What is the sequence of energy utilization from protein, lipids, carbohydrates, which comes first, second and third for providing energy for our body?

Answered Oct 26

The first option is to burn glucose, because it is the least complex, and more direct.

If you run short on glucose, you have a store of glycogen in your liver and muscles. Glycogen is made of linked glucose monomers, which can be separated and burned.

You would also use other sugars, such as lactose, which take a bit more energy input to do.

Next, you would burn lipids. These are disassembled into 2-carbon units.

Last, you would start burning proteins. This may be a bad thing, for a couple of reasons. You need to get rid of the excess nitrogen, which takes resources. And, ultimately, you would start cannibalising things like your muscle tissue. In a starvation scenario, your body would be simultaneously burning tissue proteins, and using those carbon skeletons to manufacture glucose to send to the brain, which can only use glucose.

What elements differentiate the amino acids of a protein from the sugars of a carbohydrate?

Answered Oct 25

Carbohydrates and lipids are all CHO, which includes Carbon, Hydrogen, and Oxygen. These can be in different proportions, depending on the specific molecule.

Amino acids, by definition, have an amine group, which includes a Nitrogen. They all have an N on their backbone, and some have an N on the side chain. Cysteine and Methionine have a Sulfur on the side chain.

A few enzymes use an amino acid with Selenium instead of Sulfur.

Can the DNA remain in a girl after an abortion?

Answered Oct 25

Yes. It is called fetal microchimerism.

Material from the foetus can pass through the placenta, into the mother. This can result in ongoing cell lines which are based on that foetus, with a genome based on both parents, so different to the mother’s own genome. These cell lines can persist for the rest of the woman’s life.

No, you cannot grow a new foetus from these cells.

How do astronauts survive without sex for so long?

Answered Aug 21

OK, here’s how it works.

First, it’s only a problem for the male astronauts. Research based on males between the ages of 13 and 25 shows that, a lack of sex causes a medically dangerous buildup of pressurised semen in the testicles.

So, on the space station, they have a periodic health and safety routine to alleviate this.

Basically, they open the door, and allow all the air to escape, so the entire station depressurises. The vacuum of space then pulls all of the accumulated semen from the astronauts, in one big spooge, thus relieving their painful internal pressure. Then, they close the door and fill the station with air again.

They do this about every three or four months or so.

There have been long-standing but never confirmed rumours that the old Soviet space program’s Mir station didn’t have this procedure, and that a crew member suffered a fatal explosion due to the chronic lack of sexual release.

It’s amazing what you can learn when you ask questions of random strangers on Quora, isn’t it?

To what extent does nature select for simplicity?

Updated Aug 11

Selection tends to be a numerical issue. It is largely about who survives their environment long enough to reproduce efficiently. Which leads to large numbers of progeny and descendants.

Without getting into a debate as to whether they are “really alive”, the most numerous species on the planet are bacteriophages. They are viruses which infect bacteria. They are very small, and relatively simple (although they are actually more complex and elegant than they seem at first).

The next most numerous are bacteria and archaea, which are comprised of single cells. These domains contain a range of species that can survive a very wide range of environments. Each individual species has its own needs, but, as general groups, bacteria and archaea can be found in many places that more complex life forms cannot.

Simplicity vs complexity relates to the amount of time and energy that is required for replicating yourself. A human being takes nine months, while bacteria have a theoretical minimum of 20 minutes (although, in reality, it tends to be somewhat longer, like maybe an hour, depending on conditions). The required energy and nutrients are vastly less per new bacterium.

Some species can evolve towards being more simple. If you are a microbe in an environment where certain needed molecules are plentiful, then you can lose the genes that code for enzymes to make those molecules yourself. Then, replicating yourself takes less time and resources, so you are now more efficient.

Microbes were around for a very long time before humans, and will continue long after we are gone.

Some multicellular organisms are also advantaged by relative simplicity. There are far, far more insects than there are mammals, for example. Also, their progeny are independent immediately, rather than needing years of parenting, sexual development, etc.

Why don’t people dying of thirst drink the sea water if it’s the only choice they have?

Updated Aug 14

It isn’t the “only choice” to drink sea water. The other choice is don’t drink it.

The problem is, the delusion that, any liquid will re-hydrate you.

The reality is a principle called “osmosis”.

Try drinking some saltwater. Really, I mean go ahead and do that. I suggest 2 heaping tablespoons of table-salt, in 2 litres of water. You will want more than 2% w/v of saline in the water. Spike it with a little orange juice to try to keep from vomiting. Try to get it down within an hour or two.

Then, you will RUN to the toilet, and rapidly dump the contents of your guts, with every meal that you had in the last several days.

You will also be dumping large amounts of water. Some people do this as a purgative/laxative process.

If your only supply was seawater, and you consumed it for several days, this can kill you.

Osmosis starts with a membrane, that allows some things through (like water) but not other things (like NaCl table salt or sea salt).

The salty water (with high concentrations/amounts of NaCl salt in it) will actually suck water out of the cells in your gut. Salty water sucks fresh water out of your body.

Some sodium may be absorbed by your gut, and your kidneys will also be working overtime, trying to get rid of the excess.

Another fun fact is that, poor hydration can happen with high-sugar liquids. Again, it is about the high amount of solutes (stuff floating around in the liquid) compared to solvent (the water). I have encountered rest-home staff who didn’t comprehend this, and didn’t care, as they shoved high-sugar juice at elderly people with weak kidneys.

Also, drinking your own urine in the desert sounds badass, but is actually a terrible idea, due to the sodium and urea in it.

What needed more energy, the secretory cell or the sensation cell?

Updated Jul 1

When a nerve cell fires, it depolarises its plasma membrane (in a wave, which is how the signal travels down the length of the cell). Then, it has to repolarise the membrane (using the sodium-potassium pump, which uses a lot of energy) before the next firing. A very large percentage of your body’s glucose is used by your brain.

On the other hand, a secretory cell is, by definition, sending out products and materials. Those products take energy to assemble, and then they are spewed out, and cannot be recycled.

A secretory cell will have a lot of carbon and carbon skeletons leaving its system, as they are assembled into final products. It will need a lot of energy (in terms of burning glucose, etc) in order to disassemble, and then reassemble, and export more of these things.

Every time a cell assembles something (down to just each residue in a peptide, or each 2-carbon unit in a fatty acid) consumes an energy unit, and burns an ATP.

Secretory cells also need a large number of Golgi stacks and other export machinery. Plus, raw materials like amino acids need to be replaced, so the cell will be using energy for importing from the environment

So it’s hard to say. Maybe it depends on how active the cells are at that particular moment.

What is the most primitive organism living today?

Updated Jun 8

If they are alive on Earth today, then none of them are primitive.

Every species currently existing is a product of billions of years of evolution.

A small, relatively simple, single-cell microbe species will be highly adapted to its particular environment. They can thrive just fine, live out their lives, create progeny, etc.

They replicate very rapidly, and, as a species or a strain, can adapt fairly rapidly to changes.

A species can even evolve by simplifying itself. If you live in an animal’s gut, you might lose the genes to make certain molecules which are plentiful in that environment. You would actually become more efficient, and thus, more evolved.

Unicellular organisms may seem “primitive” from a very basic view, but they start looking very complex when you look closely enough. This applies to individual cells, and to populations of individuals interacting with each other.

It’s very much about context.

There are plenty of single-celled bacteria and archaea which thrive in environmental conditions which would kill a human very quickly and painfully.

From humans’ perspectives, microbes may seem primitive and inferior. From some microbes’ perspectives, humans are clueless, enslaved providers of food, shelter, and transportation.

Perhaps one of the most “primitive” organisms on Earth are those zombies who devote their biological structures, processes, energy, and time, to alternately watching reality television, and then compulsively staring at their phone to scroll through FaceBook.

Why is it so taboo to support eugenics?

Updated May 4

The taboo is overtly around the issue of coercion.

If you use the word “eugenics”, some people (as seen in this discussion) have a knee-jerk reaction, and automatically think “Nazis”. They think about targeting whole ethnic groups, or killing people, or forcible sterilisation.

However, I think some of the discomfort is really about the issue of people being encouraged to make their own rational choices, and exercise thought-out, responsible control over our lives and our bodies. That doesn’t sit too well with the majority, who view having children as something that just automatically and randomly “happens” to everyone.

The truth is, humans and other animals engage in large-scale selective breeding for fitness (including intelligence) all the time. It’s perfectly normal.

Some people get nervous when there is new technology involved, and explicitly stated selection:

Genetic Counselor: “Well, Mr. and Mrs. Smith, we have tested your (alleles, single nucleotide polymorphisms, scary scientific sounding stuff, etc), and I have some bad news. If you were to have a child, there would be a 50% chance of a devastating genetic disease, with nothing but misery and pain for said child, and for you.”

Couple (in unison): ”Bummer. We better not have any kids.”

Or it can go the other way:

Crackly Voice From Speaker: “Hi! Welcome to Jolly Jism Drive-Through Sperm Bank! May I take your order?”

Customer: “Yes, I’d like the Rocket Scientist with Olympic Champion… Healthy, tall, blond… Clean family history for cancer or mental illness.”

Crackly Voice From Speaker: “Excellent choice! Would you like a side order of artistic talent?”

Customer: “I’ll take the classical piano playing.”

Crackly Voice From Speaker: “Great, I’m whipping up your fresh hot sample right now! Please drive forward to the pickup window.”

And people do it in a more casual way constantly:

“Ewww, that person is stupid (or has any characteristic that repulses me), and I can barely stand to interact with them, so I certainly would never consent to having any kids with them.”

Some individuals are already pushed entirely out of the breeding pool, simply because they have characteristics which lead to being persistently rejected for sexual opportunities. They don’t have any “right” to produce children when they can’t find any willing mates.

Government force is already used to some extent, via the criminal justice system. One effect of imprisoning criminals is that it removes them from the breeding pool, either temporarily or permanently.

In the book, “Freakonomics”, the authors talked about the impact of abortion (specifically legalisation in the US) on subsequent crime rates. Maybe the reason why you weren’t mugged and killed in 1995, is because your assailant was aborted back in 1975.

I would also expect that the benefits expand, because he also won’t be using law enforcement or prison resources, or fathering another generation of low-functioning street criminals. And his sister, who was aborted a few years later, also won’t be contributing to the current generation of criminals, or to multi-generational poverty and welfare dependence, recycled by low-functioning people.

Some individuals may have an honest self-assessment that, “Me having children wouldn’t benefit anyone. It would be stupid and irresponsible, and a general, long-term disaster. So therefore, I won’t have any children.” This could range from medical history, to lacking financial resources, to simply having other priorities in life.

People who are considered conventionally “attractive” are really displaying good reproductive fitness. This can range from wide hips to get a large baby’s head through, all the way to financial status symbols. People with those characteristics will receive more attention and opportunities for mating, including with other people of high reproductive fitness.

People who get upset about all of this may just be worshipping fertility. Without caring about the suffering caused by low-functioning people producing children whom they are not equipped (mentally, behaviourally, financially) to raise in a decent manner. This includes some of those low-functioning parents actively inflicting the biological disaster by using alcohol and other drugs while pregnant.

A large portion of the people who are pumping out kids do so with exactly zero rational decision-making, self-control, or actions→consequences thinking.

And that is why the film, “Idiocracy” is gradually coming true. Mass collective bad behaviour leads to mass collective bad results, including on those of us who are not engaged in that bad behaviour. The alternative to eugenics is a default to dysgenics.

In order for phagocytes to consume pathogens, they release pseudopods to engulf the pathogen. How do phagocytes do this, do they have some kind of muscle or is it something within the cytoplasm?

Answered Jan 26

Pseudopodia are sort of like fingers that form and sort of blob out of the surface of the cell that is making them.

Inside the cell, there is always a sort of girder-like supporting structure/network called the cytoskelton. This gives the cell physical support and shape, a bit like a person’s skeleton.

However, the cytoskeleton can grow or shrink very quickly, and can be made to grow in a certain place and certain direction, as needed.

The cytoskeleton is partly made of a building block called actin. It is a protein that can be stacked into long strings. Stacking it in a certain way causes the pseudopod “fingers” to poke outwards. Kind of like growing a new arm, just because you needed one at that moment.

Later, the actin filament gets taken apart, and the pseudopod shrinks back.

In your muscle tissues (where the components are more fixed in place), actin is partnered with another protein called myosin, to do contraction (pulling). There, the strings sit there parallel to each other, and contraction is a sliding motion (the chemical and mechanical actions are somewhat complicated).

In the phagocytes, there is a further process called (strangely enough) phagocytocis, in which your cell pulls in the pathogen, and puts it into a vesicle (like a bag) where the pathogen is dissolved by enzymes. This involves proteins on the cell surface pulling a small area inwards, to form the vesicle.

Some other cells, like amoeba stages of some single-cell protozoa organisms can also use pseudopodia to reach out and pull themselves along (similar to crawling).