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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Domains in cell membrane

How is movement of proteins and lipids between different domains of cell membrane prevented? Why is the noncytosolic layer not able to do lateral movements between domains but cytosolic layer is able ...
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4k views

Why restriction enzymes cut (usually) at palindromic sequences?

Restriction enzymes usually cut only at palindromic sequences. Is there any specific reason for that ? Is there any advantage for bacteria if it cuts up virus at this type of sequences ?
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8k views

Can the excessive consumption of mineral water lead to kidney stones or other health issues?

I heard that drinking too much mineral (bottled) water could lead to problems such as kidney stones because of the high amount of minerals in it. Is it true? If so, what is considered to be excessive? ...
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58 views

What does “rapamycin-sensitive oncogenic transformation” mean?

Can someone explain exactly what "rapamycin-sensitive oncogenic transformation" is? I get that it's a drug that suppresses the immune system but what does it have to do with oncogenic transformation? ...
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3answers
118 views

What biochemical molecule viewer allows for changes in amino acids and resulting tertiary structure?

I am familiar with the Jmol, Rasmol and PyMoL softwares, and was recently introduced to BioBlender. However, I am completely unaware if any of these programs (or others) are capable of loading a .pdb ...
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60 views

Diet of free-range herbivores

Giving minimal credence to estimates in popular media of the average biomass of insects/arachnids, etc. in an acre of land, it seems that a "free-range" cow (I don't mean to pick on cows) might be ...
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59 views

Are all dipeptides synthesizable?

Probably a basic question, but are all possible dipeptides synthesizable? For 20 amino acids, there should be in principle 190 dipeptides; do they all exist or is there chemistry that makes some ...
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66 views

Ways to fight black mold

Is it possible to introduce a microorganism to a colony of black mold that will kill off the black mold entirely and permanently? Is there a common microorganism that likes to eat them and is harmless ...
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22 views

What is the protein sequence taken as input in the Path-A prediction system

Considering the Path-A based metabolic pathway prediction (http://nar.oxfordjournals.org/content/34/suppl_2/W714.short). It uses machine learning for pathway prediction. Suppose that the input was a ...
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86 views

How to preserve leaves between sampling (collection) and analysis?

Suppose I spend a day in a forest, collecting different kinds of leaves, which I would like to analyze under a compound microscope. Now, obviously, measures should be taken to preserve the leaves some ...
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44 views

Glycerol 3-phosphate nomenclature

Why is Glycerol 3-phosphate named in such way? Shouldn't it be named as Glycerol 1-phosphate by proper IUPAC- nomenclature?
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22 views

Relative sweetness

I have noticed that when I eat something sweet, then afterwards, I eat something else that is sweet, the second sweet food is not as sweet as it usually is. I am pretty sure many others have a similar ...
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68 views

How do catalase and other antioxidants neutralize free radicals?

In learning about how cofactors are essential to proper enzyme function, my textbook mentioned catalase and its relation to the human body. According to my textbook, catalase is similar to hemoglobin ...
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38 views

Can plants directly use sulfuric acid?

In the explanation of the sulfur cycle, it is often said that sulfur moves from the atmosphere to the ground by acid rain in the form of sulfuric acid. Can plants directly use sulfuric acid to ...
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22 views

Are the cpli and ctli tests time senstive(i.e. is it needed to test right away in order to get accurate results)?

I'm sending the blood samples to a lab and this takes some time until the actual testing. Some information on the tests. TLI : ...
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1answer
35 views

What is the biding site code recognized by the parts of the spliceosome

Another question about another Youtube video. At 0:50, the splicing process begins to remove the non-coding section of the DNA (intron), so the different parts of the spliceosome attach to the borders ...
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93 views

Mesoporous silica particles as anti cancer drug delivery method

If this question is a little off topic for Biology, I'm sorry. I've recently read a lot about mesoporous silica nanoparticles as a promising drug delivery method. The huge range of customizability of ...
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125 views

Fatty Acid Synthesis

I have a problem in my reasoning on the fatty acid synthesis in the human body. In the synthesis process you have this homodimer. So the synthesis starts with the transfer of a acetyl group from ...
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31 views

Roles of creatine and bilirubin in foetus circulation

I think they are not inputs from maternal placenta. I think they are the results of foetus metabolism. However, I do not understand it how and where exactly. What are the roles of creatine and ...
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35 views

Does amylolysis occur in vegetables if stored below 0⁰ 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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213 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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63 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
638 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) ...
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740 views

Is there any advantage of having a mitochondria for aerobic respiration?

If we consider the pathway of breakdown of glucose which includes glycolysis, the citric acid cycle and the electron transport chain, all these processes takes place in some prokaryotes and ...
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1k views

Why is allolactose the LacI inducer?

For what reason(s) is allolactose, instead of lactose, the "natural" inducer of lac operon repressor?
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115 views

Electron transport in granal stacks

See paper for distribution of PS-I and PS-II within grana As explained in the above paper, the PS-I complex is primarily located within non-appressed thylakoid region and stroma lamella, while PS-II ...
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44 views

Are CoA and CoAS the same thing in a compound?

Is CoA-S-R the same as CoA-R, and is CH3C(=O)CoA the same as CH3C(=O)SCoA? Eg. Above is the compound on the right just coenzyme A or is it actually another compound and not just notation?
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156 views

Does precipitation influence the UV spec reading?

I have been checking my sample for Hydroxyl radical scavenging activity. I have dissolved Hydrogen peroxide in Phosphate buffer. My sample is clear and reagent is also clear but when I have mixed my ...
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268 views

What is the biochemical reason for mental fatigue?

Is it known exactly why the brain needs sleep? What's dropping low / going high when we experience mental fatigue? I can see why low glucose could result in mental fatigue, are other reasons known?
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300 views

What happens to colloidal particles in a liquid medium? And how to stabilize it?

Definition Colloid is a dispresion of small particles of one material in another. Definition 2 (Wikipedia) A colloidal system consists of two separate phases: a ...
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83 views

What biological processes can affect the temperature of the shadow a tree casts?

Assuming two trees have similar shape and leaf coverage, could differences in the biological processes among them lead to differences in the temperature of the shadow they cast? What biological ...
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1answer
23 views

Question related to L-arginine biosynthesis

With respect to the L-arginine Biosynthesis pathway, the very first reaction converts L-glutamate to N-acetyl L-glutamate. In the linked reaction scheme, why are only L-glutamate and N-acetyl ...
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90 views

Recommend good conversational books to learn about cell and developmental biology or biochemisty?

I'm an engineer by training and teaching myself the basics of cell and developmental biology. I'm using Scott F. Gilbert's Developmental Biology and Alberts' Essential Cell Biology right now, and they ...
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38 views

Question regarding an Escherichia coli reaction

With respect to this link http://www.biocyc.org/ECOLI/NEW-IMAGE?type=REACTION&object=RXN-14479 Here the enzyme is mentioned and the two reacting compounds. Now , my question is 1. When these ...
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29 views

Are more molecules of ADP than inorganic phosphate returned to the light reaction in photosynthesis?

During the dark reaction, 9 molecules of ATP are consumed for every 3 carbon dioxide molecules, yet only 6 molecules of inorganic phosphate ultimately leave the cycle. Does that mean that there is a ...
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24 views

Why are 2 electrons transported from photosystem II at the same time?

I only know that electrons are captured by the primary electron acceptor and then go through the electron transport chain, ultimately ending up at photosystem I. But why do 2 leave photosystem II in ...
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1answer
39 views

What does it mean when a protein has a different excitation spectra than wildtype, but the same emission spectra?

We have a GFP mutant that displays a different excitation spectra with emission at 510nm than the WT. However, their emission profiles with excitation at 490nm are the same, and we do not observe the ...
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1answer
94 views

How to define drug-resistant or -sensitive cell line when knowing the IC50 values?

I have got the IC50 data for a drug on different cell lines. How to define if the cell line is sensitive or resistant towards this drug? Could anyone tell me how to define this?
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48 views

Why is the resting potential of a neuron so close to the equilibrium potential of K⁺?

I know this has something to do with the K+ leak channel. I just don't understand how. I know that 3 Na+ are pumped out for every 2 K+ pumped in. This makes the cell interior net negative. I know ...
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1answer
43 views

Change in synthesis rate of a molecule changes equilibrium concentration

I was reading the topic of 'The concentration of the molecule can be adjusted quickly only if the lifetime of a molecule is short' from Molecular Biology of the Cell by Alberts. At the end of pg-837 ...
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1answer
33 views

What initiates primase to add an RNA primer to a DNA strand and what makes it stop?

What initiates primase to add an RNA primer to a DNA strand and what makes it stop adding RNA nucleotides? Is there tags added to the DNA back-bone?
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162 views

Is there a known glucosepane cross-link breaker?

I read the following on wikipedia: There is, however, no agent known that can break down the most common AGE, glucosepane, which appears 10 to 1,000 times more common in human tissue than any ...
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1answer
285 views

What causes skewed ladder bands on an agarose gel?

I frequently ran into an issue where the bands of my ladder become skewed. What causes this? Here's an example: 0.7% agarose gel, 100V, 60 minutes. Same problem occurs with 1%. I loaded 10 ul of a 20 ...
2
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1answer
316 views

Enzyme Assay, absorbance change to concentration change

I have a few issues with this question. An enzyme assay is performed and the kinetic data graphed. The y-intercept of a Lineweaver-Burk plot is 0.6 min/ΔA. The substrate being assayed has a molar ...
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1answer
34 views

Transport of mammalian insulin in vivo

What is the mechanism for transport of insulin in mammalian cells?
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38 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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2answers
80 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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1answer
294 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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1answer
730 views

Glycolysis and Non-Glucose Sugars

In my biology book's section on disaccharide metabolism and glycolysis, it states that sugars other than glucose must be acted upon to enter glycolysis. Let's take sucrose as an example. Sucrose is ...
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Where can I find an at least Semi-Comprehensive list of what biochemical reactions Acetyl-CoA participates in?

Acetyl-CoA has a number of biochemical roles in the body and I'm curious as to whether anybody knows where I can find at least a semi-comprehensive list (i.e. comprising all the major roles in the ...