5
votes
2answers
1k views

What chemicals and structures control the *direction* of plant growth in leaves, stems and roots?

If you want a specific plant, let's say the snap peas I am growing that I bought at Agway. I noticed that they grow towards the light source through the nearby window. Also I think roots work the same ...
3
votes
1answer
83 views

Understanding these SNP annotations

I am looking at the PharmaPGKB database for SNPs and trying to understand what the following annotation means: rs1801131 at 1:11854475 in CLCN6, MTHFR (VIP) Ok, ...
2
votes
1answer
71 views

Why it is so difficult to treat leukemia?

I want to ask what is the reason that T315I type CML leukemia is currently untreatable. I have read quite a few papers in this subject. Why the current genetic oriented engineering drugs failed to ...
6
votes
1answer
594 views

Why dogs move their noses when smelling?

I read on Wikipedia that: The wet nose, or rhinarium, is essential for determining the direction of the air current containing the smell. Cold receptors in the skin are sensitive to the cooling of ...
1
vote
3answers
815 views

Can animals, like monkeys, be homosexual?

I heard that some monkeys can be homosexual? a friend of mine was saying that he saw a male monkey having sex with another male monkey in the zoo, I honestly didn't believe him, I think he just got ...
2
votes
1answer
114 views

Why do ion concentrations change with different secretion rates in pancreatic juice?

Why is it that when secretory rate increases in the pancreas the concentration of chloride ions decreases, and the concentration of bicarbonate increases in the production of isotonic NaCl secretion? ...
4
votes
1answer
531 views

Why do sloths come down from the trees to defecate?

I'm under the impression that most sloths exhibit this behavior, but why? They are slow moving and so have no way of escaping from predators when on the ground. Not to mention the energy they expire ...
2
votes
2answers
163 views

Up to date B cell review

Where would I find an up to date (last 6-7 years max) review on B cells? I've tried searching through pubmed with filters, cochrane library, medline and various other resources including searching old ...
4
votes
3answers
167 views

HIV and T helper cells

As far as I know and could understand from reading about HIV, T helper cell is one of the main reasons to develop AIDS in patients infected with HIV virus, that because the absence of helper T cell ...
1
vote
1answer
687 views

Role of Fbx15 in ES cells and its use in assaying for iPS cells (Yamanaka paper and others)?

I am trying to understand the assay for iPS cells in the Takahashi & Yamanaka 2006 paper. They inserted a beta-geo cassette, which contains the neomycin resistance gene, into the Fbx15 gene. The ...
2
votes
0answers
100 views

Size of classical liver lobule across species

A classical liver lobule is made up of a central vein and the portal triads. A typical human liver weighs around 3 lbs. , while a typical bovine liver weighs around 12 lbs. I was wondering if anyone ...
2
votes
2answers
314 views

What mechanism suppresses melatonin release in humans?

I'm looking at melanopsin, a photo pigment in the human eye. One of its actions is to trigger suprachiasmatic nuclei SCN to suppress melatonin release. I'm interested in learning what is the exact ...
14
votes
1answer
602 views

Why is yawning contagious?

Why does yawning seems to be contagious? Is this similar to laughter being contagious or does it has a different reason?
4
votes
1answer
680 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 ...
4
votes
3answers
154 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 ...
1
vote
0answers
71 views

Why do animals sleep [duplicate]

Animals spend a good portion of every day doing nothing, and it seems like that time could be better spent hunting, searching for mates, etc. Also, animals are not aware during sleep, so it would be ...
3
votes
1answer
930 views

How does sugar enter neurons if they don't use insulin?

I heard somewhere that as opposed to other cells, neurons do not use insulin to get their sugar supply. Why is that? What is the alternative mechanism? I assume sugar can't just enter the cell ...
2
votes
1answer
157 views

How long does a tan last?

How long do melanocytes and melanosomes continue to protect DNA after UV exposure? Basically, if skin is tanned, then over the next month it is shed, will melanocytes continue to produce high levels ...
2
votes
0answers
47 views

Can Infant Crocodiles digest Bread? [closed]

I'm just curious as to whether crocodiles and if you require specifics, saltwater crocodiles, could eat bread as infants. I was watching Lake Placid and I was curious as to whether infant saltwater ...
2
votes
2answers
323 views

How to know if a woman is fertile without actually making her pregnant?

How to know if a human female is fertile (can give birth to child in future) without making her pregnant? Any signs, tests?
5
votes
2answers
3k views

What is the function of nodes of Ranvier in axons?

In a neuroscience class I'm taking, it was explained that myelin covers axons in sections, the uncovered sections are called nodes of Ranvier, and signals propagate much faster in the covered ...
3
votes
3answers
4k views

Separating DNA Fragments by Gel Electrophoresis. Are all the strands for one size the same?

My apologies if my question is too basic, and please point me to a more appropriate forum. I am reading the textbook "Essential Cell Biology" by Alberts et al, and am consulting other sources as ...
2
votes
1answer
192 views

Two brown-haired people have two children, P and Q. P has blond hair. Q has brown hair. What is the probability that Q is heterozygous?

Two brown-haired people have two children, P and Q. P has blond hair. We therefore believe that each parent is heterozygous and that blond hair is a recessive trait. Q has brown hair. What is the ...
9
votes
1answer
194 views

How are new people created from the DNA of an aged person. i.e. Why are we young?

The question "why do we age" has been asked numerous times. But why are we young? The cells of the adult human being are an age (time>0), but how can old cells create new cells that are younger than ...
2
votes
1answer
284 views

Copper for cell incubator to prevent contamination

For some reason the lab seems to have a problem with contamination every so often. It's virtually impossible to prevent bacteria, viruses, fungi, etc. from getting into the incubator every time you ...
1
vote
2answers
380 views

PEG-silane treatment: why incubate for 18 hours at 60 degrees Celsius?

I am conducting a biochemistry-related experiment and I have been unable to understand a step which is commonly performed. My aim in this step is to apply a PEG (Polyethylene glycol) silane layer. ...
3
votes
1answer
327 views

What factors govern the variable age of onset in Huntington's Disease?

"Huntington's disease (HD) is a neurodegenerative genetic disorder that affects muscle coordination and leads to cognitive decline and psychiatric problems." As we all know, this genetic disease ...
3
votes
1answer
614 views

How is Hypertonic Urine Produced in a Mammalian Kidney?

I know that the ascending loop of Henle is impermeable to water and ions, and, by end of the ascending limb, the osmolarity of the tubular fluid is very low due to the active transport of ions out ...
3
votes
0answers
56 views

What are polytene bands, and why are they there?

Drosophila polytene chromosomes have been particularly useful in genetic research, as it made cytogenetic gene mapping possible with very little effort. This was primarily accomplished due to polytene ...
1
vote
2answers
215 views

What gives observable light its colors? [duplicate]

I know that difference between different colors of light is difference between their wave length but I don't know what gives beautiful colors (like rainbow colors) to different wave length of ...
2
votes
2answers
374 views

What's a good and reliable database on the pharmacodynamic and pharmacokinetic data of drugs both approved and unapproved?

What's a good and reliable database for the pharmacodynamic and pharmacokinetic data of drugs both approved (in the US and elsewhere) and unapproved?
2
votes
3answers
918 views

Michaelis-Menten Kinetics: Does measuring apparent Km and Vmax take into account competing reactions?

I am learning about why it is important to measure Km and Vmax for each experimental setup because measuring the "apparent" Km and Vmax includes enzyme inhibitions of which one might not be aware. ...
3
votes
1answer
270 views

Macroevolution vs. microevolution

Where is the line usually drawn between macroevolution and microevolution? I thought that, although similar processes govern both, the line was at the species level, with macroevolution being changes ...
2
votes
1answer
41 views

What is a good review book/source for microbiological diagnosis?

I am trying to find the diagnosis figure for different bacteria where phases are illustrated. I am using at the moment: 1) First Aid for the USMLE Step 1 2013 and 2) Medical Microbiology by Murray et ...
3
votes
1answer
58 views

What's the mechanism of action of Levomepromazine's analgesic effects?

I have absolutely no idea as to how Levomepromazine elicits its analgesic effects so please do direct me to journal articles and other credible sources with you, the answerer, making a summary of ...
2
votes
1answer
458 views

Can animals use the nitrogen in chitin to build proteins?

Fungi and insects contain chitin, which is about 6% nitrogen. Can an animal - like me - make use of this as a nitrogen source to build proteins? Are there any animals that can do this? Are there ...
1
vote
1answer
101 views

Confusion related to the use of PCA to determine the background network

I was reading this paper related to use of gene expressions for predicting the drug response. I have this confusion, the paper has used PCA on the covariance matrix formed by the genes to get what is ...
42
votes
4answers
3k views

Why are there no wheeled animals?

In physics, "almost everything is already discovered, and all that remains is to fill a few unimportant holes." (See Jolly.) Therefore, on Physics SE, people are veering off into different directions: ...
1
vote
1answer
133 views

Lineage selection in plasmid evolution

I've been reading through Paulsson (2002) and I am not sure what he means by "lineage selection" in the second to last section. The paper deals with plasmid replication, and mostly concentrates on the ...
4
votes
1answer
265 views

Software for counting fly eggs

Is there any software that could be used to rapidly (quicker than humans) count the eggs laid by Drosophila on a substrate by placing them under a microscope with a camera attached? The eggs are laid ...
2
votes
2answers
290 views

What type of photosynthesis is performed by phytoplankton?

I am not a biologist, but I know there exist three variants of photosynthesis, namely C3, C4 and CAM. I would like to know what type is used by the ocean's phytoplankton? It might also be that ...
9
votes
1answer
324 views

Structure of fitness landscapes in the NK model

The NK model of rugged fitness landscapes consists of $N$ sites where fitness contribution of each site depends on its state $\{0,1\}$ and is epistatically affected by $K$ other sites. When defining ...
5
votes
3answers
373 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 ...
2
votes
2answers
458 views

What would it take to recognize a deer by its photo?

I am trying to recognize a deer by its antlers or any other means. Elaborating: I was hoping to use their antlers to recognize them but I have heard that most deers shed their antlers every year so ...
1
vote
0answers
22 views

Do the antlers re-grow in the same pattern every year? [duplicate]

I am a software engineer and I am trying to develop a system to identify a deer by its photograph. Most deers lose their antlers every year. I would like to know if they re-grow in the same pattern ...
2
votes
0answers
35 views

How is the appropriately-stratified gut microbiome acquired in organisms performing horizontal transmission?

I am studying horizontal transmission of primary symbionts in insect reproduction. This reminded me of an earlier question I had asked, in which I learned that humans analogously acquired their ...
2
votes
1answer
76 views

Whence fecal E. coli (et al.) if swallowing it is dangerous?

I don't know much about medicine, and I know even less about microbiology, but I understand that there are organisms in the lower gastrointestinal tract (and in feces) of a human, like Escherichia ...
2
votes
1answer
71 views

Carrying or packaging capacity of SAD B19 dG rabies virus

I'm wondering about the carrying capacity also referred to packaging capacity or loading capacity (how many base pairs can be packed efficiently into virions) of the pseudotyped rabies virus SAD-dG as ...
2
votes
0answers
113 views

How long does Lentivirus take to express in vivo mouse neurons?

Does anyone know how long it takes for a standard Lentivirus vector to express its genes (under a strong promoter such as CAG, CB7, etc.), after injection into the brain of a mouse? By hearsay I ...
2
votes
2answers
154 views

How does your body know when it is infected so it can invoke a fever?

How does your body know when it is infected with a virus or bacteria so it can invoke a fever or ramp up the immune system?

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