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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109 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 ($\ce{3'-PO4^{-}-5'}$). ...
6
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1answer
2k 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 ...
3
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1answer
49 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
1k 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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1answer
2k 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?
3
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1answer
699 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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0answers
47 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 ...
1
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1answer
53 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)?
3
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2answers
79 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
169 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
612 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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2answers
184 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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2answers
100 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 ...
1
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1answer
71 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 ...
4
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2answers
105 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 ...
0
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1answer
87 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
1k 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? ...
3
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1answer
307 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 ...
4
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3answers
97 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?
5
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1answer
56 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 ...
2
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1answer
344 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
105 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?
1
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1answer
98 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 ...
2
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1answer
44 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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0answers
67 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 ...
0
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1answer
155 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 ...
6
votes
1answer
985 views

Why does the heart use lipids (and not glucose)?

Fetal hearts use glucose as their primary metabolic substrate. Adult hearts use free fatty acids, which are less efficient (require more $O_2$ to synthesize the same amount of ATP); however, during ...
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0answers
53 views

Why is a nicotinamide-tryptophan combination used to treat affective episodes in a few older clinical trials?

At least one of the journal articles that reported on such clinical trials allured to the nicotinamide-tryptophan pathway that I assume must be related to the metabolism of tryptophan into serotonin ...
3
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1answer
1k views

Why is FADH2 made instead of NADH in one of the reaction of Krebs cycle?

FADH2 is made in conversion of Succinate to Fumarate. Why is this so ? Why not NADH ?
3
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1answer
103 views

Other than Acetylcarnitine what other orally-bioavailable Acetyl donors exist to assist in the conversion of CoA to acetyl-CoA?

I asked a question on bio stackexchange a few days from which I was hoping to be able to arrive at an answer for this question myself but I have had no such luck so now I am going to just ask ...
3
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2answers
463 views

Can any one reaction in a cell be at equilibrium?

I know that metabolism as a whole can never be at equilibrium (otherwise the cell is dead !) but I wonder whether a few reactions in the cell could be at chemical equilibrium at a given point of ...
2
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1answer
416 views

Is there any advantage of having a mitochondria for aerobic respiration?

If we consider the pathway of breakdown of glucose which includes glycolysis, the citric acid cycle and the electron transport chain, all these processes takes place in some prokaryotes and ...
8
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4answers
2k views

Why we have no enzyme to digest cellulose?

As we know, cellulose is the most abundant polysaccharide in nature. Why don't we have any enzyme to digest cellulose?
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0answers
46 views

Where can I find complete description of the nucleotide biosynthesis?

I'm looking for a good source for learning nucleotide biosynthesis pathway (including enzymes and possibly also structural formulas) - what is the best source I could find such pathway, presented in a ...
2
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3answers
67 views

Where can I find an at least Semi-Comprehensive list of what biochemical reactions Acetyl-CoA participates in?

Acetyl-CoA has a number of biochemical roles in the body and I'm curious as to whether anybody knows where I can find at least a semi-comprehensive list (i.e. comprising all the major roles in the ...
0
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1answer
68 views

Why to choose a grammar from a lot of grammars that can describe structure of proteins? [closed]

Why do we choose a grammar from a lot of grammars that can describe structure of proteins? Usually, there are a lot of (maybe infinite) grammars that can describe one language. Why do we choose a ...
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0answers
46 views

Domains in cell membrane

How is movement of proteins and lipids between different domains of cell membrane prevented? Why is the noncytosolic layer not able to do lateral movements between domains but cytosolic layer is able ...
7
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2answers
392 views

What exactly happens if during translation, an amino acid is not present?

Lets say that the cell wants to make a particular protein. Transcription of the appropriate gene is done and the mRNA is made. mRNA attaches to the ribosome and the translation is initiated in a ...
2
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1answer
199 views

How to calculate or know by experiment the entropy of enzymes or protein?

How do you calculate or experimentally determine the entropy of enzymes or protein? In particular, I am interested in Boltzmann and conformational entropy, and Gibbs free energy. Any references are ...
3
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1answer
216 views

Can replication occur if DNA is methylated?

Can a methylated strand of DNA be replicated without removing methylation? Does it make any difference if the strand is methylated or not (during replication)?
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4answers
159 views

Are biological systems engineered? They are often reverse engineered at a molecular level!!

Understanding biological systems, molecular biologists need to “reverse engineer” them. Is this evidence that the systems were engineered to begin with?
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0answers
127 views

What tests can be performed to test the purity and quality of the raw peptide HCG (Human Chorionic Gonadotropin)

What tests could be run to test the purity and type of HCG? We are looking to purchase HCG from China but the purity and quality varies between labs, we are able to receive samples of the raw peptide ...
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vote
1answer
95 views

How are the correct tRNAs transported to the ribosome?

I have been trying to understand how the tRNA transporting the correct amino acid required by the ribosome reaches the ribosome. The only way I can imagine this happening is that all types of ...
2
votes
1answer
110 views

How does GTP help in the step of codon recognition?

The anticodon of an incoming tRNA base pairs with the complementary mRNA codon in the A site.Hydrolysis of GTP increases the efficiency and accuracy of this step. How does GTP do so ?
8
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2answers
1k views

why is AUG the initiation codon?

Is there any reason why AUG is the initiation codon ? Why is there a need for an initiation codon ? Can't translation start with different codons?
1
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1answer
125 views

Does animal fat and meat contributes differently to our body?

Is animal fat harmful to our body or is it harmful if the amount eaten exceeds a certain amount? I have heard fat is more concentrated than protein. If I am correct then we can get more energy from ...
2
votes
2answers
2k views

Why restriction enzymes cut (usually) at palindromic sequences?

Restriction enzymes usually cut only at palindromic sequences. Is there any specific reason for that ? Is there any advantage for bacteria if it cuts up virus at this type of sequences ?
3
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1answer
116 views

Are similar smells usually based on similar chemicals?

Building off of this question: Why does freshly cut grass smell like a watermelon?, is it usually the case that things that we perceive as having similar smells are, in fact, the same or a similar ...
3
votes
1answer
820 views

What is DNA binding domain? It is not clear what the domain means

I am confused about the term DNA binding domain. Does it mean that there are some parts of the DNA that tends to coil up? Does it happen because some proteins tend to stick around that area? Also it ...
3
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0answers
36 views

Statistics on energy consumption breakdown per biological functions across organisms?

Are there any statistics available on how much energy organisms use for each biological functions (i.e. something similar to the line of "Bacteria spend X% of energy on information processing, Y% for ...