The study of chemistry within the scope of biology: the compounds that occur and the reactions involving them in living organisms.

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Transport of mammalian insulin in vivo

What is the mechanism for transport of insulin in mammalian cells?
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1answer
34 views

Activity of glucokinase

From Solomon et al, 2013 ACC Synthetic biology and from this video : Here, there are 2 competing reactions for glucose - one with glk as enzyme and other with gdh as enzyme. In the graph, y axis ...
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59 views

enzymes that stabilize DNA loops

As a follow-up of a previous question, I would like to know what enzymes or protein complexes have been used to manipulate DNA samples into stabilizing DNA loops. I have read that cohesin is one of ...
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2answers
63 views

Why only water in liquid form is essential to live?

My question is:- Only liquid water supports almost every living organism's metabolism, neither the vapour nor the condensed form of water does so. What is the chemical & the biological reason ...
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2answers
393 views

In biosynthesis of cysteine and methionine, where does the sulfur come from?

Methionine and Cysteine are the two amino acids containing sulfur. According to wikipedia, cysteine is built from methionine. However, the wikipedia also claims that methionine is synthesized from ...
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1answer
46 views

Quorum Sensing in Vibrio cholerae

This is a figure summarising the quorum sensing mechanism in Vibrio cholerae. In this video by Bonnie Bassler, she explains how quorum sensing can be targeted to control infections. At 15:09 she ...
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1answer
41 views

What are the physiological roles of Hydrogen sulfide?

I am thinking why hydrogen sulfide has its effects in the body. For instance, it is one Salmonella's virulence factor. I am not sure if such a balance equations holds ...
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32 views

Nearly Exhaustive List for Cholesterol Pathways

I have run across an interesting case that is similar to only two others I've encountered. What makes it interesting is the combination of undetectable (under normal testing conditions, can elaborate ...
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0answers
40 views

Ferredoxin synthesis pathways

I have been thinking about some alternative CO₂ fixation pathways. As almost all of them include ferredoxin reduction I started to wonder where does the ferredoxin comes from. I could not find any of ...
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2answers
80 views

PAH gene mutation

Analysis of the DNA of the Phenylalanine hydroxylase (PAH) gene in a patient with phenylketonuria revealed a mutation in the protein coding region whose predicted effect would be to replace the amino ...
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1answer
62 views

Diffusion of FAD+

Why is NAD+ free to diffuse within the mitochondrion whereas FAD+ is not ? What biochemical properties cause this difference ?
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2answers
48 views

Why is succinate dehydrogenase attached to the inner mitochondrial membrane?

Succinate dehydrogenase is attached to the inner mitochondrial membrane.All the other enzymes of the Krebs cycle are located in the matrix of mitochondria. What is the biochemical reason behind ...
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0answers
56 views

Enzymes that can catalyze multiple reactions [closed]

If the lock and key model were true, only one enzyme would be able to catalyze a reaction. However, some enzymes can catalyze multiple reactions. What are some examples of enzymes that can catalyze ...
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2answers
47 views

Clarification on Hatch and slack pathway

The following is a minor clarification that I want to make, since it is rarely addressed directly in most of the texts I have gone through. In C₄ pathway, the chloroplasts are dimorphic, that is, ...
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2answers
64 views

Why do humans circulate monosaccharides instead of disaccharides as in plants?

Plants transport food mostly in the form of disaccharides like sucrose but humans transport them in the form of a monosaccharide - glucose. What is the reason behind this ?
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1answer
782 views

Isopropanol precipitation of DNA - duration and magnitude of cold storage

DNA prep protocols often include a final precipitation step with alcohol, often isopropanol, where the DNA must be kept in the alcohol, at a low temperature such as -20C or -70C, often overnight. ...
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1answer
103 views

Pathway mediates nitroglycerin-induced relief from angina pectoris [closed]

what kind of Pathway mediates nitroglycerin-induced relief from angina pectoris,please provide some idea...
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2answers
380 views

Converting unit/mg or unit/ml into ng/ml, or vice-versa

I am working with the enzyme Cu/Zn Superoxide (SOD1) and i am quantifying them in ng/ml. However, most past studies has SOD1 quantified in unit/mg or unit/ml, and i need to compare the SOD1 level of ...
3
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1answer
40 views

How do you express and detect GLP-1 receptors?

I am currently working with a peptide which is an analogue for glp-1, but during invitro studies am not able to detect for the presence of GLP1- receptors. The cell line used is Min-6. How do I detect ...
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1answer
29 views

Correlating Ki values of pesticides to bacterial growth

Four pesticides P1 to P4 are reversible inhibitors of an enzyme E that is essential for the growth of a bacterium B. Their Ki values are given in the table below. Each of these four pesticides ...
4
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1answer
46 views

Correlating beta-lactamase expression to absorbance

When penicillin-resistant bacteria are grown in liquid culture media, β-lactamase is secreted into the medium. The supernatant of such a medium can be assayed for β-lactamase activity. ...
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12 views

To understand synthesis of e-NOS and n-NOS with respect to Ca and calmodulin

I found this sentence in my notes interesting E-NOS and n-NOS are Ca, calmoduline dependant ferments. They are synthesized from in small conc as response to physiological signals which ...
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34 views

To understand Nitric oxide, iNOS and Tumour cells

I have this figure about nitric oxide and tumor which is for schematic for me to understand it The figure should probably say that tumour cell is induced by NO or alone to go apoptosis and it ...
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2answers
27 views

To understand Second messenger signalling in I/c and E/c

I found this picture in my study materials. I think it is too schematic and ignores the big pictures. I think the thing connected to the hormone is receptor. The second messanger is then connected ...
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0answers
66 views

Osmosis - occurring in both ways?

So I did a prac to identify the osmotic potential of potato tuber cells. There were 5 test tubes with different concentrations of sucrose (0M,0.25M,0.5M,0.75M,1M); a small slice of potato was placed ...
4
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1answer
107 views

Why plants (eg. parsley) can keep vitamin C despite all the sun?

I have read that vitamin C is highly sensitive to light. So, how could parsley, for instance keep its vitamin C as it's flooded with sunlight?
3
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1answer
405 views

Classification of glycosidic anomeric bonds (alpha vs. beta)

In the process of studying for my upcoming biochemistry exam, I have stumbled over the classification of glycosidic bonds. I want to be able to distinguish $\alpha$- from $\beta$-glycosidic bonds. ...
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1answer
77 views

DNA ligase mechanism

I am unable to understand what happens to the phosphates from ATP. What are they used for ?Charging 3' end or 5'end ?
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1answer
1k views

What's the difference between protein and DNA behaviour during agarose gel electrophoresis?

I'm planning a science project about gel electrophoresis, and I'd like to know if there are any measurable, quantifiable (for example, things I could represent in a graph or chart) differences between ...
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1answer
67 views

Topology of protein

The domain structure of protein Z, which is composed of 180 amino acids, is shown in the upper part of the figure below. Protein Z is palmitoylated at a cysteine residue (the third amino acid) ...
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1answer
94 views

What are the lifetimes of cellular components on organelle or molecular level?

I was thinking that even though I know how generally the cell works, I don't really have a feeling of how volatile it is. I want to know what is the lifetime/turnover rate of different constituents of ...
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1answer
18 views

Source of energy of adipocytes

Since adipocytes export fatty acids and don't use them as an energy source, which is the main source of energy for this cells?
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1answer
42 views

Identifying mutations in a yeast strain

Cells of a triple-mutant yeast strain (leu- his- trp-) were spread either on minimal medium or on minimal medium supplemented with various combinations of histidine, leucine, or tryptophan. The ...
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0answers
55 views

What is the biochemical pathway of fluoride?

Fluoride is a common active ingredient in tooth paste to prevent dental caries. It is also added or removed from the water supply in some communities for the same reason, but in children only. My ...
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2answers
72 views

Lactate and Diabetes

Why are lactate level high in diabetes? For example, Diabetes type II have resistance to insulin, and if they do it, their gluconeogenese should be working at high levels and, because of that, uptake ...
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1answer
55 views

How is it decided that one drug is better than others by X times?

I read in Tortora and Derrickson that : Enkephelins are 200 times powerful than morphine in their analgesic effects. I wonder how exactly researchers arrive at a number (like 200 here). I also ...
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1answer
146 views

Shine-Dalgarno sequence and expressing proteins

Shine-Dalgarno sequence present in the prokaryotic mRNA plays a role in initiation of translation. In eukaryotes a Shine-Dalgarno like sequence is present but does not play an important role in ...
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0answers
44 views

Why does the ovum prefers to be arrested at metaphase 2 of meosis before fertilization? What is the possible advantage of this process?

Why does the human ovum prefers to be arrested at metaphase 2 of meosis before fertilization? What is the possible advantage of this process??Please help me with it.
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1answer
60 views

Determining limiting nutrients from a graph

The question was Which of the following statements is supported by these data? A. Phosphorus was the first limiting nutrient followed by nitrogen. B. Nitrogen was the first limiting nutrient ...
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20 views

Does amylolysis occur in vegetables if stored under 0 Celsius?

Assume that we have a plant, e.g. kale, which is prone to amylolysis if not harvested during a frost period. If it is harvested and put in a household freezer, such that it is frozen solid slowly ...
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2answers
92 views

Phospholipid Bilayer structural reversal

What would happen if the phospholipids in the phospholipid bi-layer were reversed, the fatty acid tails now facing outwards and the phosphate heads facing inwards? I'm assuming this will not affect ...
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35 views

Why black plum has a smell so much resembling tobacco?

Why black plum has a smell so much resembling tobacco? What substance does determine it? Can it be used for tobacco replacement?
2
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1answer
135 views

Why is cyanide poisonous?

I know cyanide inhibits complex IV in the electron transport chain, but I don't understand why this makes it so toxic. If cyanide is bound to the complex, can't the electrons just bypass it and ...
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1answer
52 views

Why is Thermus aquaticus and Taq Pol stable?

What is the molecular basis of the stability of the bacterium Thermus aquaticus and the enzyme Taq Pol it produces ? I have tried googling this but did not get a good answer.
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1answer
221 views

Excretion of various wastes and water requirement

A common fact is that Ammonia, Urea and Uric acid are the most common excreted metabolites and their removal needs varying amount of water, highest for ammonia (hence suited only for aquatic animals) ...
4
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1answer
76 views

What makes alcohol harmful to mammals?

During the alcohol metabolic pathway, harmful by-products are made like acetaldehyde, hydroxyethyl, superox­ide anions, and hydroxyl radicals. How do these toxic compounds harm our tissues? Many of ...
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55 views

What are the ingredients of Pheromone Trap using for controlling Fruit flies of cucumber?

Pheromone Traps are used for fruit fly control. But I have no idea which ingredients or chemicals are used for preparing Pheromone trap
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1answer
70 views

(Web)app to search metabolic/signalling pathways

I'm looking for an application where you can find pathways by selecting a chemical occurring in it. So, for example, selecting 6-phosphogluconolactone brings up the pentose phosphate pathway or any ...
2
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1answer
159 views

Independence of Light independent reaction in photosynthesis?

Inspired by a question asked to me by a classmate, I have the following question about Light-independent (dark phase) reactions in photosynthesis:- Let us suppose an algae sample was exposed to ...
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2answers
66 views

How does promoter sequence affect initiation?

I don't know if this might have been highlighted in recent research, but a textbook I have states that "the exact way in which promoter sequence affects [transcription] initiation is unclear" I'm ...