BIO 1A03 McMaster University Test 2 Review UPDATED ACTUAL Exam Questions and CORRECT Answers
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Course
BIO 1A03
Institution
BIO 1A03
BIO 1A03 McMaster University Test 2
Review UPDATED ACTUAL Exam
Questions and CORRECT Answers
Translation - CORRECT ANSWER- 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 struct...
BIO 1A03 McMaster University Test 2
Review UPDATED ACTUAL Exam
Questions and CORRECT Answers
Translation - CORRECT ANSWER- ✔✔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? - CORRECT ANSWER-
✔✔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? - CORRECT ANSWER- ✔✔- 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? -
CORRECT ANSWER- ✔✔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? - CORRECT
ANSWER- ✔✔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? - CORRECT ANSWER- ✔✔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? -
CORRECT ANSWER- ✔✔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. - CORRECT ANSWER- ✔✔True - 20 aminoacyl tRNA synthetase
How do aminoacyl tRNA synthetases work? - CORRECT ANSWER- ✔✔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 - CORRECT ANSWER- ✔✔able to deliver amino acids to growing
polypeptide chain.
What does correct translation require (in terms of codon and anti-codon)? - CORRECT
ANSWER- ✔✔Correct translation requires the correct PAIRING of tRNA anticodon with the
appropriate mRNA codon
How does codon-anticodon pairing occur? - CORRECT ANSWER- ✔✔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? - CORRECT ANSWER-
✔✔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? - CORRECT ANSWER- ✔✔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? - CORRECT ANSWER- ✔✔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) - CORRECT
ANSWER- ✔✔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
Initiation factors - CORRECT ANSWER- ✔✔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? - CORRECT
ANSWER- ✔✔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? - CORRECT ANSWER-
✔✔Initiation factors are released once translation is complete
How does translation start in the ribosome (not initiation)? - CORRECT ANSWER- ✔✔-
Methionine located in peptidyl site of ribosome
- As the ribosome translates the mRNA, each subsequent charged tRNA enters or binds to
aminoacyl (A) site
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