The study of chemistry within the scope of biology: the compounds that occur and the reactions involving them in living organisms.

learn more… | top users | synonyms

1
vote
1answer
61 views

Can we use Acetyl Phosphate instead of Acetyl CoA in TCA?

I am thinking Citric Acid cycle and activation of the end parts of Acetyl and alfa-ketoglutarate. Let's consider only now Acetyl to make things simpler. I have tried to explain the thing by symmetry ...
2
votes
3answers
66 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 ...
4
votes
2answers
86 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 ...
6
votes
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 ...
1
vote
2answers
69 views

Can excessive carbonated drink consumption lead to elevated red blood cell levels?

I've recently had a blood test and the results displayed elevated levels of erythrocytes as well as hemoglobin. (As a result my hematocrit levels were also above average) At my workplace there is a ...
1
vote
1answer
33 views

Cells created using differently aligned proteins

I remember reading that scientist were making cells (I assume bacteria), that used differently oriented proteins to create a whole new class of life. Because apparently right and left aligned proteins ...
2
votes
1answer
60 views

Substitute 25mM dNTPs mix with 10mM dNTPs

I need to make a solution of multiple compounds, one of them is dNTPs. The recipe calls for 20 μl 25 mM dNTPs in a 1250 μL master mix. Unfortunately I do not have it available at that concentration, ...
3
votes
1answer
50 views

Significance of lipids in biological membranes…?

Membranes are specifically designed by lipids to maintain internal hydrophilic environment in narrow range.There are hydrophobic amino acids among naturally occurring 20 amino acids and as well as ...
3
votes
1answer
35 views

Function of heparin and dextran sulfate for removing proteins

From this article : The reaction was terminated and the histones, and most nonhistones, were removed by adding the nuclease-treated chromosomes to a solution containing dextran sulfate (2 ...
-1
votes
1answer
52 views

Bilayer synthesis? [closed]

If we want to design a bilayer from Myristic acid (14 carbon fatty acid). The average bond length between C-C is 1.5 A. What will be average thickness of the membrane? Edited to include the OP ...
1
vote
1answer
30 views

Concentration of DNA by isopropanol

I have read that DNA can be concentrated by addition of isopropanol. What does "concentrated" mean? What does isopropanol do on a molecular level to concentrate DNA?
1
vote
2answers
45 views

Functioning of EDTA

I know that EDTA chelates metal ions. It weakens bacterial cell wall and inactivates the DNases. What is the reason why it can do so ? I guess it can inactivate DNases by altering the ...
2
votes
1answer
58 views

Structure of biological membranes?

Integral membrane proteins have functional asymmetry i.e. they have two different domains of proteins performing different functions. these proteins have Tyr and Trp amino acid residues at the ...
0
votes
1answer
39 views

What are the physiological roles of Hydrogen sulfide?

I am thinking why hydrogen sulfide has its effects in the body. For instance, it is one Salmonella's virulence factor. I am not sure if such a balance equations holds ...
2
votes
1answer
31 views

Transport of mammalian insulin in vivo

What is the mechanism for transport of insulin in mammalian cells?
2
votes
1answer
33 views

Activity of glucokinase

From Solomon et al, 2013 ACC Synthetic biology and from this video : Here, there are 2 competing reactions for glucose - one with glk as enzyme and other with gdh as enzyme. In the graph, y axis ...
0
votes
2answers
298 views

Converting unit/mg or unit/ml into ng/ml, or vice-versa

I am working with the enzyme Cu/Zn Superoxide (SOD1) and i am quantifying them in ng/ml. However, most past studies has SOD1 quantified in unit/mg or unit/ml, and i need to compare the SOD1 level of ...
3
votes
0answers
53 views

enzymes that stabilize DNA loops

As a follow-up of a previous question, I would like to know what enzymes or protein complexes have been used to manipulate DNA samples into stabilizing DNA loops. I have read that cohesin is one of ...
1
vote
2answers
59 views

Why only water in liquid form is essential to live?

My question is:- Only liquid water supports almost every living organism's metabolism, neither the vapour nor the condensed form of water does so. What is the chemical & the biological reason ...
4
votes
2answers
332 views

In biosynthesis of cysteine and methionine, where does the sulfur come from?

Methionine and Cysteine are the two amino acids containing sulfur. According to wikipedia, cysteine is built from methionine. However, the wikipedia also claims that methionine is synthesized from ...
2
votes
1answer
43 views

Quorum Sensing in Vibrio cholerae

This is a figure summarising the quorum sensing mechanism in Vibrio cholerae. In this video by Bonnie Bassler, she explains how quorum sensing can be targeted to control infections. At 15:09 she ...
6
votes
1answer
886 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? ...
1
vote
0answers
28 views

Nearly Exhaustive List for Cholesterol Pathways

I have run across an interesting case that is similar to only two others I've encountered. What makes it interesting is the combination of undetectable (under normal testing conditions, can elaborate ...
1
vote
1answer
57 views

Diffusion of FAD+

Why is NAD+ free to diffuse within the mitochondrion whereas FAD+ is not ? What biochemical properties cause this difference ?
1
vote
0answers
37 views

Ferredoxin synthesis pathways

I have been thinking about some alternative CO2 fixation pathways. As almost all of them include ferredoxin reduction I started to wonder where does the ferredoxin comes from. I could not find any of ...
-1
votes
2answers
71 views

PAH gene mutation

Analysis of the DNA of the Phenylalanine hydroxylase (PAH) gene in a patient with phenylketonuria revealed a mutation in the protein coding region whose predicted effect would be to replace the amino ...
0
votes
2answers
42 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 in the matrix of mitochondria. What is the biochemical reason behind ...
3
votes
2answers
54 views

Why do humans circulate monosaccharides instead of disaccharides as in plants?

Plants transport food mostly in the form of disaccharides like sucrose but humans transport them in the form of a monosaccharide - glucose. What is the reason behind this ?
1
vote
2answers
37 views

Clarification on Hatch and slack pathway

The following is a minor clarification that I want to make, since it is rarely addressed directly in most of the texts I have gone through. In $C_4$ pathway, the chloroplasts are dimorphic, that ...
13
votes
3answers
723 views

Why are there no organisms with metal body parts, like weapons, bones, and armour? (Or are there?)

Reading this question, Why are there no wheeled animals?, I wondered why no organisms seem to make use of the tensile and other strengths of metal, as we do in metal tools and constructions. I am ...
1
vote
0answers
45 views

Enzymes that can catalyze multiple reactions [closed]

If the lock and key model were true, only one enzyme would be able to catalyze a reaction. However, some enzymes can catalyze multiple reactions. What are some examples of enzymes that can catalyze ...
2
votes
1answer
420 views

Isopropanol precipitation of DNA - duration and magnitude of cold storage

DNA prep protocols often include a final precipitation step with alcohol, often isopropanol, where the DNA must be kept in the alcohol, at a low temperature such as -20C or -70C, often overnight. ...
0
votes
1answer
89 views

Pathway mediates nitroglycerin-induced relief from angina pectoris [closed]

what kind of Pathway mediates nitroglycerin-induced relief from angina pectoris,please provide some idea...
1
vote
1answer
29 views

Correlating Ki values of pesticides to bacterial growth

Four pesticides P1 to P4 are reversible inhibitors of an enzyme E that is essential for the growth of a bacterium B. Their Ki values are given in the table below. Each of these four pesticides ...
0
votes
0answers
12 views

To understand synthesis of e-NOS and n-NOS with respect to Ca and calmodulin

I found this sentence in my notes interesting E-NOS and n-NOS are Ca, calmoduline dependant ferments. They are synthesized from in small conc as response to physiological signals which ...
0
votes
0answers
26 views

To understand Nitric oxide, iNOS and Tumour cells

I have this figure about nitric oxide and tumor which is for schematic for me to understand it The figure should probably say that tumour cell is induced by NO or alone to go apoptosis and it ...
0
votes
2answers
24 views

To understand Second messenger signalling in I/c and E/c

I found this picture in my study materials. I think it is too schematic and ignores the big pictures. I think the thing connected to the hormone is receptor. The second messanger is then connected ...
1
vote
0answers
55 views

Osmosis - occurring in both ways?

So I did a prac to identify the osmotic potential of potato tuber cells. There were 5 test tubes with different concentrations of sucrose (0M,0.25M,0.5M,0.75M,1M); a small slice of potato was placed ...
7
votes
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?
4
votes
1answer
104 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?
3
votes
1answer
134 views

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. ...
6
votes
2answers
1k views

Very high 260/230 absorbance ratio of an RNA sample

After my most recent RNA extraction, the RNA samples had very high 260/230 absorbance ratios, (ranging from 5 to 25). I've never gotten numbers like this and I know the ratio is supposed to be ~2 in ...
2
votes
1answer
71 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 ?
1
vote
1answer
972 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 ...
15
votes
1answer
585 views

Can siRNA induce DNA methylation in mammalian cells?

Some years ago Hiroaki Kawasaki and Kazunari Taira published an article called "Induction of DNA methylation and gene silencing by short interfering RNAs in human cells" in Nature: In plants, ...
10
votes
1answer
311 views

What is the functional and structural distinction between core (H2A, H2B, H3,H4) and linker(H1/H5) histones?

Many explanations of histone biochemistry isn't quite elucidating for the undergraduate student. How does histone structure (dimers, octomers) relate to their specific functions as core or linker ...
6
votes
4answers
1k 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?
3
votes
2answers
57 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 ...
1
vote
1answer
60 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) ...
0
votes
1answer
42 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 ...