Why are cells bigger than atoms

The smallest objects that the unaided human eye can see are about 0.1 mm long. That means that under the right conditions, you might be able to see an amoeba proteus, a human egg, and a paramecium without using magnification. A magnifying glass can help you to see them more clearly, but they will still look tiny.

Smaller cells are easily visible under a light microscope. It's even possible to make out structures within the cell, such as the nucleus, mitochondria and chloroplasts. Light microscopes use a system of lenses to magnify an image. The power of a light microscope is limited by the wavelength of visible light, which is about 500 nm. The most powerful light microscopes can resolve bacteria but not viruses.

To see anything smaller than 500 nm, you will need an electron microscope. Electron microscopes shoot a high-voltage beam of electrons onto or through an object, which deflects and absorbs some of the electrons. Resolution is still limited by the wavelength of the electron beam, but this wavelength is much smaller than that of visible light. The most powerful electron microscopes can resolve molecules and even individual atoms.

Adenine

The label on the nucleotide is not quite accurate. Adenine refers to a portion of the molecule, the nitrogenous base. It would be more accurate to label the nucleotide deoxyadenosine monophosphate, as it includes the sugar deoxyribose and a phosphate group in addition to the nitrogenous base. However, the more familiar "adenine" label makes it easier for people to recognize it as one of the building blocks of DNA.

No, this isn't a mistake. First, there's less DNA in a sperm cell than there is in a non-reproductive cell such as a skin cell. Second, the DNA in a sperm cell is super-condensed and compacted into a highly dense form. Third, the head of a sperm cell is almost all nucleus. Most of the cytoplasm has been squeezed out in order to make the sperm an efficient torpedo-like swimming machine.

The X chromosome is shown here in a condensed state, as it would appear in a cell that's going through mitosis. It has also been duplicated, so there are actually two identical copies stuck together at their middles. A human sperm cell contains just one copy each of 23 chromosomes.

A chromosome is made up of genetic material (one long piece of DNA) wrapped around structural support proteins (histones). Histones organize the DNA and keep it from getting tangled, much like thread wrapped around a spool. But they also add a lot of bulk. In a sperm cell, a specialized set of tiny support proteins (protamines) pack the DNA down to about one-sixth the volume of a mitotic chromosome.

Carbon

The size of the carbon atom is based on its van der Waals radius.

Bernie's Basics

Getting your head around mind-bendingly big and unimaginably small things is really hard - our brains just weren't built to do it.

By Bernie Hobbs

To get by as a human, all evolution required of our ancestors was the ability to outrun or outwit anything that could kill them before they made a baby. Being able to mentally picture all the mammoths on the planet wasn't high on the essential skills list.

Thanks to money, or what we can buy with it, most of us can wrap our heads around the relative size of a thousand, a hundred thousand and a million. But once we get past a few million it all starts to get harder to picture. The same goes for the small stuff — we know viruses and bacteria are small, and atoms are even smaller, but just how small is as hard to grasp as Rupert Murdoch's bank balance.

But it's easy to get a grip on just how huge or tiny something is: you just compare its size to the size of things we're familiar with, like us.

On a scale of the smallest to the largest things we can see in the solar system, we sit pretty much dead middle. Or Danny DeVito does — at 1.50 metres he's 10 billion times bigger than an atom and one billion times smaller than the diameter of the sun.

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The small stuff

Our bodies are made up of cells, and compared to us they're tiny. The average human cell is about 10 -15 micrometres (µm), which means we're about 100,000 times bigger than our cells. If your cells were the size of a five cent piece, you'd be two kilometres tall.

Not all cells are that tiny. Human egg cells are about 130 µm, which is wider than a human hair (100 µm) and 30 times wider than the head of even the most ambitious sperm. But they're nothing compared to the giants of the cellular world. The nerve cells in your sciatic nerve are about a metre long - they run all the way from your spine to your foot.

Bacteria are cells too, but they're only about one tenth the size of our cells. And viruses are smaller again — they're about a hundredth the size of our cells.

So we're about 100,000 times bigger than our cells, a million times bigger than bacteria, and 10 million times bigger than your average virus!

If a virus was the size of a five cent coin, a bacterium would be the size of a dinner plate, and you would be 200 kilometres tall!

Viruses are tiny compared to all other living things, but they're giants compared to atoms and molecules.

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The really small stuff

The flu is a pretty typical virus. It's just a chunk of RNA wrapped in a bit of protein, measuring about 120 nanometres (nm) across, which makes it about a thousand times bigger than an atom.

Atoms are the basic units of matter. They're like the Lego bricks that all things are made of, from stars to steel and from oxygen to oxen. They're tiny. But even tinier than atoms are the protons, neutrons and electrons that they're made of. A hydrogen atom is 100,000 times bigger than the proton that sits in the middle of it! That's the same size difference as between you and one of your cells. So protons are tiny, and electrons and neutrons are too.

But what about at the other end of the scale?

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The big stuff

When we think of the big things in the universe, we think planets, stars and galaxies. And while Earth seems big from where we sit, it's pretty puny as far as the solar system goes: you could fit more than a million earths inside the sun.

But the sun's no galactic giant either. It's nothing compared to the really big stars. The biggest known star, VY Canis Majoris, is a hypergiant around 2000 times the size of the sun. So if the sun was the size of a ping pong ball, VY Canis Majoris would be almost as big as a footy field.

But it's not just the size of stars that's big, it's the number of them as well. No one's done a head count yet, but best estimates put the number of stars in the Milky Way at around two hundred billion. That's 200,000,000,000 stars in our galaxy alone!

And there are plenty more galaxies out there. In fact, it looks like there are around two hundred billion galaxies as well. So there is at least one galaxy out there for every star in the Milky Way — it's brain hurty time!

If you multiply the number of galaxies by the average number of stars in them, you get the number of stars in the universe, which is something like a million billion billion stars. Forget about Rupert's riches — that's a seriously big number! It looks even bigger when you write it out in full:

There are 1,000,000,000,000,000,000,000,000 stars in the universe.

It's hard to imagine a number that big, but you'd be surprised how often you come across things that size. Every time you have a glass of water you're swallowing 10 million billion billion water molecules. So there are ten times more molecules in a glass of water than there are stars in the entire universe.

It's enough to make you want to go count mammoths.

Tags: science-and-technology, astronomy-space, planets-and-asteroids, the-universe, biology, microbiology, physics, stars, galaxies

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Published 30 March 2010

Atoms and cells are the fundamental units. The former is for a chemical element, the latter for biology. Earth can not survive without atom and cell. Though both of the units are important for the universe, they are different in nature and have different functions.

Atom vs Cell

The main difference between Atom and Cell is that an atom is the smallest unit of a chemical element, and a cell is the smallest unit of the biological units. The universe is made of atoms, whereas we humans are made of cells.

This whole universe is made by atoms coming together. Solid, gas, liquid, everything is made by atoms. Atoms can be split off into electrons, protons and neutrons. Atom is an essential and inevitable part of anything which has a physical presence.

A cell is part of biology. Cells have been designated as “building blocks” of living things. We are made of cells. Cells come together and make tissues, and tissues make organs. It takes trillions of cells to make a human body.

Comparison Table Between Atom and Cell

What is Atom?

Atom is the essence of the matter. Atoms have been determined as “the basic building blocks of matter”. A matter is anything that has a physical entity. That is everything that can be touched. The whole world is made of atoms. Atoms are the base of any chemical element.

Nothing that exists is as small as an atom in a chemical element. Atoms are too small to see with naked eyes. Atoms were taken as the smallest unit, and it was thought that they can not be dissected. But later on, scientists were able to cut it, and we get to know it is made of protons, neutrons, and electrons.

Each of the atoms is consist of one nucleus at the centre, which contains protons and neutrons. The nucleus is the centre of the atoms, which is bounded by one or more electrons.

The nucleus contains neutrons and protons. Neutrons have no charge, so it is neutral. A proton has a positive charge. Whereas an electron has a negative charge. The charge of an atom will be zero if it contains the same amount of protons and electrons.

Atom takes part in all chemical reactions, and when a chemical reaction takes place, atoms can get rearranged.

What is Cell?

Cells are the rudimentary unit of life. Cells are living, functioning structural unit, that is responsible for the process of life. Cells are called “the building blocks of living beings”. This indispensable unit of living beings was first discovered by Robert Hooke in 1665.

Cells are made by molecules. Each of the cells contains a fluid called the cytoplasm, which is enveloped by a membrane. Every cell has one nucleus and membrane-bound cytoplasm. Cells are also contained with proteins, carbohydrates, lipids and nucleic acid.

Cells main function is to take part in the growth and development of an organism. Every organism is constructed of cells. Cells are alive. 

They absorb the food and water in order to keep the organisms in working order. Cells help in reproduction and pass the genetic information from one cell to the other.

Cells need the energy to carry forward their work. This requirement of energy is fulfilled by Mitochondria. Mitochondria are determined as the “powerhouse of cells”.

Main Differences Between Atom and Cell

1. An atom is a chemical unit. It is the smallest particle of a chemical element. A cell is a biological unit. It is the smallest unit of any living beings.
2. A cell is composed of molecules, and molecules are composed of atoms.
3. Cells are bigger than atoms. A cell is made by molecules that are made by atoms. Therefore atoms are smaller than cells.
4. Cells are made of molecules like proteins, carbohydrates, lipids and nucleic acid, whereas atoms are made of electrons, protons and neutrons.
5. Atoms are not alive. They do not have a life. Atoms do not consume food or water. While cells have life and they consume food and water to stay alive.
6. Atoms can not reproduce as they are not alive, but cells can reproduce.

Conclusion

Both atoms and cells are crucial and essential for the world. Atom is rudimentary for anything which has a physical presence, and cell is rudimentary for every living thing.

Atoms and cells belong to two different streams of science. Atoms belong to chemistry, and cells belong to biology. Atoms are smaller than cells and in a way even cell is made by atoms. Cells are composed of molecules, and molecules are made by atoms.

Matters or things with physical entities can not exist without atoms, and we living beings can not function without cells. Cells are responsible for any kind of live process, and our organs are made of cells.

Both atoms and cells are vital for a healthy world, where atoms take care of the matter, and cells take care of the living entities.

References

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