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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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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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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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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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Are all genes transcribed in differentiated cells?

My textbook tells me that it’s specific transcription factors that allow for a different set of genes to be expressed in different cells (differential gene expression). My book gives the example of ...
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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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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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How can you band wheat chromosomes using Giemsa dye?

I am working with wheat chromosomes and trying to stain the chromosomes. However, during staining with Giemsa dye chromosomes appear totally dark. I'm not sure why this might be. Anyone have any ideas?...
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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?
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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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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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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 ...
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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 ...
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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 ...
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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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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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564 views

Microsatellites and Minisatellites: Which of these form the basis of DNA fingerprinting?

I'm in a fix. Prepare yourself for a long read We've just learned about minisatellites and microsatellites at class (okay, by "learned", I mean we were told their definitions and essentially ...
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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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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 ...
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When should you use a stringent plasmid?

I was wondering if anyone had good examples of when you would want to use a stringent plasmid vs. a relaxed plasmid in a research setting.
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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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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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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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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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1answer
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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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339 views

Do telomeres appear at just one end of the chromosome?

I have just studied DNA Replication for my Biology Class and I have this question that leaves me stuck, though I have tried to figure it out myself. During telomere replication, I am aware Telomerase ...
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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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1answer
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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 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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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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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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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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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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Why don't restriction endonucleases digest transformed plasmids?

In the textbook that I'm using, it explains that bacteria does not digest its own chromosomal DNA because the sites that would be cut by its own endonuclease are methylated. Is there a similar ...
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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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What is the difference between the mitotic spindle and microtubules?

In mitosis, I understand that the centromeres line up on the spindle. I also know that the centrioles form microtubles between the centromeres during mitosis in the metaphase. But, are microtubles ...
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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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1answer
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Hybrid vs introgression zone in natural populations

In the book An Introduction to Molecular Ecology, the authors say that Introgression is the diffusion of alleles from one population or species into another as a result of interbreeding or ...
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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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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 ...
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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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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 ...
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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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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 ...