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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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3
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0answers
34 views

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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2answers
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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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1answer
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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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1answer
644 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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96 views

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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27 views

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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5answers
952 views

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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1answer
166 views

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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1answer
52 views

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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75 views

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 ...
3
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1answer
94 views

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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1answer
96 views

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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129 views

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
49 views

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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3answers
415 views

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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1answer
736 views

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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0answers
48 views

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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1answer
13k views

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 ...
2
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1answer
194 views

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
308 views

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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1answer
25 views

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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3answers
2k views

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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2answers
228 views

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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3answers
772 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 ...
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64 views

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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1answer
14k 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 ...
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1answer
45 views

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 ...
12
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3answers
21k views

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?
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1answer
48 views

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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1answer
4k views

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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1answer
82 views

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 ...
2
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1answer
42 views

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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0answers
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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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2answers
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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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1answer
49k views

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 ...
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1answer
34 views

What does “novel, predicted deleterious, within autozygome” mean in genetics?

I am a medical student and just got involved with a genetic lab and research. I read a lot phrases like: "Although no mutations have been reported in this gene, we think this variant is interesting ...
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1answer
69 views

Is it theoretically possible to safely eliminate most viruses in the atmosphere, hence preemptively cure all the viral diseases? [closed]

Could we create a genetically modified virus or bacteria (with inability to mutate into something dangerous for animals) that would quickly spread all over the planet and selectively kill most of the ...
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1answer
28 views

Thousands of Reporters Integrated in Parallel (TRIP) barcodes

Has anyone worked with constructing barcodes for TRIP? How does constructing of barcodes work in general? I don't seem to be able to grasp the basics of constructing these barcodes.
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2answers
334 views

How does transcription end?

In rho-dependent termination in prokaryotes, how does RNA polymerase “know” that it has reached the end of a gene and that it has to stop so that the rho-factor can bind mRNA’s rut site? Is there a ...
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Young family members to learn genetics - Amino Labs? [closed]

I'm an engineer but want to learn about biology with a niece and nephew who are early teens. I saw Amino Labs (https://amino.bio/) and thought because I work a lot with my hands, doing hands on ...
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1answer
175 views

What are the advantages of using interphase cells rather than metaphase cells for gene mapping purposes using FISH?

I have been told that interphase cells are better for gene mapping purposes than metaphase cells but don't know why.
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1answer
48 views

How do PrP mutations lead to prion disease?

My understanding is: The PrP gene in human cells is expressed as both PrP-c (normal protein) and PrP-sc (prion disease protein). This happens post transcriptionally, that is, the normal and the ...