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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Why is funnel web spider venom so lethal to humans and not so much for other mammals?

According to the information from this article, People and other primates are exquisitely sensitive to funnel web venom but, intriguingly, other mammals such as mice, rabbits, guineapigs, dogs ...
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2k views

Histidine aromaticity

I understand that the imidazole ring in histidine is aromatic. I also realize that it retains it's aromaticity when protonated. I am wondering why it is not mentioned at all in basic text books such ...
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150 views

Do acetyl-CoA, acetyl-CoA carboxylase and acetyl-glutamate carry any charge?

Do the following compounds have any charge? If not, then why? If yes, is there any database that would give me this information if the compound is negatively or positively charged? The compounds are ...
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156 views

What makes a metal safe to use for an artificial joint?

What determines if a metal is suitable for transplantation such as in the hip? What I am most interested in however is why might some metals be toxic to animals once in the body?
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224 views

Water soluble molecules

I believe I may have misunderstood water solubility this entire time. I assumed that water soluble meant that it would literally dissolve in water. It would break down into atoms. A sugar molecule ...
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218 views

Effect of testosterone hormone on cell signalling and behaviour?

A steroid, testosterone was injected in female body which led to development of secondary sexual characters but these characters were not developed over night (Response was very slow). What could be ...
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405 views

Are there dangers to Teflon and aluminium cookware?

I've been reading some articles on the internet about dangers of Teflon and aluminium to the body. My family say I'm just exaggerating the situation, and maybe I am, though I'm not sure because not ...
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97 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.
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473 views

What is our skin made up of?

Again, it is a basic question. What is our skin made up of? is it made up of many cells arranged in a systematic way or is it just like any layer say of a book?? what is the difference? where is the ...
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298 views

Besides hemoglobin, what proteins are present in red blood cells?

I knew that mature red blood cells (RBCs) lacked nuclei, but I wasn't aware until just now that they also lacked ribosomes and mitochondria. Most cells in the human body all contain a common laundry ...
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233 views

Stability of helical strands of DNA?

The DNA molecules contain phosphate groups involved in $3'\rightarrow 5'$phosphodiester linkages. These groups, in the bonded state with deoxyribose, contain 1 negative charges ($\ce{3'-PO4^{-}-5'}$). ...
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130 views

Why don't amino acids get linked in the functional groups of acidic and basic amino acids?

There are 'acidic' and 'basic' amino acids like aspartate and histidine. When protein is synthesized with those amino acids, what ensures that the to-be-assembled amino acids will not bond to the ...
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124 views

Proteins that give color (without fluorescence)

Is there proteins that have strong color, that could be seen without the need of UV and with naked eyes (with white light) - in mammalian cells? Searching for reporter, something like GFP, but that ...
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44 views

Phospholipid movement in cell membranes

What causes phospholipids to flow so quickly in cell membranes? In Biology by Cambell et al. they state that a phospholipids can travel up to 2 micrometers per second. Is that a random movement or has ...
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203 views

which signalling pathway is involved in cancer?

Columnar epithelial cells from the colonic mucosa are studied to identify abnormalities in cell signaling pathways. Abnormal epithelial cells from colonic adenocarcinoma are shown to have a mutation ...
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313 views

Signaling through G protein Coupled Receptors?

There are two different cell lines but we do not know that these cell lines have Gs or Gi proteins, associated with their G-protein coupled receptors. If we wants to know about this. Can we design a ...
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669 views

Why isn't the phosphoglycerate kinase reaction of the glycolysis pathway irreversible?

Step 7 of the glycolysis pathway is the conversion of 1,3-bisphosphoglycerate into 3-phosphoglycerate by the action of the enzyme phosphoglycerate kinase, resulting in the production of 2 ATP ...
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227 views

How does ethanol interact with insulin?

I know that ethanol increases insulin secretion--could someone explain why? All I have found till now is experimental data analyses. I am interested in mechanism of alcohol consumption.
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185 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 ...
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54 views

Energy released during the production of ATP?

When glucose is used during aerobic and anaerobic exercise, how much energy is expended or required? During aerobic exercise: $C_6H_{12}O_6 + 6 O_2 \to ATP + H_2O + 6 CO_2$ + energy During ...
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113 views

How does decreasing surface tension of lipids help to emulsify them?

According to my chemistry book, water has higher surface tension than lipids. But in my biology book it is written that "the gall forms an emulsion of water and lipids by lowering the lipid's surface ...
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39 views

How does loss of the electrochemical gradient result in heat production?

As far as I understand, uncoupling of the flow of protons and ATP-synthase provides a bypass for protons between the outer and the inner membrane of mitochondria so that the protons don't have to go ...
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67 views

Fats as energy source

As we know that the preferred source of energy for our body (source) are carbohydrates but heart muscle is an exception and need some explanation for this exception, that why the preferred source of ...
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144 views

Cellular Respiration/Fermentation Problem Leading to Lack of Energy

A young animal has never had much energy. He is brought to a veterinarian for help and is sent to the animal hospital for some tests. There they discover his mitochondria can use only fatty acids and ...
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What's the maximum pressure inside a bombardier beetle?

This question got me wondering about the pressure inside a bombardier beetle. Lots of articles mention pressure, but don't specify the amount of it: One study records the velocity of the spray to ...
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93 views

What is a triglyceride?

I'm confused on what a triglyceride is, from what my text book it says its a type of gylercide, then from a website it said Glycerides can be subdivided into two categories. The first group, the ...
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82 views

Do plants have preference for the form of nitrogen as nutrient?

In the nitrogen cycle (ecology), it is usually described that plants can use nitrogen in the form of ammonium (NH4+) and nitrate (NO3-). Do plants prefer one form of nitrogen over the other?
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What is the physiological difference between cortisone and cortisol?

There is only hydrogen bond different. Cortisol is synthesized by our body, while cortisone is given to the patient. Why you cannot give cortisol directly to the patient? I think the reason is ...
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Influence of temperature on transcription, protein binding and decay rates

I am the kind of biologist who doesn't know much about molecular genetics and about the dynamic of biochemical reactions. Question My question concerns the influence of temperature on the dynamic of ...
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104 views

Question about Monofunctional glycosylases

I am learning about Base excision repair mechanism. I understand the main idea how glycosylases are working, but I am trying to understand this with much more details. I found a paper where they are ...
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119 views

Topology of closed circular DNA

Why are covalently closed circular plasmid DNAs naturally found in an underwound state ? Is it because this makes it easier for the DNA replication machinery to access and unwind DNA ? Or is it ...
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57 views

Correlating beta-lactamase expression to absorbance

When penicillin-resistant bacteria are grown in liquid culture media, β-lactamase is secreted into the medium. The supernatant of such a medium can be assayed for β-lactamase activity. ...
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Phospholipid Bilayer structural reversal

What would happen if the phospholipids in the phospholipid bi-layer were reversed, the fatty acid tails now facing outwards and the phosphate heads facing inwards? I'm assuming this will not affect ...
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366 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?
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51 views

How does botulinum toxin enter the blood stream from the digestive tract?

To my understanding, large polypeptides such as botulinum toxin cannot pass the intestinal lining intact. How, then, can it enter the bloodstream and cause botulism poisoning?
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75 views

Questions regarding a particular paper

With respect to the following paper: Automated identification of protein-ligand interaction features using Inductive Logic Programming: a hexose binding case study I have a few questions: in page ...
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Why can't you just take a vitamin? Why you need a healthy diet on top of that?

From what I understand, your body needs certain amounts of vitamins and minerals to maintain health. Why can't we just take enough pills to obtain these vitamins and minerals?
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Is there a difference between NADH and NADH2?

I've been reading a lot about the oxidative dissimilation etc, and often I see different sources use NADH and NADH2 in the same reactions. One source uses NADH and another uses NADH2 in the exact same ...
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532 views

Why are enzyme-catalysed reactions slower at lower substrate concentration?

Suppose I'm using 200 nmoles of enzyme and 2 mmoles of substrate. The enzyme should be saturated but if I use 50 mmoles of substrate, the reaction will be faster. Why? I just can't get it! Even at ...
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How do you store membrane proteins?

We're producing some membrane proteins and they aren't amenable to freeze thaws even when we add glycerol. The proteins are solubilized in detergent above the cmc so they should be in micelle form in ...
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Simple diffusion of lipid-soluble molecules through phospholipid bilayer — does anything get “stuck” in transit?

It's a pretty elementary concept, and when I first learned of it I don't think I had the foundations to even think of such a question, but I found myself the other day thinking about the amphipathic ...
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Why is second pKa value of phosphoric acid different across different sources?

Am I missing something very fundamental here for phosphoric acid's second pKa value? I check the Wikipedia page and these are the values: (1) 2.148, (2) 7.198, (3) 12.377 Then I check Sigma-Aldrich ...
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263 views

How is respiration an unbalanced equation

The equation for respiration is C6H12O6+6O2→6CO2+6H2O+36ATP. The chemical formula for ATP is C10H16N5O13P3. How is this possible, since it violates the law of conservation of mass because it is ...
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113 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 ...
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116 views

Which are mobile and immobile elements in plants?

I am confused with this element or nutrient classification in the plants, since some authors set elements like $\ce{S}$ and $\ce{Ni}$ as mobile and other as immobile elements (Citation 1, 2, 3, 4, 5). ...
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60 views

Photolysis of Water?

In chemistry, I studied the decomposition of water as being $2H_2O_{(l)} \rightarrow 2H_{2(g)} + O_{2(g)}$. However, when water is split, the equation is $2H_2O_{(l)} \rightarrow 4H^+ + 4e^- ...
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To which negatively charged components of the cell envelopes do the crystal violet complexes bind in gram staining?

The gram positive have negative components in the peptidoglycan layer in the form of teichoic acid phosphodiester bonds, and the gram negative have negative components in their outer membrane in the ...
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77 views

Why is the ebola virus so intense now?

So i'm looking into the ebola crisis and it seems the death toll is really getting crazy. I understand that it's a cytomegalovirus and that it basically overwhelms the immune system due to it's size ...
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59 views

protein-binding sRNAs

I am actually a computational biologist, pardon me if my question description is a bit off-note, my curiosity is driving me on A bit of background and context: In bacteria, a regulatory protein ...
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191 views

Why plants (eg. parsley) can keep vitamin C despite all the sun?

I have read that vitamin C is highly sensitive to light. So, how could parsley, for instance keep its vitamin C as it's flooded with sunlight?