43
votes
Accepted
How many times has SARS-CoV-2 mutated?
This question makes a number of incorrect assumptions and I don't have time to correct them. The short answer is that the virus has mutated probably hundreds of times since it entered humans in late ...
- 14.1k
11
votes
Why is ATP the preferred choice for energy carriers?
I don’t like this sort of question because I don’t think it can really be answered and I’m very suspicious of arguments that seem to claim ATP is the only or even the best solution to the problem. ...
- 23.3k
8
votes
Accepted
What came first? The DNA or the DNA polymerases?
The straight forward answer is: we don't know. We don't have any direct evidence for what happened at that time nor any completely developed and coherent theories for how it worked.
The widely ...
- 6,851
7
votes
Accepted
Approaches towards a theory of innovation in evolution
The flaw in his argument, from what I can see in your quotes, is to equate evolution to natural selection. Natural selection was never proposed to explain all evolution, nor how advantageous traits ...
- 16.1k
7
votes
Why do nerve cells convert electric signals to chemical signals?
There are two types of synapses:
Chemical synapse
Electrical synapse
The first one is the one you are asking about. The second one corresponds to the faster synapse you are imagining. It consists ...
- 171
7
votes
Accepted
Does the Miller-Urey experiment explain the origin of life?
This is a common question. I think the experiment and its conclusions are often misunderstood.
Originally, the null hypothesis was that the ingredients for life could not have come about spontaneously,...
- 6,124
7
votes
Defining "species" (Are species an emergent property or an ensemble of quantitative differences?)
Can we give a robust definition of species?
No.
Species constantly evolve, diverge, converge, interbreed, and mix and shuffle and trade and spread genes. To draw a box at any particular point in ...
- 6,124
6
votes
Accepted
Why are there both stop and start codons?
Start and stop codons are instructions for the ribosome to start and stop protein synthesis, respectively.
The region between the start and stop codon (inclusive of them) is called ORF (open reading ...
- 35.2k
6
votes
Text Book Recommendation: Organic Evolution
Organic Evolution - Definition
'Organic evolution' was a common term. It is just rarely used today. Today, we just say 'evolution' or 'evolutionary biology' when referring to the field of study of '...
- 67.8k
6
votes
Accepted
Is evolution a means to an end?
Good question--I think the first point to address is "a means to an end" seems to imply willful action. That is, evolution (according to Ridley) would be a conscious effort by a species to optimize ...
6
votes
Accepted
What is neutral theory of evolution?
A short answer (converted from a comment): I would call neutral theory a useful null model: in particular, it may be less important that it be a factually correct description of natural systems (i.e. &...
- 5,244
6
votes
Why is DNA replication so much faster in prokaryotes than eukaryotes?
The difference in DNA replication rate between prokaryotes and eukaryotes is still under current research, but the basics are understood. It is very much a matter of complexity, as eukaryotes are more ...
- 594
6
votes
Accepted
can a cell evolve into a different species in the lab?
First it is worth noting individuals don't evolve, populations evolve.
We can observe cells giving rise to different cells, the long term E.coli experiment is a famous and ongoing example, not only ...
- 13.8k
6
votes
Why isn't speciation a negative feedback loop?
I'd suggest looking at this article, which contains an intuitive model for how hybrid incompatibilities can arise between isolated sister taxa (i.e. populations). This criterion of pre-existing ...
- 8,598
5
votes
Two 20 million yr old fossils of Hummingbirds found "The amazing thing about the fossil is that it's essentially a modern hummingbird
Hummingbirds were not created, they evolved.
Ancestors of a modern species need not be that morphologically different from their progeny, even over a time span of millions of years. And organism will ...
- 4,975
5
votes
Accepted
Evolution of the Redundancy of the Genetic Code
To fully comprehend the concept of wobble base-pairing we need to consider the nucleotide sequences of the anti-codons in the tRNAs that have to "read" the genetic code when the mRNA is being ...
- 3,487
5
votes
Why is ATP the preferred choice for energy carriers?
Preface
I have already provided an answer to this question, addressing one aspect of it: why a nucleotide triphosphate — rather than any other molecule — was the choice for an energy carrier. In that ...
- 23.3k
5
votes
Accepted
Is there selection against long proteins and long genes?
Is there evidence of selection against long proteins and long genes?
I am not aware of any such evidence and cursory googling did not reveal studies that researched a correlation between gene ...
- 1,209
5
votes
Accepted
How did mitochondria make energy long ago?
You are asking a very interesting question.
As you correctly mention, the substrates of mitochondrial metabolism (TCA or Krebs Cycle) are pyruvate and NADH, and, through oxidative reactions, ATP is ...
- 134
5
votes
Accepted
Can estimating the likelihood of protein sequences adopting functional enzyme folds show life is too complex for evolutionary timescales?
I think your acquaintance is trying to fit real science to some of his personal beliefs (that are obviously wrong).
If you read the article you'll see that it's not about evolution at all, but about ...
- 1,463
5
votes
Why do (almost) all energy carriers contain adenine?
As @canadianer comments, this question is unanswerable, and it verges on being classified as ‘opinion-based’. However, because I do not find the answer from the OP appealing, I’ve set out a few points ...
- 23.3k
5
votes
What are some examples of non-homologous sequences having similar functions?
Serine Protease Catalytic Triad
This is classic example of convergent evolution in catalytic mechanisms. Shown below are chymotrypsin (4CHA, green) and subtilisin (1ST2, blue) aligned on their ...
- 17.6k
5
votes
Accepted
Why is the GULO pseudo gene expressed in humans?
I suggest thinking about this from a different direction — something like: "What selection pressure is there for loss of expression of the GULO pseudogene?"
When thinking about that question note ...
- 5,513
5
votes
What is neutral theory of evolution?
Your question would deserve a long essay. R.C. Lewontin wrote a book ("The genetic basis of evolutionary change" - Columbia U.P) on this subject in 1974, right after the neutral theory had ...
- 136
5
votes
Population Genetics Using WGS: How do I know when I have enough individuals?
I think that many of the applications that you mention require wildly different numbers of individuals. It would help to know more about goals, questions, organism details, etc.
For example, for ...
- 8,598
4
votes
Why are there both stop and start codons?
It is important to have start and stop codons so that the molecular machinery of the cell (ribosome etc.) "know" where the actual transcript starts and ends. This is especially important, since mature ...
- 51.1k
4
votes
Why are there both stop and start codons?
Not all the RNA is to be translated into proteins. Actually most of it is for regulation and sometimes unknown use. There are non coding regions before the start codon and after the stop codon. Hence ...
- 206
4
votes
How did the genetic code evolve?
It seems that duplicate codons make translation more robust and resistant to translational misreading. There are four theories that explain existence of duplicate codons:
Stereochemical theory
...
- 1,025
4
votes
Do animals other than humans have different blood types?
The answer to this question can be found by searching the Internet.
For some blood types, evolution and environmental selective pressures
are clearly important for their persistence. For example, ...
- 1,442
4
votes
Evolution of the common honey bee's stinger
The answer to the question "has evolution designed the common Honey Bee's stinger solely for stinging man-kind?" is no.
A honey bee's barbed stinger remains in the skin of any mammal afterwards due ...
- 3,348
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