Molecular Biology Lecture 5: RNA Processing and Translation

What is required to be removed before degradation of eukaryotic mRNA can proceed?

Cap
Start codon
Poly (A) tail (correct)
Exonuclease

Which enzyme is responsible for removing the cap during degradation of eukaryotic mRNA?

Exonuclease Xrn1
tRNA molecule
Decapping protein (Dcp1) (correct)
Poly (A)-binding protein

What determines the stability of eukaryotic mRNA?

Start codon
Poly (A) tail
Exonuclease
Destabilizing sequences (correct)

Which subunit binds to the messenger RNA during translation?

30S subunit (B) Signup and view all the answers

What initiates the coding sequence in eukaryotic mRNA translation?

Start codon (B) Signup and view all the answers

What are the three major types of processing that RNA molecules undergo?

Base modification, cleavage, splicing (B) Signup and view all the answers

Which of the following statements about eukaryotic mRNA processing is TRUE?

Eukaryotic mRNA contains a cap and tail, and undergoes base modification (D) Signup and view all the answers

What is the main function of non-coding RNA?

To perform active roles other than encoding proteins (D) Signup and view all the answers

Which process involves the addition of a cap and tail to eukaryotic mRNA?

Translation (A) Signup and view all the answers

What type of RNAs are used not to carry information but to perform active roles?

non-coding RNAs (D) Signup and view all the answers

Which statement is FALSE regarding RNA processing?

RNA undergoes capping and tailing but not splicing (D) Signup and view all the answers

What is the role of the Poly(A) tail in eukaryotic mRNA?

Adds stability and protection to the mRNA (B) Signup and view all the answers

What is the function of cleavage stimulation factor (CST) in eukaryotic mRNA processing?

Binds to GU-rich tract (D) Signup and view all the answers

What happens to prokaryotic mRNA when a poly(A) tail is added?

Triggers mRNA degradation (A) Signup and view all the answers

What is the function of the spliceosome in mRNA processing?

Joins exons together after intron removal (B) Signup and view all the answers

Which component forms a small nuclear ribonucleoprotein (snRNP) in the spliceosome?

Small nuclear RNA (snRNA) (B) Signup and view all the answers

What is the main difference between the poly(A) tail function in eukaryotes and prokaryotes?

Adds stability in eukaryotes, promotes degradation in prokaryotes (B) Signup and view all the answers

What is the role of initiation factor 3 (IF-3) during translation initiation?

It prevents the large ribosomal subunit from binding during initiation. (B) Signup and view all the answers

Which molecule pairs with its complementary nucleotides in the 16S rRNA during translation initiation?

Shine-Dalgarno sequence (A) Signup and view all the answers

In eukaryotic cells, what plays a critical role similar to Shine-Dalgarno sequence in bacterial translation initiation?

Cap at the 5' end of mRNA (C) Signup and view all the answers

What is the function of elongation factor G (EF-G) in translation elongation?

Allows the ribosome to translocate down mRNA (B) Signup and view all the answers

Why does protein synthesis terminate when a termination codon is encountered?

Release factors cause the dissociation of ribosomal subunits. (C) Signup and view all the answers

What happens during translocation in translation elongation?

The ribosome moves down mRNA in the 5'—3' direction. (D) Signup and view all the answers

What are the three release factors in E. coli that form a complex with GTP and bind to the ribosome?

RF1, RF2, and RF3 (A) Signup and view all the answers

Which release factor recognizes the termination codons UGA and UAA in E. coli?

RF1 (D) Signup and view all the answers

In eukaryotic cells, what is the function of eRF2?

Binds GTP and stimulates the release of the polypeptide from the ribosome (B) Signup and view all the answers

What feature distinguishes the termination process in eukaryotic cells from prokaryotic cells?

Eukaryotic release factor eRF1 recognizes all three termination codons, unlike in prokaryotic cells (D) Signup and view all the answers

What can affect the initiation of translation according to the text?

The availability of ribosomes, tRNAs, initiation and elongation factors (B) Signup and view all the answers

How do posttranslational modifications affect eukaryotic proteins?

They affect the transport, function, and activity of proteins (B) Signup and view all the answers