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16

This controlled experiment of burger decomposition explains in detail why fast food burgers do not decompose easily. The same can be applied to fries, which are smaller and come dehydrated from the frying. The main take-aways from this experiment are: 1: Dehydration is the main reason why fast food fries/burgers do not decompose easily. Placing the burgers ...


14

In both humans and animals, the body fat stores appear as triglycerides, which can be composed of different fatty acids, but they all have about 9 kilocalories per gram (USDA). There can be different amounts of fat in different fat cells, so there can be slightly different amounts of fat in 100 grams of different types of fat tissue. Calories in 100 g of ...


10

Fatty acids are usually not considered polymers. From a biological viewpoint this is simply because there is only a very limited set of chain lengths that exists in nature (~2-20 or so) and also even numbered chains are much more common than uneven numbered ones. In contrast to this 'true' polymers can have an arbitrary length of chain length (of course ...


10

In the IUPAC Gold Book, IUPAC defines a polymer as follows: A molecule of high relative molecular mass, the structure of which essentially comprises the multiple repetition of units derived, actually or conceptually, from molecules of low relative molecular mass Fatty acids are relatively high in molecular mass compared to the monomer (which is ...


9

Why use membranes? Compartmentalising the cell has lots of advantages and purposes. In Koshland's 2002 essay, compartmentalisation was described as one of the seven fundamental pillars of life. Broadly speaking, membranes create different sets of conditions (chemical and biological) inside the cells. This allows more efficient functioning and advanced ...


8

How are diabetes and obesity connected in light of low lipase activity? Short answer: There's more than one type of diabetes. (And to complicate things, there's also more than one type of lipase. It's unclear from the question which type were mentioned in what you read.) Diabetes mellitus is usually divided into Type 1 (insulin-deficient) and Type 2 (...


8

Let's first clarify some concepts. Free fatty acids, including palmitic acid, are not present in animal tissues (or in the diet) to any large extent; they are esterified with glycerol to from triglycerides (fat), which is the storage form. This is a very important distinction, because triglycerides are chemically inert molecules that can be stored in very ...


7

Your question does not have a clear answer yet, as stated in Metabolic regulation: a human perspective / Keith N. Frayn. – 3rd ed (2010) on page 39. There is still debate about how fatty acids cross cell membranes. On that page they claim that a simple diffusion transport is possible through a 'flip-flop' mechanism, where the fatty acid inserts itself in ...


7

Yes, animals can make their own unsaturated fatty acids. Mammalian fatty acyl desaturases can introduce double bonds at the Δ5, Δ6 and Δ9 positions (i.e. numbering from the functional group). As shown in the diagram below, this means that we cannot introduce double bonds at the ω3 or ω6 positions (i.e. numbering from the ...


6

Why Bilayer and not a Monolayer Lipid monolayer vesicles are possible as you mentioned (for example micelles). However, you have to understand that the cellular interior i.e. the cytoplasm, is aqueous and therefore a monolayer vesicle like micelles would not work. In micelles, the two compartments - interior and exterior, have to be of opposite nature for ...


6

(1) Chain Length Will definitely affect melting point, as this website explains pretty well: "Melting point principle: as the molecular weight increases, the melting point increases." (2) Number of Methylene groups. This is another way of describing unsaturated from saturated fats. The more saturated a fat is, the straighter it is. Methylene groups ...


5

Glucagon and cortisol are VERY different types of hormones, though each of them can affect glucose metabolism and effectively can increase glucose concentrations in the blood (albeit through different mechanisms). Glucagon, pictured above, is a 31 amino acid peptide hormone (i.e. PROTEIN) that is released from the alpha-cells within the pancreatic islets. ...


5

From IUPAC Goldbook: A loosely defined term for substances of biological origin that are soluble in nonpolar solvents. They consist of saponifiable lipids, such as glycerides (fats and oils) and phospholipids, as well as nonsaponifiable lipids, principally steroids. That means that lipid does not mean any hydrophobic molecule. Lipids can be ...


5

There must be charge considerations in the movement of molecules in the lipid membrane. There is also a consideration that some species of phospholipids will migrate to portions of the membrane with sharper or smoother curvature. Waves of electrical potential can propagate along a lipid bilayer as well, which is very important to nerve axons and extended ...


4

There are two reasons for the asymmetry for the lipid composition of membranes in cells usually. The first which was mentioned by @Superbest is proteins which are called 'flippases' which describes three broad categories of proteins which facilitate the translocation of the lipids through the membrane, despite the fact that they all have polar or even ...


4

The following answer was giving by Michael D. Dryden from https://chemistry.stackexchange.com/questions/24797/what-is-a-triglyceride/24799#24799 There is some minor argument as far as nomenclature goes for these lipids. Most sources I can find, including IUPAC have glycerides as only including esters of glycerol with fatty acids. Monoglycerides have a ...


4

It turns out sphingilipids have many functions in humans, many of which might still remain unknown. I will discuss here only the general, known functions of sphingolipids, not about specific sphingolipids (as it'll make the answer too long). Sphingolipids are believed to protect the cell surface from harmful external factors by forming a mechanically ...


3

Okay so pyruvate carboxylase is a ligase-class enzyme, meaning it forms covalent bonds. What we see is that pyruvate is carboxylated into oxaloacetate by pyruvate carboxylase, here's our proposed reaction, What this does is replenish mitochondrial oxaloacetate levels, because when we switch into lipogenesis, TCA intermediates must be shuttled into the ...


3

Answer A is wrong because triglycerides are esters not carboxylic acids so they have -COOR group, not -COOH. Amino acids and fatty acids have -COOH groups and proteins too - on C-termini and in side chains.


3

I suspect I won't be crunching as much numbers as you'd want me to, however here are some basic points: Statins have shown a clear ability to improve the blood llipid profile. Their use in primary/secondary prevention for cardiac events is justified by the belief that less blood lipid will leave less lipids to clog the arteries with. This is an old paradigm,...


3

The cause of the swelling is lack of lymphatic carriage capability of proteins to the muscles, because of systemic conditions affecting the circulation of proteins through your lymphatic system. There will be edema extracellularly because of insufficient carriage of proteins through lymphatic system. My schematic drawing about the fluid movement between ...


3

Simple diffusion is the movement of solutes from an area of high solute concentation to an area of low solute concentration. Here are a few ways molecules will make it through membrane into cell: (A) Fuse with the membrane and enter due to like polarities i.e non-polar subtance fuses with non-polar membrane and passes through membrane (B) Small polar ...


3

There are differences. (Except mitochondrial eukaryotic membranes, which are indeed similar to bacterial membranes! (reviewed in van Meer et al., 2008)). First, bare in mind that it is thought that even different eukaryotes, such as Fungi and Humans, have different cell membrane compositions and that this is reflected in the proteins (Sharpe et al, 2010). ...


3

These conglomerations of proteins, glycolipids, and cholesterol are usually called lipid rafts. (Google Scholar shows 84,000 hits for that term, vs. 400 hits for "protein raft".) Here is a diagram of a lipid raft: (Key: A: Intracellular space or cytosol, B: Extracellular space or vesicle/Golgi apparatus lumen. 1: Non-raft membrane. 2: Lipid raft. 3: ...


2

My answer is limited to sheep. Background The metabolites referred to as ketone bodies (which I will refer to as ketones from now on) are acetoacetate and β-hydroxybutyrate. In humans these are produced in the liver when the amount of acetoacetyl CoA being produced exceeds the capacity of the TCA cycle. These acetyl groups are instead used to produce ...


2

Source : Tortora and Derrickson Principles of anatomy and physiology I read in the section on diabetes that " The breakdown of stored triglycerides causes weight loss". I assume that diabetic people are often overweight not simply because they have diabetes but because they also have many other disorders associated with it. Please feel free to correct me !...


2

It seems that there is no difference in the effects of chitosan on the uptake of saturated and unsaturated fatty acids. The study cited below (which has been done on guinea pigs) fed the animals a diet which contained different digestion-resistant fibers (maltodextrin, cellulose and chitosan) and also fats. Then the fatty acid content of the feces was ...


2

Short Answer: Yes. Long Answer: See this article: The diagrams presented show how fatty acids are synthesized in microorganisms and list the enzymes found in Escherichia coli. These reactions are performed by fatty acid synthase II (FASII), which in general contain multiple enzymes that act as one complex. FASII is present in prokaryotes, plants, fungi, ...


2

The textbook descriptions of fatty acid synthesis can be confusing because although the underlying chemistry of the process is universal, the way that it is organised is different in the systems that have been characterised, which include E. coli, yeast and vertebrates. In vertebrates: The fatty acid synthase is a dimer of identical multifunctional single ...


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