| From: Master Yoda Oz | 25/02/00
15:44:18 |
| Subject: DNA & Viruses/Diseases | post id:
41977 |
| I've read Karl's new book and
also saw his interview on 60 minutes. I was really facinated about the DNA
thing and how within the next few years scientist will be able to map our
entire DNA structure. That's cool. This means that we can grow a new hand
if it gets chopped off or we could grow a new heart if we have a coronary
breakdown, or maybe grow a new thing if our wives decide to punish us how
they see fit. I understand all that. What I don't understand is how viruses such as the common cold or HIV affect our body, and also diseases such as cancer. Do these viruses and diseases mess around with our DNA or what? what does the DNA actually do? What do viruses and diseases affect and how do they work??? | |
| From: sam | 25/02/00
15:56:22 |
| Subject: re: DNA & Viruses/Diseases | post id:
41983 |
| I thought what they were working
on was mapping just one strand of DNA - and they have been doing that for
years, so won't it be quite a lot longer than a few years before they've
mapped the entire body? | |
| From: Em | 25/02/00
16:10:35 |
| Subject: re: DNA & Viruses/Diseases | post id:
41987 |
| Hi guys, it is Friday, so if I'm
wrong, bear with me... Human Genome project stuff... I think that they are looking at one strand, but there are quite a few research groups set up working on this so progress (for sciencestuff anyway) is faster than average. I think that once you have the information from one of our cells, (stem cell?) you will have the bulk of info about nearly all of our cells, minus the specialisations for that particular type of cell (eg liver cells are different to brain cells etc). It will take considerably more time yet. Viruses Some viruses affect our DNA by inserting their own genetic material (genes) into our code, so they can replicated in our cells (using our machinery) this is how some viruses can hurt us and we can't treat them, because its our own cells doing it. On the other hand most bacteria do not need to do this to survive (and replicate) as they have their own machinery.... Hope this is what you're after Em | |
| From: lentil | 25/02/00
16:27:16 |
| Subject: re: DNA & Viruses/Diseases | post id:
41995 |
| Well this is a BIG topic, and I
will only be able to answer a small part of the question. How do viruses affect in the body? Viruses are basically a bit of genetic material (DNA or RNA) with a protein coat, they don't contain any of the equipment needed to produce new baby viruses. So what they do is hijack the machinery of the cell and use that to produce new viruses ** So when a cell is infected with a virus the cells machinery is taken over the virus to make new progeny, therefore the cellular processes are interfered with**** When the new viruses are ready to be released and sent on for a new round of infection and replication, they have to be released from the cell somehow. This is usually by bursting the cell. *** Releasing the progeny virus results in death of the cell**** The body has mechanisms in place to try and deal with infections. There are phagocytic cells (cells which will munch up anything foreign), killer cells (which recognise virus infected cells and kill them), antibodies produced and chemical called cytokines produced which are signals between cells. These cytokines recruit all these other cell types to the site of infection. These processes usually will result in the death of the virus and will limit the replication of the virus in the body. However sometimes there will be an overload of these immune mechanisms, the immune system can go into overdrive and this means that instead of attacking the virus, the immune system attacks the cells of the body. ****The inflammatory response to infection can sometimes lead to pathology**** So there are a number of different ways that viruses affect the body. HIV affects the T-lymphocytes (a cell involved in the immune response, which produces a lot of those cytokines), and leads to a decrease in the number of these cells. The result of this is that the immune system can no longer function properly to combat all the other viruses and bacteria and fungi that you encounter in everyday life (ie you have acquired an immune deficiency). The common cold virus replicates within the cells lining the nasal cavity and kills them. The body produces lots of mucus in response to this and you get a runny nose. Lentil | |
| From: lentil | 25/02/00
16:35:07 |
| Subject: re: DNA & Viruses/Diseases | post id:
41997 |
| Some viruses (like HIV) can
integrate into the host genome. This has been happening since time long
past, and it is estimated that about 5% of our DNA was originally from
viruses which have integrated into our genome. These are called Endogenous
retroviruses (ERV's). It has been postulated that these ERV's may be
responsible for some of the chronis diseases which afflict humans, such as
diabetes. I think it is interesting that viruses which infected our
ancestors could be inducing disease in people
today. Lentil | |
| From: Kothos | 25/02/00
17:33:02 |
| Subject: re: DNA & Viruses/Diseases | post id:
42011 |
Lentil, wow, I never knew that. Does that mean, if we knew which 5% it was, we could just get rid of it and we'd be a whole lot better off? Is any of that stuff beneficial, or is it all harmful? | |
| From: lentil | 25/02/00
18:05:25 |
| Subject: re: DNA & Viruses/Diseases | post id:
42026 |
| I made a mistake in the last
post, it is only about 1%, not 5% of the genome, but it is still a fair
whack. It isn't really known what a lot of this ERV DNA does, I would say that most of it is junk, remnant of infections past. Some of it could be beneficial, some harmful. Researchers are just starting to look at ERV's as a possible cause of many "autoimmune" diseases. The majority of these ERV are tolerated quite well by the human host, in part due to mutations occurring in the sequences, leading to disruption of transcription and translation of viral proteins. However a small number of ERV are able to express their proteins and it is possible that these ERV may be implicated in autoimmune disease. Coinfection with other viruses, such as Epstein Barr Virus might trigger transcription of the ERV DNA. Will try and find out if these ERV's are beneficial in any way. Lentil | |
| From: lentil | 25/02/00
18:08:14 |
| Subject: re: DNA & Viruses/Diseases | post id:
42029 |
| Another virus which (I think)
integrates into the genome and disrupts genes and causes cancer is the
Human Papilloma virus. | |
| From: lentil | 25/02/00
18:18:54 |
| Subject: re: DNA & Viruses/Diseases | post id:
42032 |
| Cancer is where you get cells
replicating at a much faster rate than normal and these cells tend to lose
their differentiation. These rapidly dividing cells can then invade normal
body tissues and interfere with the working of those organs. Why do these cells start to divide unchecked. There has been an alteration in the genes which regulate cell replication, either a) there has been an upregulation of the genes which positively affect replication or b) genes which negatively control replication ( put the brakes on cells dividing) are disrupted or changed The changes in these genes can be via mutation, or can be via disruption of the genes by a virus (Epatein Barr virus, or Human papilloma virus can do this). Lentil | |
| From: lentil | 28/02/00
14:37:21 |
| Subject: re: DNA & Viruses/Diseases | post id:
42482 |
| Well it seems that EBV is
associated with Burkitt's Lymphoma and Hodgkins Lymphoma. There is more
info at this
site http://home.wlu.edu/~advarska/index_ebv.htm plus there is info about other viruses and cancer. However, Cam, I don't think you should worry about getting cancer from your EBV. I don't mean to be callous, but you are probably more likely to die from heart disease,( which by the way may be caused by infections). Lentil | |