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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biochemistry SAT questions

Does glycogen and starch provide structural support? I know cellulose as polysaccharides does. the peptide bond is stronger than ionic, hydrogen, and van der Waal forces?(the answer said so)
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Why doesn't the avocado turn green when it is kept with its seed?

Why doesn't the avocado turn green when its kept with its seed? What does the seed release that slows down the oxidation process?
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Roles of creatine and bilirubin in foetus circulation

I think they are not inputs from maternal placenta. I think they are the results of foetus metabolism. However, I do not understand it how and where exactly. What are the roles of creatine and ...
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What exactly makes bananas go brown?

I know that often oxidation processes are mentioned when referring to the color change from yellow to brown in bananas (specifically: those that you get everywhere in supermarkets, with no seeds). ...
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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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58 views

What is an irreversible reaction?

There are reactions with large Delta G negative values. Why these reactions are irreversible? As in: out of 10 steps of Glycolysis, 3 are irreversible steps. I need an explanation for why they are ...
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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 ...
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1answer
34 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, ...
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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 ...
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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 ...
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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 ...
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Missing 4$H_2O$s (per glucose) in Cellular Respiration… Where can they be?

I having trouble understanding the equation of the cellular respiration. The thing that bothers me is the number of $H_2O$ molecules. Generally, cellular respiration is written thus : $C_6H_{12}O_6 + ...
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What can cause the swelling in high protein diet of Whey proteins?

I am thinking what can cause the swelling of high protein diet of Whey proteins. Liver does breaks those proteins to branched chain amino acids (BCAA), which can cause this swelling. However, I am ...
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What would be the reaction to the flesh?

If an acid, salt, and alcohol solution were formed into a gel, what would be the reaction if injected into flesh and what would be the effect on the skin say for rough and cracked feet, acne, newly ...
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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 ...
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1answer
21 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?
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37 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 ...
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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 ...
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In what forms do plants and animals excrete sulfur?

Sulfur is part of the amino acids cystein and methionin, plants take up sulfur in the form of $H_2S$. These organisms will also need a way to get rid of excess sulfur, how? In what compounds? Judging ...
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Transport of mammalian insulin in vivo

What is the mechanism for transport of insulin in mammalian cells?
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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 ...
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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 ...
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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 ...
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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 ...
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1answer
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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 ...
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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 ...
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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 ...
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Are DNA molecular motors described by cellular automata rules?

While watching this Molecular Visualizations of DNA it struck me how much the motion resembles Conway's Game of Life. And not only visually; each molecule/atom is described by a finite set of ...
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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 ...
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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 ...
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Diffusion of FAD+

Why is NAD+ free to diffuse within the mitochondrion whereas FAD+ is not ? What biochemical properties cause this difference ?
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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 ...
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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 ...
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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 ...
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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 ?
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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. ...
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Pathway mediates nitroglycerin-induced relief from angina pectoris [closed]

what kind of Pathway mediates nitroglycerin-induced relief from angina pectoris,please provide some idea...
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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 ...
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How do you express and detect GLP-1 receptors?

I am currently working with a peptide which is an analogue for glp-1, but during invitro studies am not able to detect for the presence of GLP1- receptors. The cell line used is Min-6. How do I detect ...
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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 ...
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Correlating B-lactamase expression to absorbance

When penicillin-resistant bacteria are grown in liquid culture media, B -lactamase is secreted into the medium. The supernatant of such a medium can be assayed for B- lactamase activity. Culture ...
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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 ...
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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 ...
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2answers
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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 ...
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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 ...
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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?
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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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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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319 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
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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) ...