GCSE Biology DNA Revision Notes
Master GCSE Biology DNA using simple revision notes, key facts and practice questions — all generated by AI for your exam.
DNA, or deoxyribonucleic acid, is the molecule that carries the genetic instructions for life. It is found in the cells of all living organisms and is responsible for heredity and the functioning of cells.
Key Concepts
- 1DNA is made up of two strands forming a double helix structure.
- 2The basic unit of DNA is called a nucleotide, which consists of a sugar, a phosphate group, and a nitrogenous base.
- 3There are four types of nitrogenous bases in DNA: adenine (A), thymine (T), cytosine (C), and guanine (G).
- 4A pairs with T, and C pairs with G, which is known as complementary base pairing.
- 5DNA replication is the process by which DNA makes a copy of itself before cell division.
Simple Explanation
DNA is like a recipe book for living things, containing all the instructions needed to build and operate an organism. It is made of two twisted strands, like a ladder, with rungs made of four different building blocks called bases. These bases pair up in specific ways to ensure the instructions are copied accurately when cells divide.
Memory Trick
“Remember 'A T the C G' to recall that Adenine pairs with Thymine and Cytosine pairs with Guanine.”
Flashcards
What does DNA stand for?
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Exam Questions
Describe and explain the structure of DNA. [6 marks]
6 marksView mark scheme hint▾
Mention the double helix, nucleotides, and base pairing.
Explain how DNA replication occurs. [4 marks]
4 marksView mark scheme hint▾
Include the role of enzymes and complementary base pairing.
What is meant by complementary base pairing? [2 marks]
2 marksView mark scheme hint▾
Define how specific bases pair with each other.
Practice Quiz
What is the primary function of DNA?
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