Flashcards in BioChem 7.2 Transcription Deck (19)
What happens after the process of transcription in eukaryotic cells?
In eukaryotic cells, the mRNA has to be modified after transcription.
How can eukaryotic RNA form into a mature mRNA?
Eukarytoic RNA has to remove introns. and Splice exons together
Why is splicing important?
mRNA splicing has to function to remove unnecessary non-coding regions before translation.
Introns allow cells to make a variety of slightly different polypeptides from the same gene. Sometimes an intron can be included in the mRNA. This will produce a slightly different polypeptide. Thus a slightly modified protein.
What is an example of a non coding region with a function?
A promoter site is an example of a non-coding DNA with a function.
When does specialization occur?
Cell specialization occurs through a process of differentiation where genes are swicthed off.
What is a major role in affecting cell specialization?
The environment plays a major role in affecting whether genes are switched off or on. It has an effect of the gene expression.
What is phenotypic plasticity?
It is the ability of an organism to develop in different ways according to its environment.
What is a nucleosome?
One nucleosome is made of 8 histone proteins, with DNA wrapped around the outside. Only eukaryotic cells have nucleosomes.
What is the function of a nucleosome?
Nucleosomes protect DNA from damage
They allow long lengths of DNA to be supercoiled for mobility of mitosis.
Nucleosomes help to regulate DNA transcription.
How do nucleosomes act to regulate DNA transcription?
While a DNA strand is wrapped around a histone protein, in a nucleosome, the enzyme RNA polymerase cannot unwrap the DNA double helix for transcription to occur.
Some parts of a cell's DNA is permanently wrapped into nucleosomes that permanently switch off the gene.
Do prokaryotic cells have nucleosomes?
No. Prokaryotic cells have naked DNA meaning that they do not have histone proteins to form nucleosomes.
How can gene expression be regulated?
Through proteins, gene expression can be regulated and therefore temporarily regulated.
This happens when proteins bind to specific base sequences in the DNA, such a promoting protein or a blocking protein on the operator site.
Is post-transcriptional modification of RNA something that occurs in prokaryotes?
No it does not.
When does gene expression occur?
transcription, translation and post-translational
What does mRNA splicing increase?
number of different proteins an organism can produce
Why does post-transcriptional modification of RNA only apply to eukaryotes?
Absence of nuclear membrane, and absence of compartmentalization allows transcription and translation to be coupled in prokaryotes
Does prokaryotic DNA contain introns?
What are introns?
Non-coding regions of DNA