All Questions
12
votes
2answers
6k views
What is the difference between HPLC and FPLC and why is FPLC preferable for protein purification?
I've used HPLC (high performance liquid chromatography) before (once, so I'm barely even qualified to know what it stands for) so I was surprised when my labmate told me she would be using an ...
12
votes
3answers
3k views
How many agarose gel bands are typical for circularised DNA
I am aware that circular DNA can be both relaxed and super coiled. However when running an agarose gel of the circular plasmid along with singly digested plasmid with BamHI and HindIII, I see 1 band ...
12
votes
2answers
220 views
Is there any reason for the variation in mitochondrial DNA size?
As my textbook An Introduction to Genetic Analysis points out, yeast mitochondrial DNA has approximately 78 kb of genetic data, while the human mitochondrial DNA contains 17 kb. Is there any evolution ...
12
votes
2answers
288 views
What is the morphological difference between Leydig cell in human and pig?
The pig is only an example, just an animal. Leydig cells have protein inclusions (Reinke crystals) that are mostly made of crystallised lipofuscin. They are secretory inclusions i.e. cells formed in ...
12
votes
1answer
514 views
Why do neurons die so quickly (relative to other cells) when deprived of oxygen?
This question could be considered a follow-up question to Why is a lack of oxygen fatal to cells?, although the top answer there does not address why damage starts to pop in.
The answer says this:
...
12
votes
3answers
191 views
What is Curved DNA?
CbpA is DNA binding protein found in E. coli and binds non-specifically to curved DNA (Cosgriff et al., 2010), when the bacterium is in a static phase of growth.
The use of "curved DNA" confuses me. ...
12
votes
1answer
293 views
How many people's DNA were involved in the compilation of the reference human genome?
I know that the reference human genome is complied from DNA portions from different people, most of whom were European. Do you know how many of them were involved? Do you know which ones were ...
12
votes
2answers
434 views
Impact of Alan Turing's approach to morphogenesis
Shortly before his untimely passing, the computing pioneer Alan Turing published his most cited paper The Chemical Basis of Morphogenesis (1952).
The central question for Turing was: how does a ...
12
votes
1answer
3k views
What is the significance and method behind Ramachandran plots?
My PI showed a Ramachandran plot in class today with minimal explanation, but I'm interested in finding out more. I understand that the Ramachandran plot shows the relation between the omega phi and ...
12
votes
1answer
131 views
Why do people dying of immune deficiency diseases appear sick?
Please forgive the obviously silly appearance of this question, and/or of the tenor which may come across as flippant or dismissive of real world suffering. My intention is none of the above.
As a ...
12
votes
4answers
297 views
Why does the cold make us sick?
From the moment we learn to communicate, we always get told, whether by our parents, or our teachers, or by anyone else, to avoid the cold, or to put a jacket on to avoid catching a cold, to dry our ...
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 ...
12
votes
1answer
1k views
How does Golgi's neural histological stain work?
What is known about the targets of Golgi staining of neurons? Are larger neurons more likely to be stained? Are specific cell types more susceptible than others?
The current wikipedia article says ...
12
votes
1answer
167 views
What is the prehistory of amino acids in cells?
As a followup to Why 20 amino acids instead of 64? and What is the smallest number of amino acids required for life?, I am trying to understand the prehistory of amino acids in cells.
All living ...
12
votes
1answer
672 views
What causes REM atonia to be lost in sleepwalking?
I understand that in normal REM sleep the voluntary muscles are in effect paralysed in order to prevent an individual acting out their dreams. This paper indicates that there are likley to be ...
12
votes
1answer
270 views
How fast will cells lyse under hypotonic conditions?
Routinely, lysis of cells with hypotonic solutions is carried out along with some physical (douncing) or enzymatic (lysozyme) method to break open the cells. If one were not to do any of these and ...
12
votes
1answer
164 views
How are epigenetic marks transmitted during cell division?
As far as I know, this is one of the biggest questions in the epigenetic field: how are the epigenetic marks like histone modifications propagated through cell division? A lot is already known about ...
11
votes
10answers
474 views
A good book for history of biology/biotechnology for lay people
I have many friends who are interested in Biology and want to know more about the subject in general (like a history of biology, from Darwin's theory, to DNA structure discovery, to the human genome ...
11
votes
4answers
531 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 ...
11
votes
2answers
11k views
Why is DNA replication performed in the 5' to 3' direction?
DNA replication goes in the 5' to 3' direction because DNA polymerase acts on the 3'-OH of the existing strand for adding free nucleotides. Is there any biochemical reason why all organisms evolved to ...
11
votes
4answers
155 views
Are there any examples of proteins with no or minimal sequence identity, but highly similar structure?
What are they, and do they share a common ancestor? How far back in evolutionary time must we go to find them?
If none are known, what computational tools might be used to search for such examples?
11
votes
3answers
605 views
How does the human body metabolize gasoline?
A Chinese man has been drinking gasoline to relieve his pain for 25 years. How does the human body metabolize gasoline? Also, what are the side-affects to gasoline?
11
votes
4answers
2k views
Do cows produce milk excessively?
Do cows produce more milk than it is required for their calves? It seems like cows are able to provide milk all the time (all year around). Is it so? Or do they, like other mammals, produce milk only ...
11
votes
2answers
951 views
What is the advantage of using starter cultures for growing bacteria?
Many DNA isolation and protein expression protocols contain instructions to use a starter culture of E. coli that is then used to inoculate the main culture.
What are the advantages of using starter ...
11
votes
3answers
348 views
Is Behe's experiment (evolving the bacterial flagellum) plausible in the lab?
[Warning: this question is motivated by a prominent proponent of "intelligent design": Prof. Michael Behe. I'm not interested in debating creationism.]
According to Wikipedia[1]:
In Darwin’s ...
11
votes
2answers
229 views
Evolution in 37 years, is it possible?
I am confused, can evolution ( speciation ) really occur in such a short time ?
In 1971, biologists moved five adult pairs of Italian wall lizards from their home island of Pod Kopiste, in the ...
11
votes
4answers
203 views
Why did high A+T content create problems for the Plasmoduim falciparum genome project?
The main paper for the Plasmodium palciparum genome project (Gardner et al., 2002) repeatedly mentioned that the unusually high A+T content (~80%) of the genome caused problems. For example they imply ...
11
votes
2answers
388 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 ...
11
votes
3answers
458 views
Why do red blood cells contain haemoglobin and not myoglobin?
So I am reading about muscles and I come across myoglobin. It has a much higher affinity for oxygen than haemoglobin. So why have animals evolved to have haemoglobin in red blood cells, rather than ...
11
votes
2answers
289 views
When did vision evolve for the first time?
Today I wondered what the first organism to evolve vision would have been. I assume that it would have been kind of primitive and basic, but of course extremely innovative and eventually useful to a ...
11
votes
3answers
445 views
What happens to dextrorotatory amino acids in humans?
As indicated by this question, most of the amino acids in the human body have the L-chirality. As enzymes also have handedness, what happens to the D-amino acids that end up within the human body? Are ...
11
votes
2answers
253 views
Are there any plants that fix their own nitrogen?
I know that most nitrogen is fixed through industrial processes and bacterial symbiotic relationships. However, are there any plants that can fix their own atmospheric nitrogen?
11
votes
1answer
180 views
Abiogenesis: Beyond the research journals as a lead in to discussions on evolution
I just came across this abstract:
Aminoacyl-tRNA synthetases (aaRSs) are responsible for creating the pool of correctly charged aminoacyl-tRNAs that are
necessary for the translation of genetic ...
11
votes
2answers
236 views
What are limiting factors for intron length?
For predicting genes from a sequenced genome, you need to set a maximum intron length. How long can introns get in animals? Is there some limit?
11
votes
2answers
210 views
Is the 'fluttering feeling' when under stress neurological or physical?
I'm sure that everyone is familiar with the sensation commonly known as "butterflies in the stomach". It is commonly experienced during periods of anxiety or stress (e.g. before high stakes job ...
11
votes
4answers
383 views
Why is the Hydra Biologically Immortal?
I have heard that the Hydra organism is biologically immortal (later I found that there are more immortal organisms). Now I know that its immortality is related to its telomerase. The thing is that we ...
11
votes
1answer
847 views
How does a plant grow before photosynthesis is possible?
During photosynthesis, a plant translates CO2, water and light into O2. I assume the carbon C is further used for the growing process. I wonder how the plant grows before the time where photosynthesis ...
11
votes
2answers
325 views
Are there neurons that can sense light shining in your ears?
I know someone who bought earphones that shine light in you ears. According to what he was told, there are neurons that sense light and then make you feel wide awake when activated, which seemed like ...
11
votes
2answers
327 views
Do human beings have pheromone receptors?
What is the current consensus on whether or not humans have receptors that detect pheromones?
If there are purported receptors, in what anatomical areas are they located? With what organ systems do ...
11
votes
1answer
331 views
Are human bodies programmed to die?
Following from this question: What is the evolutionary advantage of death?:
Is there any evidence that human bodies have systemic self-destruction built into their developmental program? I'm not ...
11
votes
2answers
146 views
Why are there N's after Sanger sequencing?
After sending a DNA sample for sequencing, the resulting sequence had N's in the beginning and end of the sequence. I know the N's mean that the computer can't tell what the base pair is, but why is ...
11
votes
2answers
117 views
How to decide which is the correct scientific name for a particular species
To start with, I am not a person having sound knowledge in biology. When I started my search for phyto-chemicals in a particular family in the plant kingdom, I got confused. The scientific papers use ...
11
votes
2answers
872 views
How do insects breathe?
Do ants even breathe? If they don't, how do they stay alive? On what resources do they depend upon to stay alive? How are they different form mammals?
11
votes
1answer
173 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?
11
votes
1answer
209 views
How do porcupines keep from pricking each other while mating?
How do porcupines keep from pricking each other while mating? It seems like they would constantly be scratching each other.
11
votes
1answer
82 views
What are the main mechanisms of interaction between the nervous and immune systems?
We know from pop science that our psychological states have an effect on our immune systems ("worrying ourselves sick", etc.), but what are the actual mechanisms through which our nervous systems pass ...
11
votes
4answers
1k views
Do white Australians have a distinct look?
Background
I've heard from many people working in tourism or similar industries that, white Australians can be recognized as Australian solely by their facial features. Being Australian myself I've ...
11
votes
1answer
199 views
How do members of cryptic species know who to mate with?
According to Wikipedia:
In biology, a cryptic species complex is a group of species which
satisfy the biological definition of species—that is, they are
reproductively isolated from each ...
11
votes
1answer
423 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 ...
11
votes
2answers
231 views
What is the tRNA gene copy variation between different yeast strains?
I just started working on predicting steady-state protein levels from different codon usage bias measures. I have whole-genome sequences (it's NGS data) from different strains of S. cerevisiae and S. ...
