Translation Flashcards
What is the primary site of translation initiation?
5’ G cap
What is the secondary site of translation initiation?
AUG start codon and Kozak or Shine-Dalgarno sequence
What is the purpose of the Cap binding complex in translational initiation?
It recruits the small subunit of the ribosome to mRNA
How does the cap binding complex regulate translation?
It ensures that only mRNA’s that are capped are translated by binding to the cap and recruiting the small ribosomal subunit to the mRNA
What are the three subunits that make up eIF4F?
A, G, E (A+G+E = eIF4F)
What is the relationship between cancer cells and eIF4F?
Cancer cells have increased levels of eIF4F that leads to higher rates of translation
Which subunit of eIF4F is the limiting subunit?
E
Describe a weak mRNA?
A mRNA that is produced minimally under normal conditions and is produced en mass due to a response to a particular stimuli, these mRNA are weak and rapidly degraded
Describe a strong mRNA.
Always present, regulating normal cell conditions, constantly being transcribed in significant amounts
Define Polysome.
Multiple ribosomes lined up on a single mRNA translating the same protein simultaneously (direction of 5-3 and N to C)
What is the role of a tRNA?
Serves as an adaptor between nucleotide sequences and amino acids
The amino acid is bound to which end of the tRNA?
3’
What is considered the second genetic code?
The aminoacyl tRNA synthetases are proteins that match the correct tRNA with the correct amino acid. The information and function that takes place in pairing the two together is considered the second genetic code
How many different aminoacyl tRNA synthetases are present in a cell?
20
What does charging refer to?
Charging is the addition of an amino acid to a tRNA through the hydrolysis of ATP. When the AA is bound to the tRNA, the tRNA is considered charged
What is the sequence of events that leads to tRNA charging?
- AA and ATP are reacted to produce an adenylated AA (AA + AMP) and PPi is released. 2. The adenylated AA binds to the tRNA releasing the AMP added in the previous step. 3. Final products are charged tRNA (tRNA + AA), AMP and PPi
What is the function of eIF2?
eIF2 escorts the methionyl tRNA to the ribosome
What is the function of eIF1 and eIF3?
binds the small ribosomal subunit in place and interacts with the cap binding complex to bring the ribosome to the mRNA