, Blesse dnur sedocs
PART I — GENES AND CHROMOSOMES
Chapter 1 — Genes Are DNA and Encode RNAs and Polypeptides
Chapter 2 — Methods in Molecular Biology and Genetic Engineering
Chapter 3 — The Interrupted Gene
Chapter 4 — The Content of the Genome
Chapter 5 — Genome Sequences and Evolution
Chapter 6 — Clusters and Repeats
Chapter 7 — Chromosomes
Chapter 8 — Chromatin
PART II — DNA REPLICATION AND RECOMBINATION
Chapter 9 — Replication Is Connected to the Cell Cycle
Chapter 10 — The Replicon: Initiation of Replication
Chapter 11 — DNA Replication
Chapter 12 — Extrachromosomal Replicons
Chapter 13 — Homologous and Site-Specific Recombination
Chapter 14 — Repair Systems
Chapter 15 — Transposable Elements and Retroviruses
Chapter 16 — Somatic DNA Recombination and Hypermutation in the Immune System
PART III — TRANSCRIPTION AND POSTTRANSCRIPTIONAL MECHANISMS
Chapter 17 — Prokaryotic Transcription
Chapter 18 — Eukaryotic Transcription
Chapter 19 — RNA Splicing and Processing
Chapter 20 — mRNA Stability and Localization
Chapter 21 — Catalytic RNA
Chapter 22 — Translation
Chapter 23 — Using the Genetic Code
PART IV — GENE REGULATION
Chapter 24 — The Operon
Chapter 25 — Phage Strategies
Chapter 26 — Eukaryotic Transcription Regulation
Chapter 27 — Epigenetics I
Chapter 28 — Epigenetics II
, Blesse dnur sedocs
Chapter 29 — Noncoding RNA
Chapter 30 — Regulatory RNA
PART I: GENES AND CHROMOSOMES
CHAPTER 1: GENES ARE DNA AND ENCODE RNAs AND POLYPEPTIDES
MULTIPLE CHOICE QUESTIONS
1. The Hershey-Chase experiment (1952) provided definitive evidence that the
genetic material of bacteriophage T2 is:
A) Protein
B) RNA
C) DNA
D) Lipid
Answer: C
Rationale: Hershey and Chase used radioactive isotopes (35S to label protein
and 32P to label DNA) to demonstrate that when phage T2 infects bacteria,
DNA—not protein—is injected into the host cell and is responsible for
directing the production of new phage particles, establishing DNA as the
genetic material of the phage.
-------------------------------------------------------------------------------
2. In the Avery, MacLeod, and McCarty experiment (1944), the "transforming
principle" that converted nonvirulent Streptococcus pneumoniae into virulent
forms was identified as:
, Blesse dnur sedocs
A) Protein
B) RNA
C) Polysaccharide capsule
D) DNA
Answer: D
Rationale: Avery and colleagues demonstrated that the transforming principle
isolated from virulent (smooth) pneumococcal cells was DNA, as treatment with
DNase abolished transforming activity while RNase and protease did not. This
was the first direct biochemical evidence identifying DNA as genetic material.
-------------------------------------------------------------------------------
3. Griffith's transformation experiment (1928) used two strains of
Streptococcus pneumoniae. Which of the following observations demonstrated
that a "transforming principle" existed?
A) Live R strain killed the mice
B) Heat-killed S strain killed the mice
C) Heat-killed S strain mixed with live R strain killed the mice and live S
strain bacteria were recovered
D) Live S strain did not kill the mice
Answer: C
Rationale: When heat-killed (avirulent) S strain was mixed with live R strain,
the mice died and live S strain bacteria were recovered from the dead mice.