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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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Number of DNA strands per chromosome

As I was reading Griffith's Introduction to genetic analysis this evidence was provided for single DNA makes single chromosome. Eventually geneticists demonstrated directly that certain chromosomes ...
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What is the difference between DNA vs RNA Editing in the context of gene therapy?

As a someone with beginner knowledge on biology, I have come across the terms "RNA editing". Take this paper for example : RNA Editing with CRISPR-Cas13 From my understanding, DNA -> RNA -> Proteins ...
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Need help in identifying and understanding the origin of an expression variant

We usually denote the origin of a mutation as either somatic or germline. This information is usually available in certain databases such as CIVIC, ClinVar, COSMIC etc. But when we come to variants ...
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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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Are all fusion genes somatic in origin or can fusion genes be germline?

Fusion genes should have an origin.These are essentially hybrid genes that are translocated in its entirety. Eg. BCR-ABL, EML4-ALK are known to be implicated in cancer pathogenesis. Do these ...
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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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What is the difference among biochemistry, molecular biology, molecular genetics and structural biology?

I have never heard of straigthforward definitions of these fields in my college lectures, and the Internet searches were not very helpful. However, from what I have learned at different subjects, this ...
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How does the difference in the sequences of a dominant and a recessive allele of a gene help in the expression of the gene? [duplicate]

When an organism is heterozygous at a specific locus for a gene and carries one dominant and one recessive allele, the organism will express the dominant phenotype. These alleles vary in their ...
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Computational approaches for making hypotheses about the effects of genetic engineering? Experiment planning methods?

Let's assume that I am searching for gene editing candidates for curing human adiposis. Are there computational frameworks that can allow me to select the best candidate-genes for editing via some ...
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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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Are mitochondrial genes decoded in the same way as nuclear genes?

Mammalian mitochondrial genomes contain only 22 tRNA-coding genes, which is an insufficient number to decode mRNAs under the standard wobble rules. How is translation of mitochondrial mRNAs achieved ...
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Selective breeding fluorescent sheep - possible?

I got into a small argument :-) Friends of mine try to draw fat line between "natural" selective breeding and applying molecular biology (CRISPR/Cas9) to put new traits in existing species. The line ...
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Increase rate of change in coding regions?

If a sequence is under selection will it acquire more changes over time because of faster fixation than if changes were neutral? Is this true or am I missing something?
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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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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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What is the frequency of AUG near-cognates (as start codon) in ‘Leaderless’ mRNA?

In typical bacteria that use SD-dependent translation initiation, the AUG start codon may sometimes be replaced by near-cognates (GUG, UUG, etc.). The frequency of these near-cognates is somewhat ...
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Relationship between the ambiguity (wobble) at codon position 3 in elongation and codon position 1 in initiation

In prokaryotes the usual observed start codon frequency is AUG > GUG > UUG. An explanation for this is that AUG is the most common initiator codon because it forms the most stable interaction with ...
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what is the difference between homozygous and heterozygous duplication?

In a genetic test result it's written homozygous duplication or heterozygous duplication Does it mean four copies of the ...
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What exacly happens at chromossome level during fecudation and in the first zygotic division?

I was reading about the viability of animal hybrids and found the following sentence here: Previously, this idea was not widely accepted, because, in general, different species have different ...
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Calculating Possible Combinations of Bases in a DNA Strand of a Given Length

In my Biology class we were asked this question: This DNA strand consists of eight pairs of nitrogenous bases. How many different sequences of eight bases can you make? Explain how you found your ...
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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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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 exactly does the phrase “chimerical sharing” mean in this abstract?

The Gizmodo article Australian Siblings Are Semi-Identical Twins, Some of the Rarest Humans Ever links to the new paper in NEJM Molecular Support for Heterogonesis Resulting in Sesquizygotic Twinning ...
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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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How does Hayflick limit relate to cellular senescence

If the Hayflick limit says that there are a maximum of around 60 cell division before a cell becomes senescent, I assume this is because the cell looses length of telomere. But how can this be if, for ...
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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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How would you use PGAl to select for mutants of beta galcodosidase gene (z-) and permease (y-)?

How would you use PGAl to select mutants of beta galcodosidase gene (z-) and permease (y-)? Or do you just use PGAL to grow these mutants after you've isolated the mutant gene and inserted it into a ...
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Is bi-allelic gene expression random?

Supposing we have the genotypes “Aa”, “AA”, and “aa”... which are not mono-allelic (not imprinted and not X-inactivated). Does the dominance of the “A” allele over “a” allele affect which gene is ...
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What do the haploinsufficiency scores in the clinVar database represent?

I understand that haploinsufficiency occurs when one of the two copies of a gene is mutated to the point of being unusable, and the single copy remaining is unable to cope with the cell's demands for ...
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Is the lac operon repressed in the presence of both glucose and lactose?

In the presence of both sugars (glucose and lactose) will there be repression of the lac operon completely? I know that more glucose means less cAMP --> less CAP --> less positive regulation, and ...
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Double stranded RNA Single stranded DNA

I have seen in textbooks referring to ds RNA and ssDNA. How a RNA can be double stranded and likewise how a DNA can single stranded and if they do exist why are there names not interchanged?
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How to identify whether something is in linkage disequilibrium?

If the following loci indicated the presence of an SNP in flu strains, is Locus 2 and Locus 3, which are located 10 bp apart in linkage disequilibrium? "When alleles and molecular markers are ...
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Which enzyme is Nick Lane referring to?

In Life Ascending the author, Nick Lane, refers to an enzyme in his introduction: '' It concerns an enzyme (a protein that catalyses a chemical reaction) that is so central to life that it is found ...
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If post transcriptional modification happens , how can a gene code for amino acids in a particular order? [duplicate]

Post transcription, introns are removed and exons are rearranged randomly. If that's the case (which it is according to the book EDEXCEL SNAB A2 topic 6) then shouldn't the protein produced be ...
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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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Cloning a coding gene into a non-expression vector

Does it make any sense to clone a CODING gene into a NON-expression vector? doing this will only give us multiple copies of the gene, while we could run PCR instead (Let's say we know the gene ...
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Are redundant codons used in translation?

I am learning about redundancy in genetics and I came across this statement in my textbook: more than one codon for an amino acid means that some codons are redundant - the process of protein ...
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Will DNA nanostructures be useful for medical applications?

There is a lot of work being done on developing small nanomechanical structures and even small nanomechanical actuators built with DNA. I have heard researchers motivate this research with claims ...
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How does DNA code for the actual *shape* of individual body parts/areas (NOT segments or Hox genes)?

Just to save the trouble - I am not asking for general information on how DNA codes for proteins and definitely not how Hox genes work. I have a very good understanding of the evolutionary process and ...
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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 ...
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Why does the HLA show a high degree of polymorphism?

I know how the HLA undergoes high degree of polymorphism (random genetic rearrangements), but I have not understood why it undergoes rearrangements. What is the advantage offered when HLA shows a high ...
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Name of dsRNA (or dsDNA) where all strands are identical

What is the name of dsRNA (or DNA) where all component strands are identical (i.e. where the complex consists of multiple copies of the same ssRNA)? Example: 2 identical ssRNAs forming a dsRNA ...
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How exactly does heterozygous sickle trait help patients survive malaria

Heterozygous sickle cell anaemia trait is known to increase the survival rate of carriers to malaria attacks. How does a recessive gene not expressed in the phenotype allow for such an advantage? Is ...
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Are there E-sites on eukaryotic ribosomes?

One of my professors mentioned something about the e-site (the exit site for the t-RNA) on a eukaryotic ribosome. There was a student in the class who objected, saying that there is no e-site on ...
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Does the deletion of Chromosome 20 cause immunity against prion disease?

I was reading recently about prion disease and it caught my attention that a normal prion protein is coded n chromosome 20, therefore, in order for an infectious prion protein to attack, there must be ...
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Is there any example of genetic mechanism of delayed onset toxic effects?

We know that exposure to many toxic chemicals during embryonic development may show toxic effects later in life. It is called Developmental Origins of Health and Disease (DOHAD). Most of the ...
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How to find idea for essay [closed]

I'm studying microbiology in Iran The university that I'm studying in doesn't provide that much help in research areas and we don't get to research or write essays that much ,while I'm trying to write ...
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Insertion Confirmation Cloning Strategy

So I am in a bit of a time constraint. Essentially, I inserted a DNA fragment via molecular cloning which contains a unique RE site. I need to confirm whether my colony has or does not have the ...
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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) ...
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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 ...