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Questions and Answers
How many sense codons code for amino acids?
How many sense codons code for amino acids?
Which of the following is a termination codon?
Which of the following is a termination codon?
What role does AUG serve in the process of translation?
What role does AUG serve in the process of translation?
How many non-sense codons are there in the genetic code?
How many non-sense codons are there in the genetic code?
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If there are 64 total codons, what is the maximum number of unique amino acids that can be coded for?
If there are 64 total codons, what is the maximum number of unique amino acids that can be coded for?
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What term describes an amino acid that is attached to its specific tRNA?
What term describes an amino acid that is attached to its specific tRNA?
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What type of bond forms between an amino acid and its specific tRNA during activation?
What type of bond forms between an amino acid and its specific tRNA during activation?
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Which type of enzyme is specifically involved in the synthesis of proteins by catalyzing the attachment of amino acids to their respective tRNA?
Which type of enzyme is specifically involved in the synthesis of proteins by catalyzing the attachment of amino acids to their respective tRNA?
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What is the first step required before an amino acid can participate in protein synthesis?
What is the first step required before an amino acid can participate in protein synthesis?
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What is the main source of energy required for the process of protein synthesis?
What is the main source of energy required for the process of protein synthesis?
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Which of the following statements is true regarding tRNA?
Which of the following statements is true regarding tRNA?
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During the activation of amino acids, what is primarily being synthesized?
During the activation of amino acids, what is primarily being synthesized?
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Which factor is primarily responsible for promoting the elongation phase of protein synthesis?
Which factor is primarily responsible for promoting the elongation phase of protein synthesis?
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What role do releasing factors play in the process of protein synthesis?
What role do releasing factors play in the process of protein synthesis?
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Which of the following is NOT a type of protein factor involved in protein synthesis?
Which of the following is NOT a type of protein factor involved in protein synthesis?
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What causes the termination of polypeptide chain elongation during translation?
What causes the termination of polypeptide chain elongation during translation?
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Which of the following codons are classified as non-sense codons?
Which of the following codons are classified as non-sense codons?
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What happens to the A site of the ribosome when a non-sense codon is presented during translation?
What happens to the A site of the ribosome when a non-sense codon is presented during translation?
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Which statement correctly describes the role of non-sense codons in the translation process?
Which statement correctly describes the role of non-sense codons in the translation process?
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During translation, what occurs immediately after encountering a non-sense codon?
During translation, what occurs immediately after encountering a non-sense codon?
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How many high energy phosphate bonds are cleaved for the formation of one peptide bond?
How many high energy phosphate bonds are cleaved for the formation of one peptide bond?
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Which two types of energy sources are primarily used in the formation of a peptide bond?
Which two types of energy sources are primarily used in the formation of a peptide bond?
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What role does GTP play in the process of peptide bond formation?
What role does GTP play in the process of peptide bond formation?
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How many ATP molecules are directly involved in the activation of amino acids for peptide bond formation?
How many ATP molecules are directly involved in the activation of amino acids for peptide bond formation?
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What is the total number of GTP molecules cleaved during the formation of one peptide bond?
What is the total number of GTP molecules cleaved during the formation of one peptide bond?
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What is the primary function of mRNA in the process of protein synthesis?
What is the primary function of mRNA in the process of protein synthesis?
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Which component is primarily responsible for linking amino acids to their corresponding tRNA?
Which component is primarily responsible for linking amino acids to their corresponding tRNA?
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How are amino acids classified in the context of protein synthesis?
How are amino acids classified in the context of protein synthesis?
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What is the role of tRNA in protein synthesis?
What is the role of tRNA in protein synthesis?
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In the protein synthesis process, what do the amino acids bind to before being incorporated into a protein?
In the protein synthesis process, what do the amino acids bind to before being incorporated into a protein?
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How many high energy phosphate bonds are cleaved in total when forming one peptide bond?
How many high energy phosphate bonds are cleaved in total when forming one peptide bond?
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Which energy source is NOT utilized during the formation of one peptide bond?
Which energy source is NOT utilized during the formation of one peptide bond?
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What is the total number of GTP molecules cleaved specifically for the binding and translocation during peptide bond formation?
What is the total number of GTP molecules cleaved specifically for the binding and translocation during peptide bond formation?
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Which process involves the cleavage of high energy bonds for peptide bond formation?
Which process involves the cleavage of high energy bonds for peptide bond formation?
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For the activation of amino acids in peptide bond formation, which of the following statements is true?
For the activation of amino acids in peptide bond formation, which of the following statements is true?
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What is formed when prokaryotic 50S and 30S ribosomal subunits combine?
What is formed when prokaryotic 50S and 30S ribosomal subunits combine?
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Which statement is true regarding the ribosomal subunits involved in prokaryotic translation?
Which statement is true regarding the ribosomal subunits involved in prokaryotic translation?
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Which component of the ribosome is responsible for catalyzing peptide bond formation?
Which component of the ribosome is responsible for catalyzing peptide bond formation?
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What is the primary movement of the ribosome after the formation of a peptide bond?
What is the primary movement of the ribosome after the formation of a peptide bond?
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What distinguishes the 70S ribosome from the 80S ribosome?
What distinguishes the 70S ribosome from the 80S ribosome?
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Which ribosomal subunit contains the peptidyl transferase enzyme responsible for peptide bond formation?
Which ribosomal subunit contains the peptidyl transferase enzyme responsible for peptide bond formation?
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Which of the following is a characteristic of prokaryotic ribosomes?
Which of the following is a characteristic of prokaryotic ribosomes?
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How do prokaryotic ribosomes facilitate protein synthesis?
How do prokaryotic ribosomes facilitate protein synthesis?
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What process follows peptide bond formation during translation?
What process follows peptide bond formation during translation?
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Which of the following statements about ribosomal movement during translation is accurate?
Which of the following statements about ribosomal movement during translation is accurate?
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What is the primary advantage of forming a polyribosome during translation?
What is the primary advantage of forming a polyribosome during translation?
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How do polysomes affect the efficiency of protein synthesis?
How do polysomes affect the efficiency of protein synthesis?
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What is the structural feature of polysomes?
What is the structural feature of polysomes?
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What is produced as a result of a polyribosome translating a single mRNA?
What is produced as a result of a polyribosome translating a single mRNA?
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Which statement accurately describes the relationship between mRNA and polyribosomes?
Which statement accurately describes the relationship between mRNA and polyribosomes?
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Study Notes
Codons
- There are 64 codons.
- 61 codons code for 20 amino acids.
- 3 codons are non-sense codons or termination codons (UAA, UAG, UGA).
Initiation Codon
- AUG codes for methionine and acts as the initiation codon for translation.
Translation Process
- Translation requires initiation, elongation and termination steps.
- Initiation: Involves initiation factors (IF).
- Elongation: Involves elongation factors (EF).
- Termination: Involves releasing factors (RF).
- Energy Sources: ATP & GTP.
Activation of Amino Acids
- Amino acids must be activated before translation.
- Amino acids bind to specific tRNA molecules via an ester bond.
- This process is called aminoacyl-tRNA synthesis.
Termination
- Elongation continues until the A site is occupied by a non-sense codon (UAA, UAG, UGA).
- This signals the termination of translation.
Energy Needs
- Four high energy phosphate bonds are cleaved for each new peptide bond formed:
- 2 ATP: Used for activation of amino acids.
- 1 GTP: Used for binding aminoacyl-tRNA to the A site.
- 1 GTP: Used for translocation.
Translation Overview
- mRNA carries genetic information from DNA to the ribosome.
- tRNA carries amino acids to the ribosome.
- Amino acids are the building blocks of proteins.
- Aminoacyl-tRNA synthetase connects specific amino acids to their corresponding tRNA molecules.
Ribosome Formation and Function
- Prokaryotic ribosomes are composed of a 30S and a 50S subunit, which assemble to form a 70S ribosome.
- The formation of a peptide bond is catalyzed by peptidyl transferase, an enzyme located within the 60S subunit.
- Following the formation of a peptide bond, the ribosome moves three nucleotides along the mRNA towards the 3' end.
Energy Requirements
- Four high-energy phosphate bonds are cleaved for each new peptide bond formed:
- Two ATP molecules are required for amino acid activation.
- One GTP molecule is used for the binding of aminoacyl-tRNA to the A site.
- One GTP molecule is used for translocation.
Polyribosomes
- Multiple ribosomes can translate a single mRNA molecule simultaneously, forming a polyribosome (or polysome).
- This process allows for the production of many polypeptides from a single mRNA molecule, increasing protein synthesis efficiency.
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