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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7
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1answer
72 views

About acetyl-coA in the Krebs Cycle of respiration

In respiration, Krebs cycle starts with acetyl coenzyme A which is made from pyruvate. However, it is said that the cycle keeps repeat it self with oxaloacetate turning back to citrate and cycle ...
4
votes
2answers
305 views

Why are human titin and mice titin considered the same protein?

I have a book that says: In humans titin is a chain of 34,350 amino acids, but in mice it is even longer with 35,213 amino acids. If two polypeptides had different amino acid sequence lengths, ...
1
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1answer
46 views

Why are nucleic acids negatively charged at physiological pH? [closed]

Why do nucleic acids and mononucleotides have a negative charge physiological ph?
0
votes
0answers
32 views

Where can I find the pathway for cAMP signaling in Dictyostelium?

I wanted the cyclic-AMP signaling pathway network of social amoeba Dictyostelium discoideum (which is necessary for the understanding of its "aggregation" life cycle) with rate constants and other ...
1
vote
0answers
16 views

Membrane-partitioning free energy [closed]

What is membrane-partitioning free energy? Can we look for difference in free energy upon partitioning in GROMACS? What are the methods I would need to use to determine the free energy of ...
2
votes
1answer
84 views

Why is photosynthesis so complex?

Actually, what is the need of such long procedure? As much as I have understood, the sole purpose of photosynthesis is to synthesize carbohydrates, which is only used for energy storage. So, why don't ...
3
votes
1answer
75 views

The effects of auto-brewery syndrome

Why are some people affected so differently by auto-brewery syndrome differently if the syndrome seems to be caused by the single organism saccharomyces cerevisiae? It is known that the syndrome has ...
0
votes
1answer
38 views

Why does vitamin D need to be exogenous?

Vitamin D is a either a hormone or a precursor to hormones. It is very unlike any other vitamins, which are either cofactors or antioxidants, or may be other chemicals necessarily performing catalytic ...
2
votes
1answer
125 views

Is honey in hot green tea unsafe?

I used Google to try to figure out what kind of mixture honey has with hot water, and I found several Ayurvedic sources claiming that honey in hot water is toxic. For example: Honey – NEVER Put It ...
1
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1answer
34 views

Stabilizing forces between the protein sequences?

we know that Protein structures from secondary to Quaternary are maintained by noncovalent or weak interactions including electrostatic interactions,van der Waals forces & hydrogen bonding. What ...
2
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0answers
51 views

What is the advantage of using plant-derived antibacterials rather than bacteria-derived antibacterials?

So obviously we have a big problem with antibiotic resistance. Most of our antibiotics originate from bacteria themselves (or are synthetic variations on scaffolds which originate from bacteria). I ...
2
votes
1answer
132 views

Difference between protein channels, protein carriers and protein pumps?

I'm revising for my biology exam and I don't fully comprehend the difference between protein channels, carriers and pumps. I know that: Protein channels do not require ATP (passive transport) The ...
-3
votes
1answer
55 views

Advocate for the pop-culture idea of withholding vaccination [closed]

While it is widely accepted that vaccination is preferable to not vaccinating, would anyone like to give a shot at providing evidence in favor of not vaccinating? Anything goes.
0
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0answers
19 views

enzyme extraction protocol for papain

I am trying to work on fab fragments by digesting whole IgG with papain but finding it difficult finding a protocol for extraction of papain. Can somebody help me with a simple protocol, if per chance ...
1
vote
0answers
17 views

Yew seed dormancy reduction

Yew seeds have very long dormancy when artificially planted. They are also adapted to passage through digestive systems of animals that eat/transport them. But could the dormancy be shorter (or the ...
0
votes
2answers
33 views

In what two ways is ATP used in coupled reactions?

I already have down "A coupled reaction is when leftover energy from a reaction fuels a reaction that needs more energy. ATP can break apart to transform into something new and use the energy created ...
4
votes
1answer
215 views

Is ATP Synthase a channel or an enzymatic protein?

Today in a biology lecture about plasma membranes and functions of proteins, we learned about channel and enzymatic proteins along other kinds of proteins. ATP synthase is considered an enzyme that ...
2
votes
2answers
74 views

How to build a trimeric protein structure from monomeric PDB file?

Problem: I have a PDB file, with a monomer, but I would like to show the entire structure - which is trimeric - but I don't understand how to merge/build or combine the monomeric units to its full ...
1
vote
1answer
33 views

gene transformation from plant to plant - transgenic plant

I want to know if the expression of a transfered gene depends on source of the gene, if e.g.: 1] I isolate a gene from plant and transfered it to the same plant? 2] I isolate a gene that is highly ...
1
vote
1answer
48 views

How does heat generated by metabolism differ compared with heat generated through exercise?

I am from a mathematical background so I don't have much knowledge on biology. I'm building a mathematical model to predict heat generation with parameters of metabolic heat generation and exercise ...
3
votes
1answer
63 views

By what mechanism is NADP+ converted to NADPH in Photosystem I? [closed]

Here is my current understanding: $\mathrm{NADP^{+}}$ takes 2 electrons from Ferredoxin at the end of the electron transport chain to generate $\mathrm{NADP^{-}}$. An $\mathrm{H^{+}}$ ion in the ...
12
votes
1answer
247 views

How does paracetamol work?

Hinz et al. 2008 found that COX-2 may be inhibited by paracetamol, and this is attributed to it's analgesic and antipyretic properties. However there are other more recent claims from Andersson et ...
1
vote
1answer
20 views

How do you calculate the charge on a polypeptide chain with changing pH?

I understand the charge placement on the N & C-terminus and also the utilization of the R-side groups in the amino acids. For example, What is the overall charge for a chain Glu-Cys-Arg-Asp with ...
0
votes
0answers
10 views

Must one autoclave LB medium after it has been made? [closed]

Is it necessary to autoclave LB medium after it has been made?
2
votes
0answers
31 views

PCR that worked previously is now only showing primer dimers and a smear on gel

PCR amplification of a promoter sequence for gel extraction worked beautifully using Phusion HF enzyme with GC (higher error but less picky) buffer. However, DNA concentration from the gel extraction ...
2
votes
0answers
36 views

Nail polish toxicity studies?

Are there any well-founded studies that authoritatively demonstrate negative effects from the use of nail polish, particularly in children? I've been brought into the fray of a couple of folks who ...
1
vote
0answers
26 views

What proportion of ingested food is exhaled as CO2? [closed]

Obviously the answer varies according to type of food, and maybe the efficiency of gut flora, but approximately how much of the food we eat ends up as carbon dioxide, as opposed to faeces or urine? ...
1
vote
1answer
43 views

Why is there only 6 H2O produced in fatty acid synthesis (palmitate)

The equation for biosynthesis is 1 Acetyl-CoA + 7 Malonyl-CoA + 14 NADPH + 14H+ -> Palmitate + 7 CO2 + 14 NADP+ + 8HS-CoA + 6 H2O I really don't understand how there is only 6 H2O produced... and ...
7
votes
1answer
63 views

Experimental Analysis: What are possible reasons for this increase in N₂O production?

My professor wanted us to each conduct an experiment for class on something we thought would interesting. My experiment was very simple, but I'm not sure how to interpret my results. (Please note that ...
8
votes
1answer
52 views

How does membrane potential vary between intraceullar membranes and the cellular membrane?

Question Does each type of membrane have a different membrane potential? I'm especially interested in answers that can cite academic papers that have attempted to measure membrane potentials. ...
0
votes
3answers
31 views

importance of cDNA sequencing of a specific gene in different plants

i want to know what if i made a sequence of cDNA of a specific gene in different plants - what is the important from the sequence and can if found difference between plants , and can i use this ...
0
votes
0answers
16 views

Dispose off a medicinal substance

Is there a protocol or a set of guidelines to safely dispose off a batch of expired drugs (as a manufacturer)? I guess the process may vary for different drugs. My specific question regarding the safe ...
1
vote
0answers
29 views

How much energy would it cost to synthesize all cholesterol requirements de novo?

Imagine a scenario in which some person is unable to absorb any dietary cholesterol because of some intestinal mutation (for example). Thus, they have no cholesterol available from their diet for ...
0
votes
1answer
16 views

What causes fruit taste enhancement?

I'm not sure if this is a biology or chemistry question, maybe both? Some fruits, such as quince and quondong, taste of nothing when raw but have an extremely strong flavour when cooked. Why?
1
vote
1answer
39 views

Are there electron or proton receptors in our nose?

We can easily smell chlorine gas and its irritating odour, but we cannot smell oxygen gas. Do few protons and electrons make such difference to our olfactory receptors?
1
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2answers
54 views

Can RNases/DNases survive in strong acid/base solutions of around 10M?

This might be a very stupid question, but I am worried about RNase/DNase contamination of my samples. Since I use 37% HCl and 10M NaOH to pH almost all my buffers, this is a potential source. I have ...
2
votes
1answer
214 views

What is the role of glycine in the running buffer for SDS-polyacrylamide gel electrophoresis

We used pH6.8 in stacking and pH8.8 in resolving gel. In the class, the professor explained that the glycine change is like: ...
5
votes
1answer
84 views

How is adrenaline a ligand?

I keep reading that adrenaline is a ligand, however from what I understand a ligand is a molecule or ion which donates a pair of electrons to a central transition metal ion in a complex. How then is ...
8
votes
0answers
148 views

Why do bananas go brown quicker in the fridge?

Perhaps the title should be: Why do specifically bananas go brown quickly when left in the fridge? Bananas go brown over time because of the oxidation of phenol residues. Bananas go brown quicker ...
0
votes
2answers
51 views

Getting PCR amplification at annealing higher than Tm!

I am amplifying a gene where in a gradient pcr i am getting amplification at an annealing temperature about 5 degrees (67) higher than Tm (62.5)? What is wrong here? Also, I am getting a very strong ...
1
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0answers
63 views

Giving life to a dead person [closed]

Could anyone please tell me whether we can conclude that no body of a dead human being can get life since all chemical reactions are irreversible in our human body?
0
votes
0answers
18 views

Will a metalloenzyme bind to its substrate in the absence of its metal ion cofactor?

A metalloenzyme is an enzyme using a specific metal ion as its cofactor. Their activity is dependent on this metal ion. For example, the T4 DNA ligase requires Mg2+ to ligate DNA strands; The ...
0
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0answers
15 views

What is the difference between cell, membrane and animal based assay?

I am reading a review about MRP1, discussing it's ability to extrude different compounds from cell interior. When describing the different experiments conducted to observe the MRP1's reaction to ...
2
votes
1answer
38 views

Chemosynthesis in Bacteria

The light reactions, if seen as a whole, are basically the oxidation of water to provide energy (ATP) to fuel the Calvin Cycle. The photons provide the activation energy for the same. How then can ...
0
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0answers
49 views

Why boiled starch is easy to digest?

I was reading about carbohydrate digestion and found information about starch digestion where the step wise digestion of starch starts with boiled starch and ends in isomaltose, maltose and alfa limit ...
3
votes
1answer
51 views

Do mitochondria digest fats?

I am a student and I'm currently using the IB biology Oxford textbook. A few weeks ago I had a test on biochemistry. I studied on my textbook and it stated the following: "Mitochondrion: (…) fat is ...
1
vote
0answers
23 views

Is pathlength correction vital to be included while quantifying protein

I am trying to quantify protein in serum/plasma samples. I have carried out biuret assay for my samples using microplate reader. While performing I encountered the doubt whether I should include ...
1
vote
2answers
168 views

Polysaccharide vs Macromolecule

I'm having trouble understanding the difference between Polysaccharide and Macromolecule. I know that polysaccharides are made of chains of monosaccharides. In addition, I know that ...
2
votes
0answers
39 views

Lipid-soluble vs. water-soluble substances through the membrane

It’s said that water-soluble substances can enter the cell membrane with less ease than lipid-soluble substances because the former encounters impedance in the hydrophobic region of the phospholipid ...
3
votes
1answer
38 views

Why would growth hormone (somatotropin) cause both lipid AND glucose release?

GH increases lipolysis (lipid breakdown) and the release of fatty acids from adipocytes into the blood. Fatty acids then can be used as energy sources to drive chemical reactions, including ...