8
votes
1answer
175 views

What are the “stars” we see after a bump on the head?

Sorry if this might appear funny. When I close my eyes for a longer time, and suddenly open it, I see some twinkling white small circles, and when i concentrate on anyone of them it disappears, as ...
3
votes
1answer
346 views

Do adipose cells divide in adults?

I have a dim recollection of having heard that when humans gain weight, adipose cells just get larger, rather than dividing. True?
2
votes
1answer
101 views

Where does an organism store reserves of amino acids?

Where does an organism store reserves of the amino acids it needs to build various proteins it needs -- in the liver ? in the blood ? in every cell ? Thanks
1
vote
2answers
184 views

Do any cells change in size or mass as mammals grow?

That is to say, are there cells that, between infancy and adulthood, get larger? Or is all growth done entirely via cell division? I'm wondering if it is safe to assume that the approximate number ...
0
votes
2answers
310 views

Why do living organisms replicate itself or procreate

Why do living organisms spontaneously replicate itself or "procreate" (my understanding is that it does). From a uni-cellular and micro-organism point of view. Is there some sort of stimulant in the ...
5
votes
1answer
88 views

What is the total number of rounds of cleavage during mammalian embryonic development?

That for frog is 12, but what about mammalian embryos? I cannot find the exact number anywhere.
4
votes
2answers
591 views

Why is Botulinum toxin the most potent poison known?

Botulinum toxin (trade name Botox) inhibits acetylcholine release in neurons and causes botulism, an acute paralytic disease which leads to nerve degeneration and takes a long time to recover. I've ...
18
votes
2answers
2k views

Do gene expression levels necessarily correspond to levels of protein activation?

I have seen a lot of research into molecular mechanisms of diseases/phenotypes use measures of RNA as a 'proxy' for the level of protein available in the cell. Is this actually valid? My problem ...
6
votes
1answer
6k views

Will a bone marrow transplant change one's blood type?

Will a bone marrow transplant change one's blood type? Or is the donor blood type matched with the person before transplant?
1
vote
1answer
84 views

Interpreting SNP-in-gene associations from GWAS studies

For most SNPs identified in GWAS studies, is the underlying assumption that if it is indeed associated with a phenotype (and lets assume its associated because it affects protein function), that you ...
2
votes
3answers
447 views

Is there such thing as “half-life” of dopamine?

If a dopamine is released at T=0 and binds to receptor D2, what determines the time when the concentration of this neurotransmitter bound to the receptor reaches half of the original concentration? In ...
9
votes
2answers
307 views

How is human biological clock modelled in modern science?

Im an engineer by education and i program a lot, so the question sounds weird to people from other disciplines. Im trying to better understand the human biological clock. Yet i do not really know ...
3
votes
1answer
61 views

Nucleotide frequencies in Kimura's two-parameter model

Here's an excerpt about Kimura's two-parameter model from Felsenstein's Inferring Phylogenies: "The model is symmetrical, and one can immediately see that, after enough time has elapsed, it ...
7
votes
2answers
75 views

What is the benefit of near-emptying the bloodstream in the mammalian kidney?

In the normal function of the kidney, the bloodstream is near emptied of fluids as it moves through the glomerulus, in which glomerular filtrate is formed. As it proceeds through the Nephron, a ...
2
votes
1answer
90 views

Have there been any experiments that duplicate chromosome copies from 23*2 to 23*3 or 23*4?

Deinococcus radiodurans is an amazing bacterium with a fantastic survival rate. It can survive to high doses of radiation, in a complete vacuum and in hydrochloric acid. How does this bacterium ...
3
votes
0answers
222 views

Why does vision go blurry after microscope use, and how to prevent it? [closed]

After using a binocular microscope recently for about 20 minutes, my vision went blurry and for an hour or so it was much harder to read small text. This occurs to a (far) lesser extent whenever I use ...
2
votes
1answer
131 views

By What Mechanism can Felines Reverse Diabetes?

To my knowledge house cats (and likely other felines) are the only animal able to go into remission after onset of Type 2 diabetes mellitus. I don't have a reference, this has been by peers in my ...
5
votes
1answer
939 views

High Glucose vs Low Glucose DMEM for Cell Culture

I've noticed that in mammalian cell culture, there are often two types of DMEM available. High Glucose and Low Glucose. Does it matter which type I use for culturing of cells (e.g. Hela or HEK293)? ...
10
votes
1answer
552 views

Could a fetus properly develop in micro/zero-gravity?

I suppose another way of looking at the question is: how important is gravity for the development of mammal fetuses? And if things would go wrong, what sort of things would they be, and what would be ...
6
votes
2answers
107 views

DAM enzyme distances move along the genome

I am fusing a protein with a Dam enzyme (http://en.wikipedia.org/wiki/Dam_(methylase)). The idea is that when the protein binds to the DNA, the Dam enzyme will start methylating nearby GATC sites, ...
4
votes
1answer
307 views

Do effects of caffeine on human body change with habitual use?

I've been reading about homeostatic nature of a lot of neurobiological processes - the brain is trying to maintain a balance by desensitizing receptors, re-uptaking and breaking down ...
8
votes
3answers
2k views

Is it better to take a half dose of paracetamol and a half dose of ibuprofen together rather than a full dose of either?

Recently, I heard on this health-related radio programme that it was better to take a half dose of paracetamol and a half dose of ibuprofen together, rather than the full dose of either one, for acute ...
7
votes
1answer
422 views

When do most mammals mate?

Is one part of the day more prevalent then other when it comes to mammal animals mating? Is there an aggregating study that has been done to see if these living beings in nature mate mostly during day ...
12
votes
1answer
3k views

Why does Penicillin only affect bacterial cell walls

I was quite fascinated by the feature Should Science Pull the Trigger on Antiviral Drugs—That Can Blast the Common Cold? in this month's Wired magazine. They explain that Penicillin is effective at ...
4
votes
0answers
177 views

How do the pharmacodynamics of the NSAIDs differ and are there “resistant” COX phenotypes?

I know that the non-steroidal anti-inflammatory drugs (e.g., aspirin, ibuprofen, naproxen) affect the enzymes cyclooxygenase (types I and II). Is there any difference in the degree to which these ...
4
votes
1answer
902 views

Conversion rate of topical Retinol to Retinoic Acid (Tretinoin)?

I'm wondering if someone out there has more information than me. Retinoids have well known metabolic pathways in vivo, and it's usually something like: ...
3
votes
2answers
93 views

Is there a timeline for the frequency of evolution of any species?

Evolution is traditionally spoken of as an inherited change over generations. Does evolution happen one change at a time - or are there multiple changes occurring between two successive generations? ...
1
vote
0answers
28 views

How could a pure culture be represented by more than one ssu rRNA sequence?

Your lab works on an organism isolated from radioactive waste. However, you show that 3 very similar, but not quite identical, ssu-rRNA sequences can be amplified from the culture even though it is ...
2
votes
2answers
240 views

Do foods with preservatives become less toxic in the gut?

Do foods with preservatives stay digestible for longer in the gut by not rotting as much (producing less toxins)?
1
vote
1answer
312 views

How can the Ames test detect a human carcinogen?

Using the Ames test, we add a mutagen to auxotrophic salmonella with mutations in the histidine pathway and rat liver extract to simulate metabolism. How would we know if the carcinogen is a human ...
4
votes
1answer
165 views

Why do we think chronic inflammation can cause cancer?

Why do we think chronic inflammation can cause cancer? I know the pathway is not fully understood, but what makes scientists believe that inflammation causes cancer?
4
votes
2answers
214 views

Is Homo sapiens the only species capable of prioritization?

Just what the title states--given an absurdly large number of assignments to perform in a limited time-frame we usually attempt to do the most important ones first. Is this ability to define and ...
2
votes
1answer
185 views

What are evolutionary implications of contraception and reduced childhood mortality rates worldwide?

I've heard the following idea this morning: Before the introduction of contraception, humans conceived quite a lot of babies (there was little to do to avoid that), but the population was kept in ...
2
votes
1answer
31 views

What range of dose should be used?

This is a dose-response experiment testing a new cancer drug. the darker line represents cancer cells. what range of dose should be used? I think it's 2-4 because this affects cancer cells only. is ...
7
votes
1answer
198 views

Recombinant protein fraction in E. coli

If a protein is heterologously expressed in E. coli under the T7 promoter, what fraction of the total protein concentration in the cell is the heterologously expressed protein? What could be its ...
2
votes
1answer
117 views

How stable is in vivo whole cell patch clamping?

For a head fixed animal, how stable is the current state-of-the-art whole cell recording from a cortical neuron? The animal's breathing, and heart beat must move the neuron relative to the recording ...
3
votes
1answer
1k views

Is “tonic activity” common for neurons firing in the brain?

I've been reading about Dorsal Raphe Nucleus, a serotonin- rich part of the brain. I noticed mentioning of "tonic activity" - regular pulsing that releases neurotransmitters. On top of this "tone" the ...
2
votes
0answers
97 views

Has anyone ever sucessfully translated xRNA or yRNA?

I've recently been researching the subject of size-expanded nucleobases in alternative genetic sets. Many papers describe the, at least, partial success in replicating xDNA and yDNA, as well as ...
3
votes
2answers
565 views

Difference between mice and rats

What is the actual biological difference between mice and rats? Are they actually the same thing with two different names depending on appearance (are they all mice for instance and we call the larger ...
9
votes
2answers
430 views

Which bacteria have the highest mutation rate?

From my reading on M. tuberculosis, I know that this organism has a pretty high mutation rate due to uncorrected sloppy replication, which leads to a high rate of development of spontaneous resistance ...
4
votes
2answers
513 views

Does the brain and the body use the same energy source (glucose/ATP)?

I've heard that the brain consumes quite a lot of oxygen and energy, compared to the rest of the body. What I'm interested in is if this is the kind of energy and oxygen that the rest of the body ...
6
votes
1answer
142 views

What is the difference between xDNA and yDNA?

Wikipedia states that: xDNA contains expanded bases, in which a benzene ring has been added, which may pair with canon bases, resulting in four possible base-pairs (8 bases:xA-T,xT-A,xC-G,xG-C, 16 ...
7
votes
1answer
60 views

Is there such thing as “meters per calorie” for living organisms?

I'm interested in learning if there's some way of quantifying the organism's metabolic efficiency associated with movement. It seems to me that some organisms would be more efficient than others at ...
5
votes
1answer
152 views

Tuna fish in Baltic sea?

Yesterday my grandmother ate fresh tuna at a friend's party. She swears it was fresh and bought at a local fish-shop. The problem is, that we live in Gdańsk, by the south-eastern side of the Baltic ...
6
votes
1answer
259 views

Determining if a specific proline is cis or trans in the protein?

While peptide bonds usually adopt the trans conformation, peptide bonds to proline can exist in either cis or trans conformation. The isomerization between cis and trans is slow, and has been shown to ...
2
votes
0answers
142 views

Virucides - Herbal and otherwise, for HHV6 type virus or any inner-cell virus

Does anyone know where I can find a reliable list of virucides (not anti-virus) that can be used by humans? This virucide must be able to affect viruses that are already inside the cells. St John's ...
10
votes
2answers
567 views

Are the inverse problems of Systems Biology impossible to solve?

I have heard Sydney Brenner give a talk (see link below) on how the entire program of Systems Biology is suspect because, according to him, a chap named Hadamard showed that inverse problems are ...
7
votes
1answer
205 views

What preceded ATP synthase?

ATP Synthase is ubiquitous throughout life on earth and so most probably evolved within the last universal common ancestor (LUCA) before that lineage diversified into the various kingdoms of life. ...
5
votes
2answers
2k views

Why does milk contained in cartons of milk expand?

In the morning, I went to the fridge to drink some chocolate milk. At night, when I took out the same carton of milk, the packaging seems expanded, like some kind of air is inside. Explain please !
3
votes
1answer
308 views

How was the diversity between ethanol fermentation and lactic acid fermentation evolved?

Quite simply, some organisms metabolize glucose under anaerobic conditions via Glucose->(2) Pyruvic Acid->(2)Ethyl Alcohol. Some organisms, however, metabolize to lactic acid. When did such a process ...

15 30 50 per page