5
votes
1answer
122 views

Congenital blindness due to retinitis pigmentosa - does it exist?

Retinitis pigmentosa (RP) patients typically become blind after a period of years in which their eye sight slowly deteriorates due to photoreceptor degeneration. Generally RP patients develop ...
2
votes
0answers
126 views

Are there sterilisation methods that do not denature proteins as heat does?

Context: Most countries require milk to be sterilised through radiation or heat to remove possible harmful bacteria. Both of these processes denature the proteins in the milk (ref). Are there methods ...
3
votes
0answers
410 views

Can't resolve protein with native PAGE

This is a native gel. Let's call the left 2 lanes protein A and the right 2 lanes protein B. B is the same as A except it has a FLAG tag. They are both homotetramers of about 65 kDa. After ...
4
votes
1answer
43 views

Oligonucleotide purification with desalting

I have ordered 36bp oligonucleotides that anneal to each other and create sticky ends to be cloned in a vector afterwards. I have tried cloning many times with different methods and I failed. Now I ...
4
votes
1answer
180 views

Nomenclature of genes and proteins

With respect to this paper: Identification of Host Proteins Required for HIV Infection Through a Functional Genomic Screen In the abstract, I found names such as Rab6 and Vps35 and TNPO3. So Rab6 ...
3
votes
1answer
48 views

Obvious phenotypic inheritance markers in humans

In humans, are there phenotypic markers that prove parenthood? For example, if mother and father have <trait characteristic> (let's say, specific ear lobe ...
3
votes
1answer
410 views

What does these $\Delta \Delta G$ numbers signify?

I was reading a paper and came across this table showing $ \Delta \Delta G$ numbers of different nucleotide sequences in DNA/RNA. I know that $\Delta G$ is free energy and $ \Delta \Delta G$ is ...
1
vote
1answer
269 views

Blast output - program to count the number of hits [duplicate]

I have to use the old version of Blast (not Blast+) to compare DNA sequences and I have to know the number of all hits. They are not given in the header and I have to know them for many many of blast ...
2
votes
0answers
76 views

How did birds become so intelligent?

I have seen a Discovery Channel video of a bird throwing stones in a pot to raise the water level so it is able to reach and drink it. A similar experiment in this paper from Current Biology shows ...
2
votes
0answers
29 views

Founders of Cnidarian colony

I know that colonial Cnidaria enlarge their colony by the means of asexual reproduction and sexual and asexual reproduction can originate individuals that will be part of other colonies. ...
2
votes
1answer
75 views

Does mung bean nuclease cleave a phosphate group when it's chewing off 5' or 3' ssDNA ends?

I'm looking to create blunt ends from sticky ends with mung bean nuclease for subsequent ligation. Does anyone know full mechanism by which mung bean nuclease will do this? In particular after the ...
4
votes
1answer
78 views

How can I reduce the background gradient in phase contrast microscopy?

I'm looking for ways to set up a phase contrast microscope to reduce the brightness gradient that appears across the background of my images. I use phase contrast to find the outlines of cells in my ...
4
votes
2answers
3k views

Why can't the human eye focus blue light?

I recently noticed that it is hard to focus on blue light sources, especially at night. When observing a blue light source, e.g. a neon sign, it looks somewhat blurry. A sign with a different colour ...
3
votes
2answers
60 views

Are restriction enzymes active at −20 °C?

I have digested my DNA with NotI enzyme and put it in the −20 °C freezer without heat inactivating it. Can restriction enzymes work at −20 °C? Should I expect STAR activity?
7
votes
1answer
315 views

Why do some vaccines last longer than others?

After reading an answer to the question of How Do White Blood Cells Learn? Or Do They?, I came to wonder something. Specifically, The effect of this is that every new B and T cell that your bone ...
6
votes
2answers
66 views

Can molecular genetics make a boolean variable from a continuous variable?

In the same kind of idea than this question. Gene expression are regulated through complex interactions. The concentration of enhancers and repressors is an important aspect that dictate the level of ...
2
votes
2answers
174 views

Local BLAST Copy Number per Hit

I generated a series of local BLAST databases using makeblastdb of metagenomic data and am searching for the presence of a particular gene. While I can do the normal BLAST analysis looking at ...
2
votes
2answers
8k views

What is a pA(2) value?

I saw this article http://www.ncbi.nlm.nih.gov/pubmed/16710314 and it mentioned pA(2) values and I had no idea what they were. What are they? What do they mean? If possible it'd be just dandy if you ...
2
votes
1answer
108 views

Edman method to identify peptides with Phenylisothiocyanate (PTH)

We all know that in this method the PTH reacts with the first amino acid (aa) from the N-terminal to the peptide and separates from it giving PTH-aa so that we can know the amino acids sequence in the ...
19
votes
2answers
1k views

Do plant-animal cross races exist?

Plants and animals have the following distinct properties: Plants live from solar energy by photosynthesis, they use solar energy to make sugar and oxygen out of carbon dioxide, which gives them ...
2
votes
1answer
734 views

Why does gaining a hydrogen in biology considered reducing a molecule? [closed]

I've learnt in chemistry that gaining electrons means reduction, while losing electrons means oxidation. But why is it in Biology textbooks I sometimes come across the term gaining hydrogen??
2
votes
1answer
69 views

Comparing gene expression levels between control and disease at different time points

I have a data set with expression levels of a list of genes, measured in replicate at two different time points between two groups; a control group and a disease group. I want to identify the changes ...
1
vote
3answers
2k views

When is the second polar body extruded from the egg nucleus?

When does the second polar body gets expelled from the egg nucleus during oogenesis ? I know that it occurs after the entry of the sperm into the secondary oocyte but does it occur before the ...
1
vote
1answer
59 views

Explaining natural selection in moth [closed]

Industrial melanism is an example of natural selection. Can it be considered as a evolution due to anthropogenic action?
6
votes
1answer
3k views

Are sensory receptors neurons?

Background There are many receptor types in the body, with various functions and various mechanisms of transduction. Receptor cells are considered to be part of the peripheral nervous system, as they ...
6
votes
5answers
286 views

Is the amount of blood that flows through every vein and artery per minute really a constant?

I was listening lectures from Mark Saltzman via Open Yale Courses. Now, if I did not understand him wrong, he said that the amount of blood that travels through every vein and artery in our bodies per ...
8
votes
1answer
755 views

What will happen if a scorpion pierces itself?

If a scorpion pierces itself, will it die or immune to its poison? If it produces the venom its blood should be immune to itself poison.
6
votes
3answers
264 views

Proteins folding

Some of us are involved in the folding@home project, spending time, money and resources. I would like to know an answer to two main questions: how do we know we fold it right? I mean these models ...
4
votes
1answer
382 views

What are the lower and upper hearing limits of the human ear?

I am looking for the loudness limits, expressed in decibels, for the human ear. Google or Wikipedia giving me only frequency limit human ear can receive, but I cannot find mention about the decibel ...
4
votes
1answer
5k views

Why did the sensitive plant (Mimosa pudica) evolve its leaf-closing mechanism?

Why did the sensitive plant, Mimosa pudica, evolve its leaf closing mechanism? Does it help in a heavy storm? Does it scare off whatever animals might think it a good meal?
3
votes
1answer
123 views

Expression/Mechanism of ROR1 in healthy tissue

ROR1 is currently under investigation as a therapeutic target for cancer (1). A number of studies show different cancers may have their metastatic potential reduced, or become apoptotic through ...
12
votes
1answer
1k views

How is Taq polymerase produced?

I've seen Taq polymerase being marketed as either "native" or "recombinant". I understand that the recombinant version is produced by specially modified Escherichia coli strains that have the gene for ...
6
votes
1answer
180 views

What are the positive effects of wrongful antibiotic use on a viral infection?

I categorically accept that bacteria differ from viruses; so antibiotics DON'T help in viral infections. I also read this and this; so no need to explain this. I've read about the negative effects (eg ...
0
votes
0answers
303 views

Barr body Giemsa staining

Why not all the female cheek cells show Barr Bodies when stained with Giemsa stain?? only 30 to 40 % female cells showed Barr Bodies . Why?
17
votes
2answers
7k views

How and why did mammals go back to the oceans?

If I understand evolutionary biology correctly, mammals first evolved on land as small, rodent-like creatures, in a time when reptiles were dominant on land. Eventually, they diversified into the ...
6
votes
2answers
287 views

Advantage of opponent color?

Opponent process is a color theory that states that the human visual system interprets information about color by processing signals from cones and rods in an antagonistic manner (source). What is ...
9
votes
3answers
416 views

How can I align more than 2 sequences locally?

ClustalW and Omega of EBI and Blast of NCBI, both globally align sequences. Smith waterman of EBI aligns sequences locally, but works with just two sequences. How can I align more than 2 sequences ...
6
votes
2answers
99 views

What level of cellular radiation is harmful for humans?

What level of radiation at the frequencies used by the cellular network(1-2 Ghz) is harmful for human health?
8
votes
3answers
9k views

How fast do cancer cells divide, compared to normal cells?

This question suggests that we have, on average, 50-70 billion cell divisions per day. I just read that cancer cells divide more often and are therefore more prone to radiation. I am wondering, for ...
5
votes
1answer
75 views

Stretching and compressing bones

The Young's modulus of elasticity when a bone is stretched is : 16×109 and when it is compressed, it is 9×109 N/m2. That means, change in length will be more if you compress a bone as compared to ...
9
votes
1answer
1k views

Why are butterflies drinking blood?

According to this video, butterflies sometimes drink blood. Do they have the organs necessary to digest blood? I thought they eat only salts and nectar, which are easy to digest compared to proteins. ...
2
votes
1answer
47 views

Are both (partial) copies of DNA transcribed in S and G2 phases of cell cycle?

For a little less than half the cell cycle, a significant number of genes are represented twice (just before dividing). Does the cell differentiate between these DNA in any way or are transcription ...
5
votes
1answer
162 views

Can reptiles digest grains?

As a caretaker of a turtle, I sometimes struggle understanding the logic behind the inclusion of corn, soybean, and wheat meals in reptile food, such ingredients seem truly aberrant from what a ...
1
vote
1answer
160 views

Yeast absorption of different spectra of light

I'd like to monitor the growth of a yeast population by shining light through it and monitoring the change in light that gets through as it grows. I'm not sure if I should use IR, or any particular ...
7
votes
3answers
175 views

Mechanism by which $lacI^{d}$ is a dominant mutation, impairing the function of normal copies of the Lac Repressor

Jacob-Monod model for the lac Operon was based on experiments using two strands of bacteria which constitutively expressed $\beta$-gal: $I^{c}$(mutation in the gene lacI , which encodes the repressor) ...
2
votes
2answers
67 views

C. elegans are either male or hermaphrodites, but why aren't there any females?

From my understanding C. elegans are mainly hermaphrodites but are occasionally males to increase genetic variation. Why is it that random females aren't born instead to achieve he same goal (genetic ...
4
votes
1answer
77 views

Can anti-aging cream work?

I have a friend who told me that anti-aging cream cannot work to reduce wrinkles as it only penetrates x amount of skin layers and can never make a long term effect. Me not knowing much about how ...
1
vote
1answer
106 views

What are genome wide functional linkages?

There are two types of interaction classifications used to describe Protein-protein interactions, namely physical and functional. Whilst physical interactions are obvious in nature and methodological ...
1
vote
0answers
30 views

Immediate Early Genes during sleep

In Neuroscience 3rd ed by Bear et al. on page 607, immediate early genes are described as related to changing synaptic strength, yet have decreased expression during sleep. The explanation given is ...
8
votes
1answer
240 views

What sample sizes are ideal for carrying out Bayesian Skyline Plots?

I am interested in creating Bayesian Skyline Plots to look at demographic changes in certain population groups. However, these populations have very little within population variation. Around 5 ...

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