4
votes
1answer
121 views

Does a non-extinct gliding species of bird exist?

According to wikipedia was Archaeopteryx rather glider than capable of active flight. As a hunting strategy it crawl up to a tree (or other high positioned place) and glide from it to a prey. Most of ...
4
votes
2answers
273 views

How many different protein coding genes are in the Human Biome?

There are approximately 20k protein-coding genes found in the human genome. This number is presumably very small when considering all the genomes found in the diverse microbes associated with the ...
4
votes
4answers
2k views

E-value BLAST cut-off

What is the best cut-off for e-value in BLAST? Some say 0.01 ,others 0.0001? Even BLAST tutorials don't give a very clear idea about which cutoff suits which purpose? Could some experts give me a ...
4
votes
1answer
118 views

What Proteins Are Universal To All Life Forms?

According to National Geographic, there are 23 proteins that are common to all life forms: All species in all three domains share 23 universal proteins, though the proteins' DNA ...
4
votes
1answer
445 views

Why Isolated, recombinant plasmid DNA without any restriction is often detected in agarose gel electrophoresis as three DNA bands?

I don't understand why three bands are found without any restriction digest. Please answer me as soon as possible. Thank you
4
votes
1answer
269 views

Is there an antagonistic association between Penicillium and Aspergillus?

Some Aspergillus species appear to like walnuts. My question concerns the association of Penicillium and Aspergillus. No sooner does Aspergillus colonize a walnut (or some other challenging carbon ...
4
votes
1answer
78 views

Blood consumption

Is consumption of blood more "dangerous" compared to meat? There was a news-article about unnatural chemicals found in the blood of mothers. This reminded me about a question I have pondered upon ...
4
votes
2answers
51 views

Could humans choose to establish fibre digesting colonies in our guts?

Humans don't digest fibre, and nor do any animals, but some creatures have micro-organisms (bacteria, I'm guessing) in their gut which digest fibre for them. My question is, could humans take some ...
4
votes
1answer
247 views

how is the plasma membrane repaired after endocytosis?

When the vesicle is swallowed of course the lipid layer internalizes. My question is how will the top segment of membrane will bind back together when that vesicle took the membrane with it inside ...
4
votes
2answers
184 views

Do miRNA and antisense RNA do essentially the same thing?

Don't they both just disrupt RNA so it can't make a protein? If so, then what is the difference between the 2?
4
votes
1answer
1k views

How does a pine cone open?

When a pine cone is wet, it remains closed. However, when it's dry it opens again. From the perspective of physics or biomechanics, what is the mechanism that allows a pine cone to open and close as ...
4
votes
2answers
339 views

Can animals make their own unsaturated fatty acids?

I know that animals can't make poly-unsaturated fatty acids (PUFA) and so require them from dietary sources. For eg.Omega -3 and Omega 6 fatty acids. My questions : Can animals synthesize other ...
4
votes
2answers
489 views

How can CI repressor both activate and repress $P_{RM}$ promoter found in $\lambda$ phage?

I'm reading a paper where the authors constructed a toggle switch that uses bidirectional $P_R/P_{RM}$ promoter found in the $\lambda$ phage. There are 3 binding sites - $O_{R1}$, $O_{R2}$, $O_{R3}$ - ...
4
votes
1answer
873 views

How do I calculate the change in allele frequency in a haploid population under selection?

From this book For simplicity, let us consider a haploid organism and assume that the frequencies of alleles $A_1$ and $A_2$ are given by $x$ and $y=1-x$, respectively. We also assume that the ...
4
votes
1answer
199 views

How do wild animals get rabies?

I can see the chain of spreading disease: Humans usually get rabies from domestic animals, those usually get it from wild animals, wild animals in their turn get from the other wild animals and here ...
4
votes
2answers
74 views

Do swarms show intelligence?

Can you think of collective and swarm behaviors as "intelligence"? Would such a concept apply to a) ant colonies and b) fish swarms?
4
votes
1answer
279 views

Sporophyte and gametophyte

My textbook says that in both groups of seedless plants (vascular plants, non-vascular plants) the gametophyte is a free-living plant, independent of the sporophyte. I don't understand this statement ...
4
votes
1answer
3k views

Under what conditions does the body burn fats, proteins and carbohydrates?

Searching the internet, I have found lots of conflicting information from various fitness sites concerning when the human body burns fats, proteins and carbohydrates. My basic understanding was that ...
4
votes
2answers
392 views

Double mutant analysis with null mutants

My professor was talking about double mutant analysis with null mutants, and how double mutant analysis won't work with hypomorphs. I really don't understand the concept of double mutant analysis. ...
4
votes
1answer
215 views

Stability of helical strands of DNA?

The DNA molecules contain phosphate groups involved in $3'\rightarrow 5'$phosphodiester linkages. These groups, in the bonded state with deoxyribose, contain 1 negative charges ($\ce{3'-PO4^{-}-5'}$). ...
4
votes
2answers
105 views

Transmission of disease from mother to fetus

Can parasite, microbes be passed from mother to fetus through the placenta ? I know some like HIV can be.
4
votes
2answers
123 views

Why don't amino acids get linked in the functional groups of acidic and basic amino acids?

There are 'acidic' and 'basic' amino acids like aspartate and histidine. When protein is synthesized with those amino acids, what ensures that the to-be-assembled amino acids will not bond to the ...
4
votes
2answers
331 views

Are identical twins exactly the same?

http://www.scientificamerican.com/article.cfm?id=identical-twins-genes-are-not-identical According to this article some identical twins show differences with respect to their copy number variants. ...
4
votes
1answer
197 views

Does Blood Loss Shorten Telomeres?

If blood loss necessitates immediate cell division to replace lost cells, does the increase in cell division correlate to shortening of telomeres? Does it further cause the Hayflick Limit to be ...
4
votes
2answers
311 views

Ecomorphs as evolutionary definitions

There have been demonstrations of ecomorphs in different taxa, where each morphology type is associated to a single environment. I know that it happens because special morphological characters ...
4
votes
1answer
77 views

Why don't individuals with sickle cell trait suffer from sickle cell anemia?

Ostensibly, in people with sickle cell trait, half of the hemoglobin in their body would be defective. Is it actually the case that sickle cell hemoglobin is produced in equal amounts? If not, how ...
4
votes
3answers
321 views

How is antibody production stopped?

Once clonal selection is done, B cells would start dividing and producing antibodies. So, after an antigen is eliminated, what stops the division of B cells and antibody production?
4
votes
1answer
145 views

What are some examples of scaling laws in biology?

I've seen that metabolic rate scales logarithmically as function of mass for many animals over an extremely large span of parameters. What other scaling laws exist at the individual level?
4
votes
3answers
157 views

Results of a complete DNA sequencing - are they 100% reusable?

Is that correct that a complete DNA sequencing (the whole genome) need only to be done once (per person)? After that is done, it the complete genome can be stored and once the new genes (and their ...
4
votes
2answers
3k views

How can I resuspend a cell pellet without harming the bacteria?

When using a preculture with Ampicillin in my protein expression, I have to get rid of the preculture medium to avoid carrying over too much beta-lactamases that will destroy the ampicillin in the ...
4
votes
1answer
223 views

What is ear wax?

A human, at some time in life or the other, must clear the auditory canal. This is usually achieved using soft-cotton buds, or such similar device. Where does this wax come from? What purpose does ...
4
votes
1answer
6k views

Does mixing alcoholic drinks really make you more drunk?

There is plenty of anecdotal evidence ("beer after wine and you'll feel fine, wine after beer will make you feel queer") that mixing alcoholic drink types leads to a stronger effect, but I can't find ...
4
votes
1answer
387 views

Why does muscle tissue have relatively constant AMP + ADP + AMP?

I was going over slides of energy expenditure in muscle cells. It mentions that in muscle tissue, the cell's energy charge ([ATP] / [AMP]) is the principle factor controlling glycolytic activity, and ...
4
votes
1answer
832 views

When is the lactase in lactose-free milk active?

Recently we have started suspecting that one of our children has hypolactasia (lactose intolerance), and so accordingly I have had my first exposure to lactose-free dairy- and dairy-like products. In ...
4
votes
1answer
197 views

Why would deers keep crossing a river full of crocodiles while some of them have been killed?

I recently watched a clip on Discovery Channel, where I saw deers crossing a river full of crocodiles, ignoring the fact that some of them would have been killed doing so. What could be an ...
4
votes
1answer
90 views

How would one describe the R-factor in crystallography?

Yes, there is the wikipedia definition, but how would one explain this concept to a non structural biologist?
4
votes
2answers
213 views

Is there a good field methods book that covers terrestrial ecology?

In the past I have used Limnological Analysis by Wetzel and Likens and Methods in Stream Ecology edited by Hauer and Lamberti to develop labs and research methods for courses and projects with an ...
4
votes
2answers
160 views

Is it possible to grow any kind of plant soilless (hydroponics)?

Hydroponics is a subset of hydroculture and is a method of growing plants using mineral nutrient solutions, in water, without soil. [wikipedia] My question is if is it possible to grow any kind of ...
4
votes
1answer
11k views

Pedigree Probability of Autosomal Recessive Trait

Here is a pedigree: The trait is autosomal recessive. The question is: What is the probability that the bottom 2 people (4 and 5) have a child with the trait? I tried doing ...
4
votes
2answers
672 views

What's the advantage of autocrine signalling?

In the antibody-mediated immune response, when the helper T cell gets activated by the costimulus (IL-2 and TNF-α secreted by the APC) which in turn produces IL-2, IL-2 acts in an autocrine manner. ...
4
votes
1answer
46 views

Relationship between toxicity of drugs and negative effects on brain

Are psychoactive drugs with lower lethal doses more neurotoxic (more damaging to the brain)? For example, tetrahydrocannabinol (one of the active components of cannabis) has a much higher lethal dose ...
4
votes
1answer
62 views

Where to find E.coli gene expression data?

I am searching E.coli whole genome expression data with different conditions, any suggestion is appreciated. Condition could be for example different growth temperature, different medias, etc. I have ...
4
votes
1answer
48 views

Do sweat pores change diameter?

In Cholinergic Urticaria, some people believe that the itching which is generally more in winters might be because that the diameter of sweat pores is less due to less activity(less sweat production) ...
4
votes
1answer
78 views

Is there a DNA analogue to ribozymes? [duplicate]

If not, is it impossible for DNA to have enzymatic activity?
4
votes
1answer
73 views

Nomenclature of genes and proteins

With respect to this paper: Identification of Host Proteins Required for HIV Infection Through a Functional Genomic Screen In the abstract, I found names such as Rab6 and Vps35 and TNPO3. So Rab6 ...
4
votes
1answer
82 views

Why does cucumber skin kill ants?

I recently read that cucumber skin is an effective repellent for some ants: Set out cucumber peels or slices in the kitchen or at the ants' point of entry. Many ants have a natural aversion to ...
4
votes
2answers
128 views

How does optogenetics work?

I am aware of the post here 'Optogenetics - How do microbial opsins work?' however it is a bit too technical for me. I am struggling to understand how the neurons can be genetically engineered to ...
4
votes
1answer
278 views

Why AZT is selective towards HIV and doesn't impair human DNA replication?

I've found this article, which is a very old one (from the time when nucleoside analogs where researched as a possible way to prevent replication of virus genetic material, before the HIV epidemics). ...
4
votes
2answers
443 views

What is biological dark matter?

I recently stumbled upon the Biological Dark Matter wiki page. Its pretty light on details, but it appears to be genetic material found in humans that doesn't fall into currently classifications. ...
4
votes
3answers
134 views

Why are the fertility rates of large predators kept low?

Predators at the top of a food chain, like lions, seem to have a relatively low fertility rate, which fits well to the ecosystem and avoids overpredation. But what is the mechanism that keeps the ...

15 30 50 per page