4
votes
0answers
164 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
820 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
92 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
229 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
303 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
160 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
211 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
171 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
178 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
111 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
985 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
92 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
509 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
422 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
421 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
136 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
141 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
242 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
131 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
536 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
191 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
1k 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
297 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 ...
11
votes
1answer
126 views

How would one calculate the availability of nucleotides to an enzyme?

How would one calculate the availability of nucleotides to an enzyme like a polymerase ? I imagine an answer in units like nucleotides per second per enzyme, but I'm also imagining an answer that is ...
2
votes
1answer
221 views

Fossils of intermediate stages?

If Humans are evolve from Monkeys, there must be stages in the evolution process, when it was 1% human and 99% monkey, 2% human and 98% monkey and so on. This is because evolution was a very slow ...
1
vote
3answers
206 views

What difference does it make in the organism's physiology/metabolism whether oxygen binds reversibly or not?

A follow-up to How does hemoglobin-free blood transport oxygen? I'm unsure about the use of physiology/metabolism in the title there. The question in mind is whether this reversible binding makes an ...
8
votes
2answers
3k views

How does sodium in one's diet affect blood pressure?

Due to high blood pressure, my doctor has recommended I go on a low-sodium diet. So, that got me wondering what it is about sodium that drives this recommendation? What does sodium do to a body ...
5
votes
3answers
139 views

Can genetically modified genes jump to bacteria in the eater's intestine?

The Guardian ran an article a while back talking about GM gene's jumping to bacteria in an eater's intestine. Has other research confirmed this phenomenon?
1
vote
0answers
49 views

The relationship between the currents of intracellular and extracellular ions of a cell

In a cell, assume that only sodium, potassium, chloride and calcium ions can cross the membrane and their currents are: $I_{Na}$, $I_{K}$, $I_{Cl}$ and $I_{Ca}$, across the whole membrane. There is ...
2
votes
1answer
57 views

Diet of free-range herbivores

Giving minimal credence to estimates in popular media of the average biomass of insects/arachnids, etc. in an acre of land, it seems that a "free-range" cow (I don't mean to pick on cows) might be ...
6
votes
1answer
287 views

$S_{0.5}$ vs $K_m$ values in enzyme kinetics

What is the difference between $S_{0.5}$ values and $K_m$ values in enzyme kinetics?
8
votes
1answer
200 views

What hair do aquatic mammals have?

I'm reading an essay on the creating of the Mammalia zoological classification (Londa Schiebinger, The American Historical Review, Vol. 98, No. 2 (Apr., 1993), pp. 382-411). It contains the statement ...
1
vote
2answers
213 views

Effect of extracellular molecules on membrane potential

I am reading about the effect of extracellular potassium and chloride on the membrane potential, and now a question has come to my mind about what would happen if we added some molecules that have no ...
4
votes
1answer
184 views

How does hemoglobin-free blood transport oxygen?

Snails... We have some kind of huge garden snails appearing lately (read since the last 10 years or so). Try as one might, it's impossible to avoid them when driving. These snails do not appear to ...
3
votes
1answer
132 views

Statement about Tropical Rainforests

I made a statement about tropical rainforests, and I want to know if it's somewhat true or not: The soil in tropical rainforests is not exceptionally fertile, because it contains few minerals. The ...
2
votes
1answer
47 views

PGC-1β Sod2 limiters/blockers

I'd like to block a percentage of PGC-1β or Sod2 expression. According to the following paper's figure beta-blockers inhibit some expression of PGC-1α. Are there any medicines/chemicals which safely ...
5
votes
1answer
127 views

What selective factors drove the evolution of lactose in lactation?

As far as I can determine, lactose, and the monosaccharide galactose have few biological uses outside of mammalian lactation. It not only required enzymes for its production, but enzymes in offspring ...
6
votes
2answers
142 views

Do omnivore mammals vary food preferences based on dietary needs?

I'm wandering if mammals that can eat many different kinds of food (omnivores) vary their preference for food not only based on the availability, but also based on dietary needs? I'm looking at this ...
2
votes
2answers
105 views

Is there some branch of biology that deals with the entire organism?

I'm reading about various parts of the human body and brain and started to wander if there's a branch of biology that deals with the entire human? I know that there are branches various -biologies, ...
3
votes
1answer
47 views

mutant down but not out

I am interested in a gene which is null lethal but I need to temporary induce diminished capacity. If a cell is homozygous is it possible to induce heterozygous phenotypes or a partial knockout from ...
10
votes
1answer
146 views

Does stress physically age our body?

Going by the assumption that stress eventually triggers a flight/fight response, and the subsequent realization that flight/fight puts the body in a system of readiness to use it's available resources ...
3
votes
2answers
126 views

What is the biological basis for a human's ability to think clearly and be aware while “fighting/competing”?

I'm interested in learning more about the biological systems or hormones or parts of the brain that affect short term (<15 minutes) ability to concentrate attention on the task and be aware of the ...
4
votes
1answer
213 views

What is the molecular basis of hangovers?

Well, most of us have experienced the wonderful feeling of the dreaded hangover. How does it work exactly? I imagine it has something to do with dehydration but what are the underlying mechanisms? ...
9
votes
1answer
222 views

Can cancer grow forever if supplied with unlimited resources?

If somehow a human could give a tumor unlimited resources, would the cancer grow forever? It seems like it would until it gets so large that it physically affects vital organs. Is what would likely ...
1
vote
0answers
50 views

Does Dorsal Raphe Nuclei firing pattern change in response to voluntary breathing?

I'm reading this paper, which discusses how Serotonin may be involved in motor functions of mammals: 5-HT and motor control: a hypothesis . The paper includes the following diagram of the Dorsal ...
4
votes
2answers
58 views

Is there a circadian component to hunger?

I'm wondering what produces the feeling of hunger in humans. Checking Wikipedia revealed that leptin and ghrelin are two hormones involved. I've also read that the digestive system produces its own ...
7
votes
3answers
621 views

Why is it sometimes difficult to resuspend E. coli in P1?

It's a curiosity question. When I'm doing minipreps after pelleting the bacteria sometimes it's very easy to resuspend them in P1 (Qiagen kit), but sometimes they form a rubbery clump that is very ...

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