BIO 1A03 MCMASTER UNIVERSITY
TEST #2 REVIEW WITH QUESTIONS
AND 100% CORRECT ANSWERS {
GRADED A+}
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
TEST #2 REVIEW WITH QUESTIONS
AND 100% CORRECT ANSWERS {
GRADED A+}
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
