? time to copy is ...
2
votes
1answer
612 views

Why do three nucleotides code for one amino acid? Why not 5 nucleotides? [duplicate]

We all know why there are 3-base codons, and why there aren't any 2-base codons. But why is there not a 4-base a 5-base codon?
5
votes
3answers
438 views

Evolution: How could all useful traits evolve simultaneously?

I have a basic question about evolution, for which I never found an answer. I understand how evolution works if we focus on one specific organ or trait. With each generation, some organism is more ...
0
votes
0answers
32 views

Simultaneous depolarisation of Sinus Node and AV node as extrasystole in myocardial infarction patient

Assume you have a patient 68 years old with previous myocardial infarction (Actually patient 201 in MIT-BIT arrhythmia database). Assume that AV node depolarises strongly. However, at the same time, ...
2
votes
0answers
79 views

Why does IUCN classify pistachio as a “Near Threatened” species?

When reading the Wikipedia entry on pistachio, I noticed that IUCN has classified the plant under "Near Threatened". On looking up its entry at IUCN, I see that its population is trending downwards, ...
1
vote
1answer
105 views

Troubleshooting for Agarose Gel Electrophoresis

SI ran my 2% agarose gel on constant voltage (100 V). For a few times it worked at CV but, after a week or so the machine would automatically switch to constant current by itself. And this only ...
2
votes
1answer
52 views

Are there any fungi that can digest humic acids?

Humic acids are a complex group of organic substances, that are generally known to be hardly biodegradable. Fungi as agroup are known for breaking down complex organic matter like cellulose or lignin. ...
0
votes
0answers
14 views

Calling for Pressure pictures about Right and Left atrium

I am trying to understand the partially patent foramen ovale in patients with right-side heart failure. I am interested how the pressure in right and left atrium change in normal case in abnormal ...
0
votes
2answers
51 views

Is Sinus node conduction necessary for heart beating?

Assume a patient with previous cardial infaction which SA node not possible to activate action potential anymore. However, SA trying to beat unsuccessfully repeatedly waisting energy. Therefore, I ...
0
votes
0answers
20 views

Laser surgery to stop damaged Sinus node from beating

I am trying to find any publication about laser surgery to stop the damaged sinus node which cannot anymore beat. I could only find publications which modifies SA node function. I am not sure if it ...
1
vote
1answer
33 views

Usage of the taxonomic classification “Pinnipedia”

According to ITIS the classification Pinnipedia is invalid, and it is proposed to rather use Caniformia. The later group however includes a range of terrestrial animals as opposed to the pinnipeds ...
4
votes
1answer
112 views

Why mosquito bite is confined to a certain shape?

I think this problem should be asked in a physiology forum rather than biology@ stackex but I'll give it a try. So my question is simple - why a mosquito bite is usually confined to a certain shape ...
3
votes
1answer
53 views

relative-rate of evolution

I am supposed to calculate the relative rate of evolution of two sequences (human and sheep) with a chicken serving as the outgroup. The sequences are pretty long, so I will just create a short ...
0
votes
1answer
23 views

Do trees have no set lifespan and “quite”immortal?

Many trees survive centuries and die only in disasters like storms and lightnings or infections. So do they have no set life span? Are they exceptionally resistant to genetic mutations and have very ...
9
votes
1answer
277 views

Did the eugenics program in Nazi Germany have a measurable effect? [closed]

Did the killing or sterilisation of people considered as living a "life unworthy of life" in Nazi Germany have any measurable effect on the "average health" of Germany? Is there any statistical ...
1
vote
0answers
60 views

What is the name of systemic tension of muscles?

I meat a overtrained friend (25 years old) who cannot rest. He has all muscles and most of the skin very tense. He is practising regularly in gym and sleep badly. He moves like a stick figure and has ...
3
votes
1answer
42 views

Why are many anti-malaria drugs gap junction antagonists?

Why are many anti-malaria drugs gap junction antagonists? My professor recently just mentioned that many of the anti-malaria drugs block gap junctions. i am wondering if this blocking is important ...
9
votes
3answers
250 views

Book recommendation on population/evolutionary genetics?

I have recently been involved in collaborations that require me to model the population genetics of eukaryotic populations. I fear I may either be "re-inventing the wheel" or making conceptual ...
1
vote
2answers
166 views

Does Science Say That We Should Die? [duplicate]

Excluding situations where you die from accidents, the main reason for death is -generaly- diseases. And usually it is about an organ which becomes "tired" after many years. These results are all ...
1
vote
2answers
76 views

How the lungs clear themselves?

Looking at my computer's fan I can say that a lot of dust is collected on it not less dust should be collected in the lungs, not to mention some inhaled parts of food. How the lungs clear themselves ...
1
vote
1answer
104 views

What happens when seeds are refrigerated before planting?

My son is doing a science research project at school, and he's chosen to research what happens when seeds are refrigerated before planting. I cannot provide any information in regards to background ...
1
vote
0answers
24 views

Which disorders are fully concordant?

I work in neuroscience, mostly Alzheimer's disease (AD), with some work in autism spectrum disorder (ASD). The work is in gene regulation and epigenomics. I'm familiar with monozygotic twin (MZ) ...
3
votes
2answers
90 views

Heterozygosity under genetic drift

The wright-Fisher model of genetic drift is: $$p_{ij} = \binom{2N}{j}\left(\frac{i}{2N}\right)^j \left(1- \frac{i}{2N}\right)^{2N-j} $$ ,where $\binom{2N}{j}$ is a binomial coefficient. From this ...
3
votes
1answer
88 views

How does GC-content evolve?

Background GC-content refers to the frequency of base pairs that are either C or G in the genome, or in other words the number of GC base pairs divided by the addition of the number of GC base pairs ...
6
votes
3answers
366 views

Why are there ecosystems?

Why would things self-organize in such a manner? I'm a mathematician and I have no baggage in ecology or biology. If the question is too broad maybe someone can point me to formal sources where this ...
2
votes
1answer
79 views

Are cell lines potentially dangerous?

More specifically, if a human subject was exposed to, say, a human cancerous cell line (via intravenous injection or through an open wound, for example), is it possible that they would develop any ...
6
votes
2answers
129 views

Why did women historically have such a high mortality rate during birth?

Historically women had a relatively high chance of dying while giving birth. At first thought it seems to me that this would be a disadvantage for the species for the obvious reason that a dead ...
1
vote
0answers
33 views

Can a tree survive if someone cuts all buds?

My thought was to cut all buds of a deciduous tree at spring and see if it can survive a year and develop new buds and leaves next spring. Assuming the tree is already grown and not a sapling. If the ...
2
votes
1answer
50 views

Why doesn't the sperm die if there is citric acid and acid phosphatases in the semen?

While studying I read that sperm needs alkaline medium for its survival.But when I studied the composition of semen it revealed that semen contains citric acid which acts as a sperm nutrient along ...
3
votes
1answer
89 views

Can oil be used instead of water in preparing wet mounts for microscopy?

Is there a reason that oil (e.g., vegetable or clear mineral) is not used to make wet mounts in microscopy? I am not referring to oil immersion technique but substituting oil for water in wet mounts ...

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