BIOD 101 Module 4 Problem Set- Questions and Answers

BIOD 101 Module 4 Problem Set- Questions and Answers
Compare and contrast purines and pyrimidines and provide examples of each.
Answer: Purines contain two carbon-nitrogen rings and four nitrogen atoms, while the
pyrimidines contain one carbon-nitrogen ring and twonitrogen atoms. Adenine and guanine
are purines, and thymine and cytosine are pyrimidines (See section 4.1 in module).
Describe the structure and arrangement of DNA.
Answer: DNA is a double helix, which means it is composed of two helicalstrands. The two
strands are held together by the ‘rungs’, which are madeof complementary pairs. The pairs
are held together by weak hydrogen bonds.
Just as the nucleotides are paired in a complementary fashion, the strands are also
arranged in a complementary- type pattern and are said to be antiparallel. In this
antiparallel arrangement, the strands are oriented with one strand being in the 5’→3’
orientation and the other strand inthe 3’→5’ orientation (See section 4.1 in module).
What is a genome?
Answer: The entire sequence of the paired bases is called a genome.