BIOC0005 - PROTEIN SYNTHESIS EXAM QUESTIONS AND
ANSWERS WITH COMPLETE SOLUTIONS VERIFIED
What are the main phases of protein synthesis?
initiation, elongation, termination
Describe the regulatory regions and sequences in mRNAs.
7-methyl guanosine cap - prevent from degradation in the cytosol.
Poly(A) tail - mRNA stability
Start codon and stop codon (AUG, UGA)
Describe the structures of tRNA that dictates it function.
3' end has the CCA sequence where amino acids are linked. The opposite end contains
the anticodon loop responsible for specificity of aminoacyl-tRNA.
Each amino acid has its own set of tRNA, which aligns the aa with the corresponding
codon.
What is the function of aminoacyl tRNA synthetases?
There are 20 aminoacyl-tRNA synthases: one of these enzymes for each amino acid.
Each aminoacyl-tRNA synthase recognizes the correct set of tRNAs for a particular
amino acid.
The interaction between tRNA and aminoacyl-tRNA synthase results in the formation of
, aminoacyl-tRNA. When in complex with tRNA, the amino acid is activated and can
participate in peptide bond formation.
Activation sequence in tRNA induces the activity in the synthase. Editing site ensure
right amino acid is bound to the synthase. Complex dissociates when amino acid is
transferred to peptide chain due to weakened affinity.
What is the purpose of ribosomal proteins?
Maintaining the stability and integrity of the ribosome, but not for catalysis
What does rRNA act as?
A ribozyme
Briefly describe the two mechanisms of initiation of translation, and the result of
this phase.
Cap-dependent initiation - the initiation complex interacts with the 5' cap structure and
scans in a 5' to 3' direction until the start AUG codon is found
Internal ribosome entry site (IRES) - initiation complex binds upstream of initiation
codon
The rate-limiting step requires hydrolysis of both ATP and GTP, forming a complex
containing the ribosome, the mRNA and the initiator Met-tRNA.
What does eIF stand for?
eukaryotic initiation factor
Describe the initiation of translation .
ANSWERS WITH COMPLETE SOLUTIONS VERIFIED
What are the main phases of protein synthesis?
initiation, elongation, termination
Describe the regulatory regions and sequences in mRNAs.
7-methyl guanosine cap - prevent from degradation in the cytosol.
Poly(A) tail - mRNA stability
Start codon and stop codon (AUG, UGA)
Describe the structures of tRNA that dictates it function.
3' end has the CCA sequence where amino acids are linked. The opposite end contains
the anticodon loop responsible for specificity of aminoacyl-tRNA.
Each amino acid has its own set of tRNA, which aligns the aa with the corresponding
codon.
What is the function of aminoacyl tRNA synthetases?
There are 20 aminoacyl-tRNA synthases: one of these enzymes for each amino acid.
Each aminoacyl-tRNA synthase recognizes the correct set of tRNAs for a particular
amino acid.
The interaction between tRNA and aminoacyl-tRNA synthase results in the formation of
, aminoacyl-tRNA. When in complex with tRNA, the amino acid is activated and can
participate in peptide bond formation.
Activation sequence in tRNA induces the activity in the synthase. Editing site ensure
right amino acid is bound to the synthase. Complex dissociates when amino acid is
transferred to peptide chain due to weakened affinity.
What is the purpose of ribosomal proteins?
Maintaining the stability and integrity of the ribosome, but not for catalysis
What does rRNA act as?
A ribozyme
Briefly describe the two mechanisms of initiation of translation, and the result of
this phase.
Cap-dependent initiation - the initiation complex interacts with the 5' cap structure and
scans in a 5' to 3' direction until the start AUG codon is found
Internal ribosome entry site (IRES) - initiation complex binds upstream of initiation
codon
The rate-limiting step requires hydrolysis of both ATP and GTP, forming a complex
containing the ribosome, the mRNA and the initiator Met-tRNA.
What does eIF stand for?
eukaryotic initiation factor
Describe the initiation of translation .
