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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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216 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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3answers
865 views

To what extent is the genetic code more than just a code?

It is worth specifying the exact meaning of "code" in this question. A code is a map from one space to another space with which it has no algorithmic connection. Thus representing 321 as 0x141 is not ...
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93 views

Distribution of Exon and Intron Sizes

Goal I am trying to get a distribution of Exons and intron sizes in Three-Spined Stickleback (Gasterosteus aculeatus). Data downloaded I downloaded some data from Ensembl. More precisely, I went ...
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1k views

Can a single strand of mRNA form different polypeptide chains?

My book has a statement: A single strand of mRNA is capable of forming a number of different polypeptide chains. In my opinion this statement is wrong because a single strand of mRNA will have same ...
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1answer
73 views

What are the significances of chromosome mapping? [closed]

The few point that I have come across are: The following are the significances of chromosome mapping: Chromosome maps help identify the location of gene of interest on a chromosome for genetic ...
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1answer
5k views

What are Codominant vs Dominant Genetic Markers?

When talking about types of genetic markers, the adjective "dominant" and "codominant" are often used. I don't fully understand their definitions and found contradicting definitions. Foll and ...
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215 views

When was the first exception to Mendelian genetics discovered?

In addition to the the question in the title I'd like to know , how scientists reacted to the exceptions?
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1answer
104 views

Cell cycle-regulated genes and mRNA

I am a mathematician and my knowledge about biology is close to zero. I am reading a bioinformatics paper and I would like to understand a bit more about the biology task they are talking about. I ...
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2answers
133 views

Is there selection against long proteins and long genes?

Background thought Titin and TTN Titin is the largest protein in the human genome with 33423 amino acids. Titin is coded by the gene TTN that must be at least $3 \cdot 33423 \approx 100kb$ long. ...
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57 views

How does epigenetics affect the birth conditions via alcohol?

Recent study has shown that epigenetics can play role in male-caused infertility and it cites for example studies which showed an enhancing of silent genes when drinking alcohol. Since the study ...
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2answers
294 views

How do I know whether or not a nuclear gene is single copy?

As a part of a phylogenetic study, I need to find a nuclear gene that meets the following requirements: Single copy gene; Highly variable gene; Gene longer than 400 bps; Gene that gives information ...
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57 views

Does any specific property decide which DNA strand acts as leading strand template?

Of the two strands of DNA, the one that unwinds in the 3' to 5' direction constitutes the leading strand template, with the other strand of course acting as the lagging strand template. Is there any ...
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1k views

Difference between null and recessive allele?

I get that in a single gene locus, an individual can have RR, Rr, or rr as the two alleles ...
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1answer
107 views

What do arranging and assigning mean in sequence annotation?

Please could someone explain these lines to me in a simple way These sequences were then arranged based on some overlapping regions present in them. This required generation of overlapping ...
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2answers
210 views

Is there a term for when a detrimental gene can be positively selected for because of linkage to a very fit gene?

Let's say that some piece of DNA would be subject to extreme negative selection if it were independently inherited, but it is very closely linked to an extraordinarily fit gene, and so the complex it ...
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1answer
688 views

What is a “noninvasive” biomarker for a disease? [closed]

What is a "noninvasive" biomarker for a disease? I know what a biomarker is, but what makes it noninvasive?
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2answers
98 views

What is meant by “Expression” of Non-Coding RNA?

I was having a look at lncRNAdb and its help says: The ENCODE project gene annotation list, GENCODE, has predicted that the human genome contains 14,470 lncRNAs whereas only a small proportion of ...
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2answers
94 views

What makes DNA sequences most different/recognizable from a biological perspective? [duplicate]

We can pretty easily quantify the amount difference between two different strings/sequences of characters. For example, if we take the words trebuchet and trebucket, we can say they have a Levenshtein ...
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3answers
997 views

T7 vs pBAD promoter strength

How do pBAD and T7 promoter strengths compare when pBAD is induced under conditions which would lead to its highest strength? Are there any papers that compare the two inducible promoter systems?
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3answers
767 views

Do transcripts always start and end with exons?

I realized that in all cases of "RefSeq Genes" annotations of hg19 I looked at spliced transcripts start (and end) with an exon. From the annotation there is no evidence of any sequence upstream or ...
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34 views

What is the highest number of genes expressed under one T7 promoter?

What is the highest number of genes expressed under one T7 promoter? Also, what is the longest polycistronic mRNA? I am interested in the context of heterologously expressing biosynthetic gene ...
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1answer
354 views

Why does pETDuet-1 only have one T7 terminator but two T7 promoters?

Why does pETDuet-1 only have one T7 terminator but two T7 promoters (vector map below)? Is there any advantage of having only one terminator? There are going to be two mRNAs transcribed from this ...
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1answer
74 views

Does mechanotransduction of cells play a role in the biocompatibility of titanium?

What exactly is mechanotransduction as the information varies between sources. Some sources indicate that mechanotransduction is the underlying principle where cells pull on the surface they grow on ...
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2answers
96 views

Which strand of a gene specifies a protein? [closed]

A gene is a segment of DNA (I hope double stranded) and each strand when transcribed form a mRNA and after being translated a protein. As from each gene there are two proteins that are being formed. ...
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1answer
942 views

Is it possible to have multiple stop codons in one exon?

I would be very happy if someone can help me to find the answers for the following related questions. Can one exon have many stop codons? Can protein synthesis happen, if the stop codon is at the ...
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2answers
3k views

Does a woman contain all the genes needed to make a man?

I know the answer of inverse is at here, but how about this question? I also read this question, can I imply to human that a woman can also contain all the genes needed to make a man? Edit: I think ...
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1answer
203 views

Can both the overlapping genes (in opposite strands) produce proteins?

I have recognized that both the forward and reverse transcripts from a genomic location code for protein products. Both do occur/express in the tissue of interest. In order to eliminate by chance ...
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1answer
62 views

How much time do the different mechanisms of gene regulation need to take effect?

I am thinking of the major regulatory mechanisms, like general transcription factors, activators, repressors, and RNA interference. If non-active regulator genes using each of the different ...
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1answer
128 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. Thanks
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1answer
668 views

How to read this DNA inversion diagram?

In the following diagram about chromosome inversion, I don't understand: Why do we need to take the reverse complement from step 1 to 2? Isn't inversion just reversing the bases in the region? How is ...
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1answer
120 views

Can difference in the expression potential of alleles lead to dominance?

Several hour ago I was in thoughts what allele dominance really means on molecular level. As we know from basic genetics, if the organism had Aa type of some gene ...
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205 views

UV light-induced mutagenesis during gel extraction

this is a very short question I did not find the answer for online, neither on this nor other fora. At the beginning of my cloning protocol, I extracted the band with the sequence of interest directly ...
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2answers
273 views

Trouble understanding overlapping genes.

I read the wikipedia passage on overlapping genes. https://en.wikipedia.org/wiki/Overlapping_gene The Tandem overlaps they speak of make sense to me, as I understand that their are different reading ...
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1answer
55 views

Synthesis of an additional DNA in Pachytene and Zygotene [closed]

I've read, that in Pachytene and Zygotene additional DNA material is synthesized, about 0,3, 0,1% respectively. Why is it so?
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1answer
10k 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 ...
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1answer
107 views

Why are some genomic regions sequenced more than the others?

We have to normalise read count data from RNA-Seq experiments in order to account for the fact that some genomic regions are mapped more than others. i.e. we get the tags per million reads (TPM). In ...
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1answer
506 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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1answer
28 views

Molecules, Targets and Isoforms

I have a question. Given a molecule A and two isoforms of a gene X, Y, and the knowledge that A targets X. Can I infere from this anything about whether A targets Y? As a motivation think about ...
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624 views

How can a mutator gene can cause a mutation when it is shut off? [closed]

defination of "Mutator" - a gene that increases the rate of mutation of one or more other genes. However, in the book "Molecular Biology of the Cell" (bruce alberts) it states that when a mutator is ...
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Mosaic segregation in C. elegans

How can mosaic segregation be used in C. elegans? Can it tell us where a given gene is expressed, or needs to be expressed for worm survival?
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1answer
2k views

What is two-start or zigzag model of 30 nm chromatin fibre?

I read some webpages describing the two-start model but could not get it. I'll be obliged if someone helped me understand the topic. The websites I have been through are: 1.http://www.nature.com/nrm/...
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1answer
39k 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
3k views

How do major and minor grooves arise in the DNA helix? [duplicate]

I understand that they arise due to the pairing of bases of two opposite stands and are sites through which important proteins needed for replication and transcription of DNA interact. But I don't get ...
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1answer
247 views

Mitochondrial Genetic code

We know that the genetic code is universal. My query is why the mitochondrial genetic code is different from universal genetic code?
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1answer
97 views

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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1answer
53 views

What are in common between transcription factors?

In terms of their structures (primary to tertiary) and locations? Why do they have these commonalities? Or are any of these commonalities critical to their functions?
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0answers
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Hydrogen bonding and the blocking thereof in nucleic acids during nuclear processes

In transcription, RNA polymerase unwinds the DNA double helix and begins attaching RNA nucleotides to the template strand. In its wake, the DNA double helix closes back—this is only natural, seeing as ...
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1answer
513 views

Does DNA polymerase I require a $3^\prime$ end?

DNA polymerase III adds nucleotides in the $5^\prime \rightarrow 3^\prime$ direction because it can only add nucleotides to the $3^\prime$ end of the previous nucleotide. This is why it requires a ...
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0answers
1k views

What type of point mutation and chromosomal mutation cause Albinism in humans?

First of all, I know that OCA1 (Oculocutaneous Albinism Type 1) is autosomal recessive which means that both parents-who are unaffected-have to pass down one copy of a mutated gene in order to ...
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2answers
189 views

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 ...