Search found 18 matches

by sorin
Fri Oct 15, 2010 12:06 pm
Forum: Cell Biology
Topic: Arrested Mitosis
Replies: 2
Views: 4393

Hi, i think short term effects will be rather small, while long-term effects will definitely lead to the organisms dead. Arrested mitosis means that tissue regeneration by stem cells will be impaired and this will first affect all tissues with a high cellular turn-over like the mucosal surfaces or t...
by sorin
Tue Oct 12, 2010 4:30 pm
Forum: Molecular Biology
Topic: Calculating the size of E. coli chromosome?
Replies: 4
Views: 8315

Hi, i don't think that you can calculate the size of e.colis genome by cutting the chromosome with 2 enzymes. 4 base cutters cut every 256 bp on average, 6 base cutters every 4096. Given a size of the chromosome of almost 5 million base bairs you would definetly end up with too many fragments, overl...
by sorin
Sun Oct 10, 2010 8:16 am
Forum: Genetics
Topic: why do RNA show smear instead of discrete bands?
Replies: 2
Views: 3285

They get separated like DNA, but remember how many different RNA molecules are in a cell,its not like chromosomes or fragments of restriction digests having a discrete size. Apart from this if you do not carefully prepare your samples RNAse contamination can occur quite often...
by sorin
Wed Oct 06, 2010 10:39 am
Forum: Genetics
Topic: genetically modified, transgenic organisms; help.
Replies: 8
Views: 8552

Hey, in principle a really great idea. making light while consuming CO2. if you manage to achieve this i promise you will win this competition and maybe some other ones... but practically you will be faced with a bunch of problems. as jackbean already said: how will you manage to get so much light o...
by sorin
Wed Sep 29, 2010 3:33 pm
Forum: Genetics
Topic: What is a strand bias
Replies: 4
Views: 9110

Re: What is a strand bias

...In E. coli (21) and in mammalian cells (22), transcription-blocking lesions are repaired preferentially when present in the transcribed strand. Transcription-coupled nucleotide excision repair has helped explain the observed bias in mutations caused by mutagens such as UV light in favor of the n...
by sorin
Wed Sep 29, 2010 11:17 am
Forum: Genetics
Topic: Genetics - Barr body
Replies: 2
Views: 3362

Hi,
i don't know exactly what will happen but i'm quite sure if there is more than one fully active x chromosome this would very likely be lethal for the individual. you can compare it with an autosomal trisomy, where most are also lethal or are causing really severe clinical symptoms.
by sorin
Wed Sep 29, 2010 10:54 am
Forum: Genetics
Topic: What is a strand bias
Replies: 4
Views: 9110

Hi, a strand bias in this case just means that one strand, here the transcribed one, is preferantially repaired by a certain DNA repair mechanism over the other one. Therefore mutations seem to be preferentially occuring at only one of the strands. I actually don't know what is the reason of the rep...
by sorin
Thu Sep 02, 2010 10:25 am
Forum: Cell Biology
Topic: cell biology
Replies: 3
Views: 2421

there are different hypotheses why mitochondria haven't lost all their genes so far. one says that some very hydrophobic proteins cannot be imported into the mitochondria from the cytoplasm (which has also been experimentally proven) and interestingly the two most hydrophobic mitochondrial proteins ...
by sorin
Mon Aug 30, 2010 11:55 am
Forum: Molecular Biology
Topic: Transcription
Replies: 4
Views: 2315

transcription initiation only occurs at the strand that is defined by specific sequence patterns, as jackbean already mentioned. At the key of this patterns are promotors, which lie 5' upstream of each gene. Promotors mediate interactions between DNA binding proteins and the RNA polymerase, whereby ...
by sorin
Sat Aug 28, 2010 10:16 am
Forum: Cell Biology
Topic: Where can i find cell biology mcqs
Replies: 1
Views: 2981

i guess it's multiple choice questions you are searching for. http://www.ets.org/Media/Tests/GRE/pdf/BioChem.pdf or http://www.ets.org/Media/Tests/GRE/pdf/Biology.pdf. these are practice books of gre test in biology or biochemistry/cell biology. they contain a whole bunch of mc questions.
hope it is what you looked for..
by sorin
Sat Aug 28, 2010 10:04 am
Forum: Molecular Biology
Topic: Life
Replies: 17
Views: 14440

that's the point. Life, as it is defined by modern biology, likely developed only once some 3-4 billion years ago. Thereafter, living cells did only arise from other living cells. But what distinguishes us from a bacterium, which is also a living organism but consists only of one single cell is that...
by sorin
Mon Aug 09, 2010 10:21 am
Forum: Molecular Biology
Topic: tRNA
Replies: 5
Views: 13403

in the nucleus (nucleoplasma, not nucleoli), however in contrast to mRNA not by Pol II but by Pol III (like the 5 S rRNA). There are several copies of the different tRNA genes throughout the genome, however i don't know the exact number now. hope it helped you...