[Curious Newbie] Questions

[Pippin]

Hello,

 

I would have a few questions regarding mankind's current knowledge of Genetics, as of 2014.

 

1. It was my understanding that we humans were defined by up to 35,000 different genes. Correct ?

 

2. Among these 35,000 different genes, how many do we know well enough to tell what impact they have on the body and proteins?

 

3. I heard it was possible to copy any human's DNA, and as a result, any human's full genome. How do we do that? How long does it take? It was also my understanding that we needed a "living" cell of the subject to do that, so it is not possible with bones, hair and whatnot. Is this still correct nowadays ?

 

4. For any human, a few of their genes are bound to change during their lifetime, and that is called a "mutation". So, you never get the original DNA of someone, only their current one, and there is no way to extract their original DNA. Correct ?

5. Assuming we can extract DNA, I figured it was only a matter of time before we find a way to (unethically) create human "clones", like we did with Dolly. But as far as I know, we don't know yet how to create a foetus solely based on their DNA (that is, solely based on a very long list of amino acids stored in computers), correct? Has there been any kind of research carried out regarding this ?

Thanks in advance for your replies. Genetics, not sure if awesome or scary!

Edited August 2, 2014 by Pippin

[fiveworlds]

1. It was my understanding that we humans were defined by up to 35,000 different genes. Correct ?

 

Don't know the exact figure I was told can't remember

 

2. Among these 35,000 different genes, how many do we know well enough to tell what impact they have on the body and proteins?

 

 

An enormous number. A large amount actually do nothing. 92% of the total genome

 

3. I heard it was possible to copy any human's DNA, and as a result, any human's full genome. How do we do that? How long does it take? It was also my understanding that we needed a "living" cell of the subject to do that, so it is not possible with bones, hair and whatnot. Is this still correct nowadays ?

 

I'm pretty sure the human genome project uses thousands if not millions of different samples not just one human. It is technically not a copy we cut the DNA into the chunk we want using drugs.

 

4. For any human, a few of their genes are bound to change during their lifetime, and that is called a "mutation". So, you never get the original DNA of someone, only their current one, and there is no way to extract their original DNA. Correct ?

 

 

This is why the human genome project uses so many samples.

 

5. Assuming we can extract DNA, I figured it was only a matter of time before we find a way to (unethically) create human "clones", like we did with Dolly. But as far as I know, we don't know yet how to create a foetus solely based on their DNA (that is, solely based on a very long list of amino acids stored in computers), correct? Has there been any kind of research carried out regarding this ?

 

 

Creating human clones would be an ethics violation. At the moment we use genetics to create drugs say somebody couldn't produce some drug they needed to survive. We would use genetics to change the DNA structure of sheep or flies or whatever. Then they produce the drug we need where they originally didn't. Though they still aren't clones. Cloning is really rare there is a few sheep like dolly but the clones tended to die.

 

http://en.wikipedia.org/wiki/Human_Genome_Project

Edited August 2, 2014 by fiveworlds

[Delta1212]

There is a complete copy of your DNA in every (nucleus-containing) cell in your body. Some cells contain mutations in that DNA from replication errors or damage, and if those errors are present in gametes they will be passed on to any offspring, but "your DNA" doesn't change throughout your life. Mutations are isolated to single cells and their descendants and won't propagate to the rest of your body.

[fiveworlds]

Mutations are isolated to single cells and their descendants and won't propagate to the rest of your body.

 

cancer http://www.cancerresearchuk.org/cancer-help/about-cancer/what-is-cancer/cells/how-cancer-starts

I think you are assuming a mutation won't propagate without any proof.

 

if those errors are present in gametes they will be passed on to any offspring

 

Chocolate was poison. We have mutated to allow us to eat chocolate over time.http://en.wikipedia.org/wiki/Theobromine_poisoning

caffeine too.

Does anybody have any idea of what a primordial sample of human DNA actually looks like?

Edited August 2, 2014 by fiveworlds

[Delta1212]

cancer http://www.cancerresearchuk.org/cancer-help/about-cancer/what-is-cancer/cells/how-cancer-starts

I think you are assuming a mutation won't propagate without any proof.

 

Chocolate was poison. We have mutated to allow us to eat chocolate over time.http://en.wikipedia.org/wiki/Theobromine_poisoning

caffeine too.

Cancer is made up of the descendants of the cell with the initial mutation. It isn't a corruption of neighboring cells. It happens when an unfortunate set of mutations accumulate in the same cell that knock out some of the protective mechanisms that keep cells from dividing out of control and results in the cell, well, dividing out of control. The resultant cancer cells can then spread to other parts of the body, but that's the result of cells with that mutation physically moving (usually through the blood stream) to other areas and continuing to divide and grow. Healthy cells don't "catch" the cancer mutation.

[fiveworlds]

Cancer is made up of the descendants of the cell with the initial mutation. It isn't a corruption of neighboring cells. It happens when an unfortunate set of mutations accumulate in the same cell that knock out some of the protective mechanisms that keep cells from dividing out of control and results in the cell, well, dividing out of control. The resultant cancer cells can then spread to other parts of the body, but that's the result of cells with that mutation physically moving (usually through the blood stream) to other areas and continuing to divide and grow. Healthy cells don't "catch" the cancer mutation.

 

 

Proof? http://www.cancer.net/navigating-cancer-care/cancer-basics/genetics/genetics-cancer

 

Mutations (changes) in genes, either inherited from your mother and father or from damage that occurred during a person’s life, contribute to the growth and development of cancer.

 

A baby should be perfectly healthy yet cancer can be inherited.

Edited August 2, 2014 by fiveworlds

[Delta1212]

Did you miss where I said that mutations in the gametes would be inherited by your offspring?

[fiveworlds]

Nope. But you also said Healthy cells don't "catch" the cancer mutation. There is an element of proof involved here cancer is known to change and adapt. There is no reason why cancer couldn't mutate all cell in the human body and only manifest in certain conditions. In which case you wouldn't know if you had the mutation or not. What I am saying is that the cancer mutation could already be present in the human genome and we would have no means of determining what that mutation was without primordial samples of human DNA prior to cancer.

Edited August 2, 2014 by fiveworlds

[Delta1212]

That isn't how cancer works. Cancer is the mutant cells that divide unchecked in the body. You can inherit mutations that make it easier for cancer to develop. You can have a healthy cell get damaged (e.g. by radiation or some other mutagen) and develop a cancer-causing mutation. You do not have cancerous cells "infecting" healthy cells and turning them into cancerous cells. You have cancerous cells reproducing out of control and killing off healthy cells as the cancerous ones soak up resources and displace said healthy cells.

 

You cannot have all the cells in your body converted into cancer cells just waiting for the right circumstances to trigger the cancer. That's not how cancer works,

[fiveworlds]

So you didn't read the links?

 

Less commonly, a mutation can be in every cell of a person’s body from birth. These mutations are typically passed from a parent to a child. This is called a germline mutation. Because this type of genetic change is in every cell of the body, including the reproductive sperm cells (in a boy’s body) and egg cells (in a girl’s body), it can be passed from generation to generation. Cancer caused by germline mutations is called inherited cancer, which makes up about 5% to 10% of all cancers.http://www.cancer.net/navigating-cancer-care/cancer-basics/genetics/genetics-cancer

 

Inheriting a cancer gene

Some people have an increased risk of some types of cancer because they already have a gene fault when they are born. They won’t necessarily develop cancer. But they are one step further along the road to developing cancer than people without that gene fault.

Inherited gene faults that increase the risk of cancer are often in genes that repair mistakes in other genes. The BRCA1 gene that increases the risk of breast and ovarian cancer is a DNA repair gene.

The faulty repair gene doesn’t work as it should. So it doesn’t repair the other genetic mistakes that we all gather as we go through life. In turn, this means you are more likely to gather enough mistakes to cause a cancer at a younger age.

We inherit genes from both our parents. If one of your parents has a gene fault you have a 1 in 2 chance (50%) of inheriting it. The more distant your relative with a gene fault is, the lower your chance of inheriting it.http://www.cancerresearchuk.org/cancer-help/about-cancer/causes-symptoms/genes-and-inherited-cancer-risk/inherited-genes-and-cancer-risk/how-inherited-genes-cause-cancer

 

It is rare but http://www.childrenshospitaloakland.org/main/news/a-baby-born-with-cancer-inspires-other-kids-battli-209.aspx

Some kids are born with full-blown cancer.

Edited August 3, 2014 by fiveworlds

[Delta1212]

So you didn't read the links?

 

Less commonly, a mutation can be in every cell of a persons body from birth. These mutations are typically passed from a parent to a child. This is called a germline mutation.

Yes, a germline mutation is a mutation in the gametes that is passed on to the offspring, as I've said repeatedly. Of course in that case, every cell in the child's body will have the mutation because the mutation was present in the initial cell and is part of that person's DNA. At no point did the child have any "healthy" cells that did not contain the mutation and which were subsequently infected.

Edited August 3, 2014 by Delta1212

[fiveworlds]

You cannot have all the cells in your body converted into cancer cells

 

So it is possible to have all the cells in your body converted into cancer cells. Fact is that baby got cancer from 2 parents now it is debatable whether they acquired cancer or weather they too inherited it from their parents and so on. In which case all of their parents cells could be cancerous and benign.

Edited August 3, 2014 by fiveworlds

[Delta1212]

So it is possible to have all the cells in your body converted into cancer cells.

No. It is possible that you could have a mutation in all of your cells that makes it more likely that any one of those cells could sustain a further mutation that causes it to become cancerous, if you inherited that mutation from your parents.

 

It is not possible for a mutation to spread from cells with the mutation to cells that did not have the mutation and convert other, healthy cells into cancer. The only way for every cell in your body to become cancerous is for each individual cell to independently sustain a mutation that causes it to become cancerous, which is a statistical impossibility.

 

The combination of mutations that allows cancer to happen is so unlikely that a collection of trillions of cells (ie you) can endure a century of exposure to constant mutagens and just general replication errors and still only have something like a 30% of it cropping up. That's just for it to occur once. There is no way in hell that is going to happen a trillion times all at once in the same person. And if it did, you would die pretty much instantly as you would no longer have a single cell left in your entire body that was functioning the way it is supposed to.

 

So no, your entire body cannot be converted into cancer cells.

[fiveworlds]

What if the mutation you inherit from your parents was already cancerous when you are born?

[Delta1212]

What if the mutation you inherit from your parents was already cancerous when you are born?

If the initial fertilized egg that will become you somehow managed to be cancerous, you would never develop to the point of being born. Cancerous cells do not function the way they are supposed to. They reproduce unchecked without regard to the structure of the rest of the body. That's what cancer is. If every cell that made up your zygote was cancerous, you would never develop into a baby.

[Pippin]

Thanks for all the replies!

I understand cell mutation better now. I thought DNA was always evolving which would have explained why twins' faces are more and more different as time goes by.

So, since every cell can possibly mute, we must use several cells to extract DNA from someone. Given a random cell from a healthy human, what is the probability that its DNA muted ? Also, is it unsafe to extract DNA from multiple hair root cells only (for example) ?

Edited August 3, 2014 by Pippin

[Bill Angel]

cancer http://www.cancerresearchuk.org/cancer-help/about-cancer/what-is-cancer/cells/how-cancer-starts

I think you are assuming a mutation won't propagate without any proof.

 

 

Chocolate was poison. We have mutated to allow us to eat chocolate over time.http://en.wikipedia.org/wiki/Theobromine_poisoning

caffeine too.

Does anybody have any idea of what a primordial sample of human DNA actually looks like?

The assertion that we have mutated over time in order to be able to consume CAFFEINE is intriguing. Large doses of caffeine are toxic. Or is it perhaps a situation where a mutation that proved to be beneficial also had the side effect of increasing human tolerance for ingesting caffeine?