11
votes
1answer
475 views

How to reduce edge effects in cell-based high-throughput experiments?

In high-throughput experiments where cells are cultured, treated, stained, and imaged in 384-well microplates, I frequently see significant edge effects. For instance, the following plot shows cell ...
5
votes
1answer
98 views

In what ways, if any, does administration of rapamycin *not* mimic calorie restriction?

Numerous sources like this say that rapamycin increases lifespan. And mTOR antagonism appears to be a large part of this (mTOR antagonism also appears to be a large part of calorie restriction's ...
7
votes
1answer
170 views

Protein construct design

I am trying to create some constructs of a certain protein deleting well defined domains (at either terminus) to determine interaction regions with other proteins etc., 3 constructs with varying ...
7
votes
1answer
93 views

obesity risk and single gene polymorphisms

I read a fairly recent meta-analysis of studies into the association between adult obesity and polymorphisms of the FTO gene (Peng et al., 2011). The paper looked at 59 studies and found that "FTO may ...
1
vote
0answers
49 views

SAM and Reverse Complements [closed]

Assume a read aligner (such as e.g. BWA) is fed with a pattern P = GACT. Now, the text that ...
6
votes
1answer
283 views

How similar are Circulating Tumor Cells and Cancer Stem Cells?

Circulating Tumor Cells (CTCs) are linked with metastasis and their presence can be used to indicate the onset of metastatic cancer. Likewise, the Cancer Stem Cell (CSC) hypothesis suggests that ...
28
votes
1answer
2k views

Is the “Great Pacific Garbage Patch” beneficial for marine wildlife?

A study was just released by researchers at Scripps Institute of Oceanography revealing a drastic increase in the amount of plastic adrift in the Pacific Ocean. According to the paper, the amount of ...
22
votes
1answer
348 views

How does a cell know its size?

Cells come in all sorts of sizes. How do they regulate their cell size to the point where similar cell types have a fairly mono-disperse size distribution? Reasked from ...
3
votes
1answer
210 views

Predicting progeny of recessive mutations using recombination

I was asked this question on a test and got it wrong, but I'd like to know how to do it. The answers are shown in the blanks below: You are studying two recessive mutations in the fruit fly D. ...
14
votes
2answers
224 views

Can methylation from DNA get copied to RNA during transcription?

Methylation on gene-body and 3'UTRs if copied to mRNA can potentially regulate post-transcription modifications or expression regulation. But I'm not sure if they are maintained after transcription or ...
13
votes
2answers
244 views

Percentage of genome devoted to regulating gene expression

Recently I've been studying the p53 tumor suppressor gene as a model for regulation of gene expression. It's amazing how many different post-translational modifications are known to regulate p53 ...
7
votes
1answer
70 views

How do nuclear receptors locate each other to form a DNA loop?

Nuclear receptors can influence transcription far up- or downstream from their own binding sites by looping DNA (Rubina et al.; J Mol Bio 2004). I am not sure how exactly the receptors first attach ...
8
votes
1answer
93 views

Why doesn't yearly screening for lung cancer decrease mortality rates?

In a large trial, screening yearly for lung cancer hasn't reduced mortality rates. Why is this? Isn't cancer best treatable when caught early? Is this because lung cancer is hard to treat anyway, ...
8
votes
1answer
3k views

Primary function of the enzyme lipoprotein lipase

I read here and here that the function of lipoprotein lipase is to facilitate fat uptake and storage in adipose tissue. Could anyone provide a slightly more expanded explanation, without going into ...
4
votes
1answer
109 views

What exactly is meant by the expression “differentially expressed”?

As far as I've seen, this expression is almost always used in relation to gene expression profiling. Unfortunately, I have no background in this area. Can someone please explain this in layman terms?
15
votes
2answers
4k views

How do the brain and nerves create electrical pulses?

I have heard that information is sent between the brain and peripheral nerves via electrical pulses or signals, but I don't understand how they create them in the first place.
12
votes
1answer
900 views

Why do neurons die so quickly (relative to other cells) when deprived of oxygen?

This question could be considered a follow-up question to Why is a lack of oxygen fatal to cells?, although the top answer there does not address why damage starts to pop in. The answer says this: ...
11
votes
1answer
764 views

Does bioluminescence occur in humans too?

I read that Japanese researchers have developed very sensitive camera that recorded bioluminescence in humans; is it possible and if so what is the mechanism behind it?
4
votes
0answers
43 views

Determine which gene is in the middle complementation [duplicate]

Possible Duplicate: Crossing mutant strains on minimal media problem I'm studying this problem for my genetics final: My Attempt: The answer for part B is met2 and the answer for part C ...
8
votes
2answers
149 views

Are there any structures in mammals that are used only by males?

There are examples of structures which only serve a purpose in females, but it seems like the opposite could also be true. Are there any structures which exist in both mammalian sexes and only serve a ...
10
votes
2answers
187 views

Did we first have swimming birds or flying birds?

Looking at the swimming birds building nests just across my garden, I suddenly wondered how evolution came to swimming birds and whether flying birds started swimming or whether swimming bird like ...
-5
votes
1answer
219 views

DNA chip contains a complete set of random hexanucleotide (6-mers) probes? (Solve) [closed]

can you tell me how to find solution to this question A DNA chip contains a complete set of random hexanucleotide (6-mers) probes. Out of the 4^6 = 4096 probes, how many will form perfect ...
8
votes
1answer
167 views

Is it plausible that eukaryotic organelles like flagella and cilia are the result of endosymbiosis with spirochetes?

This was a claim by Lynn Margulis explained over at this link. The sense organs of vertebrates have modified cilia: The rods and cone cells of the eye have cilia, and the balance organ in the ...
5
votes
1answer
703 views

The genetic and physiological origins of laughter?

This Wikipedia article defines laughter in many terms, such as... "a visual expression of happiness, or an inward feeling of joy" and "a part of human behavior regulated by the brain, ...
14
votes
3answers
504 views

What is the most difficult feature to explain evolutionarily? [closed]

I wonder what are examples of organs/structures/behaviours/cooperation that evolutionary biologists themselves find most difficult to explain -- to explain how they could appear evolutionarily -- ...
1
vote
0answers
100 views

How to find Dmax (genetics problem) [closed]

My attempt: I'm not sure this is right but this is what i did. I found the allele frequencies to be: A=0.4 B-0.3 a=0.1 b=0.2 I think to find Dmax I just multiply the two alleles with the larges ...
2
votes
0answers
38 views

How much does a human brain's metabolic rate vary? [duplicate]

Possible Duplicate: How does brain energy consumption depend on mental activity? Our brains consume about 20% of our energy when we're at rest. How variable is a human brain's energy ...
5
votes
1answer
582 views

Is it true that newborn babies don't produce tears while crying? Why?

Well, I was just going through an article on eye, where in fun facts it was mentioned that newly born (for initial 1 to 3 months) babies do not produce tear while crying. Actually, I have found this ...
20
votes
1answer
2k views

How long do your eyes need to adapt to darkness and reach full contrast?

I heard you should wait some time until your eyes adapt to darkness and are able to see smallest luminosity differences, otherwise you might overlook faint objects in the ocular. Are there any rules ...
8
votes
1answer
106 views

Why can't we breed watermelons without any remaining seeds in the flesh?

Watermelon is just starting to come in season in the northeastern U.S., and having a seedless watermelon is convenient. The only downside is, the "seedless" almost always still have the immature, ...
8
votes
1answer
198 views

Finding DNA from Amino Acid sequence problem

My attempt: First I took the single letter AA codes and made them amino acids. So, the first one is Trp which is 5'-UGG-3'. From this I got the DNA sequence 3'-CCA-5'. However, the correct ...
15
votes
1answer
356 views

How fast does the rotor in ATP synthase spin?

I'm sure the exact frequency varies, but does anyone know roughly how many revolutions per minute / second the rotating center part makes?
11
votes
3answers
382 views

How did the human brain evolve?

A common question posed is, "how did the eye evolve?", because the eye is so complex. However, this has been answered rather clearly and there are several examples around the world of animals in ...
4
votes
1answer
270 views

Finding exons in DNA problem

My attempt: I looked for the TACs because I thought this would be AUG in mRNA and ultimately Methionine (the start codon). But apparently, that's not how you do this problem. Im confused because ...
6
votes
2answers
621 views

What is the main general difference between Mitosis and Meiosis?

I found such a clause: The general principle is that mitosis creates somatic cells and meiosis creates germ cells. However, I cannot agree. Each gametogonium needs to go through mitosis before ...
7
votes
1answer
177 views

Why is the Patellar reflex not triggered when the tendon is extended slowly?

I have been previously told that the Patellar reflex (knee-jerk-reaction) exists to prevent the hyper-extension of the patellar tendon. Yet if the impact to the tendon is delivered slowly - i.e. by ...
6
votes
4answers
190 views

Genetic effects on personality

It is said that genes are partly responsible for the choices we make in our life; our genes help to create our environment, and then that environment can influence our personality. So, beside genes, ...
18
votes
1answer
1k views

Why do stars disappear when I look at them?

I've noticed that when I'm out at night stars seem to vanish when I focus on them. I assume the reason is physiological and not astronomic. Why does this happen? I would expect that things would be ...
8
votes
1answer
1k views

Does the use of “var”, “x”, and/or “ssp” in a scientific name provide specific information?

What exactly does it mean when a plant has a scientific name that specifies a vairety, for example Nothofagus solandri var. cliffortioides, or when the name includes an "x", as in Populus ...
6
votes
1answer
354 views

How Do Adherent Cells In Culture Attach To A Plastic Dish?

I am particularly interested in MC3T3-E1 cells (mouse fibroblasts), which are adherent cells. Are hemidesmosomes involved in anchoring the cells to the plastic dish? What (if any) other molecules are ...
0
votes
1answer
79 views

If inhibiting S6 kinase decreases protein translation, then could inhibiting S6 kinase could possibly slow down long-term potentiation in neurons?

From http://en.wikipedia.org/wiki/P70S6_kinase... Phosphorylation of S6 induces protein synthesis at the ribosome. P70S6 kinase is in a signaling pathway that includes mTOR (the mammalian ...
5
votes
1answer
183 views

Why isn't the p16-INK4a gene involved in apoptosis expressed in heart or liver tissues?

New York Times article explains how killing p16-INK4a positive senescent cells can help keep the surrounding cells vigorous. So here's my question: why is p16-INK4a expressed in most cells other than ...
8
votes
2answers
223 views

What are the frequency ranges of most marine mammal vocalizations?

I am trying to determine a list of frequency ranges into which marine mammal vocalizations fall. Ideally, I would like a list showing where the most popular marine mammal vocalizations fall, followed ...
8
votes
1answer
54 views

Downloadable worldwide database of disease statistics?

I am looking for a downloadable database of disease statistics. I have emailed the good folks over at HealthMap, but they haven't gotten back to me yet. As far as I can tell, their data relevant to ...
6
votes
2answers
224 views

Is there such thing as a generic “metabolic type”?

A while ago I picked up a book called "Eat right for your metabolic type". The book discussed the effects of the endocrine system on the overall shape and the speed of metabolism. The book outlined ...
2
votes
1answer
127 views

What are the effects of combining rapamycin with dietary restriction?

Are the effects additive or subadditive? In many ways, rapamycin acts like a CR mimetic, but even CR can only go so far.
7
votes
1answer
183 views

Linkage and LD: quantitative or qualitative?

My understanding is that the concept "genetic linkage" can be expressed in quantitative form, like: A predisposing gene X was found in close genetic linkage to Y. ...
7
votes
1answer
101 views

How can I normalize mRNA samples for sequencing?

Is there an easy, inexpensive, not too labor intensive way to normalise mRNA samples so that even though one loses information of gene expression levels, each of the transcripts in the transcriptome ...
2
votes
0answers
88 views

Has anybody used Evrogen's DSN-normalization protocol for cDNA normalization? [closed]

I found the link to a commercial product by Evrogen to normalise cDNA samples for gene discovery projects here: http://www.evrogen.com/technologies/normalization.shtml The most up-to-date reference ...
6
votes
1answer
684 views

Does anyone have any TOPO directional cloning tips? [closed]

I'm just about to start working on a TOPO cloning after I couldn't get it to work with standard restriction/ligation. Does anyone have any tips for TOPO cloning?

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