BIO 215 Rubenstien Final Exam UPDATED
ACTUAL Exam Questions and CORRECT
Answers
osmosis - CORRECT ANSWER - Simple diffusion of water.
Explain the 4 features of the genetic code - CORRECT ANSWER - 1) Degenerate:
multiple codons code for one amino acid (reduces the harm of mutation)
2) Non-overlapping
3) Universal (nearly): almost all species follow the codon table
4) Non-codon functions:
- AUG - Methionine = start codon
- UAA, UAG, UGA - Stop codons
Where is the ribosome located in eukaryotes? - CORRECT ANSWER - - Eukaryotes:
located in the cytoplasm or bound to the ER
Where is the ribosome located in prokaryotes? - CORRECT ANSWER - cytoplasm
what is the function of the ribosome - CORRECT ANSWER - -catalyze polypeptide
synthesis
what is the ribosome made of? - CORRECT ANSWER - many proteins and rRNA
molecules (large subunit and small subunit)
Binding sites of a ribosome - CORRECT ANSWER - mRNA binding site: ******
A (amino acyl) site:
P (peptide) site:
E (exit) site:
,Exit channel:
Describe the structure and role of tRNA molecules in translation. - CORRECT ANSWER -
aminoacyl tRNA are bound to amino acids and bring the amino acid to the ribosome so a peptide
bond can be formed.
Explain how fewer than 61 tRNA molecules function with 61 amino-acid encoding codons. -
CORRECT ANSWER - Many tRNAs can recognize/base pair with more than one mRNA
codon because the 3rd base is slightly offset so its possible to hydrogen bond with multiple
codons. (Wobble hypothesis - mRNA and tRNA line up on the ribosome in a way that permits
flexibility or wobble in the final bases of codon and anticodon)
Describe the function of action of aminoacyl-tRNA synthetases. - CORRECT ANSWER -
Every tRNA/amino acid pair has its own aminoacyl-tRNA synthetase enzyme
Catalyze formation of an ester bond
Between the 3'-OH of the tRNA and the carboxyl group of the AA
Energy provided by ATP hydrolysis
Endergonic
Mechanism of aminoacyl-tRNA sythetases - CORRECT ANSWER - 1) Amino acid & ATP
enter active site
2) AMP is joined to amino acid with the release and breakdown of pyrophosphate (2 phosphates
bonded to each other)
3) AMP is displaced by tRNA creating aminoacyl tRNA
4) Aminoacyl tRNA is released
Explain the directionality of protein synthesis with respect to the direction in which ribosomes
read mRNA; the order of addition of amino acids - CORRECT ANSWER - mRNA is read
5'→3'. Polypeptide is synthesized N→C
Describe polypeptide synthesis initiation - CORRECT ANSWER - 1) Binding of Initiation
factor proteins and GTP to the small ribosomal subunit
, - IF3 prevents large subunit from prematurely binding to small subunit
- IF1 prevents charged tRNA from prematurely binding to the A site before initiation complex
has formed
2) Initiator tRNA and mRNA bind to small ribosomal subunit with help of IFs
- Initiator tRNA is guided to start codon by IF2
3) Initiator tRNA triggers release of IF3 (allows large subunit to bind).
4) Large ribosomal subunit binds and stimulated the hydrolysis of GTP which stimulates release
of IF1 and IF2
Describe polypeptide synthesis elongation. - CORRECT ANSWER - amino acids are
added to the growing polypeptide based on the mRNA code
New tRNAs bringing new amino acids arrive at a site
Growing polypeptide chain connected to a tRNA at the p site is transferred to the new amino acid
linked to the new tRNA at the a site
Each new tRNA which has transferred its amino acid to the growing chain will be released to the
e site
Describe polypeptide synthesis and termination. - CORRECT ANSWER - Initiation:
mRNA is positioned on the ribosome Large and small subunits, and a tRNA that is loaded with
an aminal aceyltr and a synthetase Assemble the riosome and the intitial tRNA After they are
assembled we have an a site, a p site, and an e site Almost every new tRNA arrives in the a site
The only tRNA that is going to arrive at a different site is the initiatior tRNA that carries the first
amino acid (methyanine)
Elongation: amino acids are added to the growing polypeptide based on the mRNA code New
tRNAs bringing new amino acids arrive at a site Growing polypeptide chain connected to a
tRNA at the p site is transferred to the new amino acid linked to the new tRNA at the a site Each
new tRNA which has transferred its amino acid to the growing chain will be released to the e site
Termination: mRNA and polypeptide are released from the ribosome Release factor binds to the
stop codon Triggers termination and release of the completed polypeptide or protein molecule,
the final tRNA, the mRNA, and the ribosomal subunits
ACTUAL Exam Questions and CORRECT
Answers
osmosis - CORRECT ANSWER - Simple diffusion of water.
Explain the 4 features of the genetic code - CORRECT ANSWER - 1) Degenerate:
multiple codons code for one amino acid (reduces the harm of mutation)
2) Non-overlapping
3) Universal (nearly): almost all species follow the codon table
4) Non-codon functions:
- AUG - Methionine = start codon
- UAA, UAG, UGA - Stop codons
Where is the ribosome located in eukaryotes? - CORRECT ANSWER - - Eukaryotes:
located in the cytoplasm or bound to the ER
Where is the ribosome located in prokaryotes? - CORRECT ANSWER - cytoplasm
what is the function of the ribosome - CORRECT ANSWER - -catalyze polypeptide
synthesis
what is the ribosome made of? - CORRECT ANSWER - many proteins and rRNA
molecules (large subunit and small subunit)
Binding sites of a ribosome - CORRECT ANSWER - mRNA binding site: ******
A (amino acyl) site:
P (peptide) site:
E (exit) site:
,Exit channel:
Describe the structure and role of tRNA molecules in translation. - CORRECT ANSWER -
aminoacyl tRNA are bound to amino acids and bring the amino acid to the ribosome so a peptide
bond can be formed.
Explain how fewer than 61 tRNA molecules function with 61 amino-acid encoding codons. -
CORRECT ANSWER - Many tRNAs can recognize/base pair with more than one mRNA
codon because the 3rd base is slightly offset so its possible to hydrogen bond with multiple
codons. (Wobble hypothesis - mRNA and tRNA line up on the ribosome in a way that permits
flexibility or wobble in the final bases of codon and anticodon)
Describe the function of action of aminoacyl-tRNA synthetases. - CORRECT ANSWER -
Every tRNA/amino acid pair has its own aminoacyl-tRNA synthetase enzyme
Catalyze formation of an ester bond
Between the 3'-OH of the tRNA and the carboxyl group of the AA
Energy provided by ATP hydrolysis
Endergonic
Mechanism of aminoacyl-tRNA sythetases - CORRECT ANSWER - 1) Amino acid & ATP
enter active site
2) AMP is joined to amino acid with the release and breakdown of pyrophosphate (2 phosphates
bonded to each other)
3) AMP is displaced by tRNA creating aminoacyl tRNA
4) Aminoacyl tRNA is released
Explain the directionality of protein synthesis with respect to the direction in which ribosomes
read mRNA; the order of addition of amino acids - CORRECT ANSWER - mRNA is read
5'→3'. Polypeptide is synthesized N→C
Describe polypeptide synthesis initiation - CORRECT ANSWER - 1) Binding of Initiation
factor proteins and GTP to the small ribosomal subunit
, - IF3 prevents large subunit from prematurely binding to small subunit
- IF1 prevents charged tRNA from prematurely binding to the A site before initiation complex
has formed
2) Initiator tRNA and mRNA bind to small ribosomal subunit with help of IFs
- Initiator tRNA is guided to start codon by IF2
3) Initiator tRNA triggers release of IF3 (allows large subunit to bind).
4) Large ribosomal subunit binds and stimulated the hydrolysis of GTP which stimulates release
of IF1 and IF2
Describe polypeptide synthesis elongation. - CORRECT ANSWER - amino acids are
added to the growing polypeptide based on the mRNA code
New tRNAs bringing new amino acids arrive at a site
Growing polypeptide chain connected to a tRNA at the p site is transferred to the new amino acid
linked to the new tRNA at the a site
Each new tRNA which has transferred its amino acid to the growing chain will be released to the
e site
Describe polypeptide synthesis and termination. - CORRECT ANSWER - Initiation:
mRNA is positioned on the ribosome Large and small subunits, and a tRNA that is loaded with
an aminal aceyltr and a synthetase Assemble the riosome and the intitial tRNA After they are
assembled we have an a site, a p site, and an e site Almost every new tRNA arrives in the a site
The only tRNA that is going to arrive at a different site is the initiatior tRNA that carries the first
amino acid (methyanine)
Elongation: amino acids are added to the growing polypeptide based on the mRNA code New
tRNAs bringing new amino acids arrive at a site Growing polypeptide chain connected to a
tRNA at the p site is transferred to the new amino acid linked to the new tRNA at the a site Each
new tRNA which has transferred its amino acid to the growing chain will be released to the e site
Termination: mRNA and polypeptide are released from the ribosome Release factor binds to the
stop codon Triggers termination and release of the completed polypeptide or protein molecule,
the final tRNA, the mRNA, and the ribosomal subunits
