107

At the moment, there is very little scientific literature about this, but I found two papers that address the problem and are fairly easy to understand. You can find them in the references. Reference 1 is probably the most interesting and is the basis for this answer. Edit: It is also interesting to read reference 2 on the origin of SARS-CoV-2; the article ...


54

It doesn't. Viruses don't "know" anything. Mutations occur at random. Most of them don't do anything, or have a slight negative effect on the ability of the virus to infect and reproduce. However, there are billions and billions of viruses. Once in a while a random mutation will offer a significant advantage like immunity to an anti-viral drug. The viruses ...


52

There are two relatively common contagious cancers: Tasmanian Devil Facial Tumor, and Canine Transmissible Venereal Tumor. Both are truly contagious cancers, in that the cancer cells themselves are transmitted from one host to the next, and expand and cause disease in each successive host. (There was also a contagious cancer of hamsters, which has long ...


49

What do you mean by siblings? If by siblings, you accept cases of individuals having the same father but not the same mother, then of course, it is possible! Below, I will assume you are referring to full siblings (eventually twins). Age gap between twins According to the huffingtonpost, there is a case of two twins that were born 87 days apart. On ...


47

Short answer The article in particular that you reference is discussing the possibility of using a mechanism called gene drive. The concept of gene drive breaks the normal "rules" of inheritance and allows a gene to spread much more rapidly than normal in a population. Longer answer Gene drive depends on the idea of a selfish gene. There are naturally ...


43

Take a look at this little fellow: It's a flying squirrel — a shy little nocturnal rodent which lives in trees and, despite its name, does not actually fly. It does, however, have a skin membrane called a patagium between its fore and hind limbs which allows it to glide from tree to tree and thus evade ground predators. It's not hard to see how the ...


42

This is a poly(A) tail, which is a feature found in the majority of eukaryotic RNAs (especially mRNA) and is also not uncommon in RNA viruses (which essentially mimic endogenous mRNA for their own replication). As with mRNA, this poly(A) tail in coronaviruses is bound by poly(A) binding protein in the cytoplasm [1], which is involved in translation ...


40

Yes. Far-red vision (>700nm) The ability for retinal-binding proteins to absorb far-red (between 700nm-850nm) light has been experimentally confirmed in this paper. While the authors did not attempt this in vivo in an animal model, they managed to use directed mutagenesis to induce a significant shift in the absorption peak of the chromophore of the ...


37

Going through the possible answers (A) Rates tend to be very high in most populations. This is a very unclear statement. What does "high" mean? In humans, the average mutation rate per reproduction per nucleotide is of the order of $10^{-8}$ (Rahbari et al., 2016) (hence of the order of 10 - 100 mutations for the whole genome). Whether someone ...


33

It is true that the Y chromosome is shorter than the X chromosome and that there are more genes on the X chromosome. Do men have fewer genes? One could (mis)understand three things in the expression "number of genes". Number of gene copies (see Copy Number Variation) Number of genes Number of alleles Thanks to @GerardoFurtado for correcting my ...


33

It is highly unlikely that there exist any protein that is made from completely identical nucleotide sequences across the entire human population. There will certainly be regions within a gene that are highly conserved, but there is little evolutionary pressure to conserve an entire gene's nucleotide sequence across the population. This is in part due to ...


31

The first modern humans evolved about 200.000 years ago in Africa. When they lost their body hair (or at least most of it), they needed some other protection of their skin from the sun - otherwise they are prone to develop melanoma. Melanin is such a protection, and the rate of melanoma is much lower in dark skinned people. There is also a nice correlation ...


30

[G]iven two potatoes, one GMO and one natural, would you be able to detect which is which without having any samples or knowledge about what parts of DNA to consider engineered by humans? No, you can't distinguish them without knowing a priori the DNA sequence of the wildtype and of the GMO. There is no other mark left within a GMO in the general sense. ...


29

TL;DR I'd recommend Population Genetics: A Concise Guide (Gillespie) for an introduction to population/evolutionary genetics. I'd recommend A Biologist's guide to mathematical modelling in evolution and ecology (Otto and Day) if you want to ensure your knowledge in mathematics by learning their application to evolutionary biology. General Entry Books to ...


27

The two key concepts here are: sex-specific selection, and the fact that males and females share the majority of genes 1) sex-specific selection Obviously, any population where females lacked nipples would be in trouble. Men, on the other hand, have no evolutionary need for them, but they don't pay much either - there is no strong selection against men ...


27

Yes, this can happen in non-twins. There is a rare phenomenon that can occur in humans (and some other animals), called 'Superfetation'. This is when some time during pregnancy, a woman has a second oocyte fertilized and implanted. This event is an entirely separate conception, and results in two fetuses of slightly different ages in the womb simultaneously. ...


26

OK, I'll have a go although you really shouldn't combine so many questions into one. 1 The mutation protection "paradox" As already mentioned while many mutations are caught and corrected, not all of them are. You have to consider that a body (the human one, for example) contains several trillion cells, each of which contains 3 billion nucleotides ...


25

Here is a tutorial to perfectly understand Hardy-Weinberg Rule! If you feel like you just need a brief reminder, you can skip the text until the section In short... and try out the exercises just to check your understanding. Terms you should know a priori I will not define the following terms, so make sure you understand them locus allele (relative) ...


24

Check out this famous paper by Gould and Lewontin, the Spandrels of San Marco. It's essentially a criticism of your question as it's not really the right question to ask. You're engaging in what they call "adaptive storytelling". The truth is that barring fossil intermediaries it's almost impossible to infer how a species transitioned from primitive ...


24

Actually it is a very important question for laboratory animals (and, I imagine, endangered species) and was calculated to be 25 couples. With any number of animals (including humans), there is always some inbreeding happening, but you can reduce it with the number of breeding pairs and careful pairing. When you get to 25 pairs (50 animals) and have ...


24

Diploid organisms, such as we are, generally have two copies of each gene (excepting the sex chromosomes in males). In order to display the genotype for each, geneticists use shorthand. When referring to a gene, + means the wildtype, which is the "normal" version, and - means that the gene is missing, often a knockout. So a typical individual's genome for ...


23

One must always be careful not to stretch an analogy further than it can withstand, but since you started these analogies, I will follow up on them and explain the small mistake you've done in their representations. The two books are not as different as you have in mind. You are not pasting the beginning of Uncle Tom's Cabin with the ending of Harry Potter ...


22

I've been doing some reading, and have come up with the following interesting information. Telomeres During cell division the DNA is replicated, but the mechanism is imperfect and in each round of cell division a small section is lost from the end of each chromosome. To compensate and protect the genetic information there are caps – regions of excess ...


22

When dealing with humans, there are only two Biological genders as defined by the presence or absence of the Y-Chromosome. If the Y-Chromosome is not present, or through some process gets totally deactivated, the human will appear and function as a Female. XX = Female XY = Male XXY = Male (Klinefelter's Syndrome) XYY = Male (Aneuploidy - Normal ...


22

So, a quick molecular biology lesson. Proteins are the things that make up a good percentage of our cells (which make up a good percentage of us), and are the things that do the work of the cells - many are catalysts and are known as "enzymes". Proteins are encoded by genes - while the statement that one gene codes for one protein is not quite correct (...


22

Rather than discussing what heritability is not through wordy sentences, let's just talk about what heritability is. There are two "types of heritability": Heritability in the broad sense Heritability in the narrow sense. I will discuss a few concepts and slowly introduce the concept of heritability in both senses. Phenotypic trait The phenotype is the ...


22

Humans have many variants There is variation. The project I use to help understand this natural variation is gnomAD. Using VarMap and a slightly out of date gnomAD file, I counted 16007805 protein-coding variants across the human genome. This number will only go up over time. Indeed, the 1000 Genome project found that on average each person has between 250-...


21

The paper by Lobo and Levin is an attempt to learn a model that represents the inner workings of a biological system by fitting parameters to data. This is a common topic in "systems biology", a model-based approach to studying biology that is popular in some fields. Even for small systems, this is a phenomenally hard problem. Unlike most machine learning ...


21

Independent assortment. Mendel showed that his genetic markers for different traits, or phenotypes are transmitted randomly to the F1 generation. This was before the concept of linkage was discovered, so fortunately he selected unlinked genes. Segregation of alleles. The dominant and recessive alleles segregate away from each other when the germ cells are ...


21

If you need more [counter]evidence, there's a newer paper "The proximal origin of SARS-CoV-2" by Andersen et al. (March, 17) that touches on the same topic. The paper brings up two reasons why SARS-CoV-2 is not "made in a lab". The first is the (relative) [in]efficiency of its spike protein; the second is somewhat more complex to explain ...


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