"Write the base sequence and label the 3' and 5' ends of the complementary strand for a segment of DNA with the following base sequences:


d. 5'CGCGATATTA3'"

Key Concepts

DNA Structure

DNA is composed of two strands that form a double helix, with each strand made up of nucleotides. Each nucleotide consists of a phosphate group, a sugar (deoxyribose), and a nitrogenous base (adenine, thymine, cytosine, or guanine). The strands run in opposite directions, referred to as antiparallel, with one strand oriented 5' to 3' and the complementary strand oriented 3' to 5'.

Base Pairing Rules

In DNA, specific base pairing occurs between the nitrogenous bases: adenine pairs with thymine (A-T) and cytosine pairs with guanine (C-G). This complementary base pairing is crucial for the accurate replication and transcription of genetic information. Understanding these rules is essential for determining the sequence of the complementary strand based on the given template strand.

Labeling DNA Ends

The 5' and 3' ends of a DNA strand refer to the carbon numbers in the DNA's sugar backbone. The 5' end has a phosphate group attached to the fifth carbon of the sugar, while the 3' end has a hydroxyl group attached to the third carbon. Properly labeling these ends is important for understanding the directionality of DNA synthesis and the orientation of the complementary strand.