81
votes
1answer
8k views

Do bacteria die of old age?

I know that the cells of mammals at least stop dividing when they are old, and then die a programmed cell death. Then other cells have to replace them. But in a bacterial colony, each cell ...
0
votes
3answers
102 views

Conscious evolution

Does intelligence play a vital role in the evolution of an organism? In other words does an expansion of learning capacity increase the odds of evolution for the particular biological entity?
1
vote
1answer
35 views

DNA Fingerprint

I recently came across an article indicating that the half life of DNA in the most ideal situations is 521 years (http://www.nature.com/news/dna-has-a-521-year-half-life-1.11555). However, since ...
3
votes
1answer
48 views

Do river sharks (genus Glyphis) have reduced rectal glands for salt removal?

Do river sharks of the genus Glyphis have reduced or absent rectal glands for salt removal?   The rectal gland of marine sharks removes excess salts to maintain osmotic balance (Oguri 1964).  In ...
6
votes
2answers
363 views

How efficient is the human body at metabolizing food?

My friend and I were having a discussion over how "efficient" human digestion is. If a human ate a 1000 calorie hamburger, how many of those calories (how much energy) does the body process into ...
5
votes
2answers
3k views

Definition of “Effective population size”

Could you explain to me, what is the meaning of "Effective population size ($N_e$)"? I would appreciate an example as well.
0
votes
2answers
123 views

Chromatids in metaphase?

Please see the following picture: In my book, the author claims that these chromosomes are in metaphase (a metaphase stopped by cholchicin). I don't understand why they don't have two ...
1
vote
0answers
27 views

Can you change your gut microbiota by changing your diet? Would that affect calorie uptake?

I have seen peer-reviewed papers mentioning the daily changes in gut microbiota composition according to dietary changes. See for example this paper: http://genomebiology.com/2014/15/7/R89 My ...
2
votes
2answers
348 views

Is there a medical condition in which you can't cut your hair?

Just curious, does there exist a medical condition in which a patient is advised not to or simply cannot cut their (head) hair?
1
vote
0answers
91 views

What good is the MinION?

This year, Oxford Nanopore MinION has been shipped to some researchers for testing. The advantage of a table-top sequencer for diagnostics and personalized medicine is obvious. Similarly, research ...
2
votes
1answer
150 views

How does core-conductor model correspond to an actual neuron?

Hi guys, looking at your average neuron, it is very difficult for me to imagine how this could be translated into a core-conductor model On the neuron above, where would be the intracellular ...
1
vote
2answers
1k views

What would cause crows to be attracted to a human body?

On another SE site, there was a comment that told me something about biology that I already know: "A man left murdered in the fields would soon have a flock of crows mobbing his fragrant corpse." ...
1
vote
1answer
3k views

What is the difference between second and third generation sequencing

I am writing the section about history of DNA sequencing in the introduction chapter and after reading quite a few research papers, I am still confused about them. Here I compile some questions to ...
1
vote
1answer
92 views

Why is it that bacteria and fungi cannot develop resistance against essential oils?

I wonder why bacteria and fungi cannot develop resistance and mutate agains essential oils? For example, some fungi get killed by oregano oil. Being not a biologist, I hope my question is not so ...
2
votes
3answers
8k views

Why do we weigh less in the morning?

At first I thought it may be related to physics. You know, in one half of the day, the gravity changes, and the scale shows a different weight than the other. Then at night, gravity intensifies, and ...
4
votes
2answers
4k views

Why does a blood test show ethanol when no alcohol was consumed?

Why would ethanol show up in a blood test if a person had not been drinking alcohol in many years. What are other reasons for showing ethanol?
2
votes
2answers
159 views

What does it mean to perform in vitro experiments with mutant bacteria?

I came across the following sentence while reading the paper: Nanchen, Annik, et al. "Cyclic AMP-dependent catabolite repression is the dominant control mechanism of metabolic fluxes under glucose ...
2
votes
1answer
3k views

Complementarity Determining Regions (CDRs)

Complementarity determining regions (CDRs) are part of the variable domains in immunoglobulins (antibodies) and T cell receptors, generated by B-cells and T-cells respectively, where these molecules ...
1
vote
1answer
39 views

Degenerate Alignment Analysis

Can someone please tell me what is Degenerate alignment analysis? Could not find a good article on the internet that could help me understand what it means? (I have not studied biology since last 8 ...
1
vote
0answers
33 views

TAA- Tumor associated antigen [duplicate]

An approach to find Tumor associated antigens is based on transfection of expression library made from cDNA into cells expressing desired MHC haplotypes. Can someone please explain what this line ...
1
vote
1answer
26 views

Microarray probe and target

In a microarray, which one is called a target and which one is the probe? the one that is added later , is that the probe or the one present in the slots of the microarray, that is the probe? (I have ...
2
votes
1answer
245 views

Why do moths not die when they fly into a window?

Sometimes at night when I'm inside with a light on, I can hear (I'm sure) moths fly into the window, and it's so loud I can sometimes hear it over the TV from the other side of the room. Since ...
7
votes
2answers
321 views

How does Natural Selection shape Genetic Variation?

Background Importance of the additive genetic variance As stated here, the fundamental theorem of Natural Selection (NS) by Fisher says: The rate of increase in the mean fitness of any organism ...
2
votes
1answer
54 views

Why can't NMR be used on large RNA molecules?

While reading my Molecular Bio textbook, I came across a sentence that stated that NMR cannot be used on large RNA molecules to determine their structure. Why is this? Is it because RNA is single ...
4
votes
1answer
64 views

Protein Isolation from mammalian cells

What non-SDS buffer can I use to isolate protein from mammalian cells? The protein is intended for testing electron transport chain complexes.
2
votes
0answers
197 views

Origin of the 260/280 ratio?

This is not a duplicate of all the other 260/280 ratio questions, I already know that DNA is supposed to be 1.8 and RNA is supposed to be 2.0. However, this might be more appropriate for chemistry, ...
2
votes
1answer
125 views

What's the mechanism behind 'losing heat through your extremities'?

I can understand how if you are not circulating enough (warm) blood, by not moving much while in a cold environment, your extremities themselves lose heat, and become cold - but I don't understand how ...
3
votes
2answers
149 views

Is there a difference between any of these terms for proteins: “crystal structure,” “NMR structure,” “solution structure,” and “complex structure”?

My homework wants me to plot all crystal structures determined per year, but when I search on PDB for all structures, many of the articles say "crystal structure," but some say "solution structure" or ...
6
votes
1answer
323 views

What does “Mutational Variance” mean?

Background The concept of mutational variance can be found in many articles including this one for example. The mutational variance of a trait number $i$ can be found in the M-matrix in position ...
2
votes
1answer
44 views

What roles do cyclooxygenase, lipoxygenase, and epoxygenase have in signal transduction? [closed]

Besides oxidizing fatty acids to form prostglandins, leukotrienes, and epoxides, what other roles do cyclooxygenase, lipoxygenase, and epoxygenase have in signal transduction?
7
votes
1answer
2k views

What about a bat's immune system protects them from Ebola?

Current evidence indicates that fruit bats are a reservoir host for Ebola. Has any research established what is different about their cell biology or immune system that reduces virulence for them? ...
12
votes
2answers
306 views

Did Darwin ever reach the conclusion that selection will remove variation?

According to simple models of selection the genetic variance in a population should be reduced by selection. (Fisher's fundamental theorem states that the rate at which a population can evolve is ...
2
votes
1answer
117 views

What is the classification for animals with full tube digestive tracts?

What is the formal name for animals with full digestive tracts, by which I mean a mouth and an anus, and what is the classification for animals that have a single hole for exchanging food and waste?
0
votes
2answers
1k views

Negative role of Placenta

How can a placenta turn hostile to the mother or fetus ? What are the abnormalities found during placental delivery ?
8
votes
1answer
454 views

How do birds influence brood sex ratios?

This paper concludes that birds can adaptively modulate brood sex ratios. How do birds modulate brood sex ratios? Are they somehow able to influence the sex of their young? Or once young are born, do ...
1
vote
1answer
39 views

Which sex is homogametic in side-blotched lizards?

I'm just trying to find out whether the male side-blotched lizard is the hetero- or homogametic sex in side-blotched lizards (Uta stansburiana) - some reptiles are ZW system (female heterogamete) and ...
0
votes
2answers
67 views

How is it that ionic diffusion is independent of other ions?

This question arises from the explanation of what the resting potential of a cell membrane is. In the Goldman formula, there is no interaction between different ion types. If diffusion is caused by ...
8
votes
2answers
1k views

Why is the current Ebola outbreak different from previous outbreaks?

I don't know if this question has an answer at this time, but I would like to know if there is some biological reason why the current Ebola outbreak is so much more complicated and widespread than in ...
3
votes
1answer
232 views

Why do we absorb vitamins better from whole foods than from pills?

We can't rely on pills to provide us our nutrients because we don't absorb the nutrients from the pills as effectively. Presumably this is because pills are lacking components that are required for ...
2
votes
1answer
76 views

What is this vinca like vine?

What is this vinca like vine? Is it poisonous? 62521 USA Illinois
4
votes
4answers
310 views

Why can't you just take a vitamin? Why you need a healthy diet on top of that?

From what I understand, your body needs certain amounts of vitamins and minerals to maintain health. Why can't we just take enough pills to obtain these vitamins and minerals?
0
votes
1answer
692 views

Alternative protocol for evaluating RNA integrity, using a bleach gel

I hate having to run MOPS PFA agarose gels with DEPC and everything just to verify my RNA integrity. I came across an alternative protocol that uses ordinary household bleach in the gel to inhibit ...
8
votes
0answers
384 views

What is this fuzzy, black fungus that grew on my plates in the 4⁰C room? [closed]

I often find the fungus below growing on my (ostensibly) sterile plates in the 4⁰C room. Presumably it takes a few days to reach this size. The colony looks puffy and dimpled in the middle, like a ...
4
votes
2answers
189 views

Identification of this insect

These insects lived inside the wood of my bed in little round holes. They bite, lеаving very itchy red marks. And when crushed stink really bad. In the picture the lines are notebook lines for size ...
1
vote
2answers
101 views

Does chromosomal crossover result in a mutation?

Is chromosomal crossover considered a mutation? Would this be a large-scale mutation?
4
votes
1answer
278 views

Do the eyes play any role in producing the visual experiences you have during dreaming?

Sometimes, you remember a vivid picture of a dream that you saw. What is the role of your eye in this experience? Please provide me with the answer that is as simple as possible since I am in Class ...
2
votes
1answer
55 views

Is epilepsy more heritable from maternal side?

I am thinking if paternal or maternal genetic line is the risk factor. Mitochondrial DNA is coming from maternal line. I do not know the pathogenesis of epilepsy so well that I could answer my ...
3
votes
2answers
154 views

Immunodominant Peptide

Can someone please explain me the concept of Immunodominant peptide in simple language?? I did read the wiki article but did not understand it clearly. Please help! (I have not studied biology since ...
2
votes
1answer
98 views

Has it been confirmed yet that the DNA found in dinosaurs was really DNA?

I hear different sources claiming different things, bbc said they did, wikipedia says it hasn't which is it?
8
votes
2answers
2k views

Why do rabbits often have white hindquarters?

There are several species of herbivores that have a very visible white hindquarters: several kinds of deer, rabbits, antelopes, etc. Does the white fur serve a functional purpose, or is it purely ...

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