Chapter 17 - APBIO

Protein Synthesis Overview

Q: What is the "one gene-one polypeptide" hypothesis?
A: The idea that each gene codes for a single polypeptide (protein).Q: What are transcription and translation?
A: Transcription is the synthesis of RNA under the direction of DNA. Translation is the synthesis of a polypeptide under the direction of mRNA.

The Genetic Code

Q: What is a codon?
A: A three-nucleotide sequence in mRNA that codes for a specific amino acid or stop signal.Q: What is the wobble hypothesis?
A: The idea that the third nucleotide in many codons is less important for specifying the correct amino acid, allowing more flexibility in base pairing.

Transcription

Q: What is the function of RNA polymerase?
A: It pries DNA apart and hooks RNA nucleotides together based on the DNA code.Q: What is the transcription initiation complex?
A: The assembly of RNA polymerase and transcription factors at the promoter region of a gene to begin transcription.

Post-Transcriptional Modification

Q: What are the three main modifications made to eukaryotic mRNA?
A: 1) Addition of 5' cap, 2) Addition of 3' poly-A tail, 3) RNA splicing to remove introns.Q: What is alternative RNA splicing?
A: The process by which different combinations of exons from a single gene can be joined to produce multiple mRNA and protein variants.

Translation

Q: What are the three main sites on a ribosome during translation?
A: P site (peptidyl), A site (aminoacyl), and E site (exit).Q: What are the three main stages of translation?
A: Initiation, elongation, and termination.

Mutations

Q: What is a frameshift mutation?
A: A mutation caused by the insertion or deletion of nucleotides that alters the reading frame of the genetic code.Q: What is a silent mutation?
A: A base-pair substitution that does not affect the amino acid sequence of the protein.

RNA Types

Q: Name three types of RNA and their functions.
A: mRNA (carries genetic information), rRNA (part of ribosomes), tRNA (carries amino acids during translation).

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