Genetics as it applies to evolution, molecular biology, and medical aspects.
I'm new to this forum. I must admit, I am neither a biologist nor a geneticist. I am trying to get some information about genetic transmission so I figured that this was the crew to ask.
(I have 5 questions below)
I'm working with Universal Darwinism and the idea that there are multiple replicators and not just genes.
The term genetic information seems ubiquitous. My understanding is that a gene is simply information that replicates selfishly. Am I in the ballpark?
Communication is the transferring of information from one entity to another. If genes are information, and if they move from entity to entity, which is replication, they are, by definition communicated.Therefore, I can apply communication theory to the process.
Simple communication theory says that there are seven steps in communication;
1 - There is a message. The content. The information.
2 - That message is ENCODED.
3 - The encoded information is TRANSMITTED by a sender.
4 - The message is transmitted through CHANNEL; a MEDIUM
5 - The message is received by a reciever.
6 - The message is decoded.
7 - All steps are affected by the presence of noise.
Genes are information. They are encoded in DNA strands. The DNA is not the gene. It is
the encoded information. Does that sound reasonable?
If genes are information, then at some point during reproduction, that information leaves the parent. If this is true then it MUST be communicated.
So my more specific questions are:
1 - At what moment, precisely, does genetic information leave the parent, ie,
when is it transmitted?
2 - What is the medium that genetic information is transmitted through?
3 - What is the receiver?
Thank you for your time and I look forward to reading your responses.
Peace and Love and Empathy,
Why would you ask that JackBean?
At least I kind of got the point, or at least part of it. Though I'm not sure what I should say about it :)
Anyways, I do not see why heritable information and replicators could not be something else than genes and living organisms (even now we have viruses that are mostly just biological machines).
There could be replicating entities whose "genome" and "genes" would be just electric data in binary form. Think of a very advanced computer/robot/AI combination: it would have its "genes" in the form of files and it would produce exact copies of itself. Now and then, a corrupted file might destroy the progerss, or, in some rare cases, speed it up. There we already have the basic tools for Darwinian evolution for machines.
However, the exact point of this "communication" part somehow eludes me. I did not quite get it or understand what kind of answers the original poster wants to those three questions...
For humans, and other animals, the process of transmission is sexual reproduction.
Meiosis is a good place to google and get info on that.
The medium would be gametes (gametogenesis): egg/oocyte and sperm/spermatogonia
Reciever? Mmmm...either the oocyte's DNA is the reciever and the sperm's DNA is the donor, or vice versa. I vote for the former, since the oocyte has all the maternal mRNA/proteins (signaling factors) needed to establish the zygote, and the sperm's DNA is the only thing 'donated'.
Dr. Susan Blackmore has suggested a third terrestrial replicator called the Teme that is pretty much this idea. I'm not such a fan of the idea of Temes but it's interesting. She discusses Temes in a speech about memes on TED.com if you're interested.
Of course. My question is more specific. Let's look at my third question. What is the reciever? At what point is the new entity a new entity? I'm confused about when it is that the new entity becomes a seperate entity from its parents. Are the gametes seperate entities? Is my sperm me or something I produce, like say, saliva, that is not "me". Are the gametes equal or is the egg the new entity and it's simply fertilised by the sperm. It seems gray to me.
If genes are information that replicate selfishly as Dawkins suggests, then that information leaves the body. I'm just trying to get specific about it. I wish I had better language to discuss this with, but like I said, I'm not a biologist.
Thank you. I'm reading up on this. I cam across germ cells. Can you tell me if I'm way off the mark here?
The germ cell, through the process of mitosis and meiosis becomes the gamete. But the germ cell and all cells within the body for that matter, ALREADY have a full copy of the parent's DNA. So the parent never transmits the information to the gamete cell, it doesn't have to. Instead, the parent turns the gamete cell into a vehicle for the DNA to leave the body. Does that sound reasonable?
I think I can dig on the gamete being the medium. The gamete physically transports the message, the genetic information. My only question is, again, the receiver.
Yeah, this is a pretty big question for me. I can't figure out if the mother is the reveiver, if the oocyte is the reveiver or if the uterus is the reveiver, or if there is no reveiver, that the information is essentially broadcast by either parent and when the gamtetes come together, they simply create a new entity.
I think at the very least, if I can clarify for myself how the parents get their DNA into the gametes that would go a long way.
I was also toying with the idea that ribosomes had something to do with it. Within the gamete and or zygote, where are the ribosomes? It struck me as a possibility because the ribosomes are the thing that reads the newly formed DNA, the offspring's DNA, and follows the instructions to start making proteins. Not sure though.
The reason it sticks out for me is that the communication of information always involves an energy wave. Colour information is transmitted via electromagnetic radiation. Sound is transmitted by waves. In signal transduction there is an energy wave involved. It strikes me that all that is occurring up to the point of the two gametes coming together is "Xeroxing".
I'm thinking that the transmission occurs during transcription. Is the genetic information communicated to the RNAP? The ribosome? All the transcription factors? The transcription machinery? Are mRNA and tRNA the medium? I just don't understand well enough.
The more I think about it, the more it makes sense that the communication occurs during transcription. In binary fission and with horizintal transmission, are ribosomes involved? Do eukaryotes and prokaryotes alike have ribosomes? Does transcription pretty much work the same in sexual reproduction and asexual reproduction?
Well it's about communication. For instance puppy dogs are cute is an encoded message. I'm trying to convey ideas like puppies and cuteness and encoding that message in the sentence, "puppies are cute". I then transmit that message, in this case, via the internet. You receive it, decode it and poof, you have that info.
Genetic information, the actual instructions for making proteins is information. That information is encoded in DNA strands. What I'm trying to figure out is how is that encoded message transmitted and to who/what?
Anyhoo, I just want to say that I really appreciate all of your responses. This may seem remedial to some of you and perhaps the answer really is something simple, but I gotta say, biology isn't just something one can pick up over the weekend. I genuinely appreciate your attempts to walk me through this.
Peace and Love and Empathy,
OK, lets tackle these questions . . .
You are on the right track.
This is not true. Somatic cells (the cells of the body) have a complete set of DNA, while the germ cell has one half of the parent's complete set of DNA. In order to become an organism, there has to be a mating of the two halves (male and female matured germ cells in the form of an oocye/egg and sperm) to make a complete set. This is the sex part!
I think that the ribosome is just part of the machinery that works to produce the products of the information. It is not the information that is transmitted. You can have the ribosome from a bacteria, produce protein from an animal (such as E. coli producing human insulin).
This reminds me of the calcium wave that follows fertilization:
http://www.molbiolcell.org/cgi/content/full/9/7/1609 (technical with the videos,
without the technical jargon: http://www.youtube.com/watch?v=jp-RgIRg ... re=related)
or pretty colored and fast animation: http://www.youtube.com/watch?v=BH06WgFua_4
This is my favorite! It is called Epigenetics. Just because you have the gene, doesn't mean that it is expressed! Each cell, remember that I am saying somatic cells (not germ cells), has a complete DNA, but each cell will only express the genes that the cell needs to be that cell. Also during development, certain genes are turned on and off, as the cell differentiate into their identity. But then again, this is the welding of the information contained in the DNA as one signal turns on another signal, that then turns off another signal.
Each gamete is important though. They have taken just the DNA of the oocyte and put it into a complete oocyte (all the signaling proteins contained), and the embryo doesn't live, and vice versa with the sperm. Seems that they are two halves of a whole. Each gamete has been set up to provide valuable info as they come together. And I am going too far off topic I think, if I start to talk about taking somatic DNA and putting it into an oocyte with its DNA taken out (this is cloning now. and there has to be certain specified conditions of the oocyte for it to produce a viable organism), but maybe it is relevant to your transmission of info, and provides a strong support for the oocyte's cytoplasm as the receiver.
Thanks for the responses!
Ok. The germ cell has half the DNA. Gotchya. So is it that there are existing cells, they go through mitosis and meiosis and poof, you have the germ cells? The only thing I'm trying to get at is that the body isn't creating something from nothing. The germ cells just sort of "divide off" of existing cells. Is that right?
Here's a question. What is the offspring? Like physically, where does it begin? At what point can you say, this thing is no longer it's parents? When the zygote is created? When the gametes are created? Also, physically speaking, is the oocyte, this is clunky language, the body of the offspring? Like does the sperm show up with half the DNA, donate it to the oocyte and at that point the oocyte can become the new entity or physically, is the sperm a part of the new organism?
Right. It is called the expression machinery right (or it's a part of the expression machinery)? It reads the DNA and carries out the instructions right?
So do all cells, or organisms, have ribosomes? Like, are ribosomes a universal for organisms that use DNA? That's clunky. Like, do assexually reproducing, sexually reproducing, bacteria, viruses, retroviruses, plants, every kind of organism, have ribosomes or are there organisms that use something else entirely?
Thanks for the videos. They were cool. They gave me a headache, but they were cool
Epigenetics. Cool. But the somatic cells don't come into play until the new entity is 'formed' right? Like, the zygote. But zygote doesn't apply to all organisms does it? Just sexually reproducing ones right?
That is very interesting. I don't understand the first part about putting 'the DNA of the oocyte and put it into a complete oocyte'.
Somatic DNA is complete DNA right? So if you take an egg, remove the DNA then put in a complete, I guess fertilised, DNA, or maybe rather the DNA from say, my somatic cells, the egg can become a new organism? And that's what cloning is, you put the information into the physical housing of the egg, that has all of the expression machinery inside it, and the egg will use that DNA to develop. Is that right?
I'm thinking universally now. Here's an idea. Please tear it apart. All organisms will create a 'new' cell (I guess a daughter cell of some type) that will contain a copy of genetic information (either a full copy or half of the DNA). In sexually reproducing organisms two cells have to come together to share information. In asexual ones, the daughter cell can do it's own thing. With viruses, the virus transports the information into an existing cell. And with cloning, DNA is inserted into an existing cell after the initial genetic information is removed. In all cases, an actual MOLECULE is transported physically into the new cell. Is that right? Once in the new cell, the ribosomes read the information and... do their thing. They make new organisms. Whether they're viruses, single cell organisms or multi-cellular organisms. Is that right?
An associated thought. Genetic information, in the form of a molecule, doesn't have to leave 'the body', it has to leave the cell. Or in the case of say viruses, it has to enter the cell. Is that right?
Thank you again. This is all helping so much. I really appreciate it.
Peace and Love and Empathy,
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