2
votes
1answer
24 views

Effect of 260/230 values on PCR

To what extent does the 260/230 value affect the efficiency of PCR reactions ? Do the constituents leading to a low 260/230 value (EDTA, guanidine salts and oligosaccharides) inhibit PCR ? I have been ...
3
votes
1answer
100 views

Integration of several environmental signals

I am looking for examples of different functions that are good fit to how signals are computed in order to respond to the environment. Let's make my question more copmrehensible with an example... ...
4
votes
1answer
50 views

Influence of temperature on transcription, protein binding and decay rates

I am the kind of biologist who doesn't know much about molecular genetics and about the dynamic of biochemical reactions. Question My question concerns the influence of temperature on the dynamic of ...
4
votes
1answer
30 views

Can a single axon propagate multiple simultaneous action potentials?

I have not been able to locate any research that indicates whether a single axon of a neuron or nerve cell can conduct multiple simultaneous (i.e. spatially separate) action potentials. I am aware ...
0
votes
0answers
11 views

Stress-responding enhancer?

I wonder if anyone knows a well characterized human enhancer which has been shown increased activity (in e.g. reporter assays) under stressed conditions, such as DNA damage, hypoxia, ...
1
vote
2answers
41 views

What kind of spider is this? And is it dangerous? (photo)

I found this spider hanging from a web off the side of my house (in Buffalo, NY). It's probably 3-4in total length. Any thoughts on what kind of spider this is? And if it's dangerous?
2
votes
0answers
28 views

Why Hasn't my Cactus Grown Deadly Spines?

I recently purchased a small cactus plant from my local store for about $5. I've been giving the cactus lots of sunlight and a good watering every week. I've noticed that since I bought it, the ...
2
votes
1answer
46 views

Is this a grackle with an unusually long decurved bill (Phoenix AZ, USA)

Can someone help me identify this bird (sorry only had the iphone)? It looks like a grackle, but the bill is much longer than any I have seen. The bill looks like a Le Conte's thrasher, but it was all ...
1
vote
0answers
17 views

Enzyme Assay - pectinase

During assaying an enzyme at high temperature, the substrate (Pectin) is degraded by the high temperature rather than by enzyme, so, how can I minimize degradation of the substrate by the temperature? ...
0
votes
0answers
16 views

Difference in structure of B-cell epitope and T-cell epitope

What is the difference in the structure of B-cell epitope and T cell epitope? Also please enlighten me with the fact of discontinuity or conformation of the b or t cell. Went through a number or ...
3
votes
1answer
29 views

SEREX serological analysis of cDNA expression library

What is Serological Analysis of cDNA expression library? I went through this article:http://cancerimmunity.org/serex/introduction/ but could not really make out. Can someone please explain this to me ...
1
vote
0answers
20 views

Gymnosperm Spores and Seeds

In gymnosperms, what is the difference between spores and seeds? My textbook does not explain it clearly. Are seeds released during reproduction or are the spores released during reproduction? In the ...
1
vote
0answers
34 views

Why are carnivorans more efficient predators than birds or reptiles?

The Wikipedia page on island gigantism says, "Birds and reptiles generally make less efficient large predators than advanced carnivorans. What does it mean for a predator to be "efficient" and why are ...
0
votes
1answer
11 views

what is the function of satellite in a chromosome?

What is the specific function of a satellite in a chromosome ? How are sat-chromosomes different from others ? On molecular basis, what are the functional advantages of it ?
0
votes
0answers
26 views

Why aren't whales more wary of boats?

Whales of many species were hunted to near extinction in human memory, and in whale memory too. I'd imagine that some whales took no notice of boats, and others tended to avoid them, so that hunting ...
4
votes
1answer
42 views

Why do I see so many handicapped dorbeetles?

Living in southern Germany, I often visit nearby forests and pastures. From early spring to autumn, I frequently see lots of dorbeetles on my wanderings. An estimated amount of 50% of those bugs seem ...
5
votes
1answer
132 views

Importance of knowing GC Content of an organism

I was looking at the GC content percentages of few organisms. I also know calculating the GC content percentage. But, what I want to know is, what information would we get., let us suppose if human ...
3
votes
1answer
23 views

What is meant by drug tolerance?

What is meant by drug tolerance? This question is in my biology textbook for IGCSE and I have no idea what drug tolerance is. It would be very helpful if someone could clarify. Thank you.
37
votes
1answer
4k views

Do bacteria die of old age?

I know that the cells of mammals at least stop dividing when they are old, and then die a programmed cell death. Then other cells have to replace them. But in a bacterial colony, each cell ...
0
votes
3answers
78 views

Conscious evolution

Does intelligence play a vital role in the evolution of an organism? In other words does an expansion of learning capacity increase the odds of evolution for the particular biological entity?
1
vote
1answer
26 views

DNA Fingerprint

I recently came across an article indicating that the half life of DNA in the most ideal situations is 521 years (http://www.nature.com/news/dna-has-a-521-year-half-life-1.11555). However, since ...
2
votes
1answer
25 views

Do river sharks (genus Glyphis) have reduced rectal glands for salt removal?

Do river sharks of the genus Glyphis have reduced or absent rectal glands for salt removal?   The rectal gland of marine sharks removes excess salts to maintain osmotic balance (Oguri 1964).  In ...
4
votes
1answer
46 views

How efficient is the human body at metabolizing food?

My friend and I were having a discussion over how "efficient" human digestion is. If a human ate a 1000 calorie hamburger, how many of those calories (how much energy) does the body process into ...
3
votes
2answers
133 views

Definition of “Effective population size”

Could you explain to me, what is the meaning of "Effective population size ($N_e$)"? I would appreciate an example as well.
0
votes
1answer
21 views

Chromatids in metaphase?

Please see the following picture: In my book, the author claims that these chromosomes are in metaphase (a metaphase stopped by cholchicin). I don't understand why they don't have two ...
0
votes
0answers
9 views

Switch gut microbiota due to diet and effect on calorie uptake

I have seen peer-reviewed papers mentioning the daily changes in gut microbiota composition according to dietary changes. See for example this paper: http://genomebiology.com/2014/15/7/R89 My ...
1
vote
2answers
54 views

Is there a medical condition in which you can't cut your hair?

Just curious, does there exist a medical condition in which a patient is advised not to or simply cannot cut their (head) hair?
0
votes
0answers
37 views

What good is the MinION?

This year, Oxford Nanopore MinION has been shipped to some researchers for testing. The advantage of a table-top sequencer for diagnostics and personalized medicine is obvious. Similarly, research ...
2
votes
1answer
28 views

How does core-conductor model correspond to an actual neuron?

Hi guys, looking at your average neuron, it is very difficult for me to imagine how this could be translated into a core-conductor model On the neuron above, where would be the intracellular ...
1
vote
2answers
42 views

What would cause crows to be attracted to a human body?

On another SE site, there was a comment that told me something about biology that I already know: "A man left murdered in the fields would soon have a flock of crows mobbing his fragrant corpse." ...
1
vote
1answer
65 views

What is the difference between second and third generation sequencing

I am writing the section about history of DNA sequencing in the introduction chapter and after reading quite a few research papers, I am still confused about them. Here I compile some questions to ...
0
votes
1answer
28 views

Why is it that bacteria and fungi cannot develop resistance against essential oils?

I wonder why bacteria and fungi cannot develop resistance and mutate agains essential oils? For example, some fungi get killed by oregano oil. Being not a biologist, I hope my question is not so ...
2
votes
4answers
713 views

Why do we weigh less in the morning?

At first I thought it may be related to physics. You know, in one half of the day, the gravity changes, and the scale shows a different weight than the other. Then at night, gravity intensifies, and ...
2
votes
2answers
199 views

Why does a blood test show ethanol when no alcohol was consumed?

Why would ethanol show up in a blood test if a person had not been drinking alcohol in many years. What are other reasons for showing ethanol?
2
votes
2answers
35 views

What does it mean to perform in vitro experiments with mutant bacteria?

I came across the following sentence while reading the paper: Nanchen, Annik, et al. "Cyclic AMP-dependent catabolite repression is the dominant control mechanism of metabolic fluxes under glucose ...
1
vote
1answer
22 views

Complementarity Determining Regions (CDR)

Complementarity determining regions (CDRs) are part of the variable chains in immunoglobulins (antibodies) and T cell receptors, generated by B-cells and T-cells respectively, where these molecules ...
0
votes
1answer
19 views

Degenerate Alignment Analysis

Can someone please tell me what is Degenerate alignment analysis? Could not find a good article on the internet that could help me understand what it means? (I have not studied biology since last 8 ...
0
votes
0answers
13 views

TAA- Tumor associated antigen

An approach to find Tumor associated antigens is based on transfection of expression library made from cDNA into cells expressing desired MHC haplotypes. Can someone please explain what this line ...
1
vote
1answer
18 views

Microarray probe and target

In a microarray, which one is called a target and which one is the probe? the one that is added later , is that the probe or the one present in the slots of the microarray, that is the probe? (I have ...
1
vote
0answers
9 views

Can the difference in brain-signals between presumptuous thought and considered thought be detected with any existing equipment? [closed]

I am thinking that if we can detect when somebody is being presumptuous we can signal to them that they are and this may reduce mistakes made by humans due to being less than fully cognitive?
0
votes
1answer
30 views

Why do moths not die when they fly into a window?

Sometimes at night when I'm inside with a light on, I can hear (I'm sure) moths fly into the window, and it's so loud I can sometimes hear it over the TV from the other side of the room. Since ...
3
votes
0answers
36 views

How does Natural Selection Shapes Genetic Variation?

Background Importance of the additive genetic variance As stated here, the fundamental theorem of Natural Selection (NS) by Fisher says: The rate of increase in the mean fitness of any organism ...
0
votes
1answer
18 views

Why can't NMR be used on large RNA molecules?

While reading my Molecular Bio textbook, I came across a sentence that stated that NMR cannot be used on large RNA molecules to determine their structure. Why is this? Is it because RNA is single ...
0
votes
0answers
40 views

How does a cell compute/perceive gradients? (And which papers/books have written about this?)

I have heard that a biological cell can perceive the change/gradient of a chemical by integrating/differentiating in some way, i.e. that the cell can do math in some way. I really don't know much ...
5
votes
1answer
46 views

Protein Isolation from mammalian cells

What non-SDS buffer can I use to isolate protein from mammalian cells? The protein is intended for testing electron transport chain complexes.
2
votes
0answers
30 views

Origin of the 260/280 ratio?

This is not a duplicate of all the other 260/280 ratio questions, I already know that DNA is supposed to be 1.8 and RNA is supposed to be 2.0. However, this might be more appropriate for chemistry, ...
2
votes
1answer
25 views

What's the mechanism behind 'losing heat through your extremities'?

I can understand how if you are not circulating enough (warm) blood, by not moving much while in a cold environment, your extremities themselves lose heat, and become cold - but I don't understand how ...
3
votes
2answers
49 views

Is there a difference between any of these terms for proteins: “crystal structure,” “NMR structure,” “solution structure,” and “complex structure”?

My homework wants me to plot all crystal structures determined per year, but when I search on PDB for all structures, many of the articles say "crystal structure," but some say "solution structure" or ...
6
votes
1answer
66 views

What does “Mutational Variance” mean?

Background The concept of mutational variance can be found in many articles including this one for example. The mutational variance of a trait number $i$ can be found in the M-matrix in position ...
0
votes
1answer
24 views

What roles do cyclooxygenase, lipoxygenase, and epoxygenase have in signal transduction?

Besides oxidizing fatty acids to form prostglandins, leukotrienes, and epoxides, what other roles do cyclooxygenase, lipoxygenase, and epoxygenase have in signal transduction?

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