Genetic - merging with success in mind?

[Quantum Quack]

Hi guys. i don't normally post in this forum but a question occurred to me that some one may have an answer to or would like to discuss.

I was thinking about the moment of human reproductive conception. When the sperm enters the Ovary and conception occurs.

What facinates me is that there are two complete Genetic materials merging and becoming a simgular genetic material.
Where two individual DNA strings merge to become one DNA string [sorry if my terminology is off the mark]

Has medical science an answer to explain how the two strings can merge to become one? Or do they some how generate a third and final string?

I find it amazing how two completely individual strings of DNA can some how create a single unique version of both...

Care to discuss?

 

[Hercules Rockefeller]

Has medical science an answer to explain how the two strings can merge to become one? Or do they some how generate a third and final string?

Human’s (as are nearly every animal on Earth) are diploid organisms. This means that our cells have two copies of each chromosome – 23 pairs. The sperm contributes one copy of each chromosome pair, and the ovum contributes the other copy to create a new cell that has the full complement of 23 pairs. The normal process does not involve any “merging” of chromosomes or the DNA they contain. There is no “third string” that is created.

Note: Sometimes things do go awry and chromosomes do ‘translocate’ (ie. a piece of one chromosome breaks off and attaches to another. This usually has disastrous consequences for the embryo.

Having said all that, the process of development is truly amazing. Although chromosomes do not “merge”, as such, each chromosome (one of paternal origin and one of maternal origin) each carry their own allele (ie. their own ‘version’) of each of the ~ 40,000 genes that comprise the human genome. There is a stunningly intricate interplay between the alleles of each chromosome. So although your idea of “merger” does not happen at the genotypic level (ie. at the level of the DNA), the new animal that is created is definitely a merger of the two parents at the phenotypic level (ie. at the level of the whole organism).

Hope that helps. <P>

 

[Quantum Quack]

it certainly does...thanks so much....
When you say a copy is supplied does this mean what 'copy' normally means.
In other words the actual sperm and ovum provide copies only and not original genetic material???

 

[CharonZ]

Sperm and ovaries contain each a half of the whole genetic information (so that a fusion of both results in a complete set of chromosomes).

Well, things can get more complicated if you add mobile genetic elements like e.g. transposons or viral DNA (or plasmids etc.) which can indeed add genetic information to chromosomes (happens not so often in animals but are common among bacteria and even quite often in plants).

One have to keep in mind that DNA per se is nothing unique, the basic genetic "language" is common to all organsims, as such there is no species specific DNA strands per se. However the encoded genes might or might not be specific for certain organims.

As such insertions into the DNA sequence in various organisms is quite common. For instance in humans quite a lot of DNA regions could be attributed to viral insertions.