Guiding Questions
The Connection between Genes and Proteins
- Explain why dwarf peas have shorter stems than tall varieties.
- Explain the reasoning that led Archibald Garrod to first suggest that genes dictate phenotypes through enzymes.
- Describe Beadle and Tatum’s experiments with Neurospora and explain the contribution they made to our understanding of how genes control metabolism.
- Distinguish between the “one geneÐone enzyme” hypothesis and the “one geneÐone polypeptide” hypothesis and explain why the original hypothesis was changed.
- Explain how RNA differs from DNA.
- Briefly explain how information flows from gene to protein.
- Distinguish between transcription and translation.
- Compare where transcription and translation occur in prokaryotes and in eukaryotes.
- Define codon and explain the relationship between the linear sequence of codons on mRNA and the linear sequence of amino acids in a polypeptide.
- Explain the early techniques used to identify what amino acids are specified by the triplets UUU, AAA, GGG, and CCC.
- Explain why polypeptides begin with methionine when they are synthesized.
- Explain what it means to say that the genetic code is redundant and unambiguous.
- Explain the significance of the reading frame during translation.
- Explain the evolutionary significance of a nearly universal genetic code.
The Synthesis and Processing of RNA
- Explain how RNA polymerase recognizes where transcription should begin. Describe the promoter, the terminator, and the transcription unit.
- Explain the general process of transcription, including the three major steps of initiation, elongation, and termination.
- Explain how RNA is modified after transcription in eukaryotic cells.
- Define and explain the role of ribozyme.
- Describe the functional and evolutionary significance of introns.
The Synthesis of Protein
- Describe the structure and functions of tRNA.
- Explain the significance of wobble.
- Explain how tRNA is joined to the appropriate amino acid.
- Describe the structure and functions of ribosomes.
- Describe the process of translation (including initiation, elongation, and termination) and explain which enzymes, protein factors, and energy sources are needed for each stage.
- Describe the significance of polyribosomes.
- Explain what determines the primary structure of a protein and describe how a polypeptide must be modified before it becomes fully functional.
- Describe what determines whether a ribosome will be free in the cytosol or attached to the rough endoplasmic reticulum.
- Describe two properties of RNA that allow it to perform so many different functions.
- Compare protein synthesis in prokaryotes and in eukaryotes.
- Define point mutations. Distinguish between base-pair substitutions and base-pair insertions. Give examples of each and note the significance of such changes.
- Describe several examples of mutagens and explain how they cause mutations.
- Describe the historical evolution of the concept of a gene.
