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36 Cards in this Set
- Front
- Back
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How is mRNA converted into proteins?
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via tRNA and ribosomes
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What are ribosomes made up of?
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rRNA (mostly) and rProteins
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ribosome?
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site of translation
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polysome/polyribosome?
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mRNA complexed with many ribosomes
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single mRNA can be translated by more than one ___
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ribosome
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direction of protein synthesis?
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N-terminal to C-terminal
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ribosomes move on mRNA in?
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5' to 3'
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transcription and translation occruing simultaneously?
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Yes in prokaryotes.
Not common in Eu b/c txn in nucleus and t-lation in cytoplasm |
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Where on the ribosome does translation take place?
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in grove btw large and small subunits
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rRNA is important for?
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1. structure of ribosome
2. determining site of translation initiation in prok 3. catalytic role in protein synthesis |
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small subunit, large subunit, and whole ribosome?
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30S, 50S, 70S
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How is mRNA converted into protein?
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tRNA and ribosomes
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What are ribosomes made up of?
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rRNA (mostly) and rProteins
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transcription and translation occruing simultaneously?
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Yes in prokaryotes.
Not common in Eu b/c txn in nucleus and t-lation in cytoplasm |
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polysome/polyribosome?
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mRNA complexed with many ribosomes. Thus single mRNA can be translated by more than 1 ribosome.
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Direction of protein synthesis?
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N-terminal to C-terminal
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Where does translation take place on ribosome?
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groove between large and small subunits
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rRNA is important for?
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1. Structure of ribosome
2. Determining site of translation initiation in prok 3. Catalytic role in protein synthesis |
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Small Subunit, Large subunit, whole ribosome?
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30S, 50S, 70S
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Steps in protein synthesis?
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1. AA activation
2. Initiation 3. Elongation 4. Termination |
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AA activation?
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attachment of AA to tRNA
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tRNA-acceptor end?
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3' end of tRNA holding activated AA
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tRNA-anticodon loop?
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Contains triplet of nucleotides (anticodon) that are complementary to the codon on mRNA
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AA activation catalyzed by?
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at least 20 aminoacyl-tRNA synthetases which bind to the AA and cognate tRNAs. It also has proofreading activity: can correct mischarging errors
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goal of initiation?
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position ribosome properly at 5' end of mRNA
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Initiation starts when?
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Initiator tRNA recognizes AUG
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How does recognition of AUG occur?
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interaction between ribosome binding site and 16 S rRNA
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During initiation, there is the formation of a complex between?
And what does it require? |
mRNA, initiator tRNA, large and small ribosomal subunits.
Requires "initation factors" (proteins) and energy (GTP) |
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tRNA binding sites.
P site? A site? E site? |
P-binds initiation tRNA to growing polypeptide (peptidyl-tRNA)
A-binds incoming aminoacyl-tRNA E-briefly binds empty tRNA before it leaves the ribosome |
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Elongation of the polypeptide chain?
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Sequential addition of AA to growing polypeptide
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Three phases of elongation of polypeptide chain?
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1. Aminoacyl-tRNA binding to A site
2. Transpeptidation 3. Translocation |
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Transpeptidation?
Catalyzed by? |
transfer of peptide chain from peptidyl tRNA in P site to aminoacyl tRNA in A site, catalyzed by peptidyl transferase
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Translocation?
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movement of ribosome to new codon.
tRNA in A site enters P site tRNA in P site enters E site A site is empty, ready for next aminoacyl-tRNA |
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Elongation of polypeptide chain involves? and requires?
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Several elongation factors
Energy GTP |
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Termination?
Requires? Catalyzed by? |
occurs at stop codons (UAA, UAG, UGA)
Requires release factors and GTP Involves cleavage of complete polypeptide chain from tRNA Catalyzed by peptidyl transferase |
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Which two processes are catalyzed by peptidyl transferase?
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Translocation (process of "Enlongation of polypeptide chain")
and Termination |
