1
vote
1answer
2k views

What is the effect of extra-cellular potassium concentration on heart rate and conduction velocity?

If the extracellular potassium concentration surrounding a myocyte increases, then the potassium gradient accross the cell membrane decreases, and therefore the resting membrane potential will become ...
3
votes
1answer
123 views

What would classify those findings of the University of Sheffield experiment as aliens?

It's in the news that some experiment was able to capture some alien specimens during a meteor shower: ...
2
votes
1answer
3k views

How do inward rectifier potassium channels work in the heart?

Apparently in myocytes, there is an inward rectifier potassium channel that operates in phase 4 of the myocyte action potential. I have heard that while this is named as an inward rectifier, that ...
2
votes
0answers
44 views

What's behind the amazing colour combinations in pests & insects?

What's behind the amazing colour combinations in pests & insects ? Do this colour combination signals any character/ poison of the pest/insect ?
2
votes
1answer
60 views

What Biology topics are linked to the Nitrogen Cycle? [closed]

What other educational topics are linked to the Nitrogen Cycle? I am a Science teacher, and I need to organise my lessons. Thanks!
0
votes
2answers
181 views

How is it that the WI-38 cell line isolated by Hayflick in 1962 is still very much around and not affected by the 'Hayflick Limit'?

I have searched the net and I have not been able to come up with an clear answer. Edit: Here is the para quoted from Nature http://www.nature.com/news/medical-research-cell-division-1.13273 "So began ...
5
votes
2answers
2k views

Renin - enzyme or hormone?

Wikipedia says : The kidneys secrete a variety of hormones, including erythropoietin, and the enzyme renin. Can a substance be both an enzyme and a hormone ? Why is renin both an enzyme and a ...
5
votes
2answers
7k views

Which human cells have the longest and shortest lifespan?

Which cells in a human have the longest lifespan? Which cell has the shortest lifespan?
3
votes
1answer
368 views

What happens in your brain when you receive information which causes you to bristle?

I'm talking about moments when you watch a film and you bristle, or when you listen to music, etc. What kind of neurotransmitter flow changes?
3
votes
0answers
179 views

how much grass does a sheep eat in square meters per day? [closed]

I want to buy some sheeps in order to eat my garden's grass. How much grass does a sheep eat each day ??
2
votes
2answers
263 views

Changing the definition of life?

Viruses at this period of time do not fit the current definition of life. Much of the reasoning behind this is that we currently believe that all life must be made up of cells. Also, many ...
2
votes
1answer
524 views

How many consecutive cell divisions are required to form the adult human body from the single cell zygote?

The preferred question would have been what is the total number of cells in a full term human foetus and how many cell divisions are required to reach that number. However estimates of total cell ...
3
votes
2answers
816 views

How does formaldehyde/PBS or methanol fixation of cells affect lysosomal pH?

The question is fairly simple - does formaldehyde or methanol fixation in preparation for immunocytochemistry/immunofluorescent staining affect the pH of the lysosomes? Some background: I'm trying to ...
2
votes
1answer
242 views

GWAS: matched-pairs and logistic regression

Logistic regression is a common analysis tool used for GWAS when your response variable of interested is qualitative. It comes as one of the standard tools in most GWAS packages (e.g. PLINK). Most ...
7
votes
1answer
480 views

On average how many genes / alleles do people share?

I am curious about how much more a child can be alike to one parent than the other. If a child were to inherit all the alleles that are shared between both parents from one parent, but inherit all ...
1
vote
1answer
141 views

Do spouses begin to share genes over time?

I apologize if this hypothesis sounds strange by I was wondering if any research had been done on a phenomenon which I've seen and have corroborated with many other - the idea that over time spouses ...
3
votes
2answers
153 views

Why only heterogeneous SNVs for validation using genotyping arrays?

I am trying to validate the variants I found using whole genome sequencing . The standard practice, I have seen in the two publications below were to check for the number of heterozygous SNPs called ...
6
votes
3answers
149 views

What is the potential function of ultra-conserved elements in the genome?

If selection pressure results in conservation of DNA sequences, what is the most plausible explanation for the existence of ultra-conserved elements (refs here and here) given that there hasn't been ...
1
vote
1answer
266 views

What is the recommended PPM when foliar feeding L-amino acids

It is said that L-amino acids such as histidine, methionine, aspartic acid, glutamic acid, asparagine and glutamine can revert plant stomata closure, increase quality of fruits and assist maturity. It ...
1
vote
2answers
2k views

What happens if an IV drip with a saline solution slips out of the vein, but keeps dripping into the body?

A patient has a saline solution IV drip into the vein. They have somehow moved around and the needle has fallen out of the vein, but remained in the body. Nobody has noticed and for a few hours water ...
0
votes
1answer
39 views

DAT1 dopamine and cocaine binding

I've searched the internet for several minutes and I've looked at DAT but I'm having trouble finding the DAT binding location. Where (and to which aa) does dopamine and cocaine bind to hDAT1?
5
votes
1answer
50 views

A possible cause of autoimmunity

I read that Doherty and Zinkernagel found that MHC- heterozygotes present more antigens to the immune system than homozygotes; yet, the infected heterozygous mice in their experiment all ...
5
votes
1answer
89 views

Why might you NOT observe a tradeoff between two life-history traits?

I have traditionally thought of and heard about life-history traits (e.g., size at first reproduction, number of offspring, size of offspring, survival, etc., etc.) as drawing from a finite pool of ...
3
votes
1answer
104 views

Can cats use ketone bodies as only source of energy?

I recall reading that much of the energy a cat produces from its food comes from proteins which I assume would produce energy via being catabolised into amino acids which in turn, if glucogenic, would ...
5
votes
2answers
119 views

There are linear and rotary molecular motors in the cells. Do any of them have a fixed or stable frequency or speed?

Are there any linear, rotary or oscillatory molecular motors in the cells which can have fixed frequeny and which can be used as a reference for elapsed time timer? This question is with relevence to ...
2
votes
1answer
107 views

How Do Acid and Base Loving Plants Get Enough PO4?

Acidic and Basic soils experience phosphate sequestration through binding with either calcium, aluminum, or iron. How do plant that thrive in acidic and basic soils obtain the necessary phosphate? ...
3
votes
0answers
121 views

What's the Mechanism of Paradoxical Excitatory Effects with Sedating Antihistamines? [closed]

I've been reading the British National Formulary 65 (BNF-65) and it mentioned that in some, especially at higher dosages, sedating (first-generation) antihistamines, can produce paradoxical excitatory ...
2
votes
2answers
2k views

Which hormones can cross the blood brain barrier?

Can hormones such as testosterone, aldosterone and estrogen cross the blood brain barrier? I looked on Wikipedia and there no mention of it in the testosterone article. Through Googling around I also ...
1
vote
1answer
433 views

Number of introns in a genome

Humans have approximately 21000 genes but they probably make more proteins than that. This has been explained by many mechanisms like alternative RNA splicing. My question is - If what we call as ...
0
votes
2answers
61 views

3 fates of this matter

When an animal eats something, it obtains matter and energy right? But, what are the 3 possible fates of the matter and 3 possible fates energy. I don't understand what they are even asking. What ...
5
votes
1answer
267 views

Variations in Genome Sizes

Why is there wide variation in genome size amongst groups of protists, insects, amphibians and plants, but less variation within groups of mammals and reptiles?
1
vote
2answers
45 views

Why don't raisins lose water when in air?

It is common that we soak raisins in water, and they acquire water by endosmosis. That means that the cells are permeable to water, right? Then why don't they lose water when kept in air? Or kept in ...
6
votes
2answers
2k views

What did we learn with Nazi human experimentation?

Was there actually any useful knowledge gained from the Nazi experiments on human test subjects? Wikipedia cites freezing and phosphine gas reactions, but I would like to know other potential results ...
2
votes
1answer
42 views

Variation in MHC in humans

What evolutionary process lead to so much variation in MHC? What is the advantage of having such variation?
6
votes
1answer
184 views

Why does radiation sickness cause hair to fall out?

As I understand it, radiation poisoning (acute radiation syndrome) is fatal because the radiation kills cells. However, why do victims experience hair loss at such an early stage in the process?
1
vote
1answer
314 views

Calcium for Humans: Supplements vs Fortified Sources

I am intolerant to meat and milk products, but purely natural foods don't contain enough calcium for the Recommended Daily Intake. Links 2 to 4 (but NOT 1) avouch a correlation between calcium ...
-1
votes
4answers
318 views

Does evolution take place universally?

Why does evolution (namely the evolution of primates into humans) take place both uniformly and universally on the earth? Why aren't there any creatures who have not taken the same evolutionary steps ...
2
votes
2answers
134 views

How did viruses learn to utilize the workings of a cell?

This is my first post here, so excuse me for its simplicity. Viruses can infiltrate a cell, overtake it and multiply. It has projecting fibers whose ends are shaped as kind of a "key" to a mobile ...
0
votes
1answer
1k views

Female preference for males who are already in a relationship [closed]

A common saying is that women are generally more attracted towards men who are already in a relationship, and this phenomena does seem to have its own place in popular culture that is not matched by a ...
2
votes
1answer
37 views

How do processes of one osteocyte establish contact with processes of the adjacent cells within the mineralized matrix?

Are the processes and canaliculi formed and contacts established after the osteocytes are embeded in the matrix or are they formed during the embedding process itself. Is there any evidence to suggest ...
3
votes
1answer
55 views

Number of MHCs in neurons

I have read that neurons have proportionately less MHC molecules than other cells of the body. What is the advantage of this?
1
vote
1answer
202 views

Expression of plasmid genes

Are plasmid genes always expressed? If so, then isn't a bacterium wasting it's resources in expressing genes (like antibiotic resistance) which are not required in "normal" conditions? If not, then ...
2
votes
1answer
46 views

How essential is vitamin B3 to the diet?

I know this might seem contradictory since by definition a vitamin is an essential part of the diet but I have read that nicotinamide, a form of vitamin B3, can be synthesised from L-tryptophan. Is it ...
1
vote
0answers
16 views

histamine inter-cellular and cytoplasmic binding site

I noticed that HRH (histamine receptor) has an inter-cellular and cytoplasmic binding site of anti-histamines which are equal in binding energy. Does anyone know what is the function of the well ...
2
votes
2answers
187 views

Accuracy of a particular genetics test

I am a newbie in biology and I am simply trying to discover the field of genomics. Consider the question - Are genetic tests accurate? I don't believe they are as the genes may not provide the ...
1
vote
2answers
2k views

Are mature RBCs prokaryotic?

Mature mammalian RBCs have all the characteristics of a eukaryotic cell except that they don't have a nucleus, they don't have any cell organelles. Does this mean that RBCs are classified as ...
7
votes
1answer
586 views

How to reduce/eliminate cell clumping in suspension CHO cells, without using an anti clumping agent?

what is the best way to eliminate clumping suspension cells used for transfection. Anti clumping agents interfere transfection and hence can't be used. Though maintaining the cell density low helps, ...
7
votes
2answers
3k views

What evolutionary adaptations cause trees to grow tall?

I think there are some obvious costs for trees to grow tall. Carbon and other nutrients costs, maintenance cost, energy cost (for growing, to bring water (and nutrients) up to the higher leaves, ...
9
votes
3answers
153 views

Which part of the brain needs to be shut down to lose conciousness?

Whether it is mechanical (trauma), chemical (anaesthesia) or electrical - which part of the brain is shut down to cause loss of consciousness?
1
vote
1answer
60 views

Adaptability in immune system

I read somewhere that recently some people are trying to use harmless bacteria that live symbiotically in humans to express some portions of antigens of the harmful ones. Some people have raised ...

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