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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49 views

Do we actually know the molecular dynamics of any enzyme?

That is right, is there a limitation, say Heisenberg's uncertainty principle or something that limits our understanding of machinery of enzymes at atomic level? Can we know how do they actually work? ...
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2answers
2k views

Book Recommendations: GRE Subject Test In Biochemistry, Cell And Molecular Biology

There are probably a lot of really good answers that may vary significantly in terms of content. I'm looking for a set of books that I can read in preparation for the GRE Subject Test In ...
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0answers
24 views

What do the cholinergic system and protein kinase A pathways have to do with inflammation?

In the middle of a comprehensive review of all experimental research to date related to my graduation topic, I have run into a little bump in terms of how these pathways affect inflammation, and how ...
5
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1answer
127 views

What would happen if Carbon-14 was in a glucose molecule and decayed into Nitrogen?

This interested me because of Melvin Calvin's experiment with photosynthesis where he used radioactive Carbon-14. If a plant used it as a reactant to make glucose, and that Carbon-14 decayed into ...
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0answers
15 views

About electrons returning to photosystem I when supply of NADP runs out in photosynthesis

According to my textbook, in photosynthesis, when the supply of NADP runs out, electrons from photosystem I return to the electron transport chain that links the 2 photosystems and flow back to ...
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1answer
45 views

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

Why do nucleic acids and mononucleotides have a negative charge physiological ph?
7
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1answer
70 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
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2answers
303 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, ...
3
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1answer
71 views

What is the shortest mRNA the ribosome can read to produce a peptide?

This question came as a comment on a previous question regarding non-ribosomal peptide synthesis, and why Glutathione cannot be synthesized by the ribosome. In general, Glutathione has a "gamma" ...
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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 ...
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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 ...
3
votes
1answer
74 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 ...
2
votes
1answer
82 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
2answers
391 views

Why would lactate be high in diabetics?

Why are lactate level high in diabetes? For example, type II diabetes are resistant to insulin. If those patients are insulin resistant their gluconeogenesis should be working at a high rate and, ...
2
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1answer
40 views
0
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2answers
146 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 within the matrix of mitochondria, though. In biological systems, there ...
1
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1answer
49 views

What is the energy source for adipocytes?

Since adipocytes export fatty acids and glycerol and don't use them as an energy source, what is the main source of energy for adipocytes?
3
votes
1answer
1k views

How are non-glucose sugars metabolized in the body?

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 ...
4
votes
1answer
75 views

Can the kidneys utilize ketone bodies for energy?

Ketone bodies are water-soluble and should pose no problem to the kidneys because of solubility. If the kidneys are able to utilize ketone bodies for energy, then they must express the enzyme ...
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 ...
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 ...
2
votes
1answer
124 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 ...
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0answers
33 views

Is it possible to measure in vivo enzyme kinetics?

I was wondering is there way in which we can measure enzyme kinetics in vivo specifically for enzymes acting on lipid substrates (where substrate is restricted to 2D membrane as oppose to freely ...
7
votes
1answer
5k views

What is/are the molecular differences between HDL and LDL cholesterol?

Why exactly is HDL-cholesterol good for us and LDL-cholesterol bad for us. It has been well-established that LDL-cholesterol is associated with atherosclerosis and that HDL-cholesterol helps remove ...
1
vote
1answer
224 views

Why does NAD+ become reduced if it gains a hydrogen proton?

I've heard that $NAD^+$ gains a Hydrogen proton during glycolysis and the Krebs cycle and becomes reduced to $NADH$. However, isn't reduction when a molecule receives an electron? Maybe I've been ...
11
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2answers
355 views

During famine, does the human body do anything to prioritize which organs receive nutrients?

When food is scarce, the body slows its metabolic rate to conserve energy. Are there any other systems or processes that encourage prioritization of organs?
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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
votes
1answer
842 views

Making the sense of enzyme Km comparisons

I have encountered comparisons of the Michaelis-menton constant (Km) a few times. Generally speaking if Km of an enzyme is higher, then it's affinity to its substrate is lower. How does this make ...
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 ...
2
votes
2answers
76 views

Conversion and storage of glucose to glycogen

Why is excess glucose, synthesized to glycogen, stored only in limited amounts, as compared with lipids/triglycerides that are stored in our body? Why is mature glycogen arranged (polymerized) in 12 ...
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 ...
1
vote
1answer
78 views

What is a detailed chemical explanation for describing how an enzyme may lower the activation energy of a reaction?

If you can provide some sound reasoning that touches on tertiary structures of proteins and does not use a lot of advanced chemistry jargon that might be really helpful, especially for an intro ...
-3
votes
1answer
54 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.
12
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1answer
246 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 ...
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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 ...
10
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1answer
12k views

Why is ATP the preferred choice for energy carriers?

Why is ATP the most prevalent form of chemical energy storage and utilization in most cells?
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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 ...
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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 ...
2
votes
2answers
73 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 ...
4
votes
1answer
206 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 ...
1
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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
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0answers
20 views

How is the enzyme glycogen synthase regulated?

How is the enzyme glycogen synthase regulated in regards to glycogen synthesis? I think I understand that phosphorylation decreases its activity (through glycogen synthase kinase?), but what role do ...
1
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2answers
50 views

What are the differences between carnitine forms?

I've heard of L-carnitine, acetyl L-carnitine and L-carnitine L-tartrate. What form(s) occur in meat? What form does the human body manufacture? Is L-carnitine just a shortened name for L-carnitine ...
7
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2answers
80 views

Permeability of Plasma Membrane

I’m having trouble grasping why small polar molecules can cross the hydrophobic region of the membrane and not ions. Won’t the polar molecules be attracted to the watery extracellular medium and not ...
5
votes
4answers
679 views

Photosynthesis: What Powers the Splitting of Water?

The splitting of water is an endergonic (non-spontaneous) reaction, and thus would require energy (chemical work to be done) in order to happen. In Photosystem II, an enzyme catalyzes this splitting, ...
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 ...
1
vote
1answer
40 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 ...
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0answers
10 views
2
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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
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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 ...