Chapter 12: The Genetic Code and Transcription

Flashcards covering key concepts from Chapter 12 on The Genetic Code and Transcription.

What is the function of mRNA in protein synthesis?

mRNA serves as an intermediate in transferring genetic information from DNA to proteins.

What does the triplet code consist of, and how many unique codons does it create?

The triplet code consists of three nucleotides specifying one amino acid, creating 64 possible codons.

What are the characteristics of the genetic code?

The genetic code is nonoverlapping, comma-less, degenerate, unambiguous, and nearly universal.

What is the significance of start and stop codons?

Start codons initiate translation, while stop codons terminate translation.

What does the wobble hypothesis explain?

The wobble hypothesis predicts that base pairing rules at the third position of the codon and anticodon can vary, allowing for some flexibility.

What is the role of RNA polymerase in transcription?

RNA polymerase synthesizes RNA molecules on a DNA template and does not require a primer for initiation.

What is a promoter in relation to transcription?

A promoter is a region of a gene where RNA polymerase binds to initiate transcription.

What are cis-acting and trans-acting elements in gene regulation?

Cis-acting elements regulate genes on the same chromosome, while trans-acting elements regulate genes on homologous chromosomes.

How is transcription terminated in prokaryotes?

Transcription in prokaryotes is terminated by either intrinsic or rho-dependent mechanisms.

What modifications occur to pre-mRNA in eukaryotes before it becomes mature mRNA?

The primary transcript undergoes 5’ capping, poly-A tail addition, and splicing to remove introns.

How does the spliceosome function in RNA processing?

The spliceosome is a complex that facilitates the removal of introns and joining of exons in pre-mRNA.

What distinguishes a nonsense mutation?

A nonsense mutation changes a codon that specifies an amino acid into a stop codon, leading to premature termination.