2
votes
1answer
44 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 ...
1
vote
2answers
78 views
Iron deficiency anemia symptoms explanation
In my classes and on the internet, brittle nails and dry hair (or hair loss) are described as symptoms of iron deficiency anemia, but none explains the cause of such symptoms.
Does anyone have any ...
9
votes
2answers
611 views
What is Peter's rule in neuroscience?
I have heard and read about Peter's rule informally in the past, but never saw a formal definition or description.
Informally I have learned to understand Peter's rule as the assumed correlation ...
2
votes
0answers
29 views
Can Infant Crocodiles digest Bread?
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 ...
1
vote
3answers
119 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 ...
0
votes
0answers
21 views
How does Pethidine Contribute to Serotonin Syndrome?
I ask this because while I did read in this Australian Government webpage that it inhibits the reuptake of serotonin I have seen no studies that have mentioned any such interaction with the serotonin ...
1
vote
1answer
55 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 ...
4
votes
1answer
198 views
Why does sexual selection evolve beautiful features?
First question here. I have a very raw understanding of sexual selection:
Say a group of females of a certain species "likes" some feature of a certain groups of males; by "like" I mean some ...
1
vote
0answers
19 views
What are the conditions that must be satisfied in order for drugs to be deliverable via the epidural route?
I ask this because I've read that while pentazocine is approved by the FDA for the treatment of labour pain, epidural administration is not listed as one of its means of administration (which thing I ...
5
votes
1answer
78 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
2answers
42 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
1answer
33 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 ...
10
votes
1answer
215 views
Is there are evolutionary explanation for why humans and primates are ticklish? How might it have evolved?
Tickling is a rather interesting phenomenon: When humans or apes are touched in certain areas like the armpits or sides, we respond with laughter AND frantic attempts to stop the assault. Obviously ...
1
vote
2answers
62 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 ...
3
votes
1answer
48 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 ...
2
votes
0answers
36 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 ...
1
vote
2answers
72 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?
2
votes
1answer
55 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 ...
4
votes
1answer
132 views
Efficiency of a sodium-potassium pump
I am reading about transportation of ions in a cell. It is necessary to transport sodium back out and potassium back in, against their electrochemical gradient. This task is carried out by ...
2
votes
3answers
79 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.
...
1
vote
0answers
20 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 ...
9
votes
2answers
303 views
Why do people have antibodies against other blood types?
The ABO blood type divides each blood type according to whether they have the "A" and "B" antigen(s) (AB has both, O has none). People also have antibodies against the antigens they don't have (AB has ...
1
vote
1answer
43 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 ...
3
votes
0answers
38 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 ...
11
votes
1answer
396 views
Is there an advantage to linear chromosomes?
The DNA copying enzymes have a hard time working to the end of a chromosome. For circular chromosomes this is not a problem, since there is not a sharp 'end'. However, for a linear chromosome, without ...
2
votes
1answer
70 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 ...
16
votes
2answers
2k views
What is the advantage of circular DNA in bacteria?
From what I understand, bacteria have circular DNA. What advantages does it have over linear strands like for eukaryotes?
Do there exist bacteria with more than one ring of DNA?
3
votes
1answer
107 views
Zombie Ant Fungus?
Ophiocordyceps unilateralis is a parasitoidal fungus that alters the behavior of the infected.
Source: Wiki page.
How is the fungus able to alter the behavior of the infected to such specfic ...
0
votes
0answers
9 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
2answers
104 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 ...
0
votes
0answers
19 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
29 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 ...
1
vote
1answer
77 views
Confusion related to a term probe-by-background interaction
I was reading a paper related to bioinformatics where it uses the drug response on the cancer cells and the gene expression of the individual cells are studied to find any useful insights. Specially, ...
0
votes
0answers
34 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 ...
0
votes
0answers
21 views
Which receptor in particular does, “MUSCARINIC CHOLINERGIC” refer to in Goodman and Gilman?
On pg. 410 of Goodman and Gilman's The Pharmacological Basis of Therapeutics 12th Edition the term "MUSCARINIC CHOLINERGIC" is used (in the context of side effects of antidepressant agents) with ...
5
votes
1answer
2k views
Do crocodiles age?
I was watching a talk by Michio Kaku (sp?) and he mentioned that crocodiles (or possibly alligators, I forget offhand) don't actually age-- they can die, but they essentially go through no aging ...
0
votes
1answer
58 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 ...
2
votes
0answers
63 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 ...
7
votes
3answers
131 views
Mathematical Modelling of Natural Selection
I'm a math undergrad looking for some papers on modelling the process of natural selection. The only paper I've been able to find is by the pre-eminent mathematician Herbert Wilf from 2010,
There's ...
1
vote
1answer
41 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 ...
12
votes
3answers
104 views
How are long time periods measured in biological systems?
Biological systems are pretty good at measuring fairly long times, for example, menstrual cycles (month), or puberty (years). Counting days or years seems to be implausible, and chemical concentration ...
3
votes
0answers
39 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 ...
11
votes
4answers
498 views
Are there any examples of sudden leaps in evolution?
As far as I understand, various abilities like flying, sight, hearing etc. were caused by slow evolution, where those with a greater ability to to these things had better chance of survival. (If this ...
1
vote
0answers
21 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
9 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 ...
7
votes
2answers
75 views
What is the smallest molecule that can present as an antigen to the immune system in the context of allergies?
People often claim, in a colloquial sense, that they are "allergic to everything".
Is it possible to have a full-fledged IgE mediated allergic response to very small molecules? I was always under ...
0
votes
1answer
70 views
How to classify equilibrium points [closed]
I have the two differential equations:
$$\frac{dN_1}{dt} = N_1(2 - N_1 - 2N_2)$$
$$\frac{dN_2}{dt} = N_2(3 - N_2 - 3N_1).$$
I worked out the equilibrium points to be at $N_1 = 0, \frac{4}{5}$ and ...
3
votes
1answer
37 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 ...
6
votes
1answer
70 views
What are the biological mechanisms behind the increase in cancer risk and alcohol consumption?
Alcohol consumption is known to be a risk factor for developing cancer. Compared to obvious causes like tobacco where one is exposed to known carcinogens, I don't see an obvious mechanism by which ...
-6
votes
1answer
41 views
Were any brain fusion experiments ever conducted? [closed]
Did anybody ever conduct experiments on fusing living brains?
