Author Topic: Sexrepro (Real Life) questions  (Read 4222 times)

Offline Endy

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« on: August 25, 2006, 02:43:45 PM »
How come sperm don't asexually reproduce themselves. Wouldn't that make it more likely that their own individual traits would be passed along the line?

Offline shvarz

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« Reply #1 on: August 25, 2006, 08:20:23 PM »
What do you mean, reproduce themselves?  Like sperms behaving like single-cell organisms?  The simplest answer to that would be "Because that's not how they are made", I guess.  Or do you mean something else?
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Offline Numsgil

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« Reply #2 on: August 25, 2006, 10:45:05 PM »
I think he's asking why sperm don't degenerate into single celled independant organisms.  Declare independance from the body so to speak.

I think the answer is that they rarely (really only cancer I think) reproduce themselves.  Instead, they are made from other cells.  Because of this, mutations are kept to a minimum (you're not copying a copy, you're making fresh copies all the time).

Offline Elite

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« Reply #3 on: August 26, 2006, 07:31:36 AM »
Intrestingly, there is a gene in mice known as the t gene

Having two copies of the t gene causes death or permanent sterility, so having the gene should be selected against

However, the t gene distorts sperm production so that 90% of a heterozygous carrier's sperm will contain the t gene, instead of the usual 50%

The t gene 'cheats', and modifies sperm production to spread itself, and in doing so can wipe out whole populations of mice as the gene spreads through them and increases in frequency to the point where the mice can no longer have viable children

Offline Testlund

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« Reply #4 on: August 26, 2006, 09:44:02 AM »
I've never even heard of sterile mice. Usually they breed too much. I used to breed mice some years ago where I had two races, one natural brown race and one that was white with black eyes (no albino). This was the popular species which you can buy at the pet store. I'm not sure what you call them in English, but we call them husmöss = housemice here in Sweden. It's the species that has adapted to live close to humans. At one time I lost control over it a little and they started to escape, but I managed to get them and stop it. Hehe.

I've been thinking about Endy's question.... Maybe we should ask why there are multicellular organisms at all? There were only very primitive bacteria on earth for a very long time and then fairly recently in earth's history it exploded in multicellular organisms spreading all over the world. But we should be glad that sperms haven't decided yet to live on their own without their host.  
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Offline Numsgil

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« Reply #5 on: August 26, 2006, 11:59:14 AM »
The Cambrian Explosion, the time when multicellularity developed and the number of species exploded in number, had a number of relatively simoltaneous (at least, that's more or less the concensus as I understand it) advances:

1.  Eukaryotes.  Both much, much larger than regular bacteria and more highly organized.

2.  Eukaryotes gain mitochondira.  Basically symbiotic bacteria that live inside cells and help them metabolize.

3.  Sexual Reproduction.

Maybe a few others.  This is an area of active research, so it seems alot of what I thought I knew seems to be becoming obsolete :/

Offline shvarz

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« Reply #6 on: August 26, 2006, 12:42:30 PM »
Many genes try to cheat and reproduce themselves to higher frequencies in population, both from males and from females.  In females there is huge conflict between the two X chromosomes, because one of them gets permanently shut down. Also, when an egg is formed in females, only one of the X chromosomes gets picked and so there are genes which move the chances away from random for that too.
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Offline Ramiro

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« Reply #7 on: August 28, 2006, 04:58:40 PM »
Quote from: Endy
How come sperm don't asexually reproduce themselves. Wouldn't that make it more likely that their own individual traits would be passed along the line?

Basically there are two types of cell division MEIOSIS and MITHOSIS. The first produces cells with one copy of each chromosome from mother cells with the two copies, thats the way sperm cells are made. As they have ONE copy of each chromosome they can no longer make Meiosis. They could still make mithosis but for that they should make a copy of every one of their chromosomes and they simply do not have enough energy to do that, they are built to the sole purpose of swiming

Offline Brwagur

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« Reply #8 on: March 02, 2007, 04:45:24 PM »
Sperm cells are basicly a nucleus surounded with a plasma membrane, I dont think that there is any room for any other organelles besides some mitochondria so I dont think that it can produce enough proteins, ect. for it to divide or even survive for any extended period of time.

Offline MacadamiaNuts

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« Reply #9 on: March 02, 2007, 05:44:37 PM »
Quote from: Testlund
Maybe we should ask why there are multicellular organisms at all?

My guess is that big cell concretions created a microsystem where cells that were trapped inside had to find a way to adapt and 'steal' what they needed from the lucky outer cells. If they didn't do that, they would have died while only the layer of cells in the surface kept living, like corals and stromatolites. During harsh conditions, it helped them too by letting the outer cells die while keeping a benign enviroment inside.

All our cells carry the same DNA, so we are a big concretion of conspecs that use gene switches to choose a proper function depending where they are in the system.
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Offline Numsgil

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« Reply #10 on: March 02, 2007, 10:24:06 PM »
But that's only part of the story.  You can show with Darwinbots pretty easy that even a large population of genetically identical bots move to outright internal war and cannibalism after very little time.

I could also point out symbiotic relationships between organisms that are billions of years seperated in genetic history, yet still require the other for survival.  In effect, they've become a single living entity.

I think genetic similarity is neither necessary nor sufficient for the creation of complex societies and eventually multicellular critters.  It's common, but I think it's commonality has more to do with feedback loops between member cells (a single DNA change has far reaching effects for all members of the societal multicritter).

Offline cliftut

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« Reply #11 on: August 06, 2007, 05:12:04 AM »
The main reason I think reproduction wouldn't work for sperm is because they have no way of obtaining energy. Like Ramiro said, they have a single purpose; swim until you find an egg cell. They have no way of obtaining energy, and only have about enough energy to make their way to the egg cells. Reproducing on their own, would cause two problems;
1. it would spread their energy thin so that they would be incapable of making it to the egg cells.
2. it would increase the possibility of mutations in young, and even maybe allow multiple mutations. This is assuming, though, that the sperm would be capable of reaching the egg cells.

Also, for sperm to be able reproduce and still reach the egg cells, they would have to simultaneously gain the ability to gather energy. If the method of gathering energy was eating other organisms, that would mean that the sperm would start eating cells around them, and maybe even each other. This would probably result in sterility for male organisms, and the sperm would basically become bacteria, and keep eating and reproducing, which wouldn't bode well for the male that produced them... O_O

In short, repro in sperm would most likely be a bad thing in all cases.
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Offline Trafalgar

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« Reply #12 on: August 06, 2007, 04:24:33 PM »
Quote from: cliftut
The main reason I think reproduction wouldn't work for sperm is because they have no way of obtaining energy.
...
Also, for sperm to be able reproduce and still reach the egg cells, they would have to simultaneously gain the ability to gather energy.

I made a league bot (named Nanite Detonators) which does not do any energy gathering whatsoever, no shooting, no tie feeding, nothing. Starting with 5 bots, it reproduces and flies all over the place, killing any enemy bots it notices (with an instakill tie attack - setting strvenom or strpoison to 10000 or so). It reaches a max population of around 550 bots, if the opponents aren't particularly tough (after which they begin to die off, but when you've got 550 bots flying around the map at high speed, pretty much nothing can hide). In a sim with wrapping sides, it wipes out every bot I tried it against from any league. When I made another bot look friendly to it, that bot still lost due to ( a ) trying to attack or feed on the nanites and getting killed in retaliation, and ( b ) there were no veggies to eat due to the nanites killing veggies shortly after they (re)spawned.

Given a bot starting with 3000 energy and 1000 body, which is what a league bot starts with, that single bot should be quite capable of splitting off half its energy and body to create 50 or more sperm bots, which would have quite a good chance of finding any eggs out there. If the main bot waited until it had 30000 energy and 10000 body to split off half of it, and that half went towards creating nothing but sperm, then it would make an equivalent amount of sperm bots (550) as the previously mentioned group of 5 bots using all their energy and body. (Here's a bit of very simple math showing why: If 5 bots with 3000 energy and 1000 body can make 550 sperm by using all their energy and body, then 1 bot using half of its could make 55, and if 1 bot had 30000 energy and 10000 body, and still spent half of it, it would be spending 10x as much resources as the 1 bot using half of 3000e/1000b. So, it could make 10 * 55 bots, which would be 550.)

Note: I didn't read the entire thread, I mostly just read the thread-necromancer's post.
« Last Edit: August 06, 2007, 04:25:28 PM by Trafalgar »

Offline Gobo

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« Reply #13 on: November 13, 2007, 04:12:34 PM »
The question is great. It is not about what organelles or energy stermatozoa lack to reproduce. Cytological mechanics answer question how they cannot reproduce, but not why.

Let's suppose, some spermatozoa obtained "free-living" gene. Could this gene be successful? I doubt. They are not adapted for hostile environment, since they are too specialized. If it were some primitive organism with less specialized gametes, it could happen. Though I'm not ready for now to give a real-life example when gametes act like single cell organisms occasionally.
« Last Edit: November 13, 2007, 04:14:21 PM by Gobo »

Offline Peter

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« Reply #14 on: November 14, 2007, 12:17:52 PM »
It is simple sperm isn't made to reproduce itself it lacks too many cel-stuff(organels)

Why does it lack those organels, becouse we don't want it to become indepentant of ours. It has just enough energie to come to the egg-cel and it basicly can't survive long in the hostile inviroment even if it had the energie.
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