---
title: "Sugar-Phosphate Backbone — AP Bio Definition & Exam Guide"
description: "The sugar-phosphate backbone is the alternating sugar-and-phosphate frame of DNA and RNA that gives strands direction (5' to 3') and holds the bases in place."
canonical: "https://fiveable.me/ap-bio/key-terms/sugar-phosphate-backbone"
type: "key-term"
subject: "AP Biology"
---

# Sugar-Phosphate Backbone — AP Bio Definition & Exam Guide

## Definition

The sugar-phosphate backbone forms the structural framework of nucleic acids, including DNA and RNA. It consists of alternating sugar and phosphate groups, to which nitrogenous bases are attached.

## Related Study Guides

- [1.6 Nucleic Acids](/ap-bio/unit-1/nucleic-acids/study-guide/RKOM4rhL6iJsAMdbDOWU)

## Review

### Related Terms

- Deoxyribose: The sugar component in the backbone of DNA, which is connected to a phosphate group and a nitrogenous base.
- [Phosphate Group](/ap-bio/key-terms/phosphate-group): A molecule in the DNA backbone that links two sugars together.
- Nitrogenous Base: One of the three components of nucleotides, they are attached to the sugar within the backbone and are responsible for base pairing.