Why are cells so small?

Hi,
ever wondered why you have to use microscope to see cell? Well cells are small but why?

There is a simple geometrical reason for it and it has to do with volume and surface area. First let’s take the case of cell being very big and what it would mean for it.

Such a cell would have much greater volume because of greater diameter, that is quite logical, but if you compare it to the surface area (which also increased) the ratio between the two attributes increased, meaning surface area did not grow so much as volume.

Volume (no matter the shape) grows rapidly with the function d^3 where d is the diameter [1]. On the other hand, the surface area only with d^2. So, what this means for the cell is that the surface = the membranes, are going to need to work extra hard to feed and clean up the rest of the big cell. This has some limit and that is why cells tend to be rather small and only viewable with microscope.

If the diameter is 1 than both volume and area are 1. (ratio 1/1=1)
If the diameter is 3 than volume is 27 and area 9. (ratio 27/9=3)
If the diameter is 5 than volume is 125 and area 25 (ratio 125/5=5)

The cell also cannot be too small otherwise the “equipment” (organelles) would not fit in.

Dragallur

Source: https://www.youtube.com/watch?v=wuXSEOKNxN8

[1] Take a cube for example the equation for its volume is V=a^3 where a is the side.

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Altruism does not exist

Hi,
the title is pretty self-explanatory but I can expand it. What I want to write about today is the theory of selfish gene and how it interacts with selfishness and altruism. (Btw. do not forget to check out my second blog!)


So altruistic act is the act that helps others while giving you to worse position, by this I mean that it costs you some energy for example.

What I want to say that there is apparently altruistic behavior towards those who are similar to you. Who is that? Your family.

Over all you share 1/2 of genes with your siblings and with your parents and also children, nobody can get closer to you if you wont make a copy of yourself or you have twin.

From the point of the selfish gene which is in you, it is important to stay in population and not die out [1]. This means that the gene is trying to safe other genes which may be riding in different bodies.


How does he know that there is his identical gene twin in other individual? Dawkins says for example in his book The Selfish Gene, that when there is gene for altruism in your body you will know that this same gene appears in somebody else who is also behaving altruisticly. While it is always from evolutionary point of view best to safe yourself, it is also good to safe others because they may contain the same stuff as you and that is what is important, not the outer shell which is anyway just a vehicle which will disappear after few years.

To enhance this argument I will just add: if gene is able to recognise himself in other “survival machines” then it will be more often present in future generations which is basicly natural selection.


 

You can not apply this for human behaviour because we are no longer bound only by instincts and this surely is not a way to live a life. At the same time, think over your past days about you and also people around. Do you behave altruisticly or are you hiding your selfishness behind altruism? What I see often is that people do “good” things just because they want to look like doing good things over all being selfish, what do you guys think about this?

Dragallur

[1] It is of course not important for the gene. Genes are not thinking. If the gene would not be good at staying in population it would not be there.

 

 

 

How did life arise?

Hi,
I bumped into this question when I was arguing over evolution and creationism. It is very favorite claim that life had to be made by God because humans were not able to create it from dead matter, rocks for example.

This is famous problem. It is true chemists were not able to create life when simulating the early time on Earth 3.6 billion years ago (this is for simplicity, it is kind of difficult to say when exactly life arose).


Now of course there are theories and one of them is the theory of primordial soup. This is theory that in the ancient ocean there were dissolved some basic molecules which we can find even on other planets (so we have proof for them that may have been here (and almost surely were)).

So as they are floating in the dead ocean there is some great radiation coming down and hitting these molecules. Also there is what is called “primordial lighting” which is the lighting that should be able to create more complicated molecules only by hitting ammonia, hydrogen and other stuff. It was proved that there should be monomers too. Those are simple organic compounds, such as lipids or proteins.

Chemists were able to create with some radiation and electricity even amino-acids. The last step was that we were able to create purines and pyrimidines, those are building blocks of DNA and RNA which is kind of important.

RNA and DNA, key components for modern living.

Nothing more, we were not able to create life, yet. What would the next step be? Something that is called replicator.

Replicator is any molecule or lot of molecules that are able to replicate itself. This is key. If we are able to create some kind of replicator from the primordial soup, we will take a giant leap forward, because then onwards evolution takes a place.

When replicator replicates it should make exact copy of itself like in asexual reproduction. But as good secretary makes roughly one mistake per page, even the replicator will eventually make a mistake. This is called mutation and it is either helping the organism or not. This process drives evolution even that only small part of all mutations may be helpful. Those who have good mutation will have more replicas of itself and eventually there will be only those which are better, this process will repeat in what is called evolution when after hudreds of millions of years you are standing here, originating from one simple replicator, as well as me, your class mates all other animals, bacteria and viruses. This was never observed but it should work like this.

In bottom you can see the LUCA, first original organism from which we originate!


 

So will we be able to create replicator? The problem with that is that only several laboratories over world are working on this. They are working on it only for about 100 years which is not much considering geological time.

While I did not see their laboratories I bet that they are working on small areas, maybe area of swiming pool and I found, I cite:

Liquid water covered much of the Earth’s surface by 3.6 (or 3.8?) Ga, but when before that it condensed from a dense atmosphere is undefined.

We can of course speculate on what “much” means though I would guess that we can start on reasonable 50% of Earth’s surface which is 255,036,000 square kilometers. When speaking about swimming pool I will take olympic swimming pool though I guess that the chemists work with much much smaller, they would not be able to control such a big area.

Imagine controling experiments on this thing!

It means that the Earth was able to use roughly 204,028,800,000 times bigger area than chemists not talking about the fact the oceans are deeper.[1] At the same time, there were couple of millions of years for this to happen compared to 100 in laboratory.

My point is that we maybe should not expect the life to rise in our laboratories, because if it does, life is much more probable that we thought[2].

Dragallur

PS: Do not ever argument by saying that Pasteur proved that life can not rise spontaneously, because he did not.

Read more: 1) 2) 3)

[1]Of course you could argue that in laboratory you can use lighting all the time and be purposeful with your selection of molecules.

[2]Maybe we should since our techniques improve and we are getting better in simulating and controling the environment of primordial soup.

Book review 4) The Selfish Gene

Hi,
last week I finished the book Selfish Gene, here is the review.

Book: The Selfish Gene

Author: Richard Dawkins

Genre: Science

Pages: 224 (the edition above has more)

Rating: 9.5/10


When I wrote about the Origin of Species, Gaurish wrote that I will surely like Dawkins too, and I did indeed!

The main thought of this book is the importance of gene in evolution rather than the organism. Why? Because organisms die after certain time but genes are passed on if the organisms were succesful. I like how Dawkins calls these organisms like us, plants or insects or anything that carries DNA, “Survival machines”.

We are nothing more than a survival machines that was designed by the genes inside. We are just vehicles to help the genes to be passed on. If the genes are unsuccesful in designing good machine that will reproduce, they will die, but the important difference is that Darwin thought only about organisms whole, but here the main characters are strictly genes.

The book is really phenomenal, I love how there are lot of examples to various organisms and I have not been lost through whole story, and it really is a good story.

The reason why I did not give it full rating is that there could be more pictures while I understand that the edition I had was released in 1989.

In this book Dawkins also explains altruism and selfishness. As he says, altruism does not really exist, genes are always selfish and are trying to spread as much as possible. Your body can “know” that some one else has the same gene as you, then it is important for the gene to protect also the other person and this can look like altruism.[1]

I really recommend this one, right now I am reading The Blind Watchmaker again by Dawkins and as I write this The Extended Phenotype lies on my desk so I will continue with them.

Dragallur

PS: I decided to try to write post every other day so look for another one on Wednesday.

[1]This was quite simplified, read the book if you want to get the detail or wait for some post where I will explain it!

There is REAL blood in your hands

Hi,
so yeah, there is hopefully some blood in your hands. Maybe.

Or maybe not?

Today I was out for two hours and it was kinda cold. So when I got back to home my hands hurt a lot. Why?


Well you could say that there is blood in your hands, and well it would be true.

The reason for it is similar to why you need to go to toilet when your legs get cold. Body is trying to save some heat by keeping it close to other heat and also save the important parts of body (your organs). To do it, it must make all your veins and various tubes in limbs thinner. At the same time some of those liquids have to go somewhere, so they go up to your important body parts and eventually you also need to pee.

When you get back from outside, your body feels that there is much more heat so the tubes can be expanded again. This also triggers pain receptors. So rapid heating of your body causes the pain that you can feel in winter.

When you dring alcohol, the body thinks that it is warm around so the tubes are expanded even when it is freezing. Now the blood runs down to your limbs which are feeling pretty good but they lose heat very quickly since when you pull something on bigger area it cools faster. This may even kill you when it is very cold outside.

Dragallur

 

Book review 3) On the Origin of Species

Hi,
this time I will make a review of another book I just finished:

Book: The Illustrated Origin Of Species

Author: Charles Darwin (Richard E. Leakey)

Genre: Science

Pages: 220

Rating: 9/10


I started to read this book last week so I have completed it pretty quickly which is a bit suprising on my manners.

I decided to read it because my mum said that I should read it before I continue on Selfish Gene by Dawkins, so I know the basics of evolution. You probably heard about the original book: On the Origin of Species purely written by famous founder of evolution: Darwin.

This is sixth edition or so with foreword by Richard E. Leakey who is apparently paleoanthropologist and politician. Not only foreword but also several paragraphs in the book and also the illustrations are added by him. This version is shorter than the original.


The book is very good but still there are some things which I would change. There were some passages where the book was written too simply and sometimes you had to go once or twice over it. Also one or two chapters seem to be kind of weird since they start with paragraph saying that Darwin is wrong in this chapter because now we know that it is different. Those were sometimes a bit boring but I can understand that still at least it meets the “historical” value that Darwin himself wrote it.

What I found really interesting is that there were probably only few sentences where he mentioned God and Christianity, while you may remember that this book was and is often used as argument against creationism.

It simply seems that he is trying to avoid it. In one part where he talk about how cuckoo lays her eggs in nests of different birds and then the young throws brutally all the other eggs and youngs out of the nest because she needs more food, Darwin says that he does not think that God would create something so brutal and that it had to be because of uncompromising natural selection. He says the same thing about one kind of insect that lies his eggs into caterpillar which is then eaten from inside.

I really like the chapter about ants. Darwin explains their verious behaviors and I found very interesting those slaver ants. Also cool is the part where he writes that seeds can for example spread through mud that is sticked to birds leg. One of his friends even sent him a leg of a bird with dirt sticked to it to prove it!

If you want to get such an introduction as I did or you just admire Darwin, go on read the book, you will like it a lot!

Dragallur

 

Hello world!

Hi guys,

This is my first post and I would like to tell something about myself.
Firstly, I am not native speaker. Actualy, I am from Czech Republic (Central Europe) and I am fourteen years old. The reason for me to write this blog in english is that I would like to train my second language.

Secondly, I came to this page because of this page: http://www.wired.com/2015/03/advice-future-physicists/ I love physics, computers and books. That is the topic I want to write about on this blog.

Thirdly, I heard that blog learns you something if you write it longer time so that is third reason I am doing this. Well, for now that´s about it.
Dragallur