3
votes
1answer
251 views

How do I measure bacterial growth in agar dishes (either by cell mass or by cell count)?

I am doing an experiment in which I am growing S. mutans in agar dishes, and I am not sure how I would measure the growth of the S. mutans. I am also not sure if I would do this by measuring cell mass ...
3
votes
2answers
286 views

Survivorship Curves: Type II curve mortality rate is not constant?

In graphs of survivorship curves, I'm seeing that the Type II curves are straight lines, and the supplementary text says that the mortality rate is constant (i.e. the slope of the line is constant). ...
3
votes
1answer
186 views

Are there any 6 limbed reptile fossils?

Were any 6 armed "tetrapod" fossils ever found? I've seen some lobe finned fish with two sets of shoulders in an evolutionary bio book... I'm curious because I'd like 4 limbed and 2 winged dragons to ...
3
votes
1answer
104 views

Why are centrioles aligned at 90 degree with each other?

The centrioles are aligned at 90 degree with each other. What is the function of this?
3
votes
1answer
144 views

Plant a whole fruit or only seeds?

I'm trying to figure out whether it is better for the plant to reproduce by planting its whole fruits with seeds inside them, or picking the seeds out and planting them without the fruit. In my case ...
3
votes
1answer
35 views

Is there any database with RNA classification?

I am looking for a database that would provide classification of various types of RNA - information about its structure, function, etc.
3
votes
1answer
69 views

Hibernation, Metabolism and Aging

People are beginning to seriously research space travel applications of therapeutic hypothermia, specifically for reducing metabolism and stress on humans traveling to Mars. It seems that as you ...
3
votes
1answer
589 views

RNA-seq analysis - q-values in cuffdiff

I'm using cuffdiff 2.1.1 to look for differential gene expression between two conditions. Each condition has 2 biological replicates. The results I get look promising from a log fold change ...
3
votes
2answers
210 views

Factor causing Methicilin-resistance in MRSA?

I think the main reason is the natural selection that is causing methicillin-resistance. However, I am not completely sure what this means practically. Here, the original question: MRSA was isolated ...
3
votes
1answer
110 views

Are similar smells usually based on similar chemicals?

Building off of this question: Why does freshly cut grass smell like a watermelon?, is it usually the case that things that we perceive as having similar smells are, in fact, the same or a similar ...
3
votes
1answer
95 views

copper vs aluminum, what's the safest for health?

I'm working on a mini project for a milk dispenser machine, using a peltier device to cool the milk down, I have to choose between a copper or aluminum cooling block (see pictures bellow). But I'm ...
3
votes
2answers
1k views

What is the genetic basis of blood type (ABO) system?

What is the genetic basis of the A/B/B+/O/etc. blood type system? Are there definitive loci that correspond to each or can multiple different genotypes produce the same antigen profile? Also, is the ...
3
votes
2answers
80 views

Why do plasmids replicate on their own?

I know how plasmids can replicate independently of the main genome and know that they confer various properties to the bacteria and are useful in conjugation. My question is - what is the advantage ...
3
votes
1answer
332 views

Do hormones make men think of sex?

I remember hearing a saying that goes like "men think of sex every 7 minutes (or seconds?)". I take this saying to mean that men have sex related thoughts more often than women. I'm interested if ...
3
votes
1answer
78 views

What causes sinus pain and congestion?

When the sinuses flare up, it can get very painful. Thus, my question - what biological mechanisms cause the congestion and especially the pain associated with sinusitis?
3
votes
1answer
216 views

Why does the stomach ache if you take a brisk walk after lunch or dinner

After eating your lunch or dinner, if you take a brisk walk, most of the time your stomach aches. Why does that happen? What happens with respect to the body metabolism?
3
votes
1answer
46 views

Is it possible to clone a Neanderthal?

As Neanderthal DNA has been sequenced, is it possible to create a living Neanderthal?
3
votes
1answer
277 views

How can haired mammals synthesize vitamin D?

The human body can synthesize vitamin D in the skin from cholesterol, when sun exposure is adequate. But how can haired mammals do it? Do not they need it?
3
votes
2answers
379 views

Why does the body not recycle red blood cells?

This question is out of curiosity. The life expectancy of a red blood cell (RBC) is approximately 3 months, and then RBCs are disposed of. Why does the body opt to build new red blood cells rather ...
3
votes
2answers
341 views

Identification of an Insect (Hemiptera)

I found a a few of these guys on my composter, so they could have easily been eating bugs or decaying organics (or both): To me it looks like a stink bug with oversized legs, not like the ones I'm ...
3
votes
1answer
280 views

Is a “Fact” any theory for which there is overwhelming evidence in any field other than biology?

Evolution is often described as a fact, and a theory. Evolution is a heavily overloaded term, with one definition being the fact that, "changes in the frequency of alleles in populations of organisms ...
3
votes
1answer
104 views

How do different tissue culture matrices affect background in fluorescent microscopy?

In response to my previous question, I've been reading up a little bit on poly-D-lysine, Collagen I, Collagen IV, laminin, and other tissue culture coatings that promote cell adhesion. I've always ...
3
votes
1answer
95 views

Would non-human carnivores be able to survive on farmed foods?

Certain creatures that are considered carnivores are non-obligate carnivores and are technically omnivores (such as wolves/dogs). How different is the potential digestive ability of these species ...
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 ...
3
votes
2answers
161 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 ...
3
votes
3answers
880 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 ...
3
votes
1answer
636 views

Is it possible for a person to become “reinfected” with the same strain of a virus?

If a person contracts a virus, viral conjunctivitis for example, is it possible for the individual to become "reinfected" with the exact same strain of the virus once the person has it treated and the ...
3
votes
1answer
250 views

What is an epistasis group?

I have been trying to wrap my head around the concept of epistasis for a couple of days now, and I think I understand it, at least at a basic level, but I still don't understand some of the ways that ...
3
votes
1answer
133 views

What molecular processes are involved in pseudopodial extension?

I am curious as to the processes and mechanisms involved in the extension of pseudopodia in amoeba. How does the cell know and control the direction and extent of pseudopodia formation at a molecular ...
3
votes
2answers
95 views

Do dolphins really sleep?

I have always wondered, if dolphins sleep with one eye opened, do they really sleep at all? According to this article dolphins indeed shut down their brains. I already googled it. No help from ...
3
votes
1answer
483 views

Difference between “transcriptional activity” and “RNA expression”

I am working with a network object where the nodes are different events in molecular biology. Specifically; Catalytic activity of X, RNA expression of X, GTP-bound activity of X, Kinase activity of ...
3
votes
1answer
52 views

What accounts for size variation in breeds of dogs?

My assumption is that dogs vary so much in size because of artificial selection pressures coming from human breeders, but are there genetic loci that roughly determine approximate size? Do other ...
3
votes
2answers
191 views

What software is there available for Quantitative structure–activity relationship (QSAR) pharmacological studies?

QSAR modelling in pharmacology basically hangs on using mathematical modelling to approximate the effects different molecules will have on various pharmacological targets. I would like to know what ...
3
votes
1answer
78 views

How to evaluate the efficacy of an antibody for fluorescence microscopy?

I'm trying to evaluate data taken from fluorescence microscopy with antibody staining, and am wondering whether there is any standard way to evaluate the specificity of the antibody for such ...
3
votes
3answers
7k views

What type of cell do you start with in Meiosis?

Okay, I was learning about mitosis and meiosis in school and had a question. I know in Mitosis you first start off with a Diploid (2N) cell and then end up with two ...
3
votes
1answer
102 views

What is the extent of the effect of Tris on E. coli?

I was a fool and dissolved my antibiotic (Kanamycin) into Tris Buffer rather than H2O. The Kanamycin still seems to be active but a fellow labmate mentioned that Tris messes around with the membrane ...
3
votes
1answer
135 views

Neuroscience of temperature regulation and perception

The hypothalamus is known to be important in the regulation of body temperature, but I'm curious whether anyone knows about the neurocircuitry of perceived temperature. It seems like there could be a ...
3
votes
1answer
77 views

Would ovoviparous to viviparous mutation have been gradual? How would that work?

It seems unlikely that an ovoviparous ancestor of mammals long ago could have had a viviparous offspring in a sharp one-generation dividing line, but what would be the gradual steps between egg birth ...
3
votes
1answer
223 views

Questions regarding ELISA

I have recently peformed an ELISA (Enzyme-linked immunosorbent assay), but I still have some questions, let me first outline what I did: We had a number (20) of tubes containing fake 'bodily fluids' ...
3
votes
1answer
56 views

Is there a term to quantify how spread a character is on a phylogenetic tree?

Is there a term which can quantify how 'spread out' a particular character is on a tree? I want to distinguish between a character which is only restricted to a particular clade vs. a character that ...
3
votes
1answer
121 views

Can compounds be predicted from Polyketide synthases gene clusters?

I've seen a few talks on the subject. From a gene cluster, there is some decent ability to determine which domains contribute to certain functional groups in the final metabolites. It sounds like this ...
3
votes
1answer
2k views

Slow-oxidative fibres vs fast-glycotic fibres

Why do slow oxidative muscle fibres contain more mitochondria compared to fast-glycolytic muscle fibres?
3
votes
1answer
529 views

“Acellular” designation for organisms

Why do some biologists refer to single-celled organisms such as Amoeba and Paramecium as acellular (i.e., without cells) rather than unicellular (i.e., one cell)?
3
votes
1answer
272 views

Ammonium sulphate precipitation assay pH dependence

In general does the pH effect the precipitation, e.g. would a pH of 6 cause less precipitation than pH 7.5. Or are they unrelated?
3
votes
1answer
244 views

How are melatonin levels measured in humans?

I'm wondering how it is possible to measure diurnal variations of melatonin levels in humans. I keep reading that there should be a large difference in amplitude between melatonin levels measured at ...
3
votes
2answers
752 views

Transcript(omics) terminology: cDNAs, ESTs, RNA-seq, etc

I've worked pretty frequently with genome and transcriptome data for several years now, but I'm still not 100% sure I understand the proper usage for certain terminology related to transcripts and ...
3
votes
1answer
170 views

What is the relationship between Homocysteine and Norepinephrine metabolic cycles?

I've been researching neuromodulators and have taken a look at the Norepinephrine/Noradrenaline system. The diagram of biosynthesis of Norepinephrine is presented in the wikipedia article: ...
3
votes
1answer
80 views

Are there any situations in which phenylephrine is preferred to pseudoephedrine?

In the mid 2000s in the US, due to issues of drug enforcement, pseudoephedrine containing medications were brought behind the pharmacy counter and in most cases require ID, and phenylephrine was ...
3
votes
2answers
177 views

How do I create a probe for in situ hybridization?

I tried to make the probe several times but it failed again and again. It usually turns out that the probe after hydrolysis is very very short (maybe around 50nt). I did not check the RNA before ...
3
votes
1answer
68 views

What's in a Name: Statistical Genetics

The novice often performs population calculations using what is referred to as Mendelian Genetics. Soon after the publication of Mendel's results; Hardy and Weinberg presented their results after the ...

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