BCH5413 EXAM 3 EXAM SCRIPT 2026
COMPLETE QUESTIONS AND CORRECT
ANSWERS GRADED A+
●● The ribosome consists of both ribosomal RNA and ribosomal
proteins.
Which part primarily determines the shape of the ribosome.
Answer: The structure of the ribosome is dependent on the ribosomal
RNA and how they might base pair with each other at different
segments.
●● The ribosome consists of both ribosomal RNA and ribosomal
proteins.
Which part contains the peptidyl transferase activity?.
Answer: The 50S subunit (large subunit) contains the peptidyl
transferase activity.
●● The ribosome consists of both ribosomal RNA and ribosomal
proteins.
Which part contains the GTP hydrolysis activity?.
Answer: The 50S subunit (large subunit) contains GTPase activity.
,●● During protein synthesis, what kind of bond joins the amino acids?
Which parts (functional groups) of the amino acids are bonded
together?.
Answer: The 50S subunit links amino acids together through peptide
bonds. Amino acids connect to form a peptide bond through a reaction
between the amino group and carboxyl group. A peptide bond is formed
through a dehydration reaction. This involves the removal of two
hydrogens and an oxygen.
●● tRNA Charging: How does the aminoacyl-tRNA synthetases
recognize which tRNA gets its amino acid?.
Answer: Recognition will depend on nucleotides within the tRNA and
binding sites within the protein.
●● tRNA Charging: Describe the 2-step process for charging the tRNA..
Answer: The first step is the activation of the amino acid with the help
of ATP to form aminoacyl-AMP. The second step will use the energy
from the aminoacyl-AMP bond to transfer the amino acid onto the
acceptor stem of the tRNA.
●● tRNA charging: Where does the amino acid get added to the tRNA?
Be specific about the end of the RNA and the position of binding on the
RNA..
Answer: The high-energy bond between the aminoacyl and AMP will be
used to transfer the amino acid to the 3' end of the tRNA; specifically,
the amino acid will form an ester bond between the 3'carbon hydroxyl
,group on the adenosine of the tRNA and the carboxyl group of the amino
acid.
●● What is the wobble hypothesis? What is its significance?.
Answer: The wobble hypothesis is: The 3rd position base on a codon
which is allowed to be different to accommodate different tRNA, this
exception allows it to form a non Watson-Crick base pair with the
anticodon.
This is significant because the wobble allows some aminoacyl-tRNAs to
pair with more than one codon
●● True/False: Protein synthesis requires GTP..
Answer: TRUE, When binding an aminoacyl-tRNA to the A site
●● True/False: Wobble allows the different aminoacyl-tRNA to pair with
same codon..
Answer: TRUE, 3rd base of a codon is allowed to move slightly from it
snormal position, allowing same aminoacryl-tRNAs to pair with more
than one codon
●● True/False: Ligase enzyme joins the amino acids to the respective
tRNAs.
Answer: FALSE, AA attached by ester bond between 2'-OH of terminal
adenosine of tRNA
, ●● True/False: Aminoacylation of tRNAs requires GTP.
Answer: FALSE, 2 step process reuire AMP from ATP to activate AA,
then,AMP is used to transfer the AA to tRNA
●● True/False: Fmet-tRNA is the initiator tRNA in Eukaryotes.
Answer: FALSE, N-Formylmethionine=Fmet-tRNA is the initiator of
Prokaryotes
●● What differences are there between the ribosome binding in
prokaryotes vs. eukaryotes?.
Answer: During translation in prokaryotes, the ribosome binds an
operon at a ribosome binding site that precedes an open reading frame.
Once the ribosome binds, there are various soluble factors that ensure
the ribosome reads the correct code to make the correct protein.During
translation in eukaryotes, the ribosome binds the 5' cap, then scans the
mRNA for the AUG start site. The ribosome also requires soluble factors
to initiate translation.
●● What is the function of IF1?.
Answer: binds to the A site and keeps the fmet-tRNA from binding there
●● What is the function of IF2?.
Answer: binds to the fmet-tRNA and GTP and brings the complex to the
P site
COMPLETE QUESTIONS AND CORRECT
ANSWERS GRADED A+
●● The ribosome consists of both ribosomal RNA and ribosomal
proteins.
Which part primarily determines the shape of the ribosome.
Answer: The structure of the ribosome is dependent on the ribosomal
RNA and how they might base pair with each other at different
segments.
●● The ribosome consists of both ribosomal RNA and ribosomal
proteins.
Which part contains the peptidyl transferase activity?.
Answer: The 50S subunit (large subunit) contains the peptidyl
transferase activity.
●● The ribosome consists of both ribosomal RNA and ribosomal
proteins.
Which part contains the GTP hydrolysis activity?.
Answer: The 50S subunit (large subunit) contains GTPase activity.
,●● During protein synthesis, what kind of bond joins the amino acids?
Which parts (functional groups) of the amino acids are bonded
together?.
Answer: The 50S subunit links amino acids together through peptide
bonds. Amino acids connect to form a peptide bond through a reaction
between the amino group and carboxyl group. A peptide bond is formed
through a dehydration reaction. This involves the removal of two
hydrogens and an oxygen.
●● tRNA Charging: How does the aminoacyl-tRNA synthetases
recognize which tRNA gets its amino acid?.
Answer: Recognition will depend on nucleotides within the tRNA and
binding sites within the protein.
●● tRNA Charging: Describe the 2-step process for charging the tRNA..
Answer: The first step is the activation of the amino acid with the help
of ATP to form aminoacyl-AMP. The second step will use the energy
from the aminoacyl-AMP bond to transfer the amino acid onto the
acceptor stem of the tRNA.
●● tRNA charging: Where does the amino acid get added to the tRNA?
Be specific about the end of the RNA and the position of binding on the
RNA..
Answer: The high-energy bond between the aminoacyl and AMP will be
used to transfer the amino acid to the 3' end of the tRNA; specifically,
the amino acid will form an ester bond between the 3'carbon hydroxyl
,group on the adenosine of the tRNA and the carboxyl group of the amino
acid.
●● What is the wobble hypothesis? What is its significance?.
Answer: The wobble hypothesis is: The 3rd position base on a codon
which is allowed to be different to accommodate different tRNA, this
exception allows it to form a non Watson-Crick base pair with the
anticodon.
This is significant because the wobble allows some aminoacyl-tRNAs to
pair with more than one codon
●● True/False: Protein synthesis requires GTP..
Answer: TRUE, When binding an aminoacyl-tRNA to the A site
●● True/False: Wobble allows the different aminoacyl-tRNA to pair with
same codon..
Answer: TRUE, 3rd base of a codon is allowed to move slightly from it
snormal position, allowing same aminoacryl-tRNAs to pair with more
than one codon
●● True/False: Ligase enzyme joins the amino acids to the respective
tRNAs.
Answer: FALSE, AA attached by ester bond between 2'-OH of terminal
adenosine of tRNA
, ●● True/False: Aminoacylation of tRNAs requires GTP.
Answer: FALSE, 2 step process reuire AMP from ATP to activate AA,
then,AMP is used to transfer the AA to tRNA
●● True/False: Fmet-tRNA is the initiator tRNA in Eukaryotes.
Answer: FALSE, N-Formylmethionine=Fmet-tRNA is the initiator of
Prokaryotes
●● What differences are there between the ribosome binding in
prokaryotes vs. eukaryotes?.
Answer: During translation in prokaryotes, the ribosome binds an
operon at a ribosome binding site that precedes an open reading frame.
Once the ribosome binds, there are various soluble factors that ensure
the ribosome reads the correct code to make the correct protein.During
translation in eukaryotes, the ribosome binds the 5' cap, then scans the
mRNA for the AUG start site. The ribosome also requires soluble factors
to initiate translation.
●● What is the function of IF1?.
Answer: binds to the A site and keeps the fmet-tRNA from binding there
●● What is the function of IF2?.
Answer: binds to the fmet-tRNA and GTP and brings the complex to the
P site
