Molecular Biology of the Gene

These flashcards cover key concepts from Chapter 12: Molecular Biology of the Gene, including genetic material, transcription, and translation.

What is the transforming substance in Griffith's experiment?

DNA is the transforming substance.

What did Avery et al. discover regarding genetic material?

DNA is the substance that carries genetic information.

What are Chargaff's rules regarding nucleotide composition in DNA?

In each species, the amounts of adenine (A) and thymine (T) are equal, and the amounts of guanine (G) and cytosine (C) are equal.

Who is credited with discovering the double helix structure of DNA?

James Watson and Francis Crick, with help from Rosalind Franklin.

What model describes DNA replication?

The semiconservative model.

What is the role of RNA polymerase during transcription?

RNA polymerase synthesizes RNA by reading the DNA template strand.

What is a codon?

A codon is a sequence of three RNA nucleotides that specifies an amino acid.

What are the three stages of translation?

Initiation, elongation, and termination.

What modifications occur to pre-mRNA before it exits the nucleus?

Addition of a 5' cap and a 3' poly-A tail, and splicing of introns.

What is the function of transfer RNA (tRNA)?

tRNA carries amino acids to the ribosome for protein synthesis.

How do ribosomes facilitate protein synthesis?

Ribosomes provide binding sites for mRNA and tRNAs and catalyze peptide bond formation.

What are introns and exons?

Introns are non-coding segments of RNA, while exons are coding segments that are expressed.

What is the wobble hypothesis?

The wobble hypothesis explains how tRNAs can recognize multiple codons due to flexibility in base pairing at the third position.

What happens during termination of translation?

The ribosome encounters a stop codon, and a release factor causes the polypeptide chain to be released.

What is the significance of the genetic code being universal?

It allows genes to be transferred between organisms, suggesting a common evolutionary heritage.

What occurs in the initiation phase of translation?

The small ribosomal subunit binds to mRNA and the initiator tRNA binds to the start codon AUG.