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Questions and Answers
What is the primary function of messenger RNA (mRNA)?
What is the primary function of messenger RNA (mRNA)?
- It regulates gene expression.
- It carries genetic information from DNA to the ribosomes. (correct)
- It transports specific amino acids.
- It incorporates into ribosomes.
Which sugar is found in RNA instead of the sugar found in DNA?
Which sugar is found in RNA instead of the sugar found in DNA?
- Glucose
- Deoxyribose
- Fructose
- Ribose (correct)
Which of the following types of RNA is responsible for regulating the expression of mRNA molecules?
Which of the following types of RNA is responsible for regulating the expression of mRNA molecules?
- Small nucleolar RNA (snoRNA)
- Ribosomal RNA (rRNA)
- MicroRNA (miRNA) (correct)
- Transfer RNA (tRNA)
What is the role of transfer RNA (tRNA) in protein synthesis?
What is the role of transfer RNA (tRNA) in protein synthesis?
What characteristic differentiates mRNA from other types of RNA?
What characteristic differentiates mRNA from other types of RNA?
Which type of RNA is primarily involved in the structure of ribosomes?
Which type of RNA is primarily involved in the structure of ribosomes?
Which type of RNA is synthesized by RNA polymerase but does not code for proteins?
Which type of RNA is synthesized by RNA polymerase but does not code for proteins?
What is a common feature of messenger RNA (mRNA) molecules produced by most cells?
What is a common feature of messenger RNA (mRNA) molecules produced by most cells?
What is the primary function of the 5′ cap in mature mRNA?
What is the primary function of the 5′ cap in mature mRNA?
Which nucleotide is found at the 5′ end of the mRNA cap?
Which nucleotide is found at the 5′ end of the mRNA cap?
What is the role of the 5′ untranslated region (5′ UTR) in mRNA?
What is the role of the 5′ untranslated region (5′ UTR) in mRNA?
What is the main component of the coding region of mRNA?
What is the main component of the coding region of mRNA?
Which of the following statements about the 3′ untranslated region (3′ UTR) is correct?
Which of the following statements about the 3′ untranslated region (3′ UTR) is correct?
Which of the following is true about mRNA capping?
Which of the following is true about mRNA capping?
In what way does the coding region in mRNA relate to the transcription process?
In what way does the coding region in mRNA relate to the transcription process?
What is a characteristic of mitochondrial mRNA compared to eukaryotic mRNA?
What is a characteristic of mitochondrial mRNA compared to eukaryotic mRNA?
What percentage of the ribosome's weight is attributed to rRNA?
What percentage of the ribosome's weight is attributed to rRNA?
Which site on the ribosome functions as a binding site for the growing polypeptide?
Which site on the ribosome functions as a binding site for the growing polypeptide?
In prokaryotic ribosomes, what is the Svedberg coefficient for the small subunit?
In prokaryotic ribosomes, what is the Svedberg coefficient for the small subunit?
Which molecule is synthesized in the nucleoli and plays a key role in ribosome biogenesis?
Which molecule is synthesized in the nucleoli and plays a key role in ribosome biogenesis?
What is the length of the RNA molecule in the small subunit of eukaryotic ribosomes?
What is the length of the RNA molecule in the small subunit of eukaryotic ribosomes?
What structure does the rRNA core help to stabilize in the ribosome?
What structure does the rRNA core help to stabilize in the ribosome?
How many RNA molecules are present in the larger subunit of prokaryotic ribosomes?
How many RNA molecules are present in the larger subunit of prokaryotic ribosomes?
What role does the anticodon play in tRNA function?
What role does the anticodon play in tRNA function?
What are the dimensions of the eukaryotic ribosomal subunits?
What are the dimensions of the eukaryotic ribosomal subunits?
Which end of tRNA contains the anticodon?
Which end of tRNA contains the anticodon?
What is the significance of the D-arm in tRNA?
What is the significance of the D-arm in tRNA?
What forms the cloverleaf structure of tRNA?
What forms the cloverleaf structure of tRNA?
Which component of tRNA is involved in the attachment of the amino acid?
Which component of tRNA is involved in the attachment of the amino acid?
What purpose does the 3′ UTR serve in mRNA regulation?
What purpose does the 3′ UTR serve in mRNA regulation?
Which of the following components is essential for the stability and translation of mRNA?
Which of the following components is essential for the stability and translation of mRNA?
How does the poly(A) tail affect the mRNA's translation process?
How does the poly(A) tail affect the mRNA's translation process?
What role do regulatory proteins and microRNAs (miRNAs) play in gene expression?
What role do regulatory proteins and microRNAs (miRNAs) play in gene expression?
What is the purpose of the AU-rich elements within the 3′ UTR?
What is the purpose of the AU-rich elements within the 3′ UTR?
What happens to the mRNA as the poly(A) tail shortens over time?
What happens to the mRNA as the poly(A) tail shortens over time?
What function does ribosomal RNA (rRNA) serve within the cell?
What function does ribosomal RNA (rRNA) serve within the cell?
Which of the following best describes the impact of the 3′ UTR on gene expression?
Which of the following best describes the impact of the 3′ UTR on gene expression?
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Study Notes
RNA Overview
- Ribonucleic acid (RNA) is a polymer composed of nucleotide subunits linked by phosphodiester bonds.
- RNA is single-stranded, containing ribose sugar instead of deoxyribose and uracil in place of thymine.
- RNA is synthesized from DNA by RNA polymerase and can be classified into different types based on function.
Types of RNA
- Messenger RNA (mRNA): Carries genetic information from DNA to ribosomes for protein synthesis, determining the amino acid sequence.
- Ribosomal RNA (rRNA): Integral part of ribosomes, responsible for catalyzing protein synthesis and forming the ribosomal structure.
- Transfer RNA (tRNA): Transports specific amino acids to ribosomes during translation, facilitating polypeptide chain growth.
- Small Nuclear RNA (snRNA): Involved in RNA processing and splicing.
- MicroRNA (miRNA): Regulates gene expression by interacting with mRNA.
- Small Nucleolar RNA (snoRNA): Involved in rRNA modification and processing.
- Long Non-Coding RNA (lncRNA): Regulates gene expression but does not code for proteins.
- Catalytic RNA (ribozymes): Functions as an enzyme, catalyzing biochemical reactions.
Messenger RNA (mRNA) Structure and Functions
- Synthesized in the nucleus and transported to the cytoplasm for translation.
- Reflects nucleotide sequence variability based on encoded polypeptide sizes.
- Common mRNA molecules encode proteins essential for metabolism (glycolysis).
- Specific mRNAs exist for particular cell types, like hemoglobin in red blood cells.
mRNA Composition
- 5' Cap: Modified guanine nucleotide protects mRNA, aids in translation initiation, and is not present in mitochondrial or chloroplastic mRNA.
- 5' Untranslated Region (5' UTR): Regulatory region upstream from the coding sequence, important for translation control.
- Coding Region: Sequence that encodes proteins, transcribed from the DNA template by RNA polymerase.
- 3' Untranslated Region (3' UTR): Follows the termination codon and plays a role in regulation, stability, and cellular localization of mRNA.
- Poly(A) Tail: A sequence of adenine nucleotides that enhances mRNA stability and translation efficiency; involved in nuclear export and degradation rates.
Ribosomal RNA (rRNA) Structure and Functions
- rRNA is part of ribosomes, making up about 60% of their mass and facilitating protein synthesis.
- Three-dimensional rRNA structure comprises loops and helices, creating binding sites (A, P, E) for tRNA.
- rRNA functions include binding mRNA, recruitment of tRNA, and catalyzing peptide bond formation.
- Prokaryotic and eukaryotic ribosomes consist of large and small subunits, with distinct sedimentation coefficients.
tRNA Structure and Function
- tRNA has an anticodon that pairs with mRNA and a 3’ hydroxyl group that links to specific amino acids.
- Features a sugar-phosphate backbone providing directionality and structural stability.
- The anticodon loop is crucial for recognizing and binding to the correct amino acid during translation.
- D-arm and T-arm regions support stability and interactions with ribosomes, forming a cloverleaf and L-shaped tertiary structures.
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