Practice!

Sample Problem

Source: http://upload.wikimedia.org/wikipedia/commons/9/91/Chromosome.gif

Write the correct letter label for the following types of DNA

1.      DNA double-helix

2.      chromatid

3.      chromatin fiber

4.      chromosome

5.      nucleosome

6.      centromere

Solution

The answers are as follows:

1.      E, you hopefully recognized this; otherwise it’s a good idea to review this section!

2.      A, sister chromatids are genetically identical, formed during DNA replication

3.      C, made of the tightly coiled nucleosome chains

4.      F, the sister chromatids together form a chromosome

5.      D, made of DNA wrapped tightly around 8 histones, proteins that help “pack” DNA

6.      B, the specialized region of the chromosome that holds the two sister chromatids together