# A chromosome is described as a long, coiled molecule of DNA that carries genetic information in the form of genes. Explain how the structure of DNA allows genetic information to be copied accurately during DNA replication.

> WJEC A-Level Biology (Wales) — 1.5 Nucleic acids and DNA replication · Explain · 5 marks

> Before a cell can divide by mitosis, the genetic material in the nucleus must be replicated so that each daughter cell receives an identical copy of the DNA. DNA replication relies on the specific structure of the DNA molecule.

## Mark scheme (5 marks)

1. DNA is a polymer made of two strands twisted into a double helix
2. The two strands are held together by base pairs / complementary base pairing
3. The two strands separate / unzip during replication
4. Each original strand acts as a template for a new complementary strand
5. Two identical DNA molecules are produced, each containing one original strand and one new strand

## Key terms

- [DNA](https://www.gradenine.co.uk/glossary/dna)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-chromosome-is-described-as-a-a9df72bd) · Published by Druglandscape Ltd.