All Questions

6
votes
2answers
18k views

What is the function of the RNA primer in DNA replication?

During DNA replication, RNA primase puts an RNA primer in the lagging strand. What is the function of this RNA primer? Why can't the enzymes put DNA fragments directly?
3
votes
2answers
644 views

Does finite rate of increase depend on mortality of individuals in a population?

As written in my lecture handouts, there two main factors in the Geometric Growth Model of populations: $R_{0}$ is the expected lifetime reproductive output. This way, for unicellulars, for example, ...
6
votes
1answer
459 views

What happens to an ant colony when the queen dies?

Does the colony collapse? Do workers keep following the last orders? Or can future queens replace the dead one? I'm guessing this might also depend on each specific sub-species.
2
votes
1answer
113 views

What kind of mushroom(?) is this?

I found groups of these growing in the Lassen National Forest (Susanville, CA, USA). It looks like some sort of mushroom. I have Googled extensively, but can't seem to find a match.
2
votes
0answers
52 views

Why do conker flowers grow upwards?

Most trees I know that have their flowers in groups hang these groups down. I noticed, however, that conker flowers grow upwards! I guess that growing against gravity requires special effort, so ...
3
votes
1answer
1k views

How do liver and lung metastases cause death?

Metastasis to the liver and lungs are the main causes of death in colorectal cancer.(1) I understand that colorectal cancer may have metastases. But how do these metastases cause death? Reference ...
6
votes
1answer
122 views

Why does getting certain chemicals in cuts hurt?

More specifically, shampoo. What are the mechanics of detecting a noxious chemical stimulus in terms of which receptors recognise what, how do they do it, and how is this information relayed to the ...
1
vote
0answers
42 views

To what extent is immature eggs in insects (beetles) a good approximation for maximum fecundity?

To what extent is the number of immature eggs from dissected, newly emerged individuals a reasonable approximation for maximum/potential fecundity in insects (more specifically beetles)? I know that ...
1
vote
0answers
33 views

Are there precedents for considering that the coral reef biome has higher biodiversity than rain forests?

I've found conflicting references on which biomes are the most biodiverse ones. Also, which are the measures of biodiversity? Average number of different species per volume?
8
votes
2answers
105 views

Where can I find historical data on world-wide ecology parameters?

I hope this is the right StackExchange forum for such a question. I'm looking for large data sets on world-wide ecology parameters, such as annual temperatures by latitude, annual rainfall, CO₂ and ...
5
votes
2answers
288 views

What medical and commercial proteins are made using genetically modified animals?

Recombinant technologies in micro-organisms being used to produce commercial and medically useful proteins like insulin are fairly common. However some proteins are still produced commercially in ...
1
vote
0answers
58 views

Are there any examples where 'magic bullet' drugs have worked?

Magic bullets are drugs that can be administered on a micro local scale near the tumour by exploiting the different surface antigens that cancers expose. The drug attaches via an mAb (attached to the ...
5
votes
1answer
232 views

Experimental evidence for the selfish gene vs. the selfish individual

In the Selfish Gene, Dawkins makes the argument that a better view of evolution (i.e. more in accordance with experiment) is obtained if you view the basic unit of evolution to be the gene rather ...
7
votes
4answers
297 views

Can sexual reproduction create new genetic information?

Is there a small chance that in sexual reproduction a new allele forms in the off-spring that was not present in either of the parents, or are the alleles in the offspring always from at least one of ...
1
vote
1answer
31 views

cell uptake prediction

I'm generating random molecules I would like to know if they are able to pass through the cell membrane. Are there any ways (preferably computational) to predict cellular uptake of an organic molecule ...
9
votes
2answers
379 views

Is there any recent evidence for the aquatic ape theory of human evolution?

aquatic ape theory suggests that many features that distinguish humans from their nearest evolutionary relatives emerged because the ancestors of humans underwent a period when they were adapting to ...
7
votes
1answer
199 views

Why are some menstrual cycles irregular?

A friend of mine asked me this today, and I didn't know. I remember studying the menstrual cycle a few years ago, but I can't remember the details (other than it was very hormone-related), and so I ...
2
votes
2answers
804 views

What is in the space between neurons in a brain?

When neuron animations are displayed, there are frequently seen neurons, axons arranged in a lattice with a lot of empty space between. I'm interested if there is indeed empty space in the brain, or ...
1
vote
0answers
156 views

Does brain activity generate heat gradients in the brain?

I'm reading this article on guiding axon growth using temperature gradient, and it mentions that the trajectory of growth of neuron connections can be influenced by temperature gradients as little as ...
4
votes
1answer
503 views

How do I view the simulated protein structure along with ligand in VMD?

I did a simulation of a protein-ligand complex, and it has stabilized after 5 ns. I have got the respective pdb files for every ns, but when I try to view in VMD (Visual Molecular Dynamics), I cannot ...
1
vote
1answer
40 views

In vitro enzyme production

I need to express a protein in vitro but I don't know where to start. I will likely do a T7 transcription protocol but for translation I am not sure what to do. Are there any good kits?
2
votes
1answer
707 views

Do male marsupials have a pouch?

Do male marsupials have a pouch, or is it a female organ only (like the womb)?
2
votes
1answer
157 views

What is this marmot-like animal (Tigray, Ethiopia)?

I was searching what are the animals I frequently saw in the north of Ethiopia. I took some bad quality pictures. For me it looked like a large squirrel, local people called it a rat, and on the ...
5
votes
1answer
162 views

What effect do oligosaccharides, like those found in legumes, have on the composition of intestinal flora in humans and if so how so?

I know that intestinal flora metabolising oligosaccharides, like those found in legumes, is the cause for the well known fact that legumes cause flatulence, but does an oligosaccharide-rich intestine ...
1
vote
3answers
202 views

Has medical progress stopped human evolution?

We can cure many diseases nowadays, and thus the natural selection is very limited. Plus, mankind spent the whole beginning of its existence in almost the same hostile environment, and that's where he ...
0
votes
1answer
33 views

First genomic survey of human skin fungal diversity

"The researchers found that a single type of fungus, belonging to the genus Malassezia, is predominant on the head and trunk. Hands, which harbor a great diversity of bacteria, are home for relatively ...
2
votes
1answer
49 views

What does “rapamycin-sensitive oncogenic transformation” mean?

Can someone explain exactly what "rapamycin-sensitive oncogenic transformation" is? I get that it's a drug that suppresses the immune system but what does it have to do with oncogenic transformation? ...
4
votes
1answer
127 views

Is Active Transport Required For Life?

Is active transport required for all living cells to function? I was under the impression that if a cell doesn't have active transport, it either would lose molecules through the membrane and not be ...
6
votes
2answers
256 views

Intrinsic apoptosis in erythrocytes

With a lack of mitochondria, can red blood cells perform intrinsic apoptosis and do they have another way of generating cytochrome c to attach to a CARD domain and assemble the apoptosome? Or are ...
3
votes
2answers
187 views

How does the immune system distinguish own and foreign antibodies?

Therapeutic antibodies, for example Rituximab which recognises CD20 on B lymphoma cells, can cause adverse effects (e.g. http://www.ncbi.nlm.nih.gov/pubmed/19399690) One reason behind these adverse ...
2
votes
2answers
380 views

Why is a slow worm not considered a snake?

Slow worms are considered lizards as opposed to snakes, both are reptiles. Now I get that there are traits that distinguish them (eye lids, ears ...). But snake species themselves vary already quite a ...
6
votes
1answer
529 views

Cat purring: What are some possible underlying mechanisms behind purring and bone remodeling and formation?

http://www.scientificamerican.com/article.cfm?id=why-do-cats-purr The article above says that cats purr mostly when they're wounded or under duress. They hypothesis that cats purring leads to ...
1
vote
1answer
103 views

copper spiral birth control not toxic?

I Always thought that copper was toxic to the human body. So how can it be safe to place a copper object (birth control spiral) into a uterus for a duration of 5 years?
0
votes
1answer
161 views

Excretion and metabolic waste?

I know there is a difference between digestive and metabolic waste, but which one is called excretion? And what's the other one called? Thanks!
5
votes
1answer
370 views

What could account for an apparent loss of mass at death?

An interesting tidbit floating around the internet these days is that Dr. Duncan MacDougall apparently weighed people shortly before and after death, and found an average of a 21 gram discrepancy, to ...
10
votes
3answers
2k views

DNA synthesis companies: cost per base, turn-around time, codon-optimization algorithms

I would like to synthesize a 3.4kb gene (originally isolated from soil bacteria) and transform it into E. coli. There are several companies (DNA2.0, GeneScript, BlueHeron) which will synthesize the ...
0
votes
1answer
52 views

What's food mode?

I've been watching a The Crocodile Hunter episode about Komodo dragons, and Steve Irwing kept speaking about the animals being in "food mode", in which they apparently change their behavior to one of ...
2
votes
1answer
39 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
45 views

Can stress echocardiography show coronary blood flow difference before and after exercise?

Stress echocardiography means a pair of cardiac ultrasound imaging examinations, before and after exercise. I assume that coronary blood flow is increased after exercise. Is cardiac ultrasound ...
1
vote
0answers
179 views

What mammalian cell lines are easiest to grow and transfect?

I'm working with HEK293 cells, which are very easy to transfect. Does anyone have other suggestions for cell lines with very high transfection efficiency? Ideally the chromosomes would also be diploid ...
1
vote
0answers
54 views

Reverse complement of reconstruction model for assembling reads

One way to assemble fragments produced by DNA sequencing (often called reads) is to seek for the shortest common superstring that contains all the reads of a given set of reads. One model for this ...
1
vote
1answer
34 views

Transplantation of stem cells

During the autologous transplantation of stems cells from bone marrow to produce new blood cells why all the other stem cells other than the one obtained are destroyed?
3
votes
1answer
44 views

Immunity during pregnancy

I have learnt that our immune system distinguishes self from non-self by using MHC. So a mother during pregnancy should also develop antibodies against the fetus as it is also a genetically different ...
1
vote
3answers
343 views

Diffusion across cell membranes

I got this question and don't really understand the difference between the answers. Diffusion is (in cell membrane): a) passive by nature, no metabolic energy is needed b) driven process by ...
1
vote
0answers
36 views

Hippocampal regulation of hypothalamus

What is the difference between CA1-CA4 hippocampal subfields and dentate gyrus (DG) in negative regulation of hypothalamus? I`ve found only evidence that GR expression is more in CA1-2 and DG, while ...
3
votes
3answers
982 views

Knockdown of long noncoding RNA (lncRNA) - how is it done?

I don't work at the wet lab and don't know all the details about the knockdown techniques. My question is: How lncRNA knockdown is done? For example - you have lncRNA that is functional in the ...
2
votes
0answers
49 views

How to use mechanical microstrainer to extract tissue proteins from human?

Background: There are many methods to extract proteins form human tissues out there. The majority of them use an extraction buffer containing variable concentrations of detergents and protease ...
5
votes
3answers
294 views

Tool for nucleotide alignment with all nucleotide codes (e.g. R, Y, W, S, etc.)?

I have a vector sequence and would like to find the following nucleotide sequence in it. AASYWSRA This query sequence uses several degenerate symbols, defined ...
1
vote
1answer
2k views

How difficult is to renature a protein?

I know of Anfinsen's experiments and I'm aware that some denatured enzymes may regain their lost activity through the removal of the denaturant agent. What I'm unaware of is how rare is it for a ...
1
vote
1answer
58 views

What is the disadvantage of having no anticoagulation after pulmonary embolism?

Is chronic anticoagulation always given after pulmonary embolism? What are the risks or disadvantages if anticoagulation is not given? if terminated early?

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