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Questions tagged [molecular-biology]

The study of the molecular processes underlying life.

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78 views

Would I expect salt precipitate on fibres of DNA in a NaCl water solution?

I just recently conducted an experiment in my biochemistry class where we had to add DNA to distilled water, isotonic saline and 2.5M NaCl. I noticed different physical aspects depending on the ...
0
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1answer
69 views

Blackgram leaves. SDS page. Phosphate buffer method

I am doing protein analysis in blackgram leaves by using phosphate buffer method. But I cannot get proper bands on my SDS-PAGE. What should I do to get proper bands?
3
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0answers
67 views

Proteins folds: relation to splicing and post-translational modification?

Is the secondary structure pattern of protein folds related in any way to alternative splicing and post-translational modification?
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0answers
859 views

Non-Competitive Inhibition vs Allosteric Inhibition

The Vmax of a reaction is lowered in presence of a non-competitive inhibitor (compared to the control - without a inhibitor) However, (Vmax of the reaction stays the same in presence of an allosteric ...
2
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1answer
38 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?
2
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1answer
255 views

Reading an amino acid physicochemical properties diagram

I want to know if I am reading the venn diagram correctly and why there are discrepancies in the diagrams. I'm trying to determine which amino acids are considered hydrophobic and I am using this ...
2
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3answers
104 views

What are the applications of predicting the structure of proteins?

Protein molecules are very important as they are used for catalyzing almost all the chemical reactions in the cell, regulation of gene activity and provide cellular structure. However, in predicting ...
2
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0answers
154 views

How is the effect of proof-reading on error frequency during DNA replication determined?

An article in Nature Scitable on DNA Replication and the causes of Mutation states that: When an incorrect nucleotide is added to the growing strand, replication is stalled by the fact that the ...
2
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1answer
999 views

What is the structural difference between beta and gamma globin chains of Hb?

Hemoglobins are tetramers composed of pairs of two different polypeptide subunits. The subunit composition of the principal hemoglobins are α2β2 (HbA; normal adult hemoglobin), α2γ2 (HbF; fetal ...
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1answer
95 views

Which cancers are routinely treated with anti-angiogenic therapy? [closed]

I have been asked to discuss 2 of these cancers and how the therapy is used. I understand angiogenesis and its role in tumour progression, but need some help in explaining how the therapy is used.
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1answer
78 views

Cutting of DNA strand [closed]

Would EcoRI cut the following sequence?? 😕 5'CTCGAGTTCGAG3' 3'GAGCTCAAGCTC5' What is the logic of cutting? Please explain how restriction enzymes work.
3
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2answers
80 views

Using evolutionary algorithms in molecular biology? [closed]

I am currently an MSc student studying molecular biology (on paper I'm a chemist) and soon I have to talk to my supervisor about my future, PhD research topic. Besides molecular biology I'm also ...
2
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1answer
58 views

How to attain a deep conceptual grasp of key atomic/molecular/genetic/ notions? [closed]

It's a total noob question, I know. I'm a layperson trying to come to grips with basic scientific terminology. I always face a conceptual hurdle in trying to understand micro-talk. The way I'm using ...
5
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1answer
236 views

What does the “Psi” in “Psi broth” stand for?

When making competent cells I've been using a medium called "Psi broth", which per liter consists of 20 g tryptone, 5 g yeast extract and 5 g MgSO4. Today I got curious about why it's called "psi". Is ...
-1
votes
1answer
70 views

Why is suicide inhibition considered a catalytic reaction when the catalyst is irreversibly modified because of the reaction? [closed]

I understand that this might be meaningless semantics, but I'm confused and would appreciate clarification. I've always been taught that, a catalyst is, by definition, a substance that is increases ...
0
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1answer
37 views

Using cell concentration [closed]

I am doing an experiment in which I plate for example 3x10^5 cells, and every day I have to count the cells growing. I find the number and a convert it in x10^5. In my graphs I have to use the cell ...
-5
votes
1answer
54 views

Tumour cell injection into a mice [closed]

I am going to inject mice tumour cells into mice to create them tumours and I am wondering if I need to have special precautions for that, even they are cells from mice tumour I am afraid what can ...
0
votes
1answer
84 views

Reusing pipette tip

I'm new to research and one of the things I'm learning is pipetting. I've got the basics down but say I'm reusing a pipette tip because the solution I'm using is the same. So first I depress to the ...
1
vote
0answers
47 views

What is the point of storing biological samples in Trizol/TriSURE before RNA extraction?

The Wikipedia article on Trizol says that it helps break the cells and maintain RNA integrity during homogenisation of samples. Does anybody know by how much Trizol improves RNA integrity compared to ...
3
votes
2answers
50 views

Gene terminology - is one gene a concrete, single physical sequence?

Suppose you have two identical copies of the same, coding nucleotide sequence (e.g. two copies of BCL2 - a random gene I found on Wikipedia). Could you say that these are two genes (i.e. the name "...
1
vote
1answer
27 views

What does ensemble-based model of enzyme mean?

I am reading Pan et al. (2000), a paper about dihydrofolate reductase (DHFR). They claim using a ensemble-based model of DHFR. What is a ensemble-based model?
1
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0answers
133 views

Question about Racemic Mixtures in Miller-Urey Experiment

I'm studying the Miller-Urey Experiment for my Biology class, and a significant point made by my professor was that Miller made a 50/50 racemic mixture of chiral monomers. However, life is homochiral....
3
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0answers
62 views

What's the ratio of saturated to unsaturated fatty acids in human cell membrane?

It's well established that the fluidity of a cell is largely dependent upon the ratio of saturated to unsaturated fatty acids that exist within the membrane, but, what exactly are the values for this ...
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0answers
35 views

Do influenza viruses obey a Hayflick limit similar to human cells .. or do they spread and divide forever like HeLa?

I would think the latter since they are so simple and are parasitic but even proteins break down over time .. only found a few answers on the net and it was over a decade ago but nothing in any papers ...
12
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2answers
1k views

Why aren't 'exons' named 'introns'?

Why are introns called 'introns' when they are the actual ones who are getting spliced out from the pre-mRNA. Shouldn't exons be named introns as they are the ones that are 'in' and are not 'exiting'? ...
1
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0answers
45 views

Should I use glycogen in isopropanol to precipitate RNA or does glycogen have harmful consequences on downstream protocols such as RNA seq?

I have heard that one can use glycogen in isopropanol to better visualise the RNA pellet after centrifugation. What are the advantages and disadvantages of adding glycogen in isopropanol for RNA ...
2
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1answer
159 views

Power consumption of a ATP synthase in Watts

Considering the ATP synthase to be a rotating machine, does anybody know its power consumption and/or power production in Watts? At least roughly, e.g. based on the average chemical energy produced ...
3
votes
1answer
446 views

Terminology of the sequences of promoters in relation to DNA strands

I'm studying molecular biology and I'm trying to understand an experiment which shows the importance of promoters in the relative transcription level (RT). The image below comes from Rolf Knippers' ...
1
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1answer
344 views

Do dead cells always contain no nucleus?

If I examine a dead cell, can I be sure that it has not a nucleus? And what about the other organelles?
2
votes
1answer
123 views

cloning and blue white screening in pet21a

I am using pet21a as a carrier vector for my gene, with R.E BamHI and XhoI,in reverse primer I haven't added any extra nucleotide sequence so that it should code for the histag towards C-terminal. Am ...
0
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0answers
17 views

Collagen Type V

Lodish - Molecular Biology of the Cell: "Two quantitatively minor fibrillar collagens, type V and type XI, co-assemble into fibers with type I collagen, thereby regulating the structures and ...
6
votes
1answer
346 views

Is there a double helix RNA?

I wonder what is its function and if it can be the genetic material for a living organism. If not, why?
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0answers
292 views

DNA linking number, twist and writhe

The image below is taken from a molecular biology textbook. It is not clear to me that what is happening at the two writhe crossings matches up with the numbers provided. Is there a problem with ...
3
votes
1answer
52 views

Is Ellman's reagent specific for low molecular weight proteins and thiols?

Is it still possible to quantify cystein rich low molecular weight proteins such as Metallothionein in a given sample using Ellman's reagent if the sample is contaminated with some high molecular ...
2
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1answer
76 views

Can a gene be inactivated using CRISPR if it is not in the interspace of short palindromic repeats?

I have recently studied how CRISPR works but there is something that I do not understand at all. I have heard a lot of people claiming that with this method it is possible to modify any genome by ...
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2answers
36 views

Organism and plants reduce radioactivity?

I would like to ask if there are organisms or plants that could help in reducing any one of types radioactive contamination?
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0answers
33 views

How do cell signaling ensures time synchronization?

Let us suppose two cells A and B communicating with one another, I want to know how do cells ensure time synchronization while communicating. For instance, let us assume cell A sends a sequence '110'. ...
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2answers
465 views

Why EtBr migrate toward the opposite direction?

We known that DNA would run toward the positive electrode, because of they have negative electricity. then why EtBr migrate toward the opposite direction to DNA? is because they have positive ...
0
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1answer
76 views

Backcrossing in Hybrid

Can anyone help me in understanding how backcrossing helps hybrid to achieve pureline? I have been looking into the references i possess but couldn't seem to find anything
4
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1answer
63 views

Do strictly anaerobic organisms use metabolic reactions requiring oxygen?

When looking through genome annotations of strictly anaerobic organisms I see reactions featuring oxygen. I suspect these are likely an artifact of the annotation process. But I am wondering if it is ...
4
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1answer
119 views

DNA quantification in a high school bio lab

I'm working on a project in a high school bio lab (so limited resources), and I need a way to quantify the concentration of DNA in a PCR product. I can't use spectrophotometry (cheap ...
0
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1answer
68 views

Do cells communicate only in binary levels?

In modern communication we generally have various schemes to communicate the given signal, one of them is to convey information with different levels. does cell signaling too have levels apart from ...
0
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3answers
146 views

Biology Intuition and Origin of the “facts” [closed]

I am a graduate physics student but also taking biology classes. I am new to the field of bio. Most of what we do in class seem like memorizations and stating-facts. I am wondering: How can I develop ...
4
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1answer
104 views

Overexpression by integration of an additional copy vs promoter exchange

In Becker et al (2011), the authors increase the expression of several genes through different methods. For some genes (e.g., lysA, ddh), they achieve overexpression by integrating an additional copy ...
2
votes
1answer
175 views

Difference between 'fitness' and 'fitness effects'

Term 'fitness' is pretty obvious, but, often 'fitness effects' is commonly used in many research articles in the field of evolutionary biology. I suspect that 'fitness effects' has a different ...
1
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2answers
71 views

How can ionized amino acid form be important for the catalytic activity?

I can imagine that protonated amino acid form, particularly at the active site, is important for the catalytic activity so hydrogen bonds can be created between the substrate and the enzyme. However, ...
6
votes
2answers
181 views

How do membrane proteins find their target locations?

The question might be asked for any kind of "bound" proteins, but I'd like to restrict it to membrane proteins. Assuming membrane proteins (or their main parts) don't (or aren't) build in situ but at ...
1
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2answers
68 views

Reaction centre in Photosystems of higher plants

In photosystems of higher plants, there are about 250-400 pigments (number wise) in a particular photosystem. Out of which,approx 170-180 pigments are of chlorophyll a molecules. And any one of them ...
1
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1answer
87 views

Limit on the Number of Facial Phenotype [closed]

Individuals of each species all have unique facial structure variations (shape of nose, position of chin etc) from humans to birds and fish etc. We humans don't seem to be reaching mathematical limit ...
5
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1answer
736 views

Why is liquefactive necrosis only seen in brain?

Liquefactive necrosis is a type of necrosis uniquely observed in brain. This occurs due to breakdown of cellular proteins by the action of hydrolytic enzymes. In other parts of the body, usually a ...