Ch 10 Homework

What contribution did James Watson and Francis Crick make to our understanding of DNA?

They pieced together the available evidence and modeled the structure of DNA.

Who conducted experiments showing that RNA can serve as the genetic material in some viruses

Fraenkel-Conrat and Singer

Who took x-ray diffraction pictures used in constructing the structure of DNA

Franklin and Wilkins

Which relations will be found in the percentages of bases of a double‑stranded DNA molecule?

1) A+C=G+T 2) A/T=G/C 3) (A+G)/(C+T)=1.0

Identify the key structural features of a double-stranded DNA molecule.

1) DNA bases are paired purine with pyrimidine. 2) DNA strands are antiparallel and include a 5' end and a 3′ end. 3) The backbone of DNA is made of a pentose sugar and a phosphate molecule

There are two types of nucleic acids, DNA and RNA. Nearly all organisms use DNA, not RNA, as the central repository for genetic information.

1) DNA has a double‑stranded structure that ensures an accurate mechanism of duplication. 2) DNA is more resistant against enzymes that degrade nucleic acids

Select each of the characteristics that are key features of genetic material.

1) It must be able to replicate and transmit to progeny 2) It must be able to store and express information 3) It must be variable through infrequent mutation

Which of the statements describes purines and pyrimidines in double-stranded DNA molecules?

1) Pyrimidines form hydrogen bonds with purines. 2) Pyrimidines consist of a one-ring structure.

What evidence supports the hypothesis that RNA was the genetic material early in evolutionary history?

1) RNA can self‑replicate. 2) Some viruses have RNA genomes.

Who determined that DNA is responsible for transformation in bacteria

Avery, MacLeod, and McCarthy

Who discovered regularity in the ratios of different bases in DNA

Chargaff

What is the reason scientists think DNA was selected over RNA as the most common genetic material?

DNA is more stable than RNA.

Who demonstrated that heat-killed material from bacteria could genetically transform live bacteria

Griffith

Who identified DNA as the genetic material in bacteriophage

Hershey and Chase

Who determined that DNA contains nitrogenous bases

Kossel

Who discovered that DNA consists of repeating nucleotides

Levene

Who determined that DNA is acidic and high in phosphorous

Miescher

DNA has unique properties that allow it to accurately retain genetic information, even after multiple rounds of replication. One aspect of DNA that allows it to accurately store genetic information is the base pairing from Chargaff's first rule of the four nucleotide bases. If the A content of a DNA molecule is 16%, what are the percentages of the remaining bases?

T= 16% C= 34% G= 34% 16+16=32 100-32= 68 68/2= 34

What results are expected in this experiment if protein carried the genetic information of TMV instead of RNA?

The new viral progeny would be identical with the strain from which the protein had been isolated and would not exhibit the characteristics of the strain that donated the RNA.

Are the central dogma and the theory of inheritance of acquired characteristics consistent?

They are not consistent because inheritance of acquired characteristics demands a reverse flow of information, which violates the central dogma.

Who worked out the helical structure of DNA by building models

Watson and Crick

What is the key feature of DNA that allows it to be copied?

complementary base pairing