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

Is it necessary to autoclave LB medium after it has been made?
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50 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 ...
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39 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 ...
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28 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? ...
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1answer
151 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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1answer
81 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 ...
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1answer
68 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. ...
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3answers
44 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 ...
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0answers
18 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 ...
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64 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 ...
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1answer
21 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?
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1answer
51 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?
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87 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 ...
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1answer
2k 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: ...
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1answer
141 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 ...
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1answer
278 views

Why do specifically bananas go brown quicker in the fridge?

Perhaps the title should be: Why don't all fruits containing phenol residues go brown quickly when left in the fridge? Bananas go brown over time because of the oxidation of phenol residues. ...
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2answers
91 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 ...
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69 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?
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20 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 ...
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23 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 ...
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1answer
55 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 ...
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69 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
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1answer
57 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 ...
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37 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 ...
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2answers
265 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 ...
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1answer
149 views

How do lipid-soluble substances diffuse through the cell membrane?

It’s said that water-soluble substances can diffuse through cell membrane with less ease than lipid-soluble substances because the former encounters impedance in the hydrophobic region of the ...
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1answer
49 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 ...
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16 views

How much is the normal range of thiol/protein (mol/mol) concentration?

HSA(Human Serum Albumin) has just one free thiol group on Cys34. Using DTNB assay I obtained 0.4 thiol/protein (mol/mol) for this protein. I wonder if this value is a reliable number or not? does ...
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75 views

Proteases in the blood

I’m reading on hormones and the book talks about how peptide or amine hormones are easily broken down by proteases present in the blood plasma. This has led me to question the interactions between ...
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102 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 ...
2
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1answer
331 views

Why do mice have a higher metabolism?

Mice and other small animals have higher metabolic rate than humans. How does that happen on cellular level, if we look on one cell in the mouse body? What is it in this cell that will be different?...
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43 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 ...
2
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1answer
78 views

All-trans-retinal being converted back to 11-cis-retinal or vitamin A

There are two pathways all-trans-retinal can take after detaching from the scotopsin: (1) it can convert back to 11-cis-retinal, or (2) it can convert to all-trans-retinol (form of vitamin A), which ...
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1answer
31 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 ...
3
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1answer
91 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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298 views

Why does depolarisation by high intracellular K+ trigger calcium channels opening?

I have learnt that in pancreatic beta cells, glucose being metabolised in the cell causes a high ATP level, which triggers ATP-dependent potassium channels to close. This means that potassium can't ...
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2answers
143 views

Non-ribosomal peptide synthesis: why Glutathione cannot be produced by the ribosome?

Case: I am writing a summary for a class in protein structure and function, and was asked to describe some different ways that peptides are synthesized (that does not involve the ribosome). I ...
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1answer
30 views

Why would a bacterial population show initial growth when it is in unfavorable growth conditions?

This figure shows the anaerobe E. faecalis grown in aerobic conditions, E. coli grown in restricted conditions that are not specified. Why do they show an increase in abundance initially? The black ...
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1answer
248 views

Anomalous base pairing of nucleotide tautomers

What tautomers base pair with what bases? I know that adenine pairs with thymine and guanine pairs with cytosine normally. My question is what does the imino form of adenine base pair with? Regular ...
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1answer
96 views

Is there an evolutionary advantage for coconut oils to be rich in saturated fats?

I know that coconut oil is composed of multiple saturated fatty acids, but is there a reason why this would have increased the fitness of the coconut plant?
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18 views

What exactly are polyphenols and what benefits do they provide to humans?

I say somewhere that they are antioxidants, but I was wondering if the two terms are synonymous or if that is just one of many things polyphenols can do.
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1answer
65 views

On which amino-acids residue is the SDS acting on?

I would like to know exactly what is the mechanisme of the SDS, and I would like to know on which amino-acids residue the SDS is acting on. Can you help me please ? Thank you in advance !
2
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1answer
58 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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2answers
39 views

Is Roundup toxic?

Roundup, as we all know, is a herbicide that kills weeds. It does this by preventing the production of amino acids in plants. One of these amino acids is tyrosine. Tyrosine is a nonessential amino ...
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1answer
1k 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 ...
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1answer
208 views

What are 'acid stable' amino acids?

I tend to see terms amino acid, acid stable amino acid, and free amino acids used often in ...
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48 views

Which Lactobacillales (Lactic acid bacteria — LAB) strains are capable of degrading starch?

I've been researching bacteria strains but am having trouble finding amylolytic LAB strains with amylolytic and lactic acid producing character. The only species I've found, that are capable of ...
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1answer
30 views

kinetics question [closed]

An enzyme has a $V_{max}$ of 50 $\mu$mol product formed $(min * \text{mg protein})^{-1}$ and a $K_m$ of 10 $\mu$M for the substrate. When a reaction mixture contains the enzyme and a 5$\mu$M ...
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1answer
147 views

Bradford Reagent Disposal

I am a graduate student volunteering in a professor's lab being tasked with finding out how to dispose of certain hazardous materials. I have encountered a problem with disposing of Bradford's Reagent....
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2answers
80 views

metabolism preference by the body

What I know about metabolism is that,during exercise body uses carbohydrate first then fats and then protein,so my question is why does body prefer glucose first as fuel for energy and what makes ...