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Questions tagged [molecular-biology]

The study of the molecular processes underlying life.

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Molecular biology

Does every protein start with methionine? The start codon is AUG (which corresponds to methionine),then why doesn't the methionine present in the protein after the translation has done. I have ...
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1answer
16 views

Human Stem Cells and Disease

Can human stem cells be stored for use by future family members as a way to combat generational diseases like diabetes
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1answer
178 views

Why did they expect Astronaut Scott Kelley's telomere shortening to accelerate? (they got longer!)

The NPR News article and podcast Scientists Share Results From NASA's Twins Study says: SCOTT KELLY (NASA Astronaut): You know, the symptomatic stuff is fine. I don't have any long-term negative ...
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21 views

Intein Splicing

Currently I am trying to read and understand this paper on intein splicing. https://sci-hub.tw/https://www.ncbi.nlm.nih.gov/pubmed/22001202 However, I'm a little confused with Figure 4. Why do the ...
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RNAi termination

Can you stop an ongoing RNAi after transfection with a vector containing siRNA? I want to experiment on gene function loss effect, using RNAi, and gene function gain, using stopping the RNAi.
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2answers
589 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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Is it possible to stop more/extra fat from being stored in the body?

I don't mean simply by restricting eating or upping the activities, but a way to basically stop the body from adding more fat on itself down on the bio level. For example, I'm not too knowledgeable on ...
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10 views

How can MMLV reverse transcriptase add cytosines to the 3'-end of cDNA

I am working on the mechanism of SMART, a kind of reverse transcription strategy. However, I am confused about the terminal transferase activity of MMLV enzyme. It have been reported since 1998, ...
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2answers
290 views

number of chromatids seen in karyotype

The karyotype is performed on a cell whose cycle has been stopped in metaphase or pro metaphase, using colchicine or by other means. In the textbooks I read that during the S phase each of the 46 ...
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1answer
30 views

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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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
24 views

Spatially Encoded GPCRs?

I'm reading this paper, and I'm already lost in terms of what they mean by GPCR signaling is spatially encoded. How can signaling be spatially encoded?
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2answers
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What is a “pan-specific” antibody?

I am new to biology. I searched a lot to find an article that explains what "pan-specific" antibody is but I could not find anything substantial that would help me understand what it is. An example ...
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Why is AUG the initiation codon?

Is there any reason why AUG is the initiation codon? Can’t translation start with different codons?
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Rhodamine 123 Staining Function

How does Rhodamine 123 act as a probe for Mitochondrial Staining? What is the Exact Biochemical Basis? and can it Stain Chloroplast as well? Thanks in Advance
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12 views

Gene cluster of interest not being amplified in PCR

In a lab, I currently have a sample of Rhizobium sp. NT-26. This bacteria is a chemolithoautotrophic arsenite-oxidizer, and I want to clone the arsenite oxidase genes into another bacteria strain in ...
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0answers
20 views

Can sperm cells penetrate the cell membrane of non-ovum cells?

Sperm cells have tiny bags of enzymes on their tip (the acrosome) which allow them to penetrate the ovum. My question is whether or not the process that allows sperm cells to penetrate the cell ...
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What is a secretion target family protein?

I came across this link: https://www.genome.jp/dbget-bin/www_bget?btw:BF38_3398 What is this protein, is it a secreted effector protein or is it something else? What is the difference between type ...
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1answer
32 views

Approximate Cell Doubling Time?

If I know it takes 12 min to occur in mitotic fibroblast cells and I count there are 32 dividing cells in the microscope slide out of a total population of 32034 cells, how do I calculate the ...
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0answers
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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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3answers
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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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3answers
92 views

Why are there three stop codons but only one start codon?

I was wondering whether there is any specific reason that there are three stop codons but only one start codon in prokaryotic and eukaryotic cytoplasmic mRNAs.
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1answer
1k views

basic programming and bioinformatics [closed]

As a molecular biology graduate student I have decided to learn some basic programming and bioinformatics since everybody says that it is crucial. For example, what would you learn if you need to work ...
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How to detect specific mRNA dsRNA by Northern analysis?

I silenced a gene by RNAi method, for that i chose the gene and the size of the gene is 1.5kb and my insert size is 500nts. i did the transfection and i want to confirm the silencing by northern ...
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Why is there more variation in proteins than genes?

The Genome of a cell or organism is the same as that of the entire organism. However, the proteome of an organism is much greater than that of each cell (unless the organism is unicellular). How do ...
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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
29 views

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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Is there other unknown-compound in Blood?

Blood is made of red blood cells, platelets, plasma etc. Let's say, then, there are these $x$ known compounds in blood. But how can one be sure that there is no other compound other than those $x$ ...
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1answer
110 views

What is the difference between a signal peptide and a transit peptide?

From what I know, the two names are used interchangeably and I haven't found any resource which says otherwise either. Is there at all any difference, is there a transit peptide that is not a signal ...
2
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1answer
32 views

How are primary monoclonal antibodies for screening mutant cells made, physically?

I'm working with a fairly common protein expressed in a large numbers of organisms, let's say a keratin-associated beta-protein. I'm trying to develop a process which requires primary-secondary ...
2
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1answer
76 views

What is meant by “heads” and “tails” in the context of gene orientation?

I have a hard time understanding what this paper is talking about when it says: We observed maximal cleavage at sites oriented tail-to-tail and separated by -10 bp to +30 bp (Fig. 2d). Finally, ...
2
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0answers
41 views

What regulates cyclic AMP?

After reading a textbook chapter on GPCRs I am still confused by what regulates cAMP. I took in my notes that cAMP is made by adenylyl cyclase and destroyed by cAMP phosphodiesterases (also another ...
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2answers
116 views

Why is Turner syndrome a problem?

Turner syndrome is a chromosomal disorder where one of the X chromosomes is missing. For more details visit the Wikipedia page I don't understand why missing one X chromosome would be harmful. In ...
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2answers
50 views

identification of differentially expressed genes in RNA-seq analysis [closed]

I am using four different packages (viz. EBSeq, DESeq2, edgeR, LPEseq) for identification of differential genes. Now I am confused whose fold change value should I take for further downstream ...
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1answer
39 views

Storage DNA Condition

It is possible to store a digestion of cells with lysis buffer several days at -20 degrees and then proceed with the phenol chloroform isoamyl purification?
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1answer
139 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
809 views

Has anyone used Crispr/Cas to induce a knock-in in MEF cells?

Does anyone have experience with the CRISPR/CAS9 platform performed on MEF? Or does anyone recall any relevant articles?
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2answers
118 views

Storage of bacteria

Why are strains of bacteria stored when they are inactive (frozen)? What is the problem with storing growing cultures for long periods?
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1answer
55 views

How do biologists discover information from fossils? [closed]

I have a query about the study of fossils (palaeontology). Let me know about the study of fossils. How do biologist discover "DNA" information from dead and old fossils such as a dinosaur? (answer ...
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1answer
28 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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0answers
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What is the structure of DNA during Interphase? Chromatin Fibre or Beads on a string(nucleosomes)?

During Interphase, does DNA predominantly exist as Chromatin Fibre (30nm fibre) or Chromatin/beads on a string structure(10nm) ?
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1answer
66 views

Must I HPLC-purify my PCR Primers for amplicon sequencing with PacBio SMRT?

I would like to order some primers for amplicon sequencing. I am using universal tag primers (unusually long 30-mers recommended by PacBio for SMRT, both F&R) + barcodes (16-mers). The resulting ...
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the Oxidization reaction of NADH [duplicate]

Does oxidization of NADH need H+? I've seen a reaction like this👇 NADH + H+ >>>> NAD+ + 2H+ What's the use of the proton in here?
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1answer
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What chemical test can be used to tell apart meat and plant-based meat?

Long story short, I thought about this question and simple Google searches weren't enough. I know there must be some nutrient that can only be found in one of the meats but not the other, but I can't ...
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1answer
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What impedes the understanding of genotype/phenotype relationship without statistics? [closed]

Most genetic research tries to establish a relationship between a certain genotype and certain phenotype. To me this is like trying to understand a system as a black box, where you try to establish ...
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1answer
19 views

Measuring transgenic gene expression with a microplate reader

I have been working on genetically engineering an E. coli strain to autotrophically oxidize arsenite into arsenate for bioremediation of arsenic contamination in groundwater. For my research, I have ...
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1answer
99 views

How to interpret this PubChem record of L-Alanine

Using the PUG service from NCBI, I am retrieving 3d structure data for a molecule. Raw data here. I am trying to understand this record, specifically for the purpose of rendering in a 3D coordinate ...
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1answer
34 views

Where do the lysines come from during ubiquitination?

I know that Ub forms an isopeptide bond with lysine, but where do the lysine come from? Are they just always available for the Ub to find to during the ubiquitination process? Is there a free lysine ...
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0answers
20 views

Can Dpn1 digest hybrid PCR product with only one methylated strand?

In Site directed mutagenesis using PCR, after a cycle we obtain a hybrid molecule with one parental strand and other newly synthesized unmethylated strand. This is followed by Dpn1 digestion. Does ...
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Why both forward and reverse primer are added in asymmetric PCR?

If the purpose of Asymmetric PCR is to amplify single targeted strand of dsDNA then instead of adding just one primer for targeted strand why do we add both forward and reverse primer? Upon addition ...