some questions..

[rohIT]

1)why is Eukaryotic DNA more stable then Prokaryotic DNA? my book says it is because it dos not directly produce mRNA. accepted. but i still did not catch the logic.

2)during transcription, the strand which is being read to form the mRna is called Anti-sense, Non-coding and Template strand. quite obvious why it is called anti-sense. but why non-coding and template? as in, it is the strand that is being read. so it should be the one which should be thought of as coding. and the synthesized mRna is similar to the other strand and not this strand that is being read. so why is it called template?

3)about cytoplasmic inheritance. i understand that there are dna fragments floating around in the cytoplasm. my question is, why arent these free dna molecules thought of as food granules and digested by lysosomes?

4)is it normal for some muscles to twitch spontaneously? and why does it happen?

5)i understand that restriction endonucleases identify and cleave the DNA at specific palindromic sequences. now, is it because the endonuclease cleaves that specific sequence every time but unless there is the same sequence nearby on the other strand, the dna does not break?
for example, consider EcoR1, which cleaves 5' GAATTC 3' palindromic sequence. now, what i think is that it actually cleaves all the 5' GAA 3' sites but unless the same sequence is present on the other strand too, the DNA molecule doesn't actually break. please tell me if i am right.
6)Pheophytin is same as chlorophyll a with the Magnesium replaced by two protons. how is that possible considering that the Magnesium ion present at the centre of the porphyrin head actually forms a complex over there. so, do the protons form complex with the ring too? (that doesnt seem possile because there are no many orbitals to accomodate 4 pairs of electrons)

6)what is the reason for dandruff? (i have not found a proper explanation in the places i've searched)

THANKS IN ADVANCE

 

[Hercules Rockefeller]

1)why is Eukaryotic DNA more stable then Prokaryotic DNA? my book says it is because it dos not directly produce mRNA. accepted. but i still did not catch the logic.

That makes no sense. Both eukaryotic and prokaryotic DNA can be transcribed into mRNA.

Are you talking about the stability of “naked” DNA? DNA is DNA and there is no difference in stability if you are merely comparing pure DNA in aqueous solution. If you are comparing DNA environmental stability in the context of the whole organism, then prokaryotic DNA is potentially much more stable as some bacterial species can form spores that are highly resistant to adverse environmental conditions.

2)during transcription, the strand which is being read to form the mRna is called Anti-sense, Non-coding and Template strand. quite obvious why it is called anti-sense. but why non-coding and template?

“Non-coding” because its sequence is not the one that is represented in the mRNA.

“Template” because the strand acts as the template for producing a complementary strand of mRNA

3)about cytoplasmic inheritance. i understand that there are dna fragments floating around in the cytoplasm. my question is, why arent these free dna molecules thought of as food granules and digested by lysosomes?

Cytoplasmic inheritance is nothing to do with “floating DNA fragments”. It refers to the embryonic inheritance of maternal mitochondria from the ovum. Mitochondria have their own genome and own mitochondrial genes.

4)is it normal for some muscles to twitch spontaneously? and why does it happen?

I presume so. I can’t answer this question with any authority.

5)i understand that restriction endonucleases identify and cleave the DNA at specific palindromic sequences. now, is it because the endonuclease cleaves that specific sequence every time but unless there is the same sequence nearby on the other strand, the dna does not break?

Restriction endonucleases cleave double stranded DNA at specific palindromic sequences. Both strands are cleaved to produce a complete break. Palindromic sequences have the same sequence on each strand when read in the same direction.

Eg.
5’-GAATTC-3’
3’-CTTAAG-5’

 

[rohIT]

3) i didnt know cytoplasmic inheritance had to do with mitochondria. i thought it was dna fragments because mule and hinny are different...i mean, the offspring from cross between male horse and female donkey is different from an offspring from the reciprocal cross. please tell me why.

5) i know..thats what the books say too. i am just asking if the endonucleases cut at every 5' GAA 3' site, because it would, without violating the observations, explain the process of its specificity. not arguing, just asking

thanks for ur answers

 

[rodereve]

i'm doing all these answers off the top of my head, so there might be better answers with research backing

1)why is Eukaryotic DNA more stable then Prokaryotic DNA? my book says it is because it dos not directly produce mRNA. accepted. but i still did not catch the logic.

textbook might mean that the environment for the DNA in eukaryotes allows it to be more stable. while DNA is DNA, the nucleus is more suited to housing DNA than having it float around in cytoplasm which has many more fluctuations in environment

2)during transcription, the strand which is being read to form the mRna is called Anti-sense, Non-coding and Template strand. quite obvious why it is called anti-sense. but why non-coding and template? as in, it is the strand that is being read. so it should be the one which should be thought of as coding. and the synthesized mRna is similar to the other strand and not this strand that is being read. so why is it called template?

with transcription, think of it with respect to the final [RNA] transcript. The DNA strand is non-coding because the mRNA is the one that gets coded to produce the rRNA transcript. It's template because the rRNA strand is similar to the DNA template strand except that its U instead of T and its 1 strand. That sort of helps to remember it better.

3)about cytoplasmic inheritance. i understand that there are dna fragments floating around in the cytoplasm. my question is, why arent these free dna molecules thought of as food granules and digested by lysosomes?

I'm sure some are digested by lysosomes, but think of everything as a dynamic equilibrium process. some might be digested, but more are present. It's like why viral dna may be digested but more are produced, dynamic process.

4)is it normal for some muscles to twitch spontaneously? and why does it happen?

sure, there's always underlying tonic electric messages being sent to your muscles, just never goes above threshold. sometimes these messages might add onto each other (brain can't send tonic stimulation perfectly spaced out). anxiety, stress, lack of sleep might increase the chances of messages being mixed, so that may be why you get random eye twitches or leg spasms. I guess thats a really simplified explanation and won't account for everything

5)i understand that restriction endonucleases identify and cleave the DNA at specific palindromic sequences. now, is it because the endonuclease cleaves that specific sequence every time but unless there is the same sequence nearby on the other strand, the dna does not break?
for example, consider EcoR1, which cleaves 5' GAATTC 3' palindromic sequence. now, what i think is that it actually cleaves all the 5' GAA 3' sites but unless the same sequence is present on the other strand too, the DNA molecule doesn't actually break. please tell me if i am right.

Don't think of DNA endonucleases cleaving single strands, but double strands.

So when you think of 5' GAA 3', think of EcoR1 actually cleaving at this entire thing

5' GAATTC 3'
3' CTTAAG 5'

6)Pheophytin is same as chlorophyll a with the Magnesium replaced by two protons. how is that possible considering that the Magnesium ion present at the centre of the porphyrin head actually forms a complex over there. so, do the protons form complex with the ring too? (that doesnt seem possile because there are no many orbitals to accomodate 4 pairs of electrons)

not sure, would require specific reading into it. but are you sure pheophytin isn't a charged compound, maybe the protons aren't completely accommodated. maybe different configuration allows for 2 protons (complex in a ring turns linear?). just popping off ideas

6)what is the reason for dandruff? (i have not found a proper explanation in the places i've searched)

THANKS IN ADVANCE

not sure, everyone sheds dead head cells, some more than others, the process might be more stimulated by environmental (hotter places, dryer scalp), diet and heredity. in other words, I have no clue!