1
vote
1answer
525 views

What is the advantage of circular genomes for bacteria and linear genomes for other organisms?

Bacterial are a great group of organisms. They have circular genomes and never went toward linear genomes while other organisms show the opposite strategy and don't have circular genomes (disregarding ...
3
votes
1answer
184 views

Does an allergic reaction kill body cells?

I have wondered what actually happens in an allergic reaction that causes the symptoms such as pain, rash etc. Is it possible that the human body actually kills its own cells in the process?
4
votes
2answers
2k views

Simple diffusion of lipid-soluble molecules through phospholipid bilayer — does anything get “stuck” in transit?

It's a pretty elementary concept, and when I first learned of it I don't think I had the foundations to even think of such a question, but I found myself the other day thinking about the amphipathic ...
6
votes
2answers
846 views

Why is absorbance at 280 nm for protein solution going up when I measure repeatedly?

I have been measuring my protein solutions' concentrations by diluting them in water 20 fold with a final volume of 100 uL and then measuring the absorbances of these solutions in 96 well plates with ...
1
vote
1answer
1k views

Molecular cause of cramps, spasms and strengthening in muscles? (incl. intro to muscle contraction)

When motor neurons are stimulated to trigger an action potential, this potential propagates down the spine, eventually reaching a neuromuscular junction, causing the release of acetylcholine (ACh). ...
3
votes
2answers
627 views

What are gram negative and positive bacteria?

I've just finished a course of double antibiotics for Helicobacter pylori in my stomach. I looked up H. pylori and found that it was a gram-negative bacterium. I looked up gram-negative and didn't ...
2
votes
1answer
42 views

Range of feasible coefficients in an unlimited growth model

If you are given an unlimited growth model in the form: $\frac {dP(t)}{dt} = k P(t)$ Obviously the population growth would never be unlimited, but let's presume for the moment that we are ...
2
votes
2answers
239 views

How do bats distinguish between day and night?

How do bats distinguish between day and night? Do they hunt at night - if yes, how they know that? Are they afraid of sunlight?
-2
votes
3answers
157 views

A question regarding evolution

I'm not a biologist so bear with me. I know that the DNA molecule carries extremely large amounts of information. If the process of evolution is driven by completely random process .I think about it ...
2
votes
1answer
80 views

What is the mechanism behind ventilatory acclimatization?

In my respiratory physiology lectures, my professor explained that hypoxia-induced hyperventilation occurs in 2 stages when people try to acclimate at high altitudes. My question is about the ...
2
votes
0answers
67 views

Why did animals evolve genders? [duplicate]

The majority of animals have two genders, and both are needed in reproduction. It seems like it would be more advantageous for creatures to be hermaphrodites, since they could mate with any member of ...
1
vote
1answer
205 views

What is the biochemical reason for mental fatigue?

Is it known exactly why the brain needs sleep? What's dropping low / going high when we experience mental fatigue? I can see why low glucose could result in mental fatigue, are other reasons known?
6
votes
1answer
336 views

Excretion of small kangaroos while in the pouch

How is the excretion of small kangaroos done when they are in the pouch of their mother, fastened onto her teat? My question is what happens with the products; do they accumulate in the pouch?
4
votes
2answers
257 views

Question about equilibrium potential formula

My biology book says, that the equilibrium potential for an ion with a charge of +1 is: $$E_{ion}= 62mV \biggl(\log\frac{[ion]_{outside}}{[ion]_{inside}}\biggr)$$ Where does the 62 mV come from? How ...
1
vote
0answers
20 views

Which classes of drugs (filed by their pharmacology) induce a release of β-endorphin?

Which classes of drugs (filed by their binding sites) induce a release of β-endorphin? I know of agonists of the nAChRs and 5-HT1A and ethanol. Are there any others? Please cite journal articles ...
1
vote
0answers
395 views

How do Opioids Stimulate a Histamine Release?

Histamine is a neurotransmitter that also has peripheral functions such as the regulation of gastric acid secretions, allergic responses, etc. I know that opioids stimulate a release of histamine but ...
6
votes
2answers
210 views

What kind of bird species is this?

Every now and then I got a glimpse of this bird which I'm pretty sure is not native to Northern Germany where I live. There are at least three of these birds around but I usually only see something ...
1
vote
1answer
586 views

What is Chronic immobilization stress (CIS)?

I am trying to self study BNDF a little bit when I found this article: Abstract Stress impacts multiple systems within the CNS, including the hippocampus. A key molecular mediator in hippocampal ...
0
votes
2answers
48 views

Manipulating Gut flora in vivo

I am tasked with designing an in vivo experiment in humans that requires manipulating the gut flora in one sample group to gauge its effect. Please suggest ways of doing this besides administering ...
3
votes
0answers
34 views

Do sulfate reducing bacteria help during the formation of the mineral dolomite in low temperature environments?

Do sulfate reducing bacteria help during the formation of the mineral dolomite in low temperature environments? Wikipedia says The actual role of bacteria in the low-temperature formation of ...
1
vote
1answer
131 views

How do circulating androgens contribute to higher rates of hirsuteness in some women?

I was reading up on ethnic groups in which the women are naturally more hirsute (such as South Asian women) in the context of evolving standards of beauty. I came across this statement on a forum: ...
2
votes
3answers
3k views

Do cold blooded animals generate any heat?

In explaining energy and work to an 8 year-old I said that all conversion of energy generates heat as a by-product. For example, cars generate heat in their engines and running generates heat in our ...
9
votes
2answers
8k views

What is the difference between SOLiD, 454, and Illumina next-gen sequencing?

I've started teaching myself about next-generation sequencing in preparation for a new job, and I'm wondering what the main differences are between the 454, SOLiD, and Illumina/Solexa machines, in ...
5
votes
1answer
272 views

Why does strenous exercise cause vision of “lights”?

I had a hard climb a week ago. I got so tired then any time I closed my eyes I saw these lights inside my head. I see these lights almost every time that I run fast or some thing like that. What are ...
6
votes
1answer
207 views

How does skin healing work?

I stacked my bike and split my head right open. About three weeks later the scab falls off and the skin is sealed over, like magic! How does it all work? How does the brain know that part of the ...
6
votes
3answers
5k views

What's the difference between a plant and an animal?

Are there some living things where the distinction between plant and animal is blurry or unclear? I wouldn't know where to put something like yeast. I also thought of photosynthesis, but then I ...
4
votes
1answer
1k views

Why is second pKa value of phosphoric acid different across different sources?

Am I missing something very fundamental here for phosphoric acid's second pKa value? I check the Wikipedia page and these are the values: (1) 2.148, (2) 7.198, (3) 12.377 Then I check Sigma-Aldrich ...
4
votes
0answers
85 views

What are the mechanisms that cause bananas to ripen? How is or isn't it related to the banana peel ripening? [closed]

So recently our commercial kitchen got some bunches of bananas with a curious feature. On the inside they were firm and delicious (no jokes, please), on the outside they looked incredibly sickly. ...
9
votes
1answer
168 views

Systems identification in small neural network

When analyzing data from cortex, we often try to understand what each neuron does in terms of its inputs from other neurons - a specific kind of a systems identification strategy. Most current ...
8
votes
1answer
1k views

Can you consider a human as alive, or is it the cells on the body that are alive?

Sorry if this question seems strange, but in the recent time I have been interested in the question of what life is and how you can define life. My question: How long can individual cells live on a ...
9
votes
2answers
828 views

Which sex has higher variance of reproductive rate in modern societies - male or females?

Who has a more varied reproduction rate in modern western societies - men or women? The average rate is the same of course, but I wonder which sex have higher variance - higher variance means that ...
5
votes
1answer
2k views

How does formaldehyde cause protein-DNA crosslinking?

How does formaldehyde cause protein-DNA crosslinking? I would guess it's because the strongly polar water molecule interacts strongly with polar residues on a protein-DNA complex, and adding a less ...
11
votes
2answers
364 views

Why Do Most Humans & Cats Have Blue/Bluish Eyes At Birth?

I've read that the eye color at birth for most humans and for cats may not always be the the true genetic color at first. This is due to the lack of melanin in the iris. This makes sense as there is ...
2
votes
0answers
41 views

What does effect would Sulforaphane have on Kennedy's Disease?

Sulforaphane is a isothiocyanate found in cruciferous vegetables including broccoli and cauliflower. Its 2D structure is as follows: It's been found to serve as a histone deacetylase 6 (HDAC6) ...
1
vote
1answer
27 views

Do Fatty Acid Synthase Inhibitors Selectively induce Apoptosis in Cancer cells without inducing the same in healthy human cells?

Do Fatty Acid Synthase (FAS) Inhibitors (e.g. cerulenin) selectively induce apoptosis in cancer cells without inducing the same in healthy human cells?
3
votes
2answers
90 views

How common is bacterial mediated transformation? In plants? In animal cells?

The most common method to transform plants is by soaking plant tissue in cultures of agrobacteria (this is not their current classification) which transfer DNA into the plants. Is lateral gene ...
11
votes
4answers
6k views

What nutrients can humans absorb in the mouth?

For instance, I realise being able to absorb simple sugars in the mouth is pivotal in the rapid action of oral glucose gel. Thus I was wondering what nutrients in general can be absorbed directly ...
4
votes
1answer
878 views

What is the average volume of the hippocampus?

I'm trying to find any information on sizes of the hippocampus? Ideally in the average adult male & female brain
9
votes
2answers
2k views

Does Sansevieria trifasciata really absorb Carbon Dioxide at night?

There's a claim that Sansevieria trifasciata (Mother-in-law’s Tongue) generates oxygen from carbon dioxide during the night. This seems surprising to me: that process requires energy; plants generate ...
9
votes
2answers
184 views

Birds placing sticks on train tracks?

I live in a semi-rural area in Germany, close to a park which trains go through every 20 minutes. Today, I saw something that left me perplexed. There is a large population of birds that look like ...
4
votes
1answer
113 views

Why do we yawn?

I've read a new study which suggests that yawning may help you keep a cool head. Also, the findings might hold some hope for sufferers of insomnia, migraines, and even epilepsy. Is there any ...
6
votes
3answers
743 views

Is there any kind of immortality in plants?

I asked a question about immortality of hydra and learned good things about senescence. Now I would like to know about immortality in plants, if there is some kind of immortality in plants and how ...
5
votes
2answers
302 views

How to find Exons in mRNA Computationally

I'm having trouble finding a method to find exons in the original DNA sequence used to create the mRNA, even given the sequence of the mRNA, as I cannot find a way to reliably identify the beginning ...
3
votes
2answers
84 views

Why don't we form immunity to some infections?

I read another question, and its answers, about how vaccines work, but I don't see there, and and don't understand, why some infections can, seemingly, not be immunized against at all. For example, ...
3
votes
1answer
264 views

The fundamental importance of R.E.M. Sleep. (Rapid Eye Movement)

Question: I know that experiments have been conducted to determine the importance of R.E.M. sleep in our sleep cycle. It is particularly important for learning, information synthesis, and recovery ...
2
votes
1answer
147 views

Why do cells have an average 'life span'

I've heard of Henrietta Lacks. As a result of a genetic mutation, her cells never died. I've heard/read that overtime, our cells stop multiplying as much, (as an effect of aging). Why? Why do we age? ...
2
votes
1answer
45 views

What is the point of being selection-free?

I'm reading "Highly efficient endogenous human gene correction using designed zinc finger nucleases" by Urnov et al. They propose a way to use zinc finger proteins for gene therapy. They repeatedly ...
3
votes
1answer
69 views

What accounts for size variation in breeds of dogs?

My assumption is that dogs vary so much in size because of artificial selection pressures coming from human breeders, but are there genetic loci that roughly determine approximate size? Do other ...
3
votes
2answers
251 views

What software is there available for Quantitative structure–activity relationship (QSAR) pharmacological studies?

QSAR modelling in pharmacology basically hangs on using mathematical modelling to approximate the effects different molecules will have on various pharmacological targets. I would like to know what ...
1
vote
1answer
223 views

are female bonobos “always” pregnant?

Given that bonobo chimps are more sexually active then humans, are the females almost always pregnant? if not how not? also are they so sexually active in the wild as well or is it just in captivity? ...

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