DNA TIMELINE CHECK UP QUIZ

What substance did Miescher isolate from pus-soaked bandages in his experiments?

• Chromatin

• Nuclein

• Protein

• RNA

Which feature of DNA was not discovered by Friedrich Miescher?

• Its acidic nature

• Its presence in the nucleus

• Its chemical content

• Its role in heredity

Which of the following is a correct sequence of contributions leading to the understanding of DNA’s role in heredity?

• Griffith → Miescher → Hershey & Chase

• Miescher → Griffith → Avery et al.

• Avery et al. → Miescher → Watson & Crick

• Miescher → Hershey & Chase → Griffith

What was the primary goal of the experiments conducted by Avery, MacLeod, and McCarty in 1944?

• To prove that proteins are the genetic material

• To determine the chemical composition of bacterial capsules

• To identify the molecule responsible for bacterial transformation

• To map the genes of Streptococcus pneumoniae

Why was Chargaff’s discovery important for Watson and Crick’s model of DNA?

• It showed how DNA could be synthesized chemically

• It provided evidence for the double-helix and base pairing

• It explained protein folding

• It proved that DNA contains sulfur

Why was sulfur-35 used in the Hershey-Chase experiment?

• To label DNA specifically

• Because sulfur is found in proteins but not in DNA

• To make the DNA radioactive

• Because sulfur binds to nucleotides

Which of the following correctly describes a feature of the DNA model proposed by Watson and Crick?

• Sugar-phosphate backbones face inward and nitrogenous bases face outward.

• Adenine pairs with cytosine via two hydrogen bonds.

• The two DNA strands are parallel and identical.

• The two strands are antiparallel and held together by base pairing.

Which earlier findings most directly influenced Watson and Crick’s model of DNA?

• Avery’s demonstration of bacterial transformation

• Chargaff’s rules of base pairing

• Mendel’s law of segregation

• Hershey and Chase’s viral replication study

Which of the following correctly describes a consequence of Chargaff’s first rule?

• DNA has a triple helix structure

• Adenine always pairs with guanine

• The total purines equal the total pyrimidines in DNA

• The proportion of nucleotides is identical in all species

What key experimental method did Avery and his team use to identify the transforming principle?

• Centrifugation and gel electrophoresis

• Genetic crosses in Drosophila melanogaster

• Use of radioactive tracers to label DNA and protein

• Selective enzymatic digestion of macromolecules