The scientific study of the structure and function of genes at the molecular level, particularly chromosomes and DNA.

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Constant or variable number of chiasmata during recombination?

During recombination, is the number of chiasmata consistent for each gamete and are the chiasmata regions consistent within a single organism?
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39 views

Are the genes for transcriptional factors close to their targets in the genome?

Transcriptional factors (activators and repressors) are proteins which regulate transcription. Being proteins, they themselves are also made from expression of certain DNA sequences/genes. For ...
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47 views

probe amplification in MLPA

I'm reading an article about MLPA (Multiplex ligation-dependent probe amplification) and I got stuck on this sentence: The advantage of splitting the probe into two parts is that only the ...
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60 views

Chromosomomal walking

I'm having a great deal of trouble understanding chromosomal walking, especially in regards to this article: Control of male sexual behavior and sexual orientation in Drosophila by the fruitless ...
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92 views

Why are fifth order Markov Models, the ones most often used for gene prediction?

As far as we know that smallest polypeptide chain length is 60 amino acids - so if we found an Open Reading Frame (ORF) of about 60 codons without the interruption of stop codon we can consider it to ...
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23 views

Degenerate primer designing software

Can any one provide online free degenerate primer designing software. I have tried couple of them like CODEHOP is one where BLOCK formatting step finding difficulty, can anyone help me out....
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84 views

How many genes does D. melanogaster have?

Obviously there is no 100% exact number, but I came across this on flybase, the gold standard for annotation. I am confused now. "Genes located to the genome", is that what I am looking for? If so, ...
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37 views

“Signal Advance”: Unsure of meaning or contextual use

I am reading through Recombinant DNA; Genes and Genomes - A Short Course - Third Edition by James D. Watson, et. al. and I came across this paragraph in the discussion about discrete factors of ...
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40 views

How to find conserved residues across species?

I want to identify if certain phosphorylation sites are conserved for protein X across humans and yeast. I know from MS data that there are 4 phosphorylation sites in Human protein X. In order to ...
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36 views

gene transformation from plant to plant - transgenic plant

I want to know if the expression of a transfered gene depends on source of the gene, if e.g.: 1] I isolate a gene from plant and transfered it to the same plant? 2] I isolate a gene that is highly ...
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22 views

Degree of complementarity

Apologies in advance for asking bit naive question. I have looked up for this concept a lot but didn't find anything. The wikipedia (I know its not authentic all the time, but I think works well for ...
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86 views

What does it mean to clone a gene?

When I look up information related to the identification of disease genes, texts will often refer to the gene being "first cloned." What does "clone" mean in this context? Is it simply a synonym for ...
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41 views

PCR that worked previously is now only showing primer dimers and a smear on gel

PCR amplification of a promoter sequence for gel extraction worked beautifully using Phusion HF enzyme with GC (higher error but less picky) buffer. However, DNA concentration from the gel extraction ...
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30 views

genetic complementation problem

I've attached the picture of the problem. SO, based on the information I managed to assemble two large cistrons. (if the combination of two mutants yield (-) mutations are on the same chromosome) ...
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35 views

Can genes be expressed sequentially?

As I understand it, any gene on an exposed/unpacked region of a chromosome is continuously being expressed. Regulatory genes may increase or decrease the amount of protein synthesised due to its ...
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339 views

Lac operon: How can lactose enter the cell in the absence of lactose permease?

My textbook states that lactose permease...transports lactose into the cell and When lactose is added to the growth medium, the lactose molecules bind to the other site on the repressor ...
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2answers
117 views

Alternatives to PCR

PCR uses cycles of heating and cooling to denature the strands, calling for special thermostable DNA polymerases. In a cell, during replication, Helicase unwinds the DNA without the requirement of ...
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When performing mutagenesis for an assay, how do you decide on the sample size of individuals to be mutated such that all genes are covered?

If I want to study, say, gustatory response of salmons to a bile acid, I need to mutagenize a sample of salmon males. However, given that there are many genes involved in this response, what is ...
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28 views

recombination between DNA segments question

In the diagram shown above, segments A and C are copies of a repeated DNA sequence, flanking a unique stretch shown as B. A and C are in an inverted orientation relative to each other, as indicated ...
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mutations induced by transposons

Question: In contrast to chemically-induced mutations, mutations induced by transposons are more likely to ... be lethal de dominant be stable revert to wild types be a gain of function The ...
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53 views

tandem repeat sequence; causes of contraction and/or expansion question

Question: Which of the following events, occurring within a tandem repeat sequence, will cause an expansion or contraction of the array? A) Endoduplication B) homologous recombination C) ...
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Abbreviations for molecules: What are CheW, CheA, CheY?

I've encountered the abbreviations such as "CheW" and "CheA" for certain organic molecules. For example: Proteins associating with the Tar complex include the autophosphorylating protein kinase ...
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1answer
28 views

ATP to disassembly of nucleotide ratio

DNA Helicase, the enzyme that is responsible for tearing apart the strands before DNA replication, requires ATP to rip apart nucleotides. I have asked this question to several professors and they ...
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Double stranded breaks in E. coli

What could be a possible reason why no enzymes have been found that make double stranded breaks in the RecBCD pathway?
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73 views

Genomic DNA isolation from wheat

Can I use dry seed, wheat for example, in place of young leaves for isolation and purification of genomic DNA for PCR amplification? The goal of my experiment is to validate a novel gene which is ...
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116 views

how do I find the number of bp in chromosome 3 by knowing number of bp in chromosome 1?

If i have a number of bp in chromosome 1 for example(298,295,559 bp) can I use this number to find the number of bp in chromosome 3.
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How does RNA transcription know which half of the DNA to use?

I feel that I might have a complete misunderstanding here. If DNA has two strands, how does RNA transcription know which one to choose?
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DNA Replication And Primer [duplicate]

Why does nature rely on RNA primer for the start of DNA Replication? Why not simply use DNA primer and make life simple !
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Why is dsDNA nuclease activity by CRISPR/Cas9 only shown indirectly?

In Jinek et al., the authors show nuclease activity of their CRISPR/Cas9 system using the so-called Surveyor assay method. This assay recognizes small mismatches in dsDNA which are introduced by error ...
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How does intron retention make the alternative transcript non-coding?

I faced with a non-coding transcript that specified as one the isoform of BIN1. It sounds that this isoform generated as a result of alternative splicing with a intron retained; am I right? However, ...
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218 views

How do DNA-binding proteins determine that they're binding to the correct DNA base pairs?

My professor posed this question to the class today - "How do DNA binding proteins specifically bind to base pairs?" He alluded to the different arrangements of hydrogen-bond donor and acceptors in ...
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688 views

Are eukaroytic promoters located in the 5' UTR region?

I was wondering if promoter sequences are located on 5'UTR region in eukaryotic organisms?
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119 views

Catenation and decatenation by DNA Gyrase

Decatenation is done for the replication of DNA and why is Catenation done and is it related to Crossing over
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125 views

Do transposons usually jump from one chromosome to another?

If it is usual occurrence, does it mean that my one gene can change its location from one chromosome to another?
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45 views

Genetics of epilepsy

Is epilepsy genetically inheritable? If yes, is it dominant?
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216 views

How does Cro protein expressed by lambda phage kill its host?

I read that the DNA segment of lambda phage integrated in host DNA could switch between lysogenic state where cI represses the expression of Cro and lytic state where Cro expression takes over and ...
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1answer
109 views

What is a holocentric chromosome?

I was doing this question that asked: "How many centromeres does a typical chromosome have?" I thought one and the answer was:"One, except for holocentric chromosomes." So then what are ...
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122 views

Extending a small fragment of DNA

Is there a way to extend a small fragment of DNA, say 150 bp, by making copies of itself and attaching each copy of that small fragment to the end of that 150 bp sequence? For example, I want a 1 ...
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68 views

How long is saliva viable?

Does anyone know if saliva can stay viable for about 5 days, before it gets suspended into a DNA genealogy vial for testing? Background: My brother wants to do a DNA genealogy test at a US testing ...
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16 views

How and why are cells irradiated in human-rodent hybrid cell biology?

When human-rodent hybrids are made the amount of human chromosome in the hybrid can be reduced by irradiation. Why and how exactly is this irradiation step performed?
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100 views

How do signal transduction pathways utilize transcription factors to express a specific gene?

I have an inquiry regarding the regulation of genes via extracellular signaling. To my knowledge, in autocrine, paracrine, and endocrine cellular communication, large protein ligands that cannot ...
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158 views

Explanation about cytogenetic notation

What is the correct meaning of cytogenetic notation "inv(4)(p13q22)" ? Inversions at chromosome 4, at the p arm 13 is inverted AND at q arm 22 is inverted OR Inversions at chromosome 4, the ...
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77 views

Is sequencing error a function of the nucleotide being read?

Checking out on Google Scholar, I can see that for Illumina (just to consider one example) the sequencing error rate is of the order of 0.001-0.01 per nucleotide. Talking about sequencing error, ...
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350 views

How many copies of a gene?

I am studying mathematical models of transcription and translation and I am wondering: In a particular genome, how many copies of a gene coding for one particular protein should one expect? Are they ...
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Is a Ribonuclease Inhibitor protein the only mechanism employed by the human cell to protect cellular RNA from degradation by endoribonuclease?

Are there any other methods of protection for cellular RNA from degradation by endonuclease (specifically the Pancreatic Ribonuclease RNase II (Eosinophil-derived neurotoxin) and RNase III (Eosinophil ...
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554 views

Are the number of base pairs in a given chromosome same between different individuals?

This is a basic question but I couldn't find an answer through a web search; hopefully this is the right place to ask. Is the number of base pairs in a particular chromosome the same in all ...
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204 views

Gene and Protein isoform

What is the relationship between term "Gene isoform" and "Protein isoform"? Say a gene can make 3 isoforms, will it produce only (maximum) 3 isoform protein?
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286 views

Operators and Enhancers/Silencers

Wikipedia has two images, of a eukaryotic gene and of a prokaryotic gene. They show the difference that the prokaryotic gene also has an operator while the eukaryotic gene does not. Both also have ...
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Why does a gene have two alleles? [closed]

Why does a gene have two alleles? When there is a gene for producing the color pigment for a flower, why are there there two alleles, producing either same color or different color (homozygous and ...
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159 views

Sense and anti sense strand

Why the sense strand is only involved in transcription though the antisense strand just has the compliment strand of the sense strand?