Genetics Ch. 10 Homework, STRICKLAND

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.

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

(A+G)/(C+T)=1.0 A/T=G/C A+C=G+T

Enter the complementary sequence to the DNA strand shown. 5′- GCATTCAAG -3′

3' - CGTAAGTTC -5'

Identify the key structural features of a DNA molecule..

DNA bases are always paired purine with pyrimidine. DNA strands are antiparallel and include a 5′5′ end and a 3′3′ end. The backbone of DNA is made of a 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. Choose the statements that explain this phenomenon.

DNA is more resistant against enzymes that break down nucleic acids. DNA has a double‑stranded structure that ensures an accurate mechanism of duplication.

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

DNA is more stable than RNA.

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 C content of a DNA molecule is 16%, what are the percentages of the remaining bases?

G= 16 T= 34 A= 34

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

It must encode the blueprint to form proteins and other structures. It must periodically mutate to generate variation. It must be able to replicate and transmit to progeny.

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

Purines consist of a two-ring structure. Purines form hydrogen bonds with pyrimidines.

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

Some viruses have RNA genomes. RNA can catalyze enzymatic reactions.

Identify the pieces of evidence describing the features of DNA that Watson and Crick used to determine the structure of DNA.

The diameter of the DNA double helix is 2 nanometers, with each purine-pyrimidine base pair spanning an equivalent distance between the two chains. The nitrogenous bases on each DNA helix are arranged perpendicularly to the central axis. The sugar-phosphate backbones of each DNA helix run antiparallel to one another. A purine base forms hydrogen bonds to pair with a pyrimidine base located on the opposite DNA strand. Specifically, A pairs with T, and C pairs with G.

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.

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

complementary base pairing