2
votes
1answer
60 views

Is it more likely to develop a throat-ache at night?

I have noticed that I rarely develop phlemmy throat-aches in the daytime, but often notice them after I have been sleeping. Is this a recognised phenomenon? Could it be because viruses or bacteria ...
5
votes
3answers
125 views

Does the entire surface of the earth contain organisms?

Does the entire surface of the earth contain organisms? My teacher mentioned that in some parts of the earth, there aren't any organism. Is this true? Thanks in advance.
2
votes
0answers
51 views

Do humans have chemosensors for nutrients or chemicals?

I'm reading about chemoreceptors on Wikipedia, and see that the typical ones are mentioned: taste, smell, co2. I would like to learn more about the other kinds of chemoreceptors that humans may ...
8
votes
1answer
188 views

Do antigens protrude through the capsule/slime layer in prokaryotic organisms where these features are present?

In prokaryotic organisms that have a slime layer or capsule, do intrinsic/extrinsic proteins and other molecules that could be used as antigens protrude through the capsule? I assume that they ...
7
votes
1answer
3k views

Why is Hydrofluoric Acid so dangerous if its a weak acid?

I've read that Hydrofluoric acid (HF) is extremely dangerous to touch, but what exactly makes it so toxic? It's weak acid ($K_a = 7.2 \times 10^{–4}$) and dissociates approximately 1/1000 as much as ...
3
votes
1answer
314 views

Troubleshooting bioconjugates migration in a SDS-PAGE gel?

We do a lot of bioconjugation chemistry (click chemistry in particular but also NHS and Maleimide chemistries). Our method to valid the conjugation reactions have been to use SDS-PAGE gels followed ...
7
votes
1answer
959 views

How does a single-stranded RNA bind to a double-stranded DNA to form a “triplex structure”?

If you have a single-stranded RNA that is complementary to a double-stranded DNA, how do they interact to form what my prof. calls a "triplex structure"? e.g. ...
1
vote
1answer
61 views

In a human, what non-germline cells have the highest/lowest mass?

I'm just curious which cells are largest/smallest in the human body other than sperm/ova.
5
votes
1answer
722 views

How do neurons form new connections in brain plasticity?

I've been reading about brain plasticity and how the brain can "rewire" itself. One of the things that is not clear to me - how neurons can establish new connections. Does this rewiring mean that ...
8
votes
1answer
177 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
347 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
185 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
312 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
593 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
450 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
76 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
940 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
553 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
308 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
904 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
313 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
566 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
517 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 ...

15 30 50 per page