Small RNA's in the Regulation of Biological Processes Flashcards Preview

Nucleic Acid and Gene Expression > Small RNA's in the Regulation of Biological Processes > Flashcards

Flashcards in Small RNA's in the Regulation of Biological Processes Deck (10):

What is the C-value?

Genome size


What is heterochromatin?

Transcriptionally inactive chromatin


Which type of RNA is important in X chromosome inactivation?

Long ncRNA


Which is better at silencing genes, single stranded RNA or dsRNA?



Explain the biochemistry of RNAi, including DICER, AGO and RISC.

dsRNA is derived from viruses to produce siRNA which inhibits the RNA that the dsRNA is derived from. DICER breaks up the dsRNA into 21-25bp fragments. The passenger strand is then removed using Argonaute-PIWI proteins. Multiprotein RISC complexes are formed which cleave mRNA molecules that are complimentary to the siRNA,


Therapeutical use of siRNA? Why does it not trigger cytokines?

DNA fragments 25bp or less will not trigger cytokine reactions. siRNA is small enough to get into cells without invoking a cytokine response, therefore can be used to switch off genes we don't want expressed.


What form is siRNA especially useful in?



Describe how miRNA is formed?

Initially made as pri-miRNA which is processed by RNAse III endonuclease Drosha and is then transported into the cytoplasm as pre-miRNA by exporting in the nuclear membrane. Processing then allows the pre-miRNA to become single stranded and is then passed on to the RISC complex and become miRNA's.


What is gene knockdown?

Decreasing the amount of protein you get from a gene.


How much affinity do miRNA sequences have? What regions and names?

Seed region where there is perfect complementarity. Bulge where there's a bulge and no bonds. Then a region of less stringent complementarity