GS-2 Are protein and RNA not genetic material?!

[Thoroughbred_Med]

The passage states that non-genetic material in the germ plasm is responsible for germ cell formation.

4) In the experiment described in the passage, which of the following materials in the germ plasm would likely be most functional in inducing germ cell function?

1. Nuclear DNA.
2. Mitochondria.
3. RNA and protein molecules.
4. Microtubules.

THEIR EXPLANATION:
"The passage states that non-genetic material in the germ plasm is responsible for germ cell formation. This rules out nuclear DNA as an option. Mitochondria (energy) and microtubules (structural) are unlikely answers as they have very limited roles to actively change their outside environment. RNA and protein molecules can actively change the environment around them by aiding in the production of proteins, through functioning as enzymes (catalysing reactions), as structural proteins, etc. Thus they are the most likely to induce germ cell function."


... The answer is 3. RNA and protein molecules... I may have some knowledge gaps, but isn't RNA genetic material?

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[sillyjoe]

The passage states that non-genetic material in the germ plasm is responsible for germ cell formation.

4) In the experiment described in the passage, which of the following materials in the germ plasm would likely be most functional in inducing germ cell function?

1. Nuclear DNA.
2. Mitochondria.
3. RNA and protein molecules.
4. Microtubules.

THEIR EXPLANATION:
"The passage states that non-genetic material in the germ plasm is responsible for germ cell formation. This rules out nuclear DNA as an option. Mitochondria (energy) and microtubules (structural) are unlikely answers as they have very limited roles to actively change their outside environment. RNA and protein molecules can actively change the environment around them by aiding in the production of proteins, through functioning as enzymes (catalysing reactions), as structural proteins, etc. Thus they are the most likely to induce germ cell function."


... The answer is 3. RNA and protein molecules... I may have some knowledge gaps, but isn't RNA genetic material?

Hard for me to say without seeing the passage fully but they are either getting at 1 of 2 points I think:

First of all RNA can act as enzymes in reactions. For example, some of the catalytic portion of ribosomes are from rRNA so it is non-genetic. tRNA is also an example of non-genetic RNA.

The other point that is important is that in the egg that is formed the cytoplasm is filled with RNA/enzymes/ and organelles from the mother. This plays a large role in the development of germ cells. In this manner you can say that we are actually closer related to our mothers than our fathers since their RNA and proteins direct cell development. In that sense the RNA is non-genetic since it is not arising from the new genome of the offspring.

Not sure which one of these things the question is referring to. Do any of them make sense in regards to the passage?

 

[Thoroughbred_Med]

Hard for me to say without seeing the passage fully but they are either getting at 1 of 2 points I think:

Well first of all RNA can act as enzymes in reactions. For example, some of the catalytic portion of ribosomes are from rRNA so it is non-genetic. tRNA is also an example of non-genetic RNA.

The other point that is important is that in the egg that is formed the cytoplasm is filled with RNA/enzymes/ and organelles from the mother. This plays a large role in the development of germ cells. In this manner you can say that we are actually closer related to our mothers than our fathers since their RNA and proteins direct cell development. In that sense the RNA is non-genetic since it is not arising from the new genome of the offspring.

Not sure which one of these things the question is referring to. Do any of them make sense in regards to the passage?

Yes. Thank you so much for your reply. I think I got it.

I did not know the organelles, proteins, and RNA in the cytoplasm of the gastrula (or blastomere?) were the mother's.

If these non-genetic components of the cytoplasm are the mother's, than when does the cell start translating its own proteins and enzymes? After determination of the cell?

 

[sillyjoe]

Yes. Thank you so much for your reply. I think I got it.

I did not know the organelles, proteins, and RNA in the cytoplasm of the gastrula (or blastomere?) were the mother's.

If these non-genetic components of the cytoplasm are the mother's, than when does the cell start translating its own proteins and enzymes? After determination of the cell?

This is all very in depth and over my head. From what I have learned when the ovum is created there are unequal mitotic divisions that yield an egg and several polar bodies. The egg has most of the cytoplasm, while the polar bodies have minimal cytoplasm. A large amount of maternal mRNA, maternal mitochondria, and maternal proteins are in that cytoplasm. Interestingly, all of our mitochondria in our body are from our mothers and independently replicate with their own separate mitochondrial genome. When the egg is fertilized the sperm contributed JUST the genetic material. Once this happens, the maternal mRNA begins to be translated and the process of the new organisms growth begins. At some point after the activation of translation of the maternal mRNA does the transcription and translation of the organisms own genome begin.

This actually brings up some interesting ethical dilemmas when discussing cytoplasmic transfer, since a lot of the reasons you and I are unique can be contributed to the maternal mRNA and the maternal mitochondria, which eventually become our mitochondria. If you transfer the cytoplasm of an egg, but keep the genetic material who is the mother? Who contributed what attributes?

This is about as much as I know so maybe someone with a better background in this can explain.