controlling gene expression

• what is an intron?

  section of the DNA that doesnt code for an amino acid (in eukaryotes)
• what is an exon?

  section of the DNA that do code for amino acids
• what role does 5' cap and poly-A tail have (post transcriptional regulation)?


  help protect and stabilise the mRNA and delay its degradation.
• what is splicing?


  process of removing introns and joining together exons in pre-mRNA to produce a mature mRNA molecule.
• Where does cAMP activate some proteins?


  At the post-translational level
• what is protein activation controlled by?


  hormones and sugars
• Describe protein activation


  some proteins aren’t functional straight after synthesis.

  protein activation, controlled by molecules(hormones and sugars)

  this molecules bind to cell membrane and trigger the production of cAMP inside cell.

  cAMP activates the proteins by altering their 3D structure.
• how does cAMP activate protein kinase A (PKA)?


  PKA is an enzyme with 4 subunits.

  when cAMP isn’t bound, the 4 units are bound and inactive.

  when it binds, it causes a change to enzyme 3D structure, releasing the subunits.

  it is now active