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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659 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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How does GC-content evolve?

Background GC-content refers to the frequency of base pairs that are either C or G in the genome, or in other words the number of GC base pairs divided by the addition of the number of GC base pairs ...
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Activation Of Embryonic Genome

Embryonic gene activation is a process by which the embryo begins to transcribe its newly formed genome.As the embryonic gene activation occurs during early stages the paternal genome may not have any ...
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Transposons and the net amount of DNA

The retrotransposons and certain DNA-transposons, are "jumping" sequences which may be incorporated elsewhere in the genomic DNA of an organism, through varying mechanisms. This insertion is almost ...
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mutant down but not out

I am interested in a gene which is null lethal but I need to temporary induce diminished capacity. If a cell is homozygous is it possible to induce heterozygous phenotypes or a partial knockout from ...
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Why is my DNA band bulging?

This is the only image my the TA was able to get for us. And, we're using it for our lab report. The image isn't even ours. It's another group's image that we're sharing. But I don't understand why in ...
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Why are Chromosome Territories important?

Chromosomes occupy discrete regions of the nucleus, referred to as 'Chromosome Territories'. This spatial organization is emerging as a crucial aspect of gene regulation and genome stability in health ...
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Why are Barr Bodies usually seen along the edge of the nucleus under the light microscope?

We do a typical class exercise of aceto-orsein staining of buccal epithelial cells from female students to visualize Barr bodies under the light microscope. All the illustrations and pictures in the ...
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Regulation of LBD33 genes Arabidopsis. If LBD 33 gene is up-regulated by auxin then why does expression decrease when increasing auxin concentration?

I have a question regarding the regulation of lateral boundary domain genes in Arabidopsis (specifically LBD33). I am an undergraduate student trying to understand the results of a lab where I measure ...
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Why do I see so many kinetochores?

I am analysing RPE-1 cells from humans and I do not understand why I see so many kinetochores by immunofluorescence (more than 100 in many cells). They are in prometaphase.
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Question about genetic recombination

I am having some difficulty understanding a few things about genetic recombination, in part because of confusion from different diagrams in books. First of all, I wanted to verify whether I have ...
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Should gene therapy safety protocol include isolation?

In the case of a gene therapy trial where viral vectors are used to deliver genes into mammalian cells, including humans, should biosafety and ethical protocols include isolation of the patient as a ...
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Gibson assembly - primer design with A and T rich regions

I have question about Gibson assembly. I have done it several times and it always worked okay for us, but now I want to assemble together a fragment which has sequence like this: 5'...
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Inbreeding Coefficient and Coefficient of Relationship

Wikipedia gives the following formula to calculate a "path of coefficient of relationship" between an ancestor $A$ and an offspring $O$: $$\rho_{AO} = 2^{-n} \left( \frac{1+f_A}{1+f_O} \right)^{1/2} =...
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Consensus codon optimization by organism

Does a public database exist that contains this information? I'm trying to make a simple gene annotation program that will let me input a DNA sequence and then optimize it based on one of these tables ...
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Which part of the genome are the developmental sequences of embryogenesis located?

Which part or parts of the the genome are the sequences located. Are they spread across the chromosomes? If so how are they accessed sequentially with precision during embrygenesis?
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Collective term for both exons and introns

Is there a term I can use to refer collectively to both exons and introns? By collectively, I don't mean ligated as with an unprocessed transcription product. I'm just writing about exons and introns ...
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What are housekeeping and constitutive genes?

I have come across two set of definitions which are not contradictory but different. From wikipedia: A constitutive gene is a gene that is transcribed continually as opposed to a facultative gene, ...
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Are eukaroytic promoters located in the 5' UTR region?

I was wondering if promoter sequences are located on 5'UTR region in eukaryotic organisms?
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What is a CAG::ChR2 rat?

I am reading the paper: Pyramidal Cell-Interneuron Interactions Underlie Hippocampal Ripple Oscillations. The authors use CAG::ChR2 rats (for example in Figure 2) and I don't know what it means. I ...
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What if our whole body is made up of cancer cells? [closed]

Today I learnt in my biology class that cancer cells are immortal. That left me wondering what if our whole body is made up of cancer cells? Will that make us immortal? Is it possible or why is it ...
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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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What separates gene loci?

Introns are sections of noncoding DNA that separate exons within a gene locus. However, between different gene loci, I also would assume there to be noncoding regions of DNA. What are these regions ...
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What does it mean to clone a gene?

When I look up information related to the identification of disease genes, texts will often refer to the gene being "first cloned." What does "clone" mean in this context? Is it simply a synonym for ...
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Alternatives to PCR

PCR uses cycles of heating and cooling to denature the strands, calling for special thermostable DNA polymerases. In a cell, during replication, Helicase unwinds the DNA without the requirement of ...
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Are the DNA codon mappings arbitrary?

I am a Biology novice so I apologize in advance if I state anything incorrectly.... My question is, are the DNA codon mappings arbitrary? I understand that the DNA code is made up of codons which ...
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Prenatal Marketing

This is for a short story idea. Is it possible to modify the DNA of a child to make their metabolism more susceptible (physical response, addiction, etc) to a certain type of chemical i.e. a chemical ...
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Are epigenetic modifications the most stable mechanisms for cell differentiation?

Wondering what the general take is on what are the molecular mechanisms that are mostly responsible for cell type differentiation stability; ie, for a cell's identity to actually become 'locked in' ...
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Methods for microbial identification in soil

I'm trying to perform a survey of the life in a soil sample. I want to know what species of bacteria, fungi, and other organisms are in it. I've heard that ITS sequencing and 16S rRNA sequencing are ...
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What dictates which protein to synthesize at a given time?

I understand how DNA is replicated and how it directs the synthesis of proteins from amino acids through RNA polymerase, RNA and ribosomes. Now I want to understand how it works in the big picture. ...
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How does aminoacyl-tRNA synthetase recognize different tRNAs?

There are about 20 aminoacyl-tRNA synthetases, one for each amino acid. Each aminoacyl-tRNA synthetase has a binding site that recognizes a specific amino acid, and other binding areas that recognize ...
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Meaning of ‘NC number’ associated with a gene?‘

Genes in listings etc. often have a number of the type NC_000012.12 associated with them. How should this be interpreted?
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Is the promoter region of a gene transcribed?

If the RNA polymerase attaches to the promoter region of the gene, would it form the initial mRNA portion soon after attachment by reading the promoter region? Or should it slide across the DNA then ...
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trp operon repressor

Does trp repressor form a tetramer or a dimer before it binds to its corepressor tryptophan? I've been reading BIOS Molecular biology it says that it is a dimer The repressor is a dimer of two ...
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Why is mRNA used as a biomarker for cancer over tRNA or rRNA?

I cannot find a clear explanation for why mRNA is used as cancer biomarker and not tRNA or rRNA. Is there something peculiar about mRNA which cannot be fulfilled by tRNA or rRNA?
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ChIP-seq for histone modification not in agreement with RNA-seq for expression

I have ChIP-seq for H3K79me2 and H3K36me3 and RNA-seq data for treated and untreated samples. Those two histones mark active genes. Lets say, hypothetically, a peak caller finds differential sites at ...
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How does the size of insert affects the rate of Homologous Recombination in yeast?

When performing genetic knockouts in yeast using homologous recombination to replace a target gene sequence via a vector DNA, does the region between the flanking regions in the vector have to be the ...
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How can I download a gene sequence from GenBank (NCBI)? [closed]

Could you tell me the steps to find and download a gene sequence from GeneBank? I would appreciate your help.
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What is the point of DNA sequencing?

This is a very very basic question. I've looked at methods such as chromosome sequencing and shotgun sequencing. Wikipedia says that: ...
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Why do oncogenes show genetic dominance?

As we know that tumor suppressor gene causes cancer only when both the alleles are recessive in nature.But in case of oncogenes if only one allele is dominant it can cause cancer.Why in case of ...
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Understanding DNA supercoiling

While trying to understand DNA supercoiling, I came across these lines in the book Genetics by Ursula Goodenough : All natural DNA is superhelical. The axis of the duplex itself follows a helical ...
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methods for targetted deletion of genomic regions?

I would like to know what are currently used methods for targeted deletion of genomic regions in mammalian organisms or cell lines. I have heard of Zinc-Finger nucleases as a recent genetic ...
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Is complete dominance actually a genotypic process?

An example often stated for codominance is blood groups, where both alleles version of the protein is expressed and can be found in the cell membrane. An example of incomplete dominance often given ...
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Why does 4-thiouracil labelling to map RNA-binding proteins cause a T-C change?

I am now reading a paper about the purification and identification of mRNAs and its RNA binding proteins by using UV crosslinking and immunoprecipitation. I came upon this sentence which puzzled me ...
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Expected bands in polyacrylamide gel

I have something in my notes that doesn't seem right. If I use restriction enzymes on a PCR product how many bands should I see provided I know the restriction enzimes will cut the DNA? If I use two ...
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Is it possible to obtain single strands of DNA in solution? [closed]

Being that it is relatively simple to extract DNA from a variety of sources, what further technique can be used to separate the two complementary strands in solution?
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Why should you use an annealing temperature about 5°C below the Tm of your primers?

Why should you use an annealing temperature about 5°C below the Tm of your primers? According to my current research, I think it has something to do with the other reactents in the PCR, but I am not ...
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Crossing over and exon shuffling?

Campbell Biology 10e, in discussing the functions of introns, writes: The presence of introns in a gene may facilitate the evolution of new and potentially beneficial proteins as a result of a ...
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Markers for human genetic mapping

For human genetic mapping several different types of markers are used: RFLPs (Restriction Fragment Length Polymorphisms) VNTRs (Variable Number of Tandem Repeats) such as mini- and microsatellites ...
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What are microRNA, siRNA and antisense RNA?

From what I understand, microRNA binds to proteins which can cut certain mRNA strands do that this protein is not synthesised. This seems like gene silencing to me, however I have also come across the ...

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