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54 votes

How do mutations of viruses lead to drug resistance?

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, ...
Charles E. Grant's user avatar
45 votes

Effects of mRNA vaccines on human body processes

I can address some of the points made in the post. One point about the "artificiality": I think there's one fact that's often overlooked in the discussion of mRNA vaccines. SARS‑CoV‑2, for ...
panda-byte's user avatar
37 votes
Accepted

Are mutations a source of genetic variation?

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 ...
Remi.b's user avatar
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36 votes
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Specific mechanism behind lethality of yellow coat color in mice

Really interesting question: The lethal yellow mutation (also abbreviated Ay) affects the agouti signalling protein which plays a major role in pigmentation. Heterozygous expression of it leads to the ...
Chris's user avatar
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24 votes
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Is female the default sex in humans?

Summary: The idea that primary sexual determination defaults to female was proposed several decades ago and is primarily based on the observation that, in the absence of Sry, ovarian development ...
canadianer's user avatar
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20 votes
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Does a woman contain all the genes needed to make a man?

Human female cells contain most of the genetic information required to make a male, but they do not contain a critical component: The Y chromosome. This is a relatively small chromosome. Wikipedia ...
Neil Slater's user avatar
20 votes
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How did Mendel know if a plant was a homozygous tall (TT), or a heterozygous tall (Tt)?

Pea plants naturally self-fertilize. So a pea plant that hasn't been manipulated will be "true breeding" that is, homozygous for the allele in question. You can therefore tell after you've ...
swbarnes2's user avatar
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18 votes
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How do geneticists determine if a gene mutation is pathogenic?

The presence of a single variant relative to reference in a single patient is usually not considered adequate evidence to say that the variant causes a patient phenotype. It might be considered an ...
Maximilian Press's user avatar
16 votes

Genetic linkage greater than 50 centimorgans

Understanding the statistics we use when talking about recombination rate is an important question that is unfortunately too often dismissed in an intro course to evolutionary biology or population ...
Remi.b's user avatar
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13 votes

Are all carcinogens mutagens?

How can a non-mutagenic agent be carcinogenic? An agent that causes overexpression of oncogenes or inhibition of tumor suppressors, would be carcinogenic but not mutagenic. HPV, for instance, produces ...
WYSIWYG's user avatar
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13 votes

How are DNA virus cladograms actually calculated in practice? Is the procedure different for RNA viruses? Are these processes somewhat subjective?

How are DNA virus cladograms actually calculated in practice? A cladogram, or phylogenetic tree1, is constructed by comparing similarities and differences between organisms, and placing those within ...
Darlingtonia's user avatar
  • 2,589
12 votes
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How do mutations of viruses lead to drug resistance?

This is molecular evolution and is completely undirected. Mutations happen all the time, most of them disappear without anyone noticing, since they have no evolutionary advantage to permeate. This ...
Chris's user avatar
  • 51.7k
12 votes

Are all carcinogens mutagens?

Alcohol itself is non-mutagenic because it does not directly alter DNA. (Additionally ethanol enhances carcinogenesis and is itself not a carcinogen - updated) There are similar non-mutagenic ...
Asad Yamin's user avatar
10 votes

Is a gene located in the sense or the anti-sense strand?

None of the highlighted regions in your figure, is a gene. A gene is a section of DNA which gives rise to a product. Basically, a gene has an orientation (5'→ 3') i.e. it is essentially a single ...
WYSIWYG's user avatar
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9 votes
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Do any RNAs directly inhibit transcription

Yes there are reports of RNA directly inhibiting transcription. RNA induced transcriptional silencing (RITS) is a well known pathway in Schizosaccharomyces pombe (fission yeast). Initial ...
WYSIWYG's user avatar
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9 votes
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What are the potential dangers (if any) facing the twin girls recently born in China with their CCR5 gene modified?

Important notes: I am not going into the ethical aspects of editing/removing CCR5 in human embryos, neither will I discuss potential effects of introducing that mutation into the human population....
Nicolai's user avatar
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8 votes
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Are there knots in DNA?

I think a key factor is that DNA molecules are not passive bits of string that are left to move freely (which is what causes knots in string-like things that are left alone too long). For one thing ...
Oosaka's user avatar
  • 3,245
8 votes

Have there ever been "half-twins" who were halfway between siblings and twins?

Yes. A case of semi-identical twins was reported in 2006. These twins share 100% of their maternal alleles and 50% for their paternal alleles. It's hypothesized this arose from a double fertilization ...
Darlingtonia's user avatar
  • 2,589
7 votes
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Are SNPs and alleles the same thing?

Alleles are variations of a same locus that codes for a protein (gene). These alleles can come in different forms, one of which is SNP. For example, sickle cell anemia arises from an allele of the ...
Franco Grosso's user avatar
7 votes

Is the genetic term "polycistronic" still used in modern biology?

Yes, it's still used. If you search Pubmed for "polycistronic", it offers you a chart showing the counts of the term by year (top right). Downloading the CSV and making a chart shows that it's ...
iayork's user avatar
  • 14.2k
7 votes

How do mutations of viruses lead to drug resistance?

Summary: They Don't. Long explanation: Mutations happen at random. A series of factors can lead to the perceived notion that the mutation was intentional. The mutation can be harmful, beneficial, ...
Mindwin Remember Monica's user avatar
7 votes

What is the difference between non-coding and intergenic regions?

"Intergenic" is, well, an embarrassment, though it can be hard to avoid. Intergenic means, literally, between genes. Genes are, as you'd expect, genetically defined as regions of the ...
Mike Serfas's user avatar
  • 2,475
7 votes

How are DNA virus cladograms actually calculated in practice? Is the procedure different for RNA viruses? Are these processes somewhat subjective?

Disclaimer: I'm not a bioinformatician, though I occasionally dabble in it, so I may well have some things incorrect. Please feel free to correct or make your own answer. As I see it, you are asking ...
bob1's user avatar
  • 12.3k
7 votes

What is the exact definition of a "gene"?

I found a dedicated paper about the definition of what is a gene. Their short definition is: “a gene is a discrete genomic region whose transcription is regulated by one or more promoters and distal ...
KaPy3141's user avatar
  • 1,597
6 votes

Why does Nature use a 4-level system to encode information in DNA?

Why does nature use a 4-level system (DNA) to encode information? Short answer: Ease of manufacture, simplicity of matching, sufficiency for requirements. Fewer simple bases take less effort to ...
Rob's user avatar
  • 393
6 votes
Accepted

What is the difference between the mitotic spindle and microtubules?

Short answer The spindle is made up of microtubules Background From Nature: Spindle fibers form a protein structure that divides the genetic material in a cell. [...] At the beginning of nuclear ...
AliceD's user avatar
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6 votes
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Can both the overlapping genes (in opposite strands) produce proteins?

While overlapping antisense RNAs are quite well known, there are very few examples in which both the RNAs from the pair can code for proteins. However, it is not impossible. I can cite one validated ...
WYSIWYG's user avatar
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6 votes
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Do transcripts always start and end with exons?

Most (almost all, AFAIK) mRNAs and lncRNAs start with exons for the reasons already mentioned by David. In a typical splicing event, the nucleotide that is 5' to the splice donor site (lets call it ...
WYSIWYG's user avatar
  • 35.6k
6 votes
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Is there a term for when a detrimental gene can be positively selected for because of linkage to a very fit gene?

Genetic hitchhiking / genetic draft From wikipedia Genetic hitchhiking, also called genetic draft or the hitchhiking effect, is when an allele changes frequency not because it itself is under ...
Remi.b's user avatar
  • 68.1k
6 votes

Is there a term for when a detrimental gene can be positively selected for because of linkage to a very fit gene?

(For the direct answer to your question skip to the end!) Genetic linkage can affect the spread of other genes. The degree of linkage, affected by the rate of recombination between the point (...
rg255's user avatar
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