1
vote
0answers
32 views

Do primitive lymph nodes exist in 12th week embryo?

Someone told me that primitive lymph nodes do not exist during this week. However, others say they can. Here is a picture about inguinal lymph nodes from here. No primary lymph nodes are visible ...
2
votes
1answer
51 views

$F_{ST}$ when considering a multi-allelic locus

Sewall Wright defined the $F_{ST}$ in a metapopulation as being: $$F_{ST} = \frac{\text{Var}(p)}{\bar p (1-\bar p)}$$ , where $p$ is a vector of frequencies of a given allele and $\bar p$ and ...
2
votes
0answers
48 views

$F_{ST}$ and the genetic variance in metapopulations

From this video (21'15''), the speaker gives the following formulae in order to calculate the between and among populations genetic variance from the $F_{ST}$: $$V_{Among Pop} = 2 F_{ST}V_G$$ ...
3
votes
3answers
129 views

Does a reduction in stem cells mean possible earlier death?

The basis of this question relies on my understanding of these 2 facts: ...
4
votes
1answer
248 views

Are there any organisms that lack ATP synthase?

ATP synthase is used by cells to synthesise ATP from ADP using energy from a proton gradient. Depending on which sites I look at, this is either a universal feature of living cells, or it's "almost ...
1
vote
0answers
38 views

Plateletpheresis for hemophilia

Plateletpheresis is seperation of platelets from whole blood and putting the leukocytes and erythrocytes back into the blood. If the person donating platelets does not have hemophilia than could a ...
4
votes
1answer
828 views

Why do veins look blue?

I know that veins carry oxygen. Veins look blue because the oxygen-depleted blood in them is blue. Is this true??
3
votes
3answers
87 views

dsDNA translation

Since DNA is double stranded and each strand is complementary to the other, the codons on each strand will come out to be different after transcription(depending on the reading frame). Does this mean ...
0
votes
1answer
75 views

Question about what the liver does NOT do

Which of the following functions is NOT performed by the liver? a) Storage of vitamins and minerals b) converts glucose to glycogen c) converts toxins to harmless chemicals d) produces bile I chose ...
4
votes
1answer
121 views

What is this spider hunting in the tree in the night?

I took the following picture of this spider in northern Switzerland (alt: ~700m) with macro flash/lense. The picture was taken during the night in a cedar tree (Thuja occidentalis).
5
votes
1answer
141 views

What is this spider?

I took the following picture of this spider in northern Switzerland (alt: ~700m) with macro flash (then it is not so big: probably around 2-3 cm, including the legs) This spider made its web on the ...
5
votes
1answer
47 views

Implications of what the discovery of Naia means

Recently a discovery was made of a ~12,000 year old girl in Hoyo Negro in Mexico. This has been covered by many different news agencies. I'm confused however by many of the reports. Does it ...
1
vote
1answer
44 views

Why can't intermediate filaments be used as tracks by motor proteins?

A motor protein like kinesin-1 cannot use an IF as a track because it lacks polarity. Can someone elaborate on this answer?
1
vote
1answer
89 views

Error in textbook

This must be an error Just as proteins have a polarity defined by the amino and carboxyl termini, oligosaccharides have a polarity defined by their reducing and nonreducing ends. The ...
8
votes
1answer
236 views

Identify a bird

I have taken this picture of a bird in university zoo in Tel Aviv. It was approximately 25 cm high and seemed to be a flightless species. Can somebody help me identify it?
4
votes
2answers
466 views

Why digest proteins into peptides for Liquid Chromatography - Mass Spectrometry?

Digesting (trypsin or whatever other proteolytic enzyme) proteins generates multiple peptides so the degree of complexity of the sample, at the peptide level, increases a lot. In addition there is ...
2
votes
2answers
42 views

Do Noroviruses include many families?

Wikipedia says Caliciviridae Family. My notes say that Norovirus includes the following Noroviruses Norwalk-like viruses Caliciviruses Astroviruses and some small gastroenteroviruses which is a ...
2
votes
1answer
28 views

Can Rubella virus pass into brain stem?

B19 virus (about 20 nm) can; which I think is partially because of its small size; not sure of genomics has something to do with the passing. Rubella's (also called German measles) size is then again ...
3
votes
1answer
148 views

Pharmacology Half Life Calculation

I'm really stuck on this question. I'm being asked to find the half life of a drug. The Vd is 50L/kg. The clearance is 0.1 L/hr/kg. The patient weighs 70 kg. Equation is: T1/2 (halflife) = 0.693 * ...
3
votes
0answers
129 views

Human female chest model or data representation?

I am looking for professionally used representation of female chest (I know how it sounds ;). Generally - a model comprehensive enough to effectively represent human chest, with focus on breasts. ...
9
votes
2answers
1k views

How long does it take for memory to disperse after death?

1: There seem to be cases where coma patients with a non-active brain (i.e. flat EEG) have regained full consciousness. => Apparently memory and knowledge are stored independent of brain activity. 2: ...
1
vote
1answer
94 views

Can Alzheimer's disease be caused by Slow Prion infection?

I found this claim in my study materials with explanation of amyloi plaques, in comparison to CJD (Creutzfeldt-Jakob Disease). Its characteristic are Long doubling time of at least 5.2 days (I ...
2
votes
1answer
843 views

Properties of Satellite Chromosomes

I have some questions regarding Satellite chromsomes which could not be resolved by a google search. Does the satellite consist of telomeric sequences ? If not, What is the function of a satellite ? ...
4
votes
1answer
80 views

Blood consumption

Is consumption of blood more "dangerous" compared to meat? There was a news-article about unnatural chemicals found in the blood of mothers. This reminded me about a question I have pondered upon ...
5
votes
1answer
118 views

Why don't warts caused by HPV spread to the whole body?

My son had a plantar wart on his foot, which (as I understand it) is caused by a virus which only infects skin cells. Once in the skin cell the virus replicates, but when attacked by the immune system ...
2
votes
1answer
106 views

Are Night Parrots (Pezoporus occidentalis) really extinct?

This incredibly rare animal has been reported to be extinct since 1990, however several cases has been raised that night parrot was spotted in the areas of Australia. What is the cause of their ...
1
vote
1answer
68 views

downloading a reference genome for alignment

I am currently working through the code example on the MATLAB website. It requires me to download the reference genome of Arabidopsis thaliana (thale cress) so I can use BowTie2 to align the Chip-Seq ...
2
votes
1answer
101 views

How does the MMR vaccine affect lymph nodes in preventing measles?

I am trying to understand this statement about the Measles part of the MMR (Mumps, Measles and Rubella) vaccine Measles prevention: MMR (AB protect during primary and secondary viremia) Measles ...
5
votes
5answers
169 views

What are some examples of evolving networks in biology?

I'm a master student working on networks analysis in general. A network is something that has nodes and there are links between the nodes. Nodes and links could have attributes. An evolving network is ...
14
votes
1answer
1k views

What do viruses do during incubation period?

For example, there is an incubation period of around 1 to 3 days for common cold, and that of AIDS can range over to decades. What do viruses do actually do during the incubation period? What ...
1
vote
1answer
64 views

Conclusions from hybridization results

A double stranded DNA was denatured in a mixture that included mRNA from a gene in the segment. The mixture was then cooled to promote RNA and DNA hybridization. The following figure the results. ...
0
votes
1answer
37 views

Calculation of water potential

For a mesophyte growing in a moist soil, water potential of its root sap is -3 atm, then how to find the water potential of moist soil and leaf respectively?
4
votes
1answer
334 views

The parameter for setting the number of mismatches in standalone blast

In a standalone blast search, is there a parameter that could be specified to fix the number of mismatches allowed in an alignment. I went through the parameters and I could only find parameters to ...
3
votes
4answers
1k views

Bad Eyesight and Evolution

Why do many humans have bad eyesight, such as near-sightedness, which hampers performance in a wide variety of tasks? Shouldn't there be evolutionary pressure towards better eyesight?
4
votes
2answers
127 views

A photosynthesizing mouse?

N. Shubin's Your Inner Fish makes the point several times that there is a lot of functional similarity between some seemingly remote gene cousins. If that needed reinforcing we have the spider-goat, ...
1
vote
1answer
52 views

Anti-parallel DNA code operons

Coming from a software engineering standpoint, suppose I have a string of code like so: ... 5'-ATAGAC-3' ... ... 3'-TATCTG-5' ... Assume the above code is part of a larger segment. Now, reading ...
3
votes
1answer
80 views

Biological advantage of electric synapses

Electric synapses are synapses that do not process information but simply foward one action potential from one neuron to the next. There are no neurotransmitters, no inhibitory and exitatory ...
2
votes
1answer
117 views

Steps to confirm if predicted miRNA is good or bad

I aligned all miRNAs available to the supercontigs of a particular genome with certain parameters (e value of 0.01 and a word match of atleast 7 as suggested in this paper). I have also isolated the ...
3
votes
1answer
144 views

mFOLD prediction result interpretation

I am trying to predict the secondary structure of certain predicted pre-miRNAs through mFOLD which is the generally accepted technique for structure prediction in most studies. I am finding it hard to ...
0
votes
2answers
161 views

Blood Type Compatibility [closed]

It should be that because O+ blood(which is my blood type) has all antibodies but no antigens that all other blood types including O- would be incompatible making O not a universal donor so why is O ...
3
votes
3answers
3k views

Is the human body composition real?

In Fullmetal Alchemist when Ed goes to disprove to Rose the Sun God's "miracle" to bring humans back to life by proving that science (in the form of Alchemy) can create people by saying Water (35 ...
3
votes
1answer
376 views

What is “bacto” peptone?

Standard recipes for yeast medium often include "bacto-peptone". Is this the same as bacteriological peptone? Is there an authoritative source that spells it out?
1
vote
1answer
134 views

Meaning of “auto” in trans autophosphorylation?

Why this process called "auto"? Is it because each tyrosine kinase receptor subunit of the RTK dimer has the ability to phosphorylate tyrosine or other amino acid residue present in other subunit of ...
1
vote
0answers
35 views

Why do some fruits have their seeds disintegrated

Sometimes I'd come across a Lychee or a Naseberry whose seeds are kinda disintegrated.. in a thick powdered form, either completely or partially. What could cause such a thing? And is the fruit with ...
0
votes
1answer
673 views

Genes, chromosomes, base pairs and the 23 pairs

OK so I'm a bit confused. Does a chromosome consist of genes and do genes consist of DNA? What about the 23 pairs in sexual reproduction? I can't remember what the pairs consist of
8
votes
1answer
540 views

How does yeast dissolve in sugar?

There's this fascinating "kitchen experiment". Take a "brick" of baker's yeast (not dry yeast), and a couple teaspoons of sugar, put them together in a cup and stir together. There's no doubt both are ...
2
votes
1answer
110 views

How much mechanical stress can a skeletal muscle bear?

In the movie- Saw, for the last trap Bobby was told to insert metallic hooks into his pectoralis major muscle. In his fake story Bobby has raised himself successfully, but when he was "really" ...
1
vote
1answer
169 views

Breathing under water

Why can fish breathe under water but land mammals can't? How can fish extract oxygen straight from water but humans can't?
1
vote
0answers
70 views

Regulation of Cra protein level in E coli

Catabolite Activator/Repressor, Cra protein (formerly known as Fructure Repressor FruR) plays a significant role in central carbon metabolism of E coli. Its activity is inhibited by ...
12
votes
1answer
170 views

Why are fly not scared when landing on a monitor with changing graphics?

I have been wondering why would insects in general, not be scared when important changes happen on your monitor where they have landed... If you move even just a finger, they are scared to death and ...

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