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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 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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Would removing proteins kill a virus?

I was was wondering what would happen to a virus if we remove all the AUG in the RNA at the dna level, how would this effect a virus? I am aware it would kill a cellular creature for sure because ...
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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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1answer
138 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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26 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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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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1answer
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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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1answer
331 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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1answer
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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
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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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1answer
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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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1answer
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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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553 views

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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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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1answer
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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
254 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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2answers
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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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1answer
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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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3answers
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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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2answers
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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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3answers
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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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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
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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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3answers
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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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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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1answer
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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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1answer
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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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1answer
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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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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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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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2answers
359 views

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
42k 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
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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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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 ...