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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14 views

Forgot to vortex

Ugh. Did an immunofluorescence experiment last weekend, forgot to vortex both my primary and my secondary antibody solutions. And my final result looks dimmer than it should be. Is it possible that ...
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1answer
15 views

Why does the Pentose Phosphate Pathway predominate in erythrocytes?

Is it because glyceraldehyde -3-phosphate (a molecule which when enter glycolysis help produce ATP through substrate level phosphorylation) can be prepared without losing an ATP through this process?
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1answer
58 views

What is membrane-partitioning free energy? Can it be simulated?

Firstly, is there a strict definition of the "membrane-partitioning free energy"? It is banded around in membrane biology, but I have never seen it strictly defined. The only non-scholarly site that ...
3
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1answer
99 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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75 views

Can the human body create glucose out of fat?

I read conflicting views about whether or not the human body can create glucose out of fat. Can it?
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67 views

Taste of salt water

I had a question relating to chemistry and biology, so please tell me if this is suited better for the Chemistry website. My question was, if water dissolves salt by separating the two ions, the Na+ ...
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1answer
18 views

Why is the formation of an enzyme-substrate complex endergonic (induced fit model)?

In the section about the induced fit model for enzyme substrate binding, my MCAT textbook claims that "The substrate has induced a change in the shape of the enzyme. This interaction requires energy, ...
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21 views

To which functional group DNA and RNA shows higher affinity of binding [on hold]

i want to know if a DNA or RNa binds to any nano particle via functional group playing role which functional groups must have to bind DNA and RNA
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1answer
31 views

How does 2-mercaptoethanol lead to shift of the band to a higher molecular weight?

I have a project to isolate a protein with biological properties from a plant. The purified protein forms four bands with similar molecular weight on SDS-PAGE (30–35 kDa) in the presence of 5 % 2-...
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2answers
41 views

Do disaccharidases require a cofactor or coenzyme to function?

I'm doing research on lactose intolerance and am curious if disaccharidases (enzymes that break down disaccharides) require a cofactor or coenzyme to function? Reviews or references would be greatly ...
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131 views

What's the mechanism for being mentally tired?

I notice that after long tests, or long periods of critical thinking, my body and mind feel noticeably tired. Why does this happen? Are the neurons in my head not firing as quickly, or is there just a ...
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1answer
34 views

Find the concentration of free receptors in a solution of 90% free ligand and 10% receptor-ligand complex, knowing only the value of kD

I could use some guidance on how to utilise the equation for the disassociation constant kD to find the concentration of free receptors [R] in a solution containing 90% free ligand [L], and 10% bound [...
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52 views

Beta Sheets vs Alpha Helix - Strength

Is there a hard and fast rule of which one is stronger than the other, or does it depend on their context in a protein?
4
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1answer
96 views

Synthesis of Fatty Acids Longer than 16 Carbons

I understand that the human body when performing Fatty Acid Synthesis can synthesize only until C16 (palmitate). However the ER has desaturases and elongases. I know that desaturases are used to add ...
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1answer
4k views

Why is the function of lacA (encoding thiogalactoside transacetylase) not clearly understood?

It's almost half a century since the lac operon was discovered but isn't it weird that the precise role of transacetylase isn't clearly understood ? Here a wikipedia article with a link to a journal ...
3
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1answer
35 views

Why does migration distance depend on log of molecular weight in SDS-PAGE?

I really want to know why in the result of SDS PAGE, log of molecular weight(MW) and migration distance (distance from the loading well) have a linear relationship. Why is it log(MW) instead of MW? ...
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42 views

Motifs, Tertiary Structure, and Domains [closed]

I really don't understand these three terms. If somebody could explain — with illustrations — it would be of great help. Given this definition: 'The overall 3D structure of the polypeptide chain ...
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27 views

Where does transamination and deamination take place?

The only information I know is about deamination,it occurs in the liver and kidney. But in which part of the cell does deamination occur? To which tissues is transsamination specific to and in which ...
4
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1answer
54 views

Does the formation of water inside the mitochondrial matrix help contribute to the proton gradient during the electron transport chain?

Does the synthesis of water in the final step of the electron transport chain significantly increase the electrochemical gradient across the matrix? I understand that pumping protons out of the matrix ...
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1answer
18 views

Binding kinetics of 6xHis-Tag

For the planning of an experiment I would like to know the binding kinetics (kon and koff) of a 6x-His-tag to a Ni-NTA surface. I know they should differ due to surface quality and position of the ...
2
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0answers
22 views

Can the respiratory quotient be calculated from a formula or must it be measured directly?

I found the following question on the Respiratory quotient: A normal human diet has a Respiratory quotient (RQ) of approximately 0.85. Given that pure oxidation of fatty acids has a Respiratory ...
2
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1answer
62 views

Electron balance for biomass synthesis: is my professor right?

I'm studying for my exam and I came across these notes written by the professor himself. He's talking about the general reaction of biomass production in a bioreactor: $$\ce{C6H12O6 + NH4+ + O2 -> ...
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0answers
8 views

What steps need to be taken between a successfull SDSPage GE and MS/MS?

Once you have your gel with separated proteins can you simple cut out each band and plop it into solution or do you need to take extra steps?
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1answer
50 views

What is an interaction motif with respect to protein sumoylation?

While am reading about protein sumoylation this morning I got stuck on sumo interaction motifs and consensus motif line. I heard the the word motifs for the first time. What does motifs mean in this ...
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3answers
350 views

What is a membrane potential?

I know this may be silly, but I am confused to what a membrane potential actually is. I understand that at resting membrane potential is -70- -80 mV. But what does that exactly mean and how does this ...
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1answer
50 views

Use of western blotting

I ran across this paper recently. http://www.ncbi.nlm.nih.gov/pubmed/21151122 I am confused on their use of Western blotting. Their unmodified protein (no PTM group) has a band and their modified ...
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1answer
374 views

Why should phospholipid non-polar tails be “protected” in the membrane bilayer?

lipids are arranged within the membrane with polar head towards the outer side and non polar tails towards inner side, this ensures that the non polar tail is protected from aqueous environment. My ...
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1answer
2k views

Ripening bananas artificially: What is the biological reason

I am a resident of the tropical island of Sri Lanka, and we have a strange traditional method to ripen our banana harvest quickly. What we do is this: We dig a pit in earth that is enough to put the ...
2
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1answer
97 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
47 views

Why is oxygen and CO2 measured in pressure instead of mmoles/L like other ions?

Na, K, Cl...All measured in mmol/L in plasma. Why is oxygen and CO2 measured in pressure (mmHg)? (I guess it has something to do with them being bound to RBC but I don't know why the difference).
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4 views

In a condensation reaction, which of the reactants loses their OH group? [migrated]

You have Propanoic Acid ( CH3CH2COO-O-H) so an OH on the end You have Ethanol (CH3CH2-OH) so an OH on the end When you combine the two for a condensation reaction you have the OH group from 1 ...
2
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1answer
104 views

How to retrieve logical expression (KO based) for reactions from KEGG?

Whether a module is complete or not can easily be checked by evaluating the Definition entry associated with the module; e.g. in module M00010, it is given by <...
3
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1answer
19 views

How would one determine whether a chemical will upregulate a certain class of proteins?

I'm trying to determine whether certain organic chemicals will upregulate classes of proteins that possess deacylase activity.  How would I go about this experiment? I'm assuming I would use some ...
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1answer
67 views

Which organisms have their cell wall made of polysaccharides and amino acids?

I came across a question which somewhat goes like In which of the following kingdom, most of the members have a cell wall made of polysaccharide and amino acids ? - Monera or Fungi. To me it ...
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1answer
44 views

Lifetime of secondary messengers such as Calcium or IP3

Can anyone suggest me literature on the lifetime of secondary messengers such as calcium or IP3? A book would be preferred. What I am specifically looking for is a validation that secondary messengers ...
2
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3answers
139 views

Extending a small fragment of DNA

Is there a way to extend a small fragment of DNA, say 150 bp, by making copies of itself and attaching each copy of that small fragment to the end of that 150 bp sequence? For example, I want a 1 ...
2
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1answer
56 views

Difference between the P4 and P5 subtypes of P-type ATPases in plants

In plants there are various kinds of P-type ATPases. What is difference between P4-ATPase and P5-ATPase?
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0answers
22 views

Plasmid electrophoresis with DNases

DNases are used for treatment of cystic fibrosis. A normal DNase catalyzes the hydrolytic cleavage of phosphodiester bond in one strand of DNA. Scientists, in order to improve efficacy of DNases, use ...
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0answers
26 views

How do organoarsenics improve digestion efficiency in poultry?

It struck me as very surprising that these organoarsenic compound with structure looking not very compatible with living system is widely used as food additive to increase weight gain and improve food ...
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1answer
14 views

When is Pheophytin used in electron transfer to the q cycle in plants?

If I understand it correctly: (short version) The Q cycle starts with PQH2 it removes the 2H(+) and gives one electron to Plastocyanin and the other to a stored Plastoquinone to charge it to ...
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2answers
2k views

Why is the DNA helix anti-parallel? [duplicate]

Why is it that DNA strands are running in anti-parallel fashion? Given the chemical base-pairing, they could have been parallel just as well.
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0answers
24 views

Insulin and leptin action on Anorexigenic Neurons in Hypothalamus?

Receptors for Insulin are present on liver, adipose tissue and muscles BUT also Insulin Receptors are present in arcuate nucleus of hypothalamus where it influences anorexogenic neurons through IRS2 ...
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0answers
10 views

Hyperglycemia in Type 1 Diabetes?

Glucose transporters GLUT1, GLUT2, are always present in hepatocytes membrane and GLUT3 on brain cells but the glucose transporters for skeletal muscles, cardiac cells and adipose tissue are not ...
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1answer
37 views

Why are both glucagon and cortisol released in hypoglycemia?

Cortisol is released in response to prolonged stresses; one situation when cortisol is released is when blood glucose level is low. In this situation cortisol acts on adipose tissue promoting fatty ...
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4answers
3k views

What implications has the missing 2'-OH on the capability of DNA to form 3D structures?

The chemical difference between RNA and DNA is the missing 2'-hydroxyl group in the nucleotides that build DNA. The major effect of that change that I know of is the higher stability of DNA compared ...
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0answers
27 views

Fate of Acetyl CoA in well fed state?

When we have eaten well and take fat rich diet then in this condition Acetyl CoA produced from fatty acid breakdown will be gone to storage in adipose tissue or not? If it will go for storage then why ...
3
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0answers
22 views

Effect of ethanol and detergent on cell membranes problem

I am currently writing my biology report for an experiment I did on how ethanol and detergent affect the cell membrane. For my ethanol experiment, all went as expected BUT for my detergent experiment, ...
5
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1answer
63 views

Do two compatible tRNA codons bond together?

Can two tRNA with complementary anti-codons link together? For instance UUU with AAA. If not, why not?
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23 views

Loooking for dataset of proteotypic and non-proteotypic peptide

I'm experimenting with peptide prediction using machine learning. I need some data for testing. I already have one dataset, but I need another one or two for verification. I'm looking for data for a ...
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2answers
347 views

What is the importance of urea in mass spectrometry?

What is the importance of urea in mass spectrometry? We use 8M urea to FASP our proteins prior to mass spectrometry. What is the significance of using 8M urea? and how does it affect the proteins?