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Questions and Answers
Which structure does the small subunit of a prokaryotic ribosome contain?
What is the function of the peptidyl transferase activity?
Which of the following statements about tRNA structure is correct?
Which site of the ribosome is primarily involved in the exit of tRNA?
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What is located at the CCA end of a tRNA molecule?
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Which of the following correctly describes the tertiary structure of tRNA?
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Study Notes
Ribosome Structure
- Ribosomes consist of two subunits: a small subunit and a large subunit
- The small subunit binds to mRNA
- The large subunit has peptidyl transferase activity
- Peptidyl transferase is an enzyme that catalyzes the formation of peptide bonds between amino acids
- The large subunit also contains three distinct tRNA binding areas: the E, P, and A sites
- The E site is the exit site, where tRNA molecules leave the ribosome after they have delivered their amino acids
- The P site is the peptidyl site, where the tRNA molecule carrying the growing polypeptide chain is located
- The A site is the aminoacyl site, where the tRNA molecule carrying the next amino acid to be added to the polypeptide chain binds
- Ribosome subunits are measured in Svedberg units (S) which reflects sedimentation and relates to size and shape
- Prokaryotic ribosomes have a 30S small subunit and a 50S large subunit, totaling 70S
- Eukaryotic ribosomes have a 40S small subunit and a 60S large subunit totaling 80S
tRNA Structure
- tRNA is a small RNA molecule that is responsible for carrying amino acids to the ribosome
- tRNA has a cloverleaf shape, formed by short complementary sequences
- tRNA structure is organized into three levels:
- Primary structure that is the linear sequence of the molecule
- Secondary structure that is the cloverleaf shape formed by base pairing
- Tertiary structure that is the 3-dimensional L shape formed by folding
- tRNA structure includes the following elements:
- Amino acid attachment site (CCA end)
- Acceptor stem
- Pseudouridine
- DHU loop
- Extra arm
- Anticodon
- The anticodon on tRNA binds to the mRNA codon
- The cloverleaf structure includes four double-stranded regions (arms or stems)
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Description
Test your knowledge on the structure and function of ribosomes. This quiz covers key concepts such as subunit composition, binding sites, and the role of peptidyl transferase in protein synthesis. Challenge yourself and see how well you understand these essential cellular components.
