5
votes
2answers
266 views

How Sex Evolved ? and when?

As I know evolution comes bit by bit mutation by mutation How sex evolved which requires a major change in at least two individuals one to become male and one to become female ? When that happened ...
2
votes
1answer
66 views

Most human-like teratoma ever recorded?

I'm curious to learn about the most human teratoma ever recorded. By most human I mean the teratoma which most resembles the form of a human being. I suppose there are several criteria which would ...
4
votes
2answers
347 views

Can animals make their own unsaturated fatty acids?

I know that animals can't make poly-unsaturated fatty acids (PUFA) and so require them from dietary sources. For eg.Omega -3 and Omega 6 fatty acids. My questions : Can animals synthesize other ...
9
votes
1answer
139 views

Why do so many people have group O blood?

Please forgive me in case my question wouldn't make much sense. I was reading about ABO blood groups on Wikipedia, where I learnt that O is a recessive allele, and that it seems the A allele predates ...
1
vote
2answers
378 views

Were early human beings (about 100 - 200 K years ago) far more promiscuous than we are now?

I found that many friends of mine are quite easy in sexual relationship. Ex, I knew a lot of girls went to the night club & met a stranger & brought home to sleep with him even she had never ...
0
votes
1answer
787 views

Identifying internal structure of dissected prawn

Note: Some of the images might be disturbing. I have dissected prawn for the first time. Would like your help in identifying some structures . This is the dissection of the posterior part of the ...
2
votes
1answer
470 views

What is optical density in Lowry's protein estimation method?

I have a few questions: What is an OD value? Why do we use blank solution in Lowry's protein estimation method? If The OD of a protein is 0.01, what does it mean? Thanks in advance.
2
votes
1answer
58 views

About stem cells and Cancer

Do stem cells have an apoptosis mechanism and , if they do could this be used to repair the cell self-destruction pathways in a cancer cell?
3
votes
2answers
307 views

How are two species with similar phenotypes identified as different?

How are two species with similar phenotypes identified as different? Have two different individuals that were thought to be different species ever been determined to be from the same species ( or ...
1
vote
1answer
52 views

Any forms of pneumonia that can be caught?

I am aware of the fact that there are several different types of pneumonia. However, I am wondering if any of these types of pneumonia are contagious from person to person. Is this possible?
2
votes
1answer
111 views

How is a stem-cell induced to assimilate a knock-in DNA construct?

While looking at (daylight) color perception I came across a paper by Jeremy Nathans (et al., Proc. Nat. Acad. Sci., vol. 100 no. 20, 2003, full text here) in which he describes the creation of a ...
3
votes
1answer
24 views

Polarized epithelium and localization of ion channels

I'm trying to learn more about polarized epithelial cells of the gut. I am familiar with classic brush border transporters localized to the apical memebrane to facilitate nutrient absorption. I am ...
3
votes
1answer
97 views

How compatible are mammalian digestive systems?

I'm interested in what kinds of nutrients mammals extract from food and would like to know how similar are the outputs of these systems. For example, if it is possible to successfully replace one ...
3
votes
1answer
94 views

Amino acid profile of GPCRs

You are studying cellular signalling through a newly identified GPCR. Specifically you’re working on a pair of newly identified GPCRs, GPCR-A and GPCR-B. Each binds the same small ligand, but ...
2
votes
1answer
412 views

Why are hybrids infertile?

Let's take a quote from Wikipedia about zebroids. Donkeys are closely related to zebras and both animals belong to the horse family. These zebra donkey hybrids are very rare. In South Africa, they ...
1
vote
2answers
128 views

Which was the last significant event in human evolution? What's next?

At 10.000 BC (12 ka), we became the last of the Homo species on Earth. In evolutionary terms this is a very little time range to something happen, but I'm wondering anyway, in this meantime which are ...
2
votes
1answer
81 views

Saliva test for Toxoplasma gondii?

I am trying to find some reliable gene kit by which you can rapidly test Toxoplasma gondii. I am not sure if it exists. I have an intuition that some tests done during 90s-00s on this species had high ...
0
votes
1answer
18 views

Is nutrient absorption different in Hypersensitive I patients?

I am thinking how the nutrient absorption differs between between patients with allergies (Hypersensitivity I) and those not. The current guideline about number of eggs in diet is one daily ...
1
vote
1answer
88 views

What is the pathogenuc mechanism of brown pigment lipofuscin in muscle atrophy?

I think it is autophagy. Lysosomal degradation. Autophagocytosis. Example of the brown pigment (lipofuscin) here: I am not sure if autophagy is the right answer to the "pathogenic" mechanism of ...
0
votes
1answer
21 views

Can pulmonary infarction be asymptomatic?

I think it can because there are many parts in lungs. Like for some COPD patients. However, I am not sure if COPD patients can have infarction. Lungs have parallel circulation. Red infarct is ...
0
votes
1answer
23 views

To characterise diameter of capillaries in organs

I know that there exist Continuous capillaries (skeletal muscle, adipose tissue, connective tissue, pulmonary circulation), Fenestrated capillaries (small intestine, renal glomerulus, exocrine ...
1
vote
1answer
35 views

Are there any forms of heart failure where cell size decreases?

I think hypertrophy happens in most of the cases. However, I am not sure if hypertrophy always happens. I started to think about wet lungs (pulmonary reason for the left-sided heart failure). Can the ...
2
votes
1answer
36 views

What can thrombosis lead to?

I am thinking this question. Thrombosis can result in organisation of thrombus, sepsis thromboembolism, fibrinoid swelling adiposity. I fibrinoid swelling (edema) (4) can occur. Also, I think (3) ...
0
votes
1answer
64 views

Fibrinous inflammation, exudate and scarring in monotonous movements and ageing

I have palpated many hard organs during my work and studies. I have seen many young and old people who have hard organs, like very hard shoulder - very common. I have interviewed some of them, some ...
2
votes
1answer
58 views

phylogenetic Independent contrasts with unresolved tree

I have a dataset containing morphological and performance measures of species from various groups, including insects, lizards, frogs, spiders etc, and want to analyse the relationship between these ...
1
vote
0answers
150 views

Effects of Genetic Drift on Linkage Disequilibrium

From what I understood of @Canadianer's answer here... Genetic drift randomly causes negative or positive linkage disequilibria, by changing allele frequencies through random sampling. Natural ...
4
votes
1answer
168 views

Why do mosquitoes not collect blood after platelets activate?

This may be anecdotal... The Indian sub-continent is in the rainy part of summer. It follows the mosquito population goes up. So when I sliced my palm, I expected the mosquitoes to collect there in ...
8
votes
2answers
561 views

Can a neuron make a synapse onto itself?

I was wondering if a neuron can make a synapse to itself? I suspect that it would be extremely unusual for a neuron to do this. Anyway, has anyone seen even a single instance of this? Is the process ...
5
votes
3answers
207 views

Can children restore brain cells?

By "children" I mean young people at the age of 10 or lower. I know that the adult brain cannot restore brain cells, but what about children? I mean, the brain must develop from a few cells to a 90 ...
9
votes
1answer
191 views

Seeing strange things in light

I have noticed that if you look directly at tubelight (I have only white ones in my home) and close your eyes little, you see little random shaped colourless things sometimes with slow speed and ...
3
votes
1answer
344 views

How does chromosome cross-over occur?

I have heard that during meiosis, homologous chromosomes from each parent "cross-over", which enables the off-spring to inherit some alleles from the mother and some alleles from the father. The ...
2
votes
3answers
701 views

Why is it that drinking caffeinated tea does not help one to stay awake?

I have never felt after drinking tea that I can have the power of being able to work late at night. Neither have I felt that it helps me to be awake while working or keeping eyes opened while I am not ...
2
votes
3answers
212 views

Many spermatozoa, but just one ovum

Why do men produce so much spermatozoa, that will get discarded, but women, just ovulum, but it's a good one. Couldn't men produce good spermatozoa as a limited edition? Where is the evolutionary ...
2
votes
2answers
151 views

Are there free electrons in muscles, hair, or skin?

Electric shock occurs upon contact of a (human) body part with any source of electricity that causes a sufficient current through the skin, muscles, or hair. In metals many electrons are said to be ...
1
vote
1answer
32 views

To have TBE vaccine during allergic times with mild asthmatic symptoms?

My assistant says that if you have asthmatic symptoms you cannot have TBE (Tick Born Encephalitis) vaccine, although you are living in the active zone of TBE. Cases mild allergic symptoms allergic ...
2
votes
2answers
50 views

In which direction plants' root grow in weightlessness? [duplicate]

As far as I know, roots of plants grow to the direction of Earth's gravity - this is called gravitropism. But what happens if plants are in space? Are they able to perceive gravity in state of ...
1
vote
1answer
31 views

Could super-caffeinating somebody's bloodstream be dangerous?

I'm currently planning out an RPG based on Misfits. Basically young offenders get super powers. I want one of the villains to have a really lame power that they use to become incredibly dangerous. I ...
2
votes
1answer
332 views

Why do genetic drift generates negative linkage disequilibrium?

The very first sentence of the abstract of this article are: "In finite populations subject to selection, genetic drift generates negative linkage disequilibrium, on average, even if selection ...
3
votes
1answer
284 views

Why basement membrane thickens in diabetes mellitus?

Untreated diabetes mellitus may lead to blindness and kidney failure because the basement membrane of small blood vessels in these organs thickens due to increased production of collagen and laminin. ...
1
vote
1answer
143 views

Heterozygosity and overdominance

Consider $m$ loci with heterozygote advantage (overdominance) such that the fitness of the two homozygotes is $1-\frac{s}{2}$ and the fitness of the heterozygotes is $1+\frac{s}{2}$, where $s>0$. ...
2
votes
0answers
49 views

Why is post-vaccination fever for 4CMenB so frequent?

When considering the introduction of 4CMenB vaccine, the Joint Committee on Vaccination and Immunisation said: The sub-committee noted that the clinical trials data suggest that when 4CMenB ...
3
votes
1answer
137 views

Are people genetically predisposed to being interested in specific fields/ideas? How does specialization occur?

I'm not sure if I formulated my question well, but I'm curious about a couple statements made by Steven Pinker and and James Heckman. In this interview: ...
1
vote
1answer
106 views

What is the current molecular explanation of Mendel's pea cross?

With reference to the simplest Punnet square for Mendel's pea plant experiments it occurred to me that I could not connect the little I know about genetics to the little I know about molecules. The ...
1
vote
1answer
71 views

Could the Warburg effect be used to starve cancer cells in situ?

What is wrong with the following chain of reasoning? Nearly all cancer cells rely on high rates of glucose uptake (upto 200 times more than normal cells). This is known as the the Warburg effect. ...
1
vote
0answers
66 views

Relationship between small and large fast-twitch motor units

When large fast-twitch motor units are temporarily fatigued, non-fatigue small motor units in the same muscle are impaired for small delicate tasks. Why? When impulses from the brain comes down, the ...
6
votes
4answers
217 views

Is there a comprehensive life science techniques/methods database?

There are so many techniques/methodologies in the life sciences that we can use to interrogate interesting questions. The thing is, most of us are completely unaware of the available methods we can ...
1
vote
1answer
204 views

definition of tempo and mode in evolution

I am reading Punctuated Equilibria: The Tempo and Mode of Evolution Reconsidered, which mentions the "tempo" and "mode" of evolution. I'm not familiar with the related literature and when I google the ...
1
vote
1answer
29 views

Effect of the health of the male parent at the time of conceiving

Does it matter at all in determining the traits of a baby what the current health of the father is? For example, let's say I got diabetes at the age of 40 because of the poor lifestyle choices. Will ...
1
vote
1answer
52 views

Are bronchioles and alveoli covered by respiratory epithelium?

Which parts of respiratory apparatus are covered by respiratory epithelium and which are covered by other kinds of epithelium?
3
votes
1answer
61 views

How does tree resin capture arthropods?

In regards to a published paper of a spider about to make a meal out of a parasitic wasp (http://www.tandfonline.com/doi/abs/10.1080/08912963.2011.640399#.U1kSV14gVBU), it reminded me of a issue I've ...

15 30 50 per page