BIO 1A03 McMaster University Test 2
Review Questions with 100% Correct
Answers | Latest Version 2024 | Verified
Translation - ✔✔Cellular components are able to read the genetic message in mRNA and translate the
message into specific primary amino acid sequence of a protein
How does tRNA structure allow for SPECIFICTY in translation? - ✔✔
1. Plays critical role in ENABLING the translation of the information
2. Each type of tRNA molecule is not identical and can translate a specific codon into a specific amino
acid
What is the structure of tRNA? - ✔✔- single RNA strand (70-90 nucleotide length)
- four double helical segments and three characteristic loops
How are the four double helical segments and three loops in tRNA molecules formed? - ✔✔Formed due
to the large degree of complementarity along stretches of tRNA which results in many stretches of
hydrogen bonding between complementary bases.
What are anticodons? In what direction are they conventionally written? - ✔✔Three-base sequence in a
transfer RNA molecule base that pairs with a complementary codon in mRNA
They are conventionally written in the 3' to 5' direction
What is at the 3' end on tRNA? - ✔✔There is a protruding amino acid attachment site made up of CCA
nucleotide sequence (terminal "A" is point of attachment for amino acid during tRNA molecule
activation)
How is the activation of a tRNA molecule with a specific amino acid carried out? - ✔✔Activation is
carried out by a family of enzymes called aminoacyl tRNA synthetase
,True or False; Each enzyme is specific to the type of tRNA and corresponding amino acid it will bind. -
✔✔True - 20 aminoacyl tRNA synthetase
How do aminoacyl tRNA synthetases work? - ✔✔The active site of the enzyme recognizes the anticodon
end of the tRNA and the region of the amino acid attachment site.
Once bound to active site, enzymes catalyze covalent attachment of tRNA molecule to its amino acid
(energy from ATP Hydrolysis)
Charged tRNA - ✔✔able to deliver amino acids to growing polypeptide chain.
What does correct translation require (in terms of codon and anti-codon)? - ✔✔Correct translation
requires the correct PAIRING of tRNA anticodon with the appropriate mRNA codon
How does codon-anticodon pairing occur? - ✔✔The 5' end of codon (mRNA) will bind with the 3' end of
the anticodon (tRNA)
What is meant by the term wobble? What does it help to explain? - ✔✔Greater flexibility for base
pairing between third nucleotide of a codon and corresponding base of tRNA anticodon
Wobble helps explain the redundancy of genetic code
When does translation initiation in Eukaryotes occur? - ✔✔In eukaryotes, it occurs when a translational
initiation complex forms towards the 5' cap of the mRNA and then scans the mRNA until an AUG start
codon is encountered
How does translation initiation in Prokaryotes occur? - ✔✔Since there are no 5' caps, translation
initiation complex will assemble at one or more ribosome binding sites called Shine-Dalgarno sequences
(Located a few bases upstream the translation start codon)
, What is the unique ability of prokaryotic translation? (think operons) - ✔✔Translation can occur along
multiple regions of prokaryotic mRNA sequence
- Allows prokaryotes to have specific open reading frames for more than one protein along mRNA
Eukaryotic translation initiation requires what components? - ✔✔Two ribosomal subunits
mRNA
Charged tRNA
Initiation factors
Initiation factors - ✔✔Bind to 5' cap of mRNA which allows for the recruitment of the small ribosomal
subunit
Other initiation factors will bind to tRNA that is charged with methionine
The partially assembled small subunit and tRNA do what once initiated? - ✔✔They will move along the
mRNA in a 5' to 3' direction until AUG is encountered
- When this occurs, large ribosomal subunit is able to bind to the rest of the initiation complex using
energy from GTP hydrolysis
What happens to initiation factors once translation is complete? - ✔✔Initiation factors are released once
translation is complete
How does translation start in the ribosome (not initiation)? - ✔✔- Methionine located in peptidyl site of
ribosome
- As the ribosome translates the mRNA, each subsequent charged tRNA enters or binds to aminoacyl (A)
site
GTP-bound elongation factor - ✔✔Each incoming charged tRNA is delivered in association with these
When the correct codon-anticodon pairing is made, GTP is hydrolyzed and aminoacyl end of tRNA is
released from elongation factor
Review Questions with 100% Correct
Answers | Latest Version 2024 | Verified
Translation - ✔✔Cellular components are able to read the genetic message in mRNA and translate the
message into specific primary amino acid sequence of a protein
How does tRNA structure allow for SPECIFICTY in translation? - ✔✔
1. Plays critical role in ENABLING the translation of the information
2. Each type of tRNA molecule is not identical and can translate a specific codon into a specific amino
acid
What is the structure of tRNA? - ✔✔- single RNA strand (70-90 nucleotide length)
- four double helical segments and three characteristic loops
How are the four double helical segments and three loops in tRNA molecules formed? - ✔✔Formed due
to the large degree of complementarity along stretches of tRNA which results in many stretches of
hydrogen bonding between complementary bases.
What are anticodons? In what direction are they conventionally written? - ✔✔Three-base sequence in a
transfer RNA molecule base that pairs with a complementary codon in mRNA
They are conventionally written in the 3' to 5' direction
What is at the 3' end on tRNA? - ✔✔There is a protruding amino acid attachment site made up of CCA
nucleotide sequence (terminal "A" is point of attachment for amino acid during tRNA molecule
activation)
How is the activation of a tRNA molecule with a specific amino acid carried out? - ✔✔Activation is
carried out by a family of enzymes called aminoacyl tRNA synthetase
,True or False; Each enzyme is specific to the type of tRNA and corresponding amino acid it will bind. -
✔✔True - 20 aminoacyl tRNA synthetase
How do aminoacyl tRNA synthetases work? - ✔✔The active site of the enzyme recognizes the anticodon
end of the tRNA and the region of the amino acid attachment site.
Once bound to active site, enzymes catalyze covalent attachment of tRNA molecule to its amino acid
(energy from ATP Hydrolysis)
Charged tRNA - ✔✔able to deliver amino acids to growing polypeptide chain.
What does correct translation require (in terms of codon and anti-codon)? - ✔✔Correct translation
requires the correct PAIRING of tRNA anticodon with the appropriate mRNA codon
How does codon-anticodon pairing occur? - ✔✔The 5' end of codon (mRNA) will bind with the 3' end of
the anticodon (tRNA)
What is meant by the term wobble? What does it help to explain? - ✔✔Greater flexibility for base
pairing between third nucleotide of a codon and corresponding base of tRNA anticodon
Wobble helps explain the redundancy of genetic code
When does translation initiation in Eukaryotes occur? - ✔✔In eukaryotes, it occurs when a translational
initiation complex forms towards the 5' cap of the mRNA and then scans the mRNA until an AUG start
codon is encountered
How does translation initiation in Prokaryotes occur? - ✔✔Since there are no 5' caps, translation
initiation complex will assemble at one or more ribosome binding sites called Shine-Dalgarno sequences
(Located a few bases upstream the translation start codon)
, What is the unique ability of prokaryotic translation? (think operons) - ✔✔Translation can occur along
multiple regions of prokaryotic mRNA sequence
- Allows prokaryotes to have specific open reading frames for more than one protein along mRNA
Eukaryotic translation initiation requires what components? - ✔✔Two ribosomal subunits
mRNA
Charged tRNA
Initiation factors
Initiation factors - ✔✔Bind to 5' cap of mRNA which allows for the recruitment of the small ribosomal
subunit
Other initiation factors will bind to tRNA that is charged with methionine
The partially assembled small subunit and tRNA do what once initiated? - ✔✔They will move along the
mRNA in a 5' to 3' direction until AUG is encountered
- When this occurs, large ribosomal subunit is able to bind to the rest of the initiation complex using
energy from GTP hydrolysis
What happens to initiation factors once translation is complete? - ✔✔Initiation factors are released once
translation is complete
How does translation start in the ribosome (not initiation)? - ✔✔- Methionine located in peptidyl site of
ribosome
- As the ribosome translates the mRNA, each subsequent charged tRNA enters or binds to aminoacyl (A)
site
GTP-bound elongation factor - ✔✔Each incoming charged tRNA is delivered in association with these
When the correct codon-anticodon pairing is made, GTP is hydrolyzed and aminoacyl end of tRNA is
released from elongation factor
