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Questions and Answers
What is the primary function of the 5' cap added to pre-mRNA?
What is the primary function of the 5' cap added to pre-mRNA?
Which of the following accurately describes introns?
Which of the following accurately describes introns?
How many adenine bases typically comprise the 3' poly(A) tail added to mRNA?
How many adenine bases typically comprise the 3' poly(A) tail added to mRNA?
What is the role of RNA splicing in the maturation of pre-mRNA?
What is the role of RNA splicing in the maturation of pre-mRNA?
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Which characteristic is essential for the detection of a complete mRNA message?
Which characteristic is essential for the detection of a complete mRNA message?
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What role do ribosomes play in protein synthesis?
What role do ribosomes play in protein synthesis?
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What must a polypeptide chain do after translation to become a functional protein?
What must a polypeptide chain do after translation to become a functional protein?
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Which structure forms first during the folding of a polypeptide chain?
Which structure forms first during the folding of a polypeptide chain?
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What effect can post-translational modifications have on a protein?
What effect can post-translational modifications have on a protein?
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How can mutations in DNA affect protein production?
How can mutations in DNA affect protein production?
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What direction does RNA polymerase read the template strand during mRNA synthesis?
What direction does RNA polymerase read the template strand during mRNA synthesis?
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What can result from a nonsense mutation?
What can result from a nonsense mutation?
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What is the tertiary structure of a protein?
What is the tertiary structure of a protein?
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What type of bond does RNA polymerase catalyze to build the pre-mRNA molecule?
What type of bond does RNA polymerase catalyze to build the pre-mRNA molecule?
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What can be a consequence of protein misfolding?
What can be a consequence of protein misfolding?
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How does RNA polymerase handle incorrect nucleotides during pre-mRNA synthesis?
How does RNA polymerase handle incorrect nucleotides during pre-mRNA synthesis?
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What happens when RNA polymerase reaches a specific termination sequence?
What happens when RNA polymerase reaches a specific termination sequence?
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Which of the following bases is found in RNA but not in DNA?
Which of the following bases is found in RNA but not in DNA?
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What is the nucleotide incorporation rate of RNA polymerase during mRNA synthesis?
What is the nucleotide incorporation rate of RNA polymerase during mRNA synthesis?
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Which of these statements about the synthesized pre-mRNA is correct?
Which of these statements about the synthesized pre-mRNA is correct?
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What is the maximum number of base pairs exposed to RNA polymerase at one time during transcription?
What is the maximum number of base pairs exposed to RNA polymerase at one time during transcription?
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What is the role of the spliceosome in the maturation of mRNA?
What is the role of the spliceosome in the maturation of mRNA?
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Where does translation occur in eukaryotic cells?
Where does translation occur in eukaryotic cells?
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Which molecule is primarily responsible for delivering amino acids to the ribosome during translation?
Which molecule is primarily responsible for delivering amino acids to the ribosome during translation?
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How does a ribosome read the mRNA template during translation?
How does a ribosome read the mRNA template during translation?
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What initiates the translation process at the ribosome?
What initiates the translation process at the ribosome?
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What structural component forms the ribosome?
What structural component forms the ribosome?
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What is the function of codons in the mRNA sequence?
What is the function of codons in the mRNA sequence?
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Which of the following correctly describes the nature of tRNA?
Which of the following correctly describes the nature of tRNA?
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What is the final structure that a polypeptide adopts after folding?
What is the final structure that a polypeptide adopts after folding?
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Which of the following is NOT a type of post-translational modification?
Which of the following is NOT a type of post-translational modification?
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What is the role of proteases in protein processing?
What is the role of proteases in protein processing?
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How do post-translational modifications impact proteins?
How do post-translational modifications impact proteins?
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Which of the following statements about cleavage as a post-translational modification is true?
Which of the following statements about cleavage as a post-translational modification is true?
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What is the potential impact of the addition of complex molecules as a post-translational modification?
What is the potential impact of the addition of complex molecules as a post-translational modification?
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Why are there so many types of post-translational modifications?
Why are there so many types of post-translational modifications?
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What may result from the cleavage of a polypeptide chain?
What may result from the cleavage of a polypeptide chain?
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Which of the following processes is NOT commonly associated with post-translational modifications?
Which of the following processes is NOT commonly associated with post-translational modifications?
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What is the role of glycosylation in post-translational modifications?
What is the role of glycosylation in post-translational modifications?
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Which amino acids are most commonly involved in the formation of disulfide bonds?
Which amino acids are most commonly involved in the formation of disulfide bonds?
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Which type of enzyme is responsible for adding a polysaccharide molecule during glycosylation?
Which type of enzyme is responsible for adding a polysaccharide molecule during glycosylation?
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What happens during the phosphorylation process in proteins?
What happens during the phosphorylation process in proteins?
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Acetylation as a post-translational modification primarily affects which functional group?
Acetylation as a post-translational modification primarily affects which functional group?
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Which post-translational modification can directly influence the interaction of proteins with other molecules?
Which post-translational modification can directly influence the interaction of proteins with other molecules?
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Where in the cell does the modification of glycosylation primarily occur?
Where in the cell does the modification of glycosylation primarily occur?
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Study Notes
Protein Biosynthesis
- Protein biosynthesis, also known as protein synthesis, is a crucial cellular process. It maintains cellular protein levels by producing new proteins and balancing loss from degradation or export.
- This process is broadly divided into two key phases: transcription and translation.
Transcription
- During transcription, a segment of DNA, called a gene, is copied into a template molecule called messenger RNA (mRNA).
- This process occurs within the nucleus of a cell.
- RNA polymerase enzymes carry out this conversion.
- A single strand of pre-mRNA is produced, complementary to the DNA template strand.
Post-transcriptional modifications
- Pre-mRNA undergoes alterations to become mature mRNA before export into cytoplasm.
- 5' cap addition: The 5' end of pre-mRNA is modified with a guanine nucleotide cap to prevent degradation and aid ribosome binding.
- 3' poly(A) tail addition: A string of adenine nucleotides is added to the 3' end to stabilize mRNA and enable its export from the nucleus.
- RNA splicing: Introns (non-coding regions) are removed from the pre-mRNA molecule, and exons (coding regions) are joined together by spliceosomes, creating a mature mRNA molecule.
Translation
- In the cytoplasm, the ribosomes read the mature mRNA sequence.
- Ribosomes use transfer RNA (tRNA) molecules to bring the correct amino acids to the ribosome that corresponds with the mRNA codons.
- Covalent peptide bonds are formed between the amino acids, creating a polypeptide chain.
- This process continues until a stop codon is reached.
- Polypeptides then fold into their three-dimensional (3D) structures.
Protein Folding
- Polypeptide chains fold to form functional proteins.
- Secondary, tertiary, and quaternary structures determine function.
- Protein folding is crucial for function.
Post-translational modifications
- After translation, proteins may undergo further modification to become fully functional proteins.
- These modifications may involve cleavage, addition of chemical groups like methylation, acetylation, or phosphorylation.
- Glycosylation is another common modification, adding polysaccharide chains.
Errors in Proteins
- Mutations in DNA can cause changes in amino acid sequences which can alter protein function or folding.
- Mutations can lead to misfolding, which can cause diseases such as Alzheimer's and Parkinson's.
- Errors in protein biosynthesis and folding have a role in various diseases.
Termination
- RNA polymerase stops transcribing mRNA at defined termination points in DNA.
- This ends protein synthesis after a stop codon (e.g. UAA, UAG,or UGA)
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Description
Explore the essential stages of protein biosynthesis, including transcription and translation. This quiz delves into the mechanisms of how genes are expressed and the modifications that pre-mRNA undergoes to become mature mRNA. Test your knowledge on the key processes that sustain cellular functions.
