AQA · GCSE · Combined Science
Course version: 8464 · Version from Sept 2018
Students should be able to describe the structure of DNA and define genome.
Full specification wording
DNA and the genome: Students should be able to describe the structure of DNA and define genome.
DNA is a polymer made up of two strands that coil around each other to form a structure known as a double helix.
Checked against the AQA 8464 specification (opens in a new tab) on .
- Point 1 of 8
- 3 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
DNA is a polymer made up of two strands that coil around each other to form a structure known as a double helix. The DNA is contained in structures called chromosomes, which are found in the nucleus of a cell. The genome is the entire genetic material of an organism. In humans, the genome includes all the DNA found in the chromosomes within the nucleus, as well as the DNA in mitochondria. A clear exam answer will state that DNA is a polymer forming a double helix and precisely define the genome as the entire genetic material of an organism, avoiding confusion with a single gene.
What earns the marks
- State that DNA is a polymer.
- Describe DNA as consisting of two strands.
- Explain that the two strands coil together to form a double helix.
- State that DNA is contained in structures called chromosomes.
- Define the genome as the entire genetic material of an organism.
Common mistakes and how to put them right
Describing DNA as a single straight strand.
Put it right: DNA consists of two strands twisted into a double helix.
Defining genome as a single gene or a single chromosome.
Put it right: The genome is the entire genetic material of an organism, including all its genes.
Confusing a gene with a genome.
Put it right: A gene is a small section of DNA on a chromosome that codes for a specific sequence of amino acids, whereas the genome is the entire genetic material.
Exam tips
- When describing DNA structure, always mention that it is a polymer and forms a double helix.
- For the genome definition, use the exact phrase 'entire genetic material of an organism' to ensure you get the mark.
Try the lesson
The start of the DNA and the genome: Students should be able to describe the structure of DNA and define genome. lesson, made from checked teaching notes for this specification point.
Have a go first
What is the definition of a genome?
Listen
DNA is a polymer made up of two strands that coil around each other to form a structure known as a double helix. The DNA is contained in structures called chromosomes, which are found in the nucleus of a cell. The genome is the entire genetic material of an organism. In humans, the genome includes all the DNA found in the chromosomes within the nucleus, as well as the DNA in mitochondria. A clear exam answer will state that DNA is a polymer forming a double helix and precisely define the genome as the entire genetic material of an organism, avoiding confusion with a single gene. A strong answer earns marks for these points. State that DNA is a polymer. Describe DNA as consisting of two strands. Explain that the two strands coil together to form a double helix. State that DNA is contained in structures called chromosomes. A common slip: describing DNA as a single straight strand. Instead, DNA consists of two strands twisted into a double helix. Exam tip: When describing DNA structure, always mention that it is a polymer and forms a double helix.
Key words
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DNA structure
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Double helix model
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The genome as all genetic material
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See every definition
- DNA structure
- A polymer made up of two strands that coil around each other to form a structure known as a double helix.
- Double helix model
- The structure formed when two strands coil around each other.
- The genome as all genetic material
- The entire genetic material of an organism, including all its genes.
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