Translation and Proteins - GRE
Card 0 of 88
Which of the following is not a phase in translation?
Which of the following is not a phase in translation?
There are four phases in translation: activation, initiation, elongation, and termination. Activation is the process that joins the correct amino acid to the correct tRNA. When the tRNA has an amino acid bound to it, it is "charged." Initiation occurs when the small ribosomal subunit binds the 5' end of mRNA, with the help of initiation factors and other proteins. The structure then recruits a methionine tRNA to the start codon to begin the elongation process. Elongation occurs as charged tRNA molecules transfer their amino acids to the growing polypeptide. Termination results when a stop codon is recognized by release factors and the completed protein is released from the ribosome.
Modification of the transcript occurs after translation has been completed.
There are four phases in translation: activation, initiation, elongation, and termination. Activation is the process that joins the correct amino acid to the correct tRNA. When the tRNA has an amino acid bound to it, it is "charged." Initiation occurs when the small ribosomal subunit binds the 5' end of mRNA, with the help of initiation factors and other proteins. The structure then recruits a methionine tRNA to the start codon to begin the elongation process. Elongation occurs as charged tRNA molecules transfer their amino acids to the growing polypeptide. Termination results when a stop codon is recognized by release factors and the completed protein is released from the ribosome.
Modification of the transcript occurs after translation has been completed.
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Which of the following is not a type of modification that can occur after translation?
Which of the following is not a type of modification that can occur after translation?
Post-translational modifications that may occur after a protein is translated include numerous processes to alter the structure or function of the protein. Trimming modification involves removal of the N- or C - terminal propeptides from zymogens to generate mature proteins. Covalent alterations, including phosphorylation, glycosylation and hydroxylation, are frequently used to modify the structure or energy state of a protein. Proteasomal degradation requires the attachment of ubiquitin to defective proteins to tag them for degradation and digestion. Amino acids from degraded proteins can often be recycled to generate new molecules.
5' capping occurs in the nucleus after transcription and is required for transport of RNA out of the nucleus prior to translation.
Post-translational modifications that may occur after a protein is translated include numerous processes to alter the structure or function of the protein. Trimming modification involves removal of the N- or C - terminal propeptides from zymogens to generate mature proteins. Covalent alterations, including phosphorylation, glycosylation and hydroxylation, are frequently used to modify the structure or energy state of a protein. Proteasomal degradation requires the attachment of ubiquitin to defective proteins to tag them for degradation and digestion. Amino acids from degraded proteins can often be recycled to generate new molecules.
5' capping occurs in the nucleus after transcription and is required for transport of RNA out of the nucleus prior to translation.
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Which of the following ensures that viral gene translation occurs even when host translation is inhibited?
Which of the following ensures that viral gene translation occurs even when host translation is inhibited?
Viruses utilize IRES to allow translation to occur in a 5' cap-independent manner. Translational machinery (ribosomes) are located to the IRES so that translation can occur. 5' guanine cap and 3' poly-A tails are mRNA modifications that are normally necessary to initiate translation, but are cap-dependent. The promoter regulates genes expression on the level of transcription, whereas the 5' UTR regulates translation.
Viruses utilize IRES to allow translation to occur in a 5' cap-independent manner. Translational machinery (ribosomes) are located to the IRES so that translation can occur. 5' guanine cap and 3' poly-A tails are mRNA modifications that are normally necessary to initiate translation, but are cap-dependent. The promoter regulates genes expression on the level of transcription, whereas the 5' UTR regulates translation.
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Most translation occurs by a mRNA cap-dependent mechanism, however, translation can occur by cap-independent initiation. One mechanism by which eukaryotic cells can initiate cap-independent translation is by which of the following approaches?
Most translation occurs by a mRNA cap-dependent mechanism, however, translation can occur by cap-independent initiation. One mechanism by which eukaryotic cells can initiate cap-independent translation is by which of the following approaches?
The correct answer is the internal ribosome entry site. This site is a specific nucleotide sequence that allows for translation initiation in the middle of a mRNA sequence, rather than at the 5' end, and does not require the cap-dependent elF4F initiation complex or the 5'cap. The poly(A)-binding protein complexes with the 3' end of mRNA strands during translation initiation via the cap-dependent mechanism.
The correct answer is the internal ribosome entry site. This site is a specific nucleotide sequence that allows for translation initiation in the middle of a mRNA sequence, rather than at the 5' end, and does not require the cap-dependent elF4F initiation complex or the 5'cap. The poly(A)-binding protein complexes with the 3' end of mRNA strands during translation initiation via the cap-dependent mechanism.
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Which amino acid is the "start" amino acid in a peptide chain?
Which amino acid is the "start" amino acid in a peptide chain?
The correct answer is methionine. The ATG codon triplet in a mRNA strand codes for the start of the peptide, and this first amino acid that is coded by ATG is methionine.
The correct answer is methionine. The ATG codon triplet in a mRNA strand codes for the start of the peptide, and this first amino acid that is coded by ATG is methionine.
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In prokaryotes what site on the mRNA does the ribosome bind to initiate translation?
In prokaryotes what site on the mRNA does the ribosome bind to initiate translation?
The Shine-Dalgarno sequence is the ribosomal binding site in in prokaryotic mRNA that is located around 8 bases upstream of the start codon.
The Shine-Dalgarno sequence is the ribosomal binding site in in prokaryotic mRNA that is located around 8 bases upstream of the start codon.
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To which of the following structures in a typical molecule of tRNA is an amino acid attached?
To which of the following structures in a typical molecule of tRNA is an amino acid attached?
Amino acids are attached to the CCA tail of a tRNA. These are found at the 3' end of tRNA molecules and are important for recognition by aminoacyl tRNA synthetases (enzymes that actually attach the amino acids to the tRNA). The anticodon loop, as the name suggests, contains the anticodon, which will be important during translation for recognizing mRNA sequences. The D-loop and the variable loop are other portions of the tRNA that are important for maintaining structure and recognition.
Amino acids are attached to the CCA tail of a tRNA. These are found at the 3' end of tRNA molecules and are important for recognition by aminoacyl tRNA synthetases (enzymes that actually attach the amino acids to the tRNA). The anticodon loop, as the name suggests, contains the anticodon, which will be important during translation for recognizing mRNA sequences. The D-loop and the variable loop are other portions of the tRNA that are important for maintaining structure and recognition.
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Chloramphenicol prevents protein translation by which of the following mechanisms?
Chloramphenicol prevents protein translation by which of the following mechanisms?
Tetracycline blocks the binding of aminoacyl tRNA to the A site of the ribosome.
Cyclohexamide blocks the translocation reaction on ribosomes.
Rifamycin blocks the initiation of RNA chains by binding to RNA polymerase.
Chloramphenicol blocks the pepidyl transferase reaction on the ribosome.
Tetracycline blocks the binding of aminoacyl tRNA to the A site of the ribosome.
Cyclohexamide blocks the translocation reaction on ribosomes.
Rifamycin blocks the initiation of RNA chains by binding to RNA polymerase.
Chloramphenicol blocks the pepidyl transferase reaction on the ribosome.
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During translation, which site in the ribosome allows for tRNA moelcules to enter the complex?
During translation, which site in the ribosome allows for tRNA moelcules to enter the complex?
The ribosomal complex has three sites where tRNA moelcules can be oriented during the process of translation: the A site, the P site, and the E site. During polypeptide elongation, a tRNA with an attached amino acid will enter at the A site. It will then move to the P site, now holding the growing polypeptide chain. All tRNAs no longer holding an amino acid will exit the ribosome at the E site.
The ribosomal complex has three sites where tRNA moelcules can be oriented during the process of translation: the A site, the P site, and the E site. During polypeptide elongation, a tRNA with an attached amino acid will enter at the A site. It will then move to the P site, now holding the growing polypeptide chain. All tRNAs no longer holding an amino acid will exit the ribosome at the E site.
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On which of the following molecules could you find an anticodon?
On which of the following molecules could you find an anticodon?
In order to make sure that the proper amino acid is added to the growing polypeptide chain, an anticodon found on the tRNA carrying the amino acid must be a match for the codon found on the mRNA.
In order to make sure that the proper amino acid is added to the growing polypeptide chain, an anticodon found on the tRNA carrying the amino acid must be a match for the codon found on the mRNA.
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Which of the following most accurately describes the chronological order of ribosome biogenesis in eukaryotes?
Which of the following most accurately describes the chronological order of ribosome biogenesis in eukaryotes?
Ribosomal proteins are translated in the cytoplasm and rRNA genes are transcribed in the nucleolus. Following protein translation, these proteins enter the nucleus through nuclear pores and localize to the nucleolus. Here, transcribed rRNA associates with the ribosomal proteins to form the 60S and 40S eukaryotic ribosomal subunits. Prokaryotes have 50S and 30S subunits. The ribosomal subunits then translocate to the cytoplasm where they join together to form fully functional ribosomes.
Ribosomal proteins are translated in the cytoplasm and rRNA genes are transcribed in the nucleolus. Following protein translation, these proteins enter the nucleus through nuclear pores and localize to the nucleolus. Here, transcribed rRNA associates with the ribosomal proteins to form the 60S and 40S eukaryotic ribosomal subunits. Prokaryotes have 50S and 30S subunits. The ribosomal subunits then translocate to the cytoplasm where they join together to form fully functional ribosomes.
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How many ribosomal binding sites are there and what are their functions?
How many ribosomal binding sites are there and what are their functions?
The correct answer is there are three sites. A site binds aminoacyl-tRNA, P site binds peptidyl-tRNA, E site binds free tRNA before ribosomal exit.
The correct answer is there are three sites. A site binds aminoacyl-tRNA, P site binds peptidyl-tRNA, E site binds free tRNA before ribosomal exit.
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Which of the following is not an example of post-translational modification?
Which of the following is not an example of post-translational modification?
Polyadenylation is an example of post-transcriptional modification. This process involves adding large repeats of adenine bases to the 3' end of mRNA molecules, known as the poly-A tail.
Myristoylation is the process of adding myristate (a fatty acid) to a protein, alkylation is the process of adding an alkyl group, and ubiquination is the process of adding a molecule of ubiquitin (a small protein often used to signal degradation).
Polyadenylation is an example of post-transcriptional modification. This process involves adding large repeats of adenine bases to the 3' end of mRNA molecules, known as the poly-A tail.
Myristoylation is the process of adding myristate (a fatty acid) to a protein, alkylation is the process of adding an alkyl group, and ubiquination is the process of adding a molecule of ubiquitin (a small protein often used to signal degradation).
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In which of the following organelles does the initial linkage of a sugar for post-translation modification N-linked glycosylation most commonly occur?
In which of the following organelles does the initial linkage of a sugar for post-translation modification N-linked glycosylation most commonly occur?
Two of the more common types of glycosylation, N-linked and O-linked, occur at different points and in different places in the cell. N-linked glycosylation takes place in the lumen of the endoplasmic reticulum, while O-linked glycosylation takes place in the Golgi body.
The other options, the mitochondria and the nucleus, are not involved in these post-translational modifications.
Two of the more common types of glycosylation, N-linked and O-linked, occur at different points and in different places in the cell. N-linked glycosylation takes place in the lumen of the endoplasmic reticulum, while O-linked glycosylation takes place in the Golgi body.
The other options, the mitochondria and the nucleus, are not involved in these post-translational modifications.
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Please complete the following statement:
"The addition of a CH3CO group to the N-terminus of a protein is the most common form of protein modification. This chemical modification is called                 ."
Please complete the following statement:
"The addition of a CH3CO group to the N-terminus of a protein is the most common form of protein modification. This chemical modification is called                 ."
This question requires knowing either that CH3CO is an acetyl group, or that acetylation is the most common protein modification. Each of the other modifications described are biologically occurring modifications, but acetylation was the correct answer for the given statement.
This question requires knowing either that CH3CO is an acetyl group, or that acetylation is the most common protein modification. Each of the other modifications described are biologically occurring modifications, but acetylation was the correct answer for the given statement.
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Which of the following is not an example of post-translational modification?
Which of the following is not an example of post-translational modification?
Polyadenylation is an example of post-transcriptional modification. This process involves adding large repeats of adenine bases to the 3' end of mRNA molecules, known as the poly-A tail.
Myristoylation is the process of adding myristate (a fatty acid) to a protein, alkylation is the process of adding an alkyl group, and ubiquination is the process of adding a molecule of ubiquitin (a small protein often used to signal degradation).
Polyadenylation is an example of post-transcriptional modification. This process involves adding large repeats of adenine bases to the 3' end of mRNA molecules, known as the poly-A tail.
Myristoylation is the process of adding myristate (a fatty acid) to a protein, alkylation is the process of adding an alkyl group, and ubiquination is the process of adding a molecule of ubiquitin (a small protein often used to signal degradation).
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In which of the following organelles does the initial linkage of a sugar for post-translation modification N-linked glycosylation most commonly occur?
In which of the following organelles does the initial linkage of a sugar for post-translation modification N-linked glycosylation most commonly occur?
Two of the more common types of glycosylation, N-linked and O-linked, occur at different points and in different places in the cell. N-linked glycosylation takes place in the lumen of the endoplasmic reticulum, while O-linked glycosylation takes place in the Golgi body.
The other options, the mitochondria and the nucleus, are not involved in these post-translational modifications.
Two of the more common types of glycosylation, N-linked and O-linked, occur at different points and in different places in the cell. N-linked glycosylation takes place in the lumen of the endoplasmic reticulum, while O-linked glycosylation takes place in the Golgi body.
The other options, the mitochondria and the nucleus, are not involved in these post-translational modifications.
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Please complete the following statement:
"The addition of a CH3CO group to the N-terminus of a protein is the most common form of protein modification. This chemical modification is called                 ."
Please complete the following statement:
"The addition of a CH3CO group to the N-terminus of a protein is the most common form of protein modification. This chemical modification is called                 ."
This question requires knowing either that CH3CO is an acetyl group, or that acetylation is the most common protein modification. Each of the other modifications described are biologically occurring modifications, but acetylation was the correct answer for the given statement.
This question requires knowing either that CH3CO is an acetyl group, or that acetylation is the most common protein modification. Each of the other modifications described are biologically occurring modifications, but acetylation was the correct answer for the given statement.
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Which of the following is not a phase in translation?
Which of the following is not a phase in translation?
There are four phases in translation: activation, initiation, elongation, and termination. Activation is the process that joins the correct amino acid to the correct tRNA. When the tRNA has an amino acid bound to it, it is "charged." Initiation occurs when the small ribosomal subunit binds the 5' end of mRNA, with the help of initiation factors and other proteins. The structure then recruits a methionine tRNA to the start codon to begin the elongation process. Elongation occurs as charged tRNA molecules transfer their amino acids to the growing polypeptide. Termination results when a stop codon is recognized by release factors and the completed protein is released from the ribosome.
Modification of the transcript occurs after translation has been completed.
There are four phases in translation: activation, initiation, elongation, and termination. Activation is the process that joins the correct amino acid to the correct tRNA. When the tRNA has an amino acid bound to it, it is "charged." Initiation occurs when the small ribosomal subunit binds the 5' end of mRNA, with the help of initiation factors and other proteins. The structure then recruits a methionine tRNA to the start codon to begin the elongation process. Elongation occurs as charged tRNA molecules transfer their amino acids to the growing polypeptide. Termination results when a stop codon is recognized by release factors and the completed protein is released from the ribosome.
Modification of the transcript occurs after translation has been completed.
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Which of the following is not a type of modification that can occur after translation?
Which of the following is not a type of modification that can occur after translation?
Post-translational modifications that may occur after a protein is translated include numerous processes to alter the structure or function of the protein. Trimming modification involves removal of the N- or C - terminal propeptides from zymogens to generate mature proteins. Covalent alterations, including phosphorylation, glycosylation and hydroxylation, are frequently used to modify the structure or energy state of a protein. Proteasomal degradation requires the attachment of ubiquitin to defective proteins to tag them for degradation and digestion. Amino acids from degraded proteins can often be recycled to generate new molecules.
5' capping occurs in the nucleus after transcription and is required for transport of RNA out of the nucleus prior to translation.
Post-translational modifications that may occur after a protein is translated include numerous processes to alter the structure or function of the protein. Trimming modification involves removal of the N- or C - terminal propeptides from zymogens to generate mature proteins. Covalent alterations, including phosphorylation, glycosylation and hydroxylation, are frequently used to modify the structure or energy state of a protein. Proteasomal degradation requires the attachment of ubiquitin to defective proteins to tag them for degradation and digestion. Amino acids from degraded proteins can often be recycled to generate new molecules.
5' capping occurs in the nucleus after transcription and is required for transport of RNA out of the nucleus prior to translation.
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