Questions tagged [molecular-genetics]

The scientific study of the structure and function of genes at the molecular level, particularly chromosomes and DNA.

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Why do eukaryotic organisms have introns in their DNA?

We touched on introns and exons in my bio class, but unfortunately we didn't really talk about why Eukaryotes have introns. It would seem they would have to have some purpose since prokaryotes do not ...
Gordon Gustafson's user avatar
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1 answer
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Specific mechanism behind lethality of yellow coat color in mice

Our high school genetics chapter has some extra information about L.Cuenot. It only covered his research, and the fact that mice homozygous for yellow coat color would die before birth. It was an ...
Amarylis Vaselaar's user avatar
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Effects of mRNA vaccines on human body processes

I would like to understand the effect of an mRNA vaccine on more complex processes in the human body. To what extent does this "artificial", external addition of mRNA interfere with the body'...
choXer's user avatar
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Do animals other than humans have different blood types?

Humans have the ABO and Rhesus blood typing systems. I have two questions about it: Why have we evolved these blood types? Do other animals have different blood types as well?
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Regulation of chromatin structure

Recently, I reviewed the different levels of chromatin structure. The primary level is nucleosomes, where DNA is bound to histones, and has structural similarity to "beads on a string." The secondary ...
Daniel Standage's user avatar
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Are mutations a source of genetic variation?

Here is a question from the book SAT II Success Biology E/M (where the SAT is the exam taken by the American high school students): Which of the following statements is true about mutations? (A) ...
Elena Kolumba's user avatar
18 votes
3 answers
650 views

What is the reason behind choosing the reporter gene when experimenting on your gene of interest?

I noticed within example experiments in class that different reporter genes are chosen to be inserted near your gene of interest to prove whether or not the gene is being expressed. For example, you ...
Kyra's user avatar
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Genetic linkage greater than 50 centimorgans

Classically, the linkage between two loci can be measured in centimorgans (cM), which represents the percent chance that these two loci will recombine an odd number of times (generating a recombinant ...
Superbest's user avatar
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Is female the default sex in humans?

I was taught in school that female is the default sex in humans based on the following logic: Development into a human male requires the activation of the SRY gene in the foetus. If that doesn't ...
user1205901 - Слава Україні's user avatar
15 votes
1 answer
874 views

Can DNA act as a translation substrate?

I get conflicting answers. One would think if it was true, it would be rather seminal and widely known. There are papers from Khorana[1], Holland[2], and Bretscher[3] (late 60s) that suggest that it ...
mdna's user avatar
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How did the genetic code evolve?

The genetic code is redundant, there are 20 amino acids for 64 possible nucleotide combinations (triplet codons). Therefore some amino acid are coded by several different codons. While leucine is ...
Remi.b's user avatar
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Paralogous genes in genome-wide association studies?

Has anybody tested if paralogous genes are over-represented among the genes identified by genome-wide association studies (GWAS)? For example, if a GWAS study finds 200 genes associated to the ...
yahoo301503's user avatar
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Are all carcinogens mutagens?

I assume that all carcinogens must be mutagens, but I've read that this is not the case. However, I can't find any good examples or an explanation of why it is not the case. How can a non-mutagenic ...
user avatar
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Does a man contain all the genes needed to make a woman?

This question is brought on by a Sci Fi novel I am thinking about writing. The plot device involves a colonist in charge of building a population on a new planet who loses his supply of embryos and so ...
wedstrom's user avatar
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Why is AUG the initiation codon?

Is there any reason why AUG is the initiation codon? Can’t translation start with different codons?
biogirl's user avatar
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Are all mutagens carcinogens?

Not all carcinogens are mutagens. Alcohol and estrogen, for example, does not damage DNA. It's one of the assumptions of the Ames test that mutagenicity implies carcinogenicity, but is this always ...
Resonating's user avatar
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What are the potential dangers (if any) facing the twin girls recently born in China with their CCR5 gene modified?

According to this Nature news article, a Chinese researcher claims to have made the world's first genome-edited baby using the popular CRISPR–Cas9 genome-editing tool. A gene called CCR5 was modified ...
user23823's user avatar
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Why does replication require primers while transcription does not?

In transcription, there is no need for any primer. I guess the basic mechanism of DNA polymerase & RNA polymerase is the same. So why does replication have the need for a primer?
anamitra ruj's user avatar
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How does the stem-loop cause intrinsic transcription termination?

In this animation, towards the end (about three quarters) the process of transcription termination is shown. It states that the transcribed RNA forms a hairpin loop (or stem-loop), which halts the ...
arik-so's user avatar
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1 answer
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How did Mendel know if a plant was a homozygous tall (TT), or a heterozygous tall (Tt)?

I had some issues while studying Mendel’s rules of inheritance. How did Mendel, while running his test crosses, know if the plants in his F0 generation were TT (homozygous tall) or Tt (heterozygous ...
Smarika Singh's user avatar
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3 answers
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Are the number of base pairs in a given chromosome same between different individuals?

This is a basic question but I couldn't find an answer through a web search; hopefully this is the right place to ask. Is the number of base pairs in a particular chromosome the same in all ...
unknown's user avatar
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What is positive and negative supercoiling?

Is the following correct? Positive supercoiling = the coiling of DNA helix (B-DNA) on itself during intesified coiling of the two DNA stands in right handed direction negative supercoiling = the ...
Tyto alba's user avatar
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What is the functional and structural distinction between core (H2A, H2B, H3,H4) and linker(H1/H5) histones?

Many explanations of histone biochemistry isn't quite elucidating for the undergraduate student. How does histone structure (dimers, octomers) relate to their specific functions as core or linker ...
LanceLafontaine's user avatar
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2 answers
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Do single crossovers occur in circular polynucleotides?

Single crossovers in circular pieces of DNA do not seem to be a big topic, because if they happened, they would lead to a kind of combined chromosome with two inner strands and one large outer strand. ...
Armatus's user avatar
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Why does Nature use a 4-level system to encode information in DNA?

First, I am not a biologist, so this question might be naive: Computer information processing and storage is based on 2-digit system of bits with values 0 and 1. Now, DNA stores the information in a ...
Mario Krenn's user avatar
10 votes
1 answer
15k views

What is the difference between "cistron" and "gene"?

I'm asking after reading the cognate wikipedia.en article on "cistron". I am still not sure about the difference between the two terms. To me it seems valid to picture a "cistron" as the genome wide ...
pidoretroma's user avatar
10 votes
3 answers
2k views

Why did scientists think humans had 100,000 genes (before the Human Genome Project)?

One of the major results of the Human Genome Project (HGP) was that humans have far fewer separate genes than previously thought. From a 2004 article about the HGP: Francis S. Collins, director of ...
tel's user avatar
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What is the highest competency possible for E coli?

I am looking to find a highly competent E coli strain. I am making a library of a ~6.6kb plasmid and I am not getting high enough efficiency. Does anyone have a suggestion of a strain/protocol with ...
Justin Smith's user avatar
10 votes
2 answers
419 views

Is there a dominant gene for right-handedness?

Has there been any definitive research about handedness being genetic? Also, why is right-handedness clearly dominant in humans? I'm interested in evolutionary theories, as well as any molecular ...
LanceLafontaine's user avatar
10 votes
3 answers
33k views

What's the difference between shotgun sequencing and clone based sequencing?

In a lecture during my undergraduate degree we were introduced to the race to complete the human genome. Celera were competing with Sanger and collaborators to sequence the human genome. Celera ...
James's user avatar
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Methods of nuclear transfection - nuclear transport

I am reading through the ENCODE papers, which is taking me well out of my comfort zone in terms of modern laboratory techniques. At the risk of asking a question which may well be thoroughly answered ...
masonk's user avatar
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2 answers
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Why do DNA and RNA have the functions they have?

I know that there are two most important directions of genetic information transfer in living organisms: DNA->DNA and DNA->RNA. The first is replication, and the second is transcription. I wonder if ...
ymar's user avatar
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4 answers
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Are there constraints on where intron/exon boundaries occur with respect to the triplet codons of the reading frame?

I did a quick search (here and elsewhere) and couldn't find anything on this subject. If all introns in a given primary transcript were spliced out in the same way, then this wouldn't matter. But ...
diogenes's user avatar
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9 votes
3 answers
491 views

Splice in with CRISPR/Cas

I need to splice a gene into a human cell genome, with highest rate possible. I mean, doesn't really matter where the gene enters, nor does it matter if some cells die as a result of this. CRISPR ...
Robertos's user avatar
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9 votes
1 answer
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RNA migrating slower than DNA on Formaldehyde Gel?

So I ran into an interesting problem. I'm getting a linear DNA band that is twice as long (4x bases, but as denatured probably only 2x) as an RNA band running at the same size in a formaldehyde gel. ...
Atl LED's user avatar
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9 votes
1 answer
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What determines the number of chromosomes an organism carries?

This is an extension of this question about What limits chromosomal length?. I am wondering what could be the specific reasons behind the number of chromosomes an organism carries. In other words, ...
cagliari2005's user avatar
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How do mutations of viruses lead to drug resistance?

For instance, after starting zidovudine monotherapy against HIV, resistance develops against the drug because of a point mutation in the RNA transcriptase enzyme to which the drug binds. So how does ...
user73023's user avatar
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8 votes
5 answers
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What's the aim of genetically modifying of foods/organisms?

On news, articles etc. experts talking about Genetically Modified Foods and Organisms often mentions about their disadvantages like, their potential to harm human health allergies may become more ...
pikk's user avatar
  • 511
8 votes
6 answers
1k views

What is the lowest common denominator of cancer?

What is the lowest level attribute that all cancers share? Also, what is the highest level attributes that all cancers share?
David Walz's user avatar
8 votes
2 answers
2k views

Redundancy of the genetic code

One particular codon codes only for one amino acid, but an amino acid can be coded for by several different codons. Now according to the genetic code, the codon UUU ...
user avatar
8 votes
1 answer
2k views

How to clone and sequence a gene transcript of unknown sequence?

How might I go about amplifying a gene transcript (mRNA) from animal tissue of which little is known about the genome? In some applications, I have used reverse transcriptase PCR to amplify all mRNA ...
user avatar
8 votes
2 answers
7k views

Gene & Protein nomenclature: N-Myc, c-Myc, et. al

Can someone explain (or point me to an explanation of) exactly what is meant by all the different symbols I see used for writing genes and proteins? I think I know that for genes, we use an italic ...
Kevin Ford The Submariner's user avatar
8 votes
1 answer
3k views

Smallest unit on which selection can act

Traditionally, the individual was considered to be the smallest unit on which Natural Selection (NS) acts. Today, we usually consider the gene as being the unit of NS. Of course, we should also ...
Remi.b's user avatar
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8 votes
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Difference between mutation and DNA damage

What is the strict difference between mutation and DNA damage? As far as I understand it, a mutation is an alteration in the genetic sequence, having "tricked" the repairing machinery and thus ...
Katz's user avatar
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8 votes
1 answer
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Why some cells don't produce purines?

It is said that erythrocytes, polymorphonuclear leukocytes and brain cannot produce purines. And the reason given as per this site is: Human brain tissue has a low level of PRPP glutamyl ...
JM97's user avatar
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8 votes
1 answer
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How is the exogenous DNA protected from degradation during bacterial transformation?

During transformation, a bacterium can take up DNA from its environment. A small fraction of bacterial species are known to be naturally competent, meaning that they can engage in this sort of ...
Cody Gray - on strike's user avatar
7 votes
2 answers
1k views

How do geneticists determine if a gene mutation is pathogenic?

I am analysing information about patients with neurodevelopmental disorders using the DECIPHER genomics database. I am looking for patients who have only a specific gene deleted and no other mutations ...
ceno980's user avatar
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7 votes
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996 views

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

The May 24, 2022 Bloomberg opinion piece Monkeypox Isn’t Looking Like a Covid-Sized Threat; It’s still early, but contact-tracing efforts and analysis of the virus’s genome offer hope that this ...
uhoh's user avatar
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7 votes
1 answer
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Can DNA & RNA be considered as nature's programming language?

The final frontier of Biological Sciences could be considered understanding the effects of variation in the DNA (and RNA). If after fertilization the DNA of the zygote could be genetically ...
arnabanimesh's user avatar
7 votes
1 answer
467 views

Do nucleosomes ever completely unwrap during transcription?

In eukaryotic transcription will the nucleosomes ever completely unwind the DNA and the histone complex disassemble? If an operon is more 160 base pairs it seems it must.
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