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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 open complex in E.coli DNA replication?

The E.coli DnaB helicase is essential for replication initiation from the chromosomal origin of replication ( oriC ) and is present in vivo as a protein complex with six monomers of the DnaC ATPase ...
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Do any RNAs directly inhibit transcription

In eukaryotes, microRNAs and small interfering RNAs, as part of protein complexes, can attack specific messenger RNAs with complementary sequences, thereby inhibiting translation. However, RNA can ...
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261 views

Why is trisomy a problem?

I understand that a missing part of genetic information is a problem - the cell does not know how to synthesize a specific protein. But why is it a problem when there's one more copy of a chromosome? ...
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264 views

Why is compensatory negative supercoiling generated in a positively supercoiling ccDNA?

I was reading DNA replication in E.coli in Lehninger Principles of Biochemistry 6th Ed. and stumbled upon the following -- The tight right handed wrapping of DNA around DnaA oligomeric complex ...
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Why does our body produce double the amount of a protein from DNA after duplication?

It is said that if a duplication mutation occurs on the DNA strand, the proteins that it is coded for would be doubled in production as a result. Why is it so? Doesn't our body have feedback ...
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2k views

What is Tandem repeat?

After reading - (wikipedia) Tandem repeats occur in DNA when a pattern of one or more nucleotides is repeated and the repetitions are directly adjacent to each other. ( a paper) A tandem ...
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Do transcription factors block transcription entirely?

Transcription factors bind to the DNA to block the transcription of a certain gene, right? But while they are bound to the DNA, do they completely block any transcription of this gene for as long as ...
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How is randomness of the branch migration process ensured?

Branch migration (part of genetic recombination) is a random process. It looks like Ruv-ABC proteins are mainly responsible for this process, but how is randomness ensured? After all, it can only be a ...
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Does the genome make sense without knowledge of the ovum?

Much of the literature for laypeople seems to consider (and to spread the idea) that an animal (or a plant, I guess) is characterised by its genome. I do not know whether the same goes for more ...
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Research from the early molecular genetics era that supported protein as the primary carrier of genetic information?

I can't seem to find anything on my own. Surely there were experiments performed (possibly using bacteriophages) that managed to come to this conclusion? Specifically I'm interested in anything pre-...
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Gaps in FASTA formatted genome?

I'm just getting interested in genetic structure and I decided to find a FASTA formatted genome (human) and I found one here. However, I'm confused. I know that A can only match up to T and C to G but ...
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656 views

Why is aneuploidy usually lethal?

So, I was reading about aneuploidy and how a zygote with one extra or less chromosome usually would not survive to full term. I suppose this happens because aneuploidy leads to some kind of protein ...
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Is RFLP markers are dominant or codominant? [duplicate]

there are several markers used in molecular biology,. marker analysis. RFLP is most commonly used marker which having several advantages. is RFLP marker co-dominant or dominant ?
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Choosing PCR conditions

How does one choose PCR conditions? Does it depend on the taxon, on the DNA concentration, on the primers or anything else?
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207 views

Are there any drawbacks to having immutable DNA during lifetime?

Imagine that there is a way to prevent cell DNA from being changed once zygote has been formed. Would this have any negative effects on the target organism? Does DNA change during the lifetime as part ...
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808 views

Rescue cell lines function

I'm reading in a paper in which the authors have made three cell lines to study the function of a gene of interest (Mbd3): The one is knocked out for the gene of interest [Mbd3 -/-], the other is ...
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How can both strands of DNA code for proteins with similar functions?

It's not clear from the question but for example: AAAAAAA TTTTTTT The top strand would create a different protein than the bottom, and with the huge amount of nucleotide in a gene, I think it's ...
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210 views

How is monoclonality or polyclonality determined?

I was reading up Kaposi sarcoma and Robbins Pathology says, ..many features suggest that KS is not a malignant tumor despite the ominous name ...spindle cells in many KS lesions are polyclonal or ...
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257 views

Books: DNA replication [closed]

In what books can I find a detailed literature on the mechanism of function of different enzymes and proteins involved in DNA replication of E. coli ?
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124 views

Do the two catalytic cores of DNA polymerase III operate in the same direction?

This diagram is from Molecular Cell Biology by Lodish, 2000 which states: The other core-polymerase molecule, which elongates the lagging strand, moves with its β-subunit clamp in the direction ...
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Type I and Type II Topoisomerases

Type I topoisomerase changes the linking number by ±1 by changing the number of twist present in a DNA, breaking only one strand. Type II topoisomerase changes the linking number by ±2 by changing ...
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652 views

Can coding DNA be used for DNA fingerprinting?

I am confused if coding DNA can be used for DNA fingerprinting because I have read that non-coding segments of DNA are used to identify and analyze DNA. I want to know if coding DNA segments are of ...
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1k views

Does DNA helicase or topoisomerase actually “unwind” DNA?

I am reading through my textbook (Genetics, Brooker 4th edition) and the summary it gives seems imprecise for the functionality of helicase and topoisomerase. The following is an exerpt: ...
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112 views

How are the very first telomeres added?

Here is an image of telomerase adding telomerase. As we can see, the telomerase sort of binds to a bit of the existing "3' flanking end of [the] telomere" - it's almost half and half. My question ...
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What´s the role or function of the homologous arms in a donor template in a knockout/knock edition via Crispr-cas9?

I have to make an exposition in my university about Crispr-cas9 edition and I have some questions about the method. In the knock out/knock in technique is used a plasmid containing the DNA that ...
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Why do we need two markers to measure a recombination rate?

In calculating recombination, Why is it necessary to take into account pairs of loci where one marker is heterozygous? Why is it necessary to take into account pairs of loci where both markers are ...
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91 views

What sequences are between adjacent genes?

The human genome has a lot of non-coding regions, which include regulatory elements, repetitive DNA, and introns. Suppose there are two adjacent genes on a chromosome, and their positions on 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 RAS undruggable?

Why can't mutated RAS get inactivated by GTPase? Why don't we have any inhibitors for RAS-GTP binding? Why is RAS undruggable? How can mutated RAS be inactivated? I had been researching on the topic ...
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483 views

Picking up Plasmid DNA using Nanodrop, but not using Electrophoresis

I am currently trying to see if 2 bacteria contains plasmids or not. I had used promega plasmid extraction kit on the bacteria. I ran a gel electrophoresis (.8% gel) with the extract product, however ...
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158 views

What is the difficulty with cloning and genetic engineering in humans?

I asked this question many years ago and was told by my molecular biology professor that humans were (simply) more complicated than goats. So, I didn't get a straight answer, but supposing he told ...
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5k views

How to edit/insert new gene after cutting with CRISPR/cas9

I'm a student started who has started learning about CRISPR/Cas9. As I understand it, CRISPR/Cas9 is an enzyme that is used to cut a gene at a specific sequence. I would like to know how scientist do ...
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103 views

What is the meaning of -//- sign?

Does $-//-$ sign between trpR and P indicate separation of the trpR gene from the operon? Or could the sign mean that the trpR gene may be present adjacent or far away from the operon, both the ...
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100 views

trp operon repressor

Does trp repressor form a tetramer or a dimer before it binds to its corepressor tryptophan? I've been reading BIOS Molecular biology it says that it is a dimer The repressor is a dimer of two ...
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Is induction and derepression the same thing?

Induction This is a definition that our professor mentioned in class $-$the process of turning on the expression of gene in the response to a substance in the enviornment is called induction. ...
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What does the phrase 'background level' mean?

I was reading BIOS Biochemistry and stumbled upon a phrase 'background level' in the following excerpt $-$ The lac operon contain lacZ,lacY and lacA genes encoding $beta$-galactosidase, galactoside ...
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27 views

Method of figuring out how much of a certain mRNA is present in a bacterium

I am trying to develop a method for figuring out how much of a certain mRNA is present in a bacterium. This is what I have so far: Perform a mRNA extraction Using Electrophoresis, to isolate the ...
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house keeping gene variation under treatment

I am injecting BCG in mice ears to measure the local inflamation response in the infection side, one ear in the same mouse is kept as control by injecting PBS, in the other one, BCG is injected. When ...
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70 views

How to prevent a old promoter region from attaching onto a plasmid instead of a new one during ligation?

What I am trying to do is take out a existing promoter region in a plasmid, and replace it with a new one. So first I use the appropriate restriction enzymes to get rid of the existing promoter region....
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56 views

Can you knockout a gene specifically in the dorsal root ganglion in adult mammals? [closed]

Since the dorsal root ganglion is so small, would that be easier than the entire body?
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69 views

How does gene editing in one cell affect other cells?

I have read about gene editing and I have some questions concerning this technology: With gene editing, are we correcting the genes in all the cells or a single cell? If the gene editing is done for ...
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1k views

Is brachydactyly due to mutation?

I have this so called "clubbed thumbs"also known as brachydactyly. It is of D-type. I searched for it on internet and found that it is a dominant inherited disease. But to my surprise,none of my ...
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Can it be said that proteins determine phenotypic traits?

I am not ignoring the function of genes, or the gene-environment interactions. What I want to know is if behind every "observable characteristic" we can find a protein -or a group of proteins- which ...
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137 views

What are chemical candidates for replicator molecule?

I have read Selfish gene by Richard Dawkins and idea is that at random some molecule was synthesized that had a property if there is enough 'materials' to construct ...
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1k views

Is every protein encoded by just one gene?

Beadle and Tatum proposed the “one gene, one enzyme” hypothesis in the 1940s, and this was later modified to “one gene, one protein”, i.e. that one gene codes for one protein. Have any exceptions to ...
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Can a cleaved plasmid “close” without exact matching “sticky ends”?

Say if you have a multiple restriction site and use two restriction enzymes on it to cleave a plasmid, can it recombine with ligase? My concern is that without the small sequence of nucleotides ...
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How common is it for environmentally occurring bacillus strain to contain some sort of plasmid?

I am designing a method for testing whether two new bacillus isolates, that are ionic silver resistant, store the silver resistance mechanism on a plasmid or on the chromosome of the bacteria. In my ...
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Correlation of non-coding DNA with coding DNA

I sequenced the first exon of the MC1R gene of 15 labradors (genomic DNA) to look for the loss-of-function mutation (C.916C>T) and as expected, it was where it should have been (916th base pair). As i ...
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Are the subordinate genes of a repressed operon really “turned off”?

Operons are often described using all or nothing language. A repressor binding to the operator is usually presented as "turning off" the regulated genes. Case in point, Scitable at Nature.com says: ...
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DNA replication in E.coli

What is the difference between replication and to divide? My A level bio book says that it takes 20 min for E.coli to divide and in next page it's written that E.coli completes replication within ...