Skip to main content
Ch.23 - Organic and Biological Chemistry
Chapter 23, Problem 13

If the sequence T-A-C-C-G-A appeared on one strand of DNA, what sequence would appear opposite it on the other strand?

Verified step by step guidance
1
Step 1: Understand that DNA is composed of two strands that form a double helix, where each strand is complementary to the other.
Step 2: Recall the base pairing rules in DNA: Adenine (A) pairs with Thymine (T), and Cytosine (C) pairs with Guanine (G).
Step 3: Start with the first base of the given sequence, which is Thymine (T), and find its complementary base, which is Adenine (A).
Step 4: Move to the next base in the sequence, which is Adenine (A), and find its complementary base, which is Thymine (T).
Step 5: Continue this process for each base in the sequence: C pairs with G, C pairs with G, G pairs with C, and A pairs with T, to determine the full complementary sequence.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Base Pairing in DNA

DNA is composed of two strands that run in opposite directions and are held together by base pairs. The bases adenine (A) and thymine (T) pair together, while cytosine (C) pairs with guanine (G). This complementary base pairing is crucial for the structure of DNA and ensures accurate replication and transcription.
Recommended video:
Guided course
01:30
Conjugate Acid-Base Pairs

Antiparallel Structure of DNA

The two strands of DNA are oriented in opposite directions, known as antiparallel orientation. One strand runs from the 5' to 3' direction, while the opposite strand runs from 3' to 5'. This orientation is essential for the proper functioning of enzymes that replicate and transcribe DNA.
Recommended video:
Guided course
01:42
Resonance Structures

DNA Replication and Complementarity

During DNA replication, each strand serves as a template for creating a complementary strand. The sequence of nucleotides on one strand dictates the sequence on the opposite strand due to the specific pairing rules. Understanding this complementarity is vital for predicting the sequence of the opposite strand based on a given sequence.
Recommended video:
Guided course
01:09
Heisenberg Uncertainty Principle