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USMLE
New FA Biochem 3
Question | Answer |
---|---|
Names of the steps in protein synthesis | 1. Initiation 2. Elongation 3. Termination |
Sequence of events in the initiation step of protein synthesis. | 1. Initiation factors assemble the 40S ribosomal subunit with the initiator tRNA 2. mRNA and (60S?) ribosomal subunit combine with the 40S subunit. 3. Initiation factors are released. |
Sequence of events in the elongation step of protein synthesis. | 1. Aminoacyl tRNA binds to the A site 2. Peptidyltransferase catalyzes peptide bond formation 3. Peptidyltransferase transfers growing polypeptide to aa in A site 4. Ribosome advances 3 nucleotides toward 3' end of RNA moving peptidyl RNA to P site |
Sequence of events in the termination step of protein synthesis. | 1. Completed protein is released from ribosome. 2. Ribosome dissociates. |
Role of ATP in protein synthesis | ATP does tRNA Activation (charging) |
Role of GTP in protein synthesis | GTP does tRNA Going places (aka translocation) and Gripping |
Role of A site in protein synthesis | A site holds incoming Aminoacyl tRNA. |
Role of P site in protein synthesis | P site accomodates growing Peptide. |
Role of E site in protein synthesis | E site holds Empty tRNA as it Exits |
Which post-translational modification involves removal of N or C terminal pro-peptides from zymogens to generate mature proteins? | Trimming |
What happens in post-translational trimming? | removal of N or C terminal pro-peptides from zymogens to generate mature proteins |
Which post-translational modification involves phosphorylation? | post-translational covalent alteration |
What happens during post-translational covalent alterations? | Either: 1. Phosphorylation 2. Glycosylation 3. Hydroxylation |
Which post-translational modification involves glycosylation? | post-translational covalent alteration |
Which post-translational modification involves hydroxylation? | post-translational covalent alteration |
What happens during proteasomal degradation? | Attachment of ubiquitin to defective proteins to tag them for breakdown. |
Ubiquitin or Ubiquinone: Proteosomal degradation | Ubiquitin |
Ubiquitin or Ubiquinone: Coenzyme Q in oxidative phosphorylation | Ubiquinone |
Where in the cell does the following occur: Fatty acid oxidation (beta-oxidation) | Mitochondria |
Where in the cell does the following occur: acetyl-CoA production | Mitochondria |
Where in the cell does the following occur: Krebs cycle | Mitochondria |
Where in the cell does the following occur: Glycolysis | Cytoplasm |
Where in the cell does the following occur: Fatty acid synthesis | Cytoplasm |
Where in the cell does the following occur: Hexose Monophosphate Shunt | Cytoplasm |
Where in the cell does the following occur: Protein Synthesis | Rough endoplasmic reticulum in the cytoplasm |
Where in the cell does the following occur: Steroid synthesis | Smooth endoplasmic reticulum in the cytoplasm |
Where in the cell does the following occur: Gluconeogenesis | Pathway has steps in the mitochondria and in the cytoplasm |
Where in the cell does the following occur: Urea cycle | Pathway has steps in the mitochondria and in the cytoplasm |
Where in the cell does the following occur: Heme synthesis | Pathway has steps in the mitochondria and in the cytoplasm |