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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1answer
673 views

Does drinking coffee have negative effects?

From what I collected, coffee is a magical potion that lets you feel energetic, and essentially not-sleepy. But are there any tradeoffs? I mean, if it was so beneficial, wouldn't the human body ...
4
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2answers
3k views

DNA as an acid? [duplicate]

Possible Duplicate: Does DNA react in all of the ways most other acids do? Even if DNA is made up of nucleotide bases, it is said to be an acid. Why is this?
3
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1answer
263 views

Ammonium sulphate precipitation assay pH dependence

In general does the pH effect the precipitation, e.g. would a pH of 6 cause less precipitation than pH 7.5. Or are they unrelated?
4
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1answer
242 views

If proteins have an overall charge, how do membrane proteins traverse through the hydrophobic region of the plasma membrane?

These two concepts seem almost contradictory, proteins have a net negative charge due to the amino acids in them each having a small negative charge, yet membrane proteins are able to exist traversing ...
9
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1answer
264 views

Does DNA react in all of the ways most other acids do?

As I understand it from my basic chemistry, there are some fundamental reactions that exist between any acid and other substances for example acid-base reactions that form a salt, and the existence of ...
4
votes
1answer
4k views

Does mixing alcoholic drinks really make you more drunk?

There is plenty of anecdotal evidence ("beer after wine and you'll feel fine, wine after beer will make you feel queer") that mixing alcoholic drink types leads to a stronger effect, but I can't find ...
5
votes
1answer
80 views

In which way would the yeast cell cope with the excess amount of methionine in the growth media?

I guess that when there is surplus of methionine in the cell it is incorporated in the TCA cycle as a succinyl CoA, with cysteine as a by-product. But now the cell has the surplus of cysteine. What ...
4
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1answer
247 views

Are there any intersections between the biochemical pathways of uracil biosynthesis (or metabolism) and methionine degradation in eukaryotes?

Is there any way in which uracil biosynthesis or metabolism could help cell in degradation of toxic levels of methionine?
7
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1answer
235 views

When giving blood, what is the specific Iron measurement they take?

I went to give blood the other day, and they take an "iron" measurement prior to actually drawing the blood. My level was 16.4 -- but what specific type of iron were they measuring? I've heard of ...
7
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1answer
459 views

How to prevent protein precipitation?

I'm trying to label a protein with fluorescent dye (TMR succinimidyl ester), but having trouble getting the protocol to work. The protein seems to be stable in distilled water at a the recommended ...
7
votes
1answer
119 views

Pharmacologically, can tricyclic antidepressants have a side-effect profile similar to neuroleptics?

Torticollis (wryneck, cervical dystonia) is a neurologic movement disorder causing involuntary muscle spasms in the neck. Often, neuroleptics can cause such a side effect. I'm wondering if this ...
2
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3answers
80 views

Is DNA mutation locally energetically stabilizing the DNA molecule

I am no biologist, but as a physicist, a spontaneous mutation (seen as a chemical transformation) should lower the energy of the system, at least locally. So I wonder if any research has been done ...
0
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1answer
409 views

Is breathing in deodorant fumes dangerous for my brain?

I noticed that I sometimes get dizzy when I accidentaly breathe in too much Axe. Also, I find the smell of alchohol rich deodorants quite unpleasant. But, I was wondering, is it actually dangerous? ...
7
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1answer
132 views

Making penicillin using animals - specifically, a goat

In the scifi novel Lucifer's Hammer, one of the characters (a biologist, if I remember correctly) finds himself in a post-apocalyptic world and tries to make penicillin to save his own life. To do ...
5
votes
3answers
229 views

Biological Pathway of Lipid Hypothesis

I've read a lot on both sides of the debate of low carb vs low fat diets trying to make some sense of what is being proposed. The lipid hypothesis runs roughly along the lines that we have lots of ...
4
votes
1answer
89 views

Why isn't there any repulsive force between Na+ and K+ disrupting thier roles in transmembrane voltage/ action potentials

Pretty self explanatory question. I have a basic grasp on the "How" and "Why" of Reversal/Action Potential in and between neurons, but this question lingers.
5
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1answer
303 views

What are the units of enzyme activity?

I was looking at this graph of turnip peroxidase activity and I saw that they use units of 1/sec for enzyme activity. What does this unit intuitively represent and how is it calculated?
9
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1answer
2k views

Why is GTP gamma S non hydrolyzable?

GTP gamma S is routinely used in studies of G proteins to stably activate the G protein. Comparing the structures of GTP gamma S and GTP, the Sulphur atom replaces the Oxygen attached to the leaving ...
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0answers
66 views

When should endocytosis inhibitors be used in cell binding assays?

I'm beginning to do some cell-binding assays and I would like for my proteins to not be endocytosed by my mammalian cells. Typical suggestions are for the cells to be kept on ice and that the binding ...
5
votes
2answers
682 views

Isotype control antibodies in Flow Cytometry

In a Flow Cytrometry, one can add an Isotype Control Antibody to allow another antibody to bind more specific to the cells. My question is, how can the Isotype Control Antibody add specificity to the ...
7
votes
3answers
226 views

What alternatives are there to the amyloid hypothesis?

Given the recent failure of the Bapi clinical trial, there is a lot of questions that have arised from he amyloid hypothesis. However, I can't really think of many other mechanisms that don't involved ...
8
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2answers
2k views

What is the concentration of ATP in an average cell?

Can someone give me some references showing the average concentration of ATP in a cell?
13
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2answers
776 views

Is the EC50 of an activating protein for an enzyme a good indicator for the binding affinity Kd?

We work with a membrane protein system where measuring the affinity between the enzyme and the upstream activating protein has been difficult, and when measured in detergent solution, it is almost 100 ...
10
votes
1answer
341 views

How would I explain different properties of the same protein in different species?

I recently finished an experiment where I analyzed the rate of ATP hydrolysis of Heat shock protein 104 in three species of fungi. They have shown to all have different rates of ATPase activity. How ...
7
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2answers
273 views

How to compute properties of peptides ?

I have been tasked with writing a program for computing properties of a give set of peptides. These peptides are given as 1-letter amino acid sequences and I need to compute the following : Length ...
9
votes
2answers
127 views

What role does a protein's size have on protein-protein interactions?

Protein-protein interactions are when two or more proteins bind together, possibly for some important biological function. Recently, I'm starting to look more into proteins, and in particular, ...
5
votes
2answers
537 views

Why insects are so energy-efficient while flying?

Why are insects so energy-efficient while flying? Is it because of their light weight and aerodynamics or due to very efficient biochemical transformations (food->energy)?
8
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3answers
9k views

Why can't the brain and red blood cells use fuels other than glucose?

The question is rather straight forward: I have always been curious as to why, but cannot find an explanation online. I can imagine that the mechanism is different for each, but why does brain tissue ...
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2answers
3k views

Why is glucose our primary source of energy?

Is there any evolutionary reason for glucose being the "main" molecule used as a source of energy, beginning with glycolysis and subsequently cellular respiration (after being converted to two ...
3
votes
1answer
147 views

Negative feedback in the fructose metabolism in liver

What happens in liver when large amount of fructose is consumed? I vaguely remember my biochemistry lecturer telling us that the enzymes that process fructose in the liver does not have negative ...
17
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4answers
2k views

Why are there exactly four nucleobases in DNA?

Does someone know why DNA is composed of four nucleobases? In particular, is there an explanation for the number? Why four and not two, or eight?
11
votes
1answer
914 views

Why does hair turn grey or white, and why does it happen later for some?

The question is pretty simple: what is happening molecularly when hair turns grey or white? I would imagine that it is due to the lack of a particular compound. I'm also interested in why some ...
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vote
2answers
288 views

How are proteins formed?

Somewhere, I have read that we need to consume proteins to make amino acids to make new proteins. What does it suggest? How do we make proteins from proteins?
3
votes
1answer
1k views

What are the units of Q10 (temperature sensitivity)?

Q10 is the increase in a rate (e.g. activity of an enzyme) observed with a 10 degree temperature increase. According to Wikipedia: It is apparent that the units of R (e.g. mol/g/s) cancel out, ...
3
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1answer
310 views

Does caffeine increase the speed at which sperm travels?

I'm not even sure if this claim is true, but... This source states that Caffeine gives both types of sperm a boost, but the Y-sperm would get a little more of a boost. This article reinforces ...
6
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1answer
327 views

Are the cytosol and extracellular fluids electrically neutral?

I've found several sources that state that overall, the cytosol of a cell is electrically neutral. The extracellular fluid is also purportedly electrically neutral. How can that be when we have ...
6
votes
2answers
711 views

What is the correct model for enzyme-substrate complementarity?

This Wikibook shows both proposed models of enzyme-substrate complementarity, the Lock and Key model and the Induced Fit model. I've always been taught that the Induced Fit model is the proper one. ...
3
votes
1answer
305 views

Troubleshooting bioconjugates migration in a SDS-PAGE gel?

We do a lot of bioconjugation chemistry (click chemistry in particular but also NHS and Maleimide chemistries). Our method to valid the conjugation reactions have been to use SDS-PAGE gels followed ...
1
vote
1answer
185 views

Which concentration of BSA is recommended for dynamic light scattering experiments?

What is the recommended concentration of BSA to be mixed with water so as to prepare a very dilute solution in order to clearly study the intensity-intensity correlation with single scattering ? I ...
7
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1answer
145 views

What makes a wet dog so stinky?

Similarly, what makes a wet down comforter so stinky? Why do they make no smell except when liquid is added?
4
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1answer
485 views

Why are omega-3 fatty acids so easily oxidized when they're incorporated in cellular membranes?

Apparently, this has led to results with clinical significance, as we can see at http://extremelongevity.net/2011/10/03/daily-fish-oil-consumption-may-reduce-lifespan/... The researchers fed a ...
8
votes
1answer
224 views

How Antioxidants affects Human Metabolism?

I'd like to know how antioxidants affects the human metabolism and which ones are essential for metabolism processes.
1
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1answer
127 views

How to manufacture different sized micelles in nano -scale?

I am trying to answer q5: "How can you manufacture micelles in A) nanometerer -scale B) and in ten nanometer -scale?" My Thinking Observations and some thinking Oil in ...
2
votes
1answer
237 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 ...
5
votes
1answer
169 views

Are quaternary protein monomers unique to a particular protein complex?

I know that quaternary protein structures are formed exclusively via non-covalent bonds. My biochemistry professor discussed a viral capsid that is essentially one quaternary structure with 240 ...
6
votes
1answer
184 views

Decreasing the alcohol proof and faster in hangover, why?

My russian friend says that the USSR agents used/use the trick that they offered the victim first vodka and then last wine. I have noted that this puts you faster to hangover: decreasing the alcohol ...
32
votes
4answers
14k views

Death because of distilled water consumption

One of my friends said that I would die if I drank distilled water (we were using it in a chemistry experiment) I gave it a go and surprisingly did not die. I did a bit of Googling and found this ...
7
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1answer
174 views

Protein construct design

I am trying to create some constructs of a certain protein deleting well defined domains (at either terminus) to determine interaction regions with other proteins etc., 3 constructs with varying ...
6
votes
1answer
2k views

Molecularly, why can you straighten or perm hair?

I'm aware that hair can be curly because of the disulfide bond interactions in between cysteine amino acids in alpha-keratin filaments. However, I'm curious as to the biochemistry involved in ...
2
votes
1answer
620 views

What is the reaction mechanism of dopamine hydroxylase converting dopamine to norepinephrine?

The reaction is basically shown below. Dopamine hydroxylase is an enzyme, so I'm not sure if we can have a theory based on organic chemistry. On the other hand, maybe there is a theory that involves ...