5
votes
2answers
4k 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
297 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
143 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 ??
3
votes
2answers
221 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
447 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 ...
4
votes
2answers
694 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
190 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
302 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
124 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
142 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 ...
7
votes
3answers
139 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
222 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 ...
2
votes
1answer
1k 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
84 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
0answers
78 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
110 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
96 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
88 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
327 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
50 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
240 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
44 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 ...
1
vote
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
150 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?
0
votes
1answer
228 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 ...
-2
votes
4answers
264 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
116 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 ...
-1
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
29 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
53 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
167 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
43 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
173 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
1k 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
371 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, ...
6
votes
3answers
2k 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, ...
8
votes
3answers
143 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
52 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 ...
6
votes
1answer
1k views

Why does the heart use lipids (and not glucose)?

Fetal hearts use glucose as their primary metabolic substrate. Adult hearts use free fatty acids, which are less efficient (require more $O_2$ to synthesize the same amount of ATP); however, during ...
3
votes
0answers
279 views

Virus titre and copy number of integration

If I need to preform a genome-wide high throughput screen using pooled shRNA library infection followed by deconvolution by deep sequencing, how would I determine the optimal infection rate at which ...
1
vote
0answers
60 views

Why is a nicotinamide-tryptophan combination used to treat affective episodes in a few older clinical trials?

At least one of the journal articles that reported on such clinical trials allured to the nicotinamide-tryptophan pathway that I assume must be related to the metabolism of tryptophan into serotonin ...
4
votes
1answer
153 views

Are the brains of any herbivorous animals capable of utilising ketone bodies as an energy source?

I ask this question because earlier today I heard from a lecturer at my university that a sheep's brain cannot utilise ketone bodies as an energy source and hence with insufficient glucose supply for ...
2
votes
1answer
517 views

Molecular Evolution: Mrbayes never stops?

When I use my own data to build Bayesian phylogenetic trees using the software Mrbayes, after many generations, it never reaches stopping status (namely, the average standard deviation of split ...
0
votes
2answers
156 views

Introductory biology text for an outsider

I'm a maths major and I have an interest in learning biology. I know very, very little; I know how babies are made and that's about it. Could anyone recommend a stimulating text to read for it's own ...
1
vote
1answer
249 views

L1 - L5 layers of the brain

I have read in some papers about the layers L1-L5 of the brain (e.g. in this paper). I could not find a definition of these layers. I have found information about the layers V1-V5 in the visual ...

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