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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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What is the most complex biological organism (or precursors) that we have been able to synthesize from raw materials?

In the Miller–Urey experiment they produced several amino acids. I'm not sure if there were other similar experiments that got further. http://www.jcvi.org/cms/press/press-releases/full-text/article/...
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To what extent is the genetic code more than just a code?

It is worth specifying the exact meaning of "code" in this question. A code is a map from one space to another space with which it has no algorithmic connection. Thus representing 321 as 0x141 is not ...
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Can bacteria pick up lethal plasmids?

I am sorry if this question is too general, and does not have any concrete answer. I was explaining to my non-biology-background friend about plasmids and how they are picked up by bacteria from the ...
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Can DNA be flattened?

DNA is always shaped like a double helix. But could you flatten the double helix (which is essentially just a twisted ladder) and would DNA still be able to duplicate and control cells?
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Is gene only the portion of a single strand which codes for a particular protein?

I know that gene is a segment of DNA that codes for a specific protein. But is it a segment of a single DNA molecule or a DNA duplex? The given image shows a section of a dsDNA. Source of image:...
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Abbreviations for molecules: What are CheW, CheA, CheY?

I've encountered the abbreviations such as "CheW" and "CheA" for certain organic molecules. For example: Proteins associating with the Tar complex include the autophosphorylating protein kinase ...
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Genetics of epilepsy

Is epilepsy genetically inheritable? If yes, is it dominant?
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Restriction endonucleases are found in?

Quoting from : Scientific American July 1975 The Manipulation of genes by Stanley Cohen : Restriction endonucleases (and modification methylases) are widespread in microorganisms; genes for ...
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Which restriction enzyme would i use?

Plasmid pBr322 includes two genes that confer antibiotic resistance: a gene for ampicillin and a gene for tetracycline. The cutting site for the restriction enzyme BamH1 is in the middle pf the ...
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Is there any independent non-DNA based information system in the cell

The information in protein is not neccessarily independent of the genome as the information of amino-acid sequence comes directly from the genome. The process of post-translational modification may ...
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What are Expressed Sequence Tags (EST)?

I read in an article that ESTs are partial or sub-sequences of cDNA. What are ESTs exactly? Which part of cDNA is cut in order to make ESTs? Why are they so instrumental in genomic research?
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Is every protein encoded by just one gene?

Beadle and Tatum proposed the “one gene, one enzyme” hypothesis in the 1940s, and this was later modified to “one gene, one protein”, i.e. that one gene codes for one protein. Have any exceptions to ...
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Is it possible to have multiple stop codons in one exon?

I would be very happy if someone can help me to find the answers for the following related questions. Can one exon have many stop codons? Can protein synthesis happen, if the stop codon is at the ...
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How do DNA-binding proteins recognize the correct DNA base pairs?

My professor posed this question to the class today - "How do DNA binding proteins specifically bind to base pairs?" He alluded to the different arrangements of hydrogen-bond donor and acceptors in A-...
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Explanation about cytogenetic notation

What is the correct meaning of cytogenetic notation "inv(4)(p13q22)" ? Inversions at chromosome 4, at the p arm 13 is inverted AND at q arm 22 is inverted OR Inversions at chromosome 4, the p13 ...
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Telomere and its effect on aging

The cloned sheep, Dolly, was said to have died very soon because the cells used to create it were taken from an adult sheep with an aged telomere. Why doesn't this happen with humans? Why aren't we ...
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960 views

Various Genetic Loads and their Definitions

In population genetics, we talk about several types of genetic loads (also called just loads). I am asking for a exhaustive list and a short definition. Here are for example some genetic loads that ...
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Inbreeding depression and dominance

From this article, second paragraph of the second page A classic theoretical result is that the mean of a character controlled by a single locus i with two alleles Ai1 and Ai2 is only affected by ...
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How does promoter sequence affect initiation?

I don't know if this might have been highlighted in recent research, but a textbook I have states that "the exact way in which promoter sequence affects [transcription] initiation is unclear" I'm ...
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Organisms that use more than the 20+2 commonly occurring amino acids?

I know scientists have created synthetic bacteria, with a genetic code containing 6 letters instead of 4, with the aim of creating more complex proteins (using amino acids outside of the standard 20+2,...
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Gene terminology - is one gene a concrete, single physical sequence?

Suppose you have two identical copies of the same, coding nucleotide sequence (e.g. two copies of BCL2 - a random gene I found on Wikipedia). Could you say that these are two genes (i.e. the name "...
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What is the role of tracrRNA in CRISPR-cas9?

From what I understand, in a CRISPR cas9 complex, gRNA is comprised of tracrRNA and crRNA. I've read that crRNA is the part which is matched to the DNA which is targeted, but what role does tracrRNA ...
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Can coding DNA be used for DNA fingerprinting?

I am confused if coding DNA can be used for DNA fingerprinting because I have read that non-coding segments of DNA are used to identify and analyze DNA. I want to know if coding DNA segments are of ...
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Do transposons usually jump from one chromosome to another?

If it is usual occurrence, does it mean that my one gene can change its location from one chromosome to another?
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Why increasing the vector concentration does not increase the effeciency of bacterial transformation?

I was reading some old description of the protocols used for the transformation of bacterial cells. In the description I read that the transformation works best with low amount of DNA, and if we ...
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How does alternative splicing work?

I am trying to find out what controls what exons are spliced out, and I keep coming across the term cis regulator, but I cannot seem to find a clear explanation of what happens... Thank you in ...
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Why aren't introns found on the ends of pre-RNA?

We recently learned in genetics class that exons always cap the ends of nascent RNA. I have been trying to figure out the reason why introns can't instead be found on the ends instead of exons. The ...
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Why do we use DNA sequencing methods such as shotgun?

I am learning about DNA cloning for the first time. What I understand is that, in order to clone DNA, we break-up the original gene into shreds. Then try to piece it back together. Why exactly do we ...
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Heterochromatin production limitations

Currently playing with some ideas for a project and needed some guidance. I am wondering, both in Drosophila melanogaster and in general, is the amount of heterochromatin a cell/nucleus can produce ...
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Telomere shortening during replication

It is widely know that each cell cycle during DNA replication some fraction of the telomeres is lost, and this phenomenon is called the end replication problem. Well this is due to the fact that the ...
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Lyonization and X-linked disorders?

Lyonization or X-chromosome inactivation is the conversion of all but one, X-chromosomes in Females into non-coding heterochromatin (i.e. deactivated) leading to the formation of one or more Barr ...
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Knockdown of long noncoding RNA (lncRNA) - how is it done?

I don't work at the wet lab and don't know all the details about the knockdown techniques. My question is: How lncRNA knockdown is done? For example - you have lncRNA that is functional in the nucleus....
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What Ultimately Controls DNA Transcription?

Transcription of DNA and further splicing of mRNA is regulated by various transcription factors, small nuclear RNAs and so on; similarly such related mechanisms as transposition of transposons. All ...
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Why did translation develop a specific codon for initiation?

The translation of mRNA is initiated by a specific methionine-accepting tRNA at a specific initiation codon, usually AUG (complementary to the tRNA anticodon). However translation at suitable (albeit ...
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Antibiotic resistance

I have a biological puzzle that's been perplexing me for years. Can you review my logic and tell me where I'm wrong or if I'm on to something. As I understand it, most, if not all genetic ...
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Can a cleaved plasmid “close” without exact matching “sticky ends”?

Say if you have a multiple restriction site and use two restriction enzymes on it to cleave a plasmid, can it recombine with ligase? My concern is that without the small sequence of nucleotides ...
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Exon skipping in mammals

I've heard from several sources that the predominant form of alternative splicing (at least in mammals) is exon skipping. However, my personal evidence is only anecdotal: I've heard it and read it, ...
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1answer
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Book Recommendation: Complex Traits and Complex Genetic Architecture

I am looking for a book (or any good source of information) that offers an in-depth discussion and models about the evolution and analysis of complex traits and complex genetic architecture. Do you ...
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Process of Transcription

During the process of Conversion to Ribonucleoside Monophosphates the various ribonucleoside triphosphates break off their high energy bonds after linkage to the DNA.But the first ribonucleotide ...
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When DNA is at its uncondensed form, what can it do?

I think it can do two things: The cell may be duplicating the genome during S phase. The cell may be transcribing the DNA into mRNA. Question: Can the two activities occur at the same time or one ...
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Do tRNAs that recognize multiple codons have any preference for one over another?

What are the effects of the different binding strength/affinity between the synonymous codons corresponding to a single tRNA ?
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Is it possible to use virus for genetic modification of embryos during the fetus stage

I know this probably sounds rather hypothetical and not very feasible but I would very like an answer telling why it is possible or not possible and why. With the advancement of crispr and other dna ...
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Have we ever observed fertile offspring with a different number of chromosomes than the parents?

Chimpanzees are supposedly the closest relative of humans from a DNA perspective, they are both diploid, and they both undergo meiosis. However, chimpanzees have 24 chromosome pairs while humans have ...
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Why is aneuploidy usually lethal?

So, I was reading about aneuploidy and how a zygote with one extra or less chromosome usually would not survive to full term. I suppose this happens because aneuploidy leads to some kind of protein ...
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Correlation of non-coding DNA with coding DNA

I sequenced the first exon of the MC1R gene of 15 labradors (genomic DNA) to look for the loss-of-function mutation (C.916C>T) and as expected, it was where it should have been (916th base pair). As i ...
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Does DNA polymerase I require a $3^\prime$ end?

DNA polymerase III adds nucleotides in the $5^\prime \rightarrow 3^\prime$ direction because it can only add nucleotides to the $3^\prime$ end of the previous nucleotide. This is why it requires a ...
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Recombination between DNA segments question

In the diagram shown above, segments A and C are copies of a repeated DNA sequence, flanking a unique stretch shown as B. A and C are in an inverted orientation relative to each other, as indicated by ...
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Is sequencing error a function of the nucleotide being read?

Checking out on Google Scholar, I can see that for Illumina (just to consider one example) the sequencing error rate is of the order of 0.001-0.01 per nucleotide. Talking about sequencing error, let'...
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Why do genes with closely related functions often reside on different chromosomes?

Why do genes with closely related products are so often positioned on different chromosomes? To illustrate what I mean, here is an example from immunology: the invariant region of MHC is on ...
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654 views

Problem on number of amino acids that an alien can use

A new life form discovered on a distant planet has a genetic code consisting of five unique nucleotides and only one stop codon. If each codon has four bases,what is the maximum number of unique amino ...

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