Campbell and Reece 8th edition

[Stephen1993]

hi everyone
i am here because i am doing Cell's biology and so i got questions to ask

to start of with i am using the Campbell and Reece 8th edition textbook when studying for Cell's biology

ok page 9
The sequence of nucleotides along a gene is transcribed into a RNA, which is then translated into a specific protein with a unique shape and function. In the translation process, all forms of life employ essentially the same genetic code. A particular sequence of nucleotides says the same thing to one organism as it does to another. Differences between organisms reflect differences between their nucleotide sequences.

i get the first sentence but i don't get the others

thank you

[JackBean]

you should probably read a little bit more about the genetic code. I think there was a good chapter in Harper's biochemistry.

Anyway, the point is, that the genetic code (i.e. what sequence in DNA/mRNA will be translated into which amino acid in protein) is universal. That is, we share this genetic code with all organisms including bacteria etc. Thus it doesn't matter, whether one piece of mRNA will get human or E. coli, both will translate it into exactly the same protein.


_______
Footnote for more advanced, you shouldn't read this now.
Yes, I know there are exceptions as from everything and it's not that simple.

[Stephen1993]

thank you for the help

another quick question
pg 102
"A prominent structure within the nondividing nucleus is the nucleolus ..."
I thought all cells divide?

thank you

[JackBean]

they may be, but they are not dividing all the time. Even if so, there are the G1, S and G2 phases

[Stephen1993]

thank you

do prokaryotes have mitochondria??
because in the textbook (can't remember the page no.) it says that prokaryotes do not have mitochondria
then how do bacteria have the energy to move if they don't have mitochondria???

thank you

[JackBean]

no, bacteria have no organelles, either mitochondria, either plastids, either nucleus, either Golgi etc.
However, they have some similar membrane sacks on their plasma membrane, which function in energy gaining. Anyway, they are able to get energy without them. Even we are (for some time; look for fermentation)

[Stephen1993]

ok cheers

would mRNA be classify under in transcription or translation????

thank you

[JackBean]

depends on what you're interested in. It's the product of transcription and template in translation. Isn't there any chapter about nucleic acids?

[Stephen1993]

hello

This is about the endomembrane system

Describe the route taken by a secreted protein, from synthesis to export and explain the importance of transport vesicles in this journey.
i couldn't find the "importance of transport vesicles" in the textbook and so i am wondering if if you could tell me .

thank you

[jwalin]

If you must have noticed the proteins travel from one organelle to another. This transport is made possible by the vesicles. Now one can ask why does this have to be so? Its simple a protein needs to reach a specific place for its post translational modification and there must be something that must guide it to that place. But then a further question should be- why dont the proteins haev some sequence on them that will guide them to the particular place/ organelle- a few reasons. 1. the protein would get exposed to a different environment in the cytoplasm this would affect its str and func. 2. you would need to change all the proteins that need to be transferred and then once transferred a further change should be made (the signalling sequence would have to be removed) 3. its more efficient.

Hope that answers your question

[Stephen1993]

thank you for that

another question
"We now have an explanation of why carbohydrates is always found on the outside surface of the plasma membrane. It is because the carbohydrate was originally added by enzymes in the lumen of the ER, and membrane asymmetry is preserved when budding or fusing occurs. If carbohydrate is on the inside of the ER membrane, it will also be on the inside of the ER membrane, it will also be on the inside of the vesicle and Golgi membrane, but it will be on the outside of the plasma membrane after exocytosis occurs.
Could you please explain what this means??

thank you

[Stephen1993]

hello

i got a question
State where signal receptors may be located in target cells

thank you