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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Classification of glycosidic anomeric bonds (alpha vs. beta)

In the process of studying for my upcoming biochemistry exam, I have stumbled over the classification of glycosidic bonds. I want to be able to distinguish $\alpha$- from $\beta$-glycosidic bonds. ...
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1answer
68 views

DNA ligase mechanism

I am unable to understand what happens to the phosphates from ATP. What are they used for ?Charging 3' end or 5'end ?
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864 views

What's the difference between protein and DNA behaviour during agarose gel electrophoresis?

I'm planning a science project about gel electrophoresis, and I'd like to know if there are any measurable, quantifiable (for example, things I could represent in a graph or chart) differences between ...
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1answer
58 views

Topology of protein

The domain structure of protein Z, which is composed of 180 amino acids, is shown in the upper part of the figure below. Protein Z is palmitoylated at a cysteine residue (the third amino acid) ...
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1answer
82 views

What are the lifetimes of cellular components on organelle or molecular level?

I was thinking that even though I know how generally the cell works, I don't really have a feeling of how volatile it is. I want to know what is the lifetime/turnover rate of different constituents of ...
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1answer
17 views

Source of energy of adipocytes

Since adipocytes export fatty acids and don't use them as an energy source, which is the main source of energy for this cells?
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39 views

Identifying mutations in a yeast strain

Cells of a triple-mutant yeast strain (leu- his- trp-) were spread either on minimal medium or on minimal medium supplemented with various combinations of histidine, leucine, or tryptophan. The ...
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0answers
54 views

What is the biochemical pathway of fluoride?

Fluoride is a common active ingredient in tooth paste to prevent dental caries. It is also added or removed from the water supply in some communities for the same reason, but in children only. My ...
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2answers
53 views

Lactate and Diabetes

Why are lactate level high in diabetes? For example, Diabetes type II have resistance to insulin, and if they do it, their gluconeogenese should be working at high levels and, because of that, uptake ...
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1answer
54 views

How is it decided that one drug is better than others by X times?

I read in Tortora and Derrickson that : Enkephelins are 200 times powerful than morphine in their analgesic effects. I wonder how exactly researchers arrive at a number (like 200 here). I also ...
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1answer
104 views

Shine-Dalgarno sequence and expressing proteins

Shine-Dalgarno sequence present in the prokaryotic mRNA plays a role in initiation of translation. In eukaryotes a Shine-Dalgarno like sequence is present but does not play an important role in ...
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37 views

Why does the ovum prefers to be arrested at metaphase 2 of meosis before fertilization? What is the possible advantage of this process?

Why does the human ovum prefers to be arrested at metaphase 2 of meosis before fertilization? What is the possible advantage of this process??Please help me with it.
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1answer
46 views

Determining limiting nutrients from a graph

The question was Which of the following statements is supported by these data? A. Phosphorus was the first limiting nutrient followed by nitrogen. B. Nitrogen was the first limiting nutrient ...
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19 views

Does amylolysis occur in vegetables if stored under 0 Celsius?

Assume that we have a plant, e.g. kale, which is prone to amylolysis if not harvested during a frost period. If it is harvested and put in a household freezer, such that it is frozen solid slowly ...
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2answers
83 views

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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0answers
30 views

Why black plum has a smell so much resembling tobacco?

Why black plum has a smell so much resembling tobacco? What substance does determine it? Can it be used for tobacco replacement?
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1answer
117 views

Why is cyanide poisonous?

I know cyanide inhibits complex IV in the electron transport chain, but I don't understand why this makes it so toxic. If cyanide is bound to the complex, can't the electrons just bypass it and ...
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1answer
50 views

Why is Thermus aquaticus and Taq Pol stable?

What is the molecular basis of the stability of the bacterium Thermus aquaticus and the enzyme Taq Pol it produces ? I have tried googling this but did not get a good answer.
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1answer
168 views

Excretion of various wastes and water requirement

A common fact is that Ammonia, Urea and Uric acid are the most common excreted metabolites and their removal needs varying amount of water, highest for ammonia (hence suited only for aquatic animals) ...
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1answer
76 views

What makes alcohol harmful to mammals?

During the alcohol metabolic pathway, harmful by-products are made like acetaldehyde, hydroxyethyl, superox­ide anions, and hydroxyl radicals. How do these toxic compounds harm our tissues? Many of ...
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50 views

What are the ingredients of Pheromone Trap using for controlling Fruit flies of cucumber?

Pheromone Traps are used for fruit fly control. But I have no idea which ingredients or chemicals are used for preparing Pheromone trap
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1answer
62 views

(Web)app to search metabolic/signalling pathways

I'm looking for an application where you can find pathways by selecting a chemical occurring in it. So, for example, selecting 6-phosphogluconolactone brings up the pentose phosphate pathway or any ...
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1answer
128 views

Independence of Light independent reaction in photosynthesis?

Inspired by a question asked to me by a classmate, I have the following question about Light-independent (dark phase) reactions in photosynthesis:- Let us suppose an algae sample was exposed to ...
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2answers
62 views

How does promoter sequence affect initiation?

I don't know if this might have been highlighted in recent research, but a textbook I have states that "the exact way in which promoter sequence affects [transcription] initiation is unclear" I'm ...
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1answer
86 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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1answer
1k views

Why is fructose not glucose the main energy source of sperm?

The seminal fluid contains fructose as the main energy source for the sperm and not glucose. Why is fructose and not glucose the primary energy source for these sperm, since glucose is the ...
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1answer
46 views

Common Ancestry of ETCs and ATP Synthase complexes

Rickettsiales are widely regarded as the ancestor of eukaryotic mitochondria through endosymbiosis. Cyanobacteria are widely regarded as the ancestor of eukaryotic chloroplasts through endosymbiosis. ...
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1answer
903 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 ...
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711 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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595 views

How does blue white screening work in selecting E coli that have taken up a plasmid vector?

The plasmid vector I am referring to is pCR 2.1 - TOPO. I added the vector to the E coli and plated them up onto LB+amp+X-gal plate, then incubated. After incubation the plates had two types of ...
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44 views

Is an antivenom venomous?

What happens when someone takes an anti-venom for an animal they weren't bit by, either for incorrect identification of the animal they were bit by or if they weren't bit at all? I am looking for the ...
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1answer
46 views

How does ultraviolet light influence the decay process of wood?

Given a piece of wood, how does putting it in the sun or not influence the rate of decay due to rot (assuming that it's in an otherwise humid environment)?
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2answers
77 views

Humidity for wood rotting

If I put a piece of wood in a humid environment (basically humid air), it will start to rot. Does the humidity influence the rotting speed, and if so, what is the relation between the rotting speed ...
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3answers
146 views

What does it mean for a distribution to be “consistent with a two rate-limiting stochastic steps”?

I'm reading a study (full text here) that examine the dynamic of nuclear translocation of a transcription factor in budding yeast, in response of calcium stress. They found that it occurs in bursts, ...
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1answer
448 views

Is Zymase, A Complex of Enzymes? Which ones?

Some websites state that the enzyme zymase (which I understand to be a complex of several enzymes) is responsible for catalyzing glycolysis in order to produce pyruvate. On the other hand, some ...
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156 views

Question about production of CFTR protein

How do organelles such as ribosomes, ER, Golgi and vesicles produce CFTR protein and mucus?
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90 views

Which hydroxyl from either the phosphate or the glycerol is taken during synthesis of a phospholipid head?

The oxygen anion in the phosphate group is likely to be bonded with a hydrogen cation and thus forming a hydroxyl. When the phosphate group is condensed with glycerol to make a phospholipid, is the ...
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1answer
68 views

Creative ways to deactivate alpha-amylase taken from fungi

I can deactivate $\alpha$-amylase in ways such as extreme temperature controls, pH controls of the solution it stays in, or adding salt to the solution. However, are there any other unique or ...
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2answers
96 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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1answer
76 views

Lizards are sometimes called cold-blooded because they depend on their surrounding temperatures to keep them warm.

Predict how the composition of the cell membrane of a lizard might change from winter to summer. Justify predictions. Can someone please help me figure this out. Does it have to do with fluidity?
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1answer
794 views

The real definition of carbohydrates

Carbohydrates are often defined as compounds with only C, H, and O and the H and usually the O atoms are in a 2:1 ratio. Exceptions like deoxyribose exist, but why is it recognized as a carbohydrate? ...
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1answer
254 views

Is there an optimal composition and length for protein linkers in FRET?

I'm designing a protein that I'd like to use in FRET reporting. General idea on the shape is: FRETprotein1--Linker--CleavageSite--Linker--FRETprotein2. I would like to know what AA are best for the ...
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3answers
90 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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1answer
45 views

How do rodenticides with delayed effect work?

Most modern rodenticides are claimed to cause death no earlier than several days after ingestion. That's quite strange - once a chemical was ingested it will be absorbed in the digestive system and ...
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1answer
276 views

Glycolysis and Non-Glucose Sugars

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 ...
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1answer
79 views

Hydrophilicity and polarity [closed]

If any given molecule is polar, and is capable of hydrogen bonding, I can be sure that it's hydrophilic. However, are those two the only conditions that make a molecule hydrophilic?
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1answer
89 views

Which is the correct statement on proteins?

I need help with one of the questions on my biochemistry assignment Choose the correct statement on proteins: a) proteins are folded by alpha-helix b) proteins can preserve their function even if ...
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1answer
39 views

What Biology topics are linked to the Nitrogen Cycle? [closed]

What other educational topics are linked to the Nitrogen Cycle? I am a Science teacher, and I need to organise my lessons. Thanks!
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58 views

How is Energy Generated in Cats?

I recall reading that much of the energy a cat produces from its food comes from proteins which I assume would produce energy via being catabolised into amino acids which in turn, if glucogenic, would ...
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1answer
110 views

Calcium for Humans: Supplements vs Fortified Sources

I am intolerant to meat and milk products, but purely natural foods don't contain enough calcium for the Recommended Daily Intake. Links 2 to 4 (but NOT 1) avouch a correlation between calcium ...