AQA · GCSE · Biology
Course version: 8461 · Version from Sept 2018
The genome of an organism is the entire genetic material of that organism.
Full specification wording
DNA and the genome: The genome of an organism is the entire genetic material of that organism.
The genome is the complete set of genetic material in an organism, not just the genes.
Checked against the AQA 8461 specification (opens in a new tab) on .
- Point 6 of 9
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
The genome is the complete set of genetic material in an organism, not just the genes. It includes all the DNA in the chromosomes, plus the DNA in mitochondria and, in plant cells, in chloroplasts. In humans the genome is the whole of the nuclear DNA together with mitochondrial DNA. The word 'entire' matters: a single gene, or even all the protein-coding genes, is only part of the genome. Studying a genome means reading the full base sequence. This matters because non-coding DNA regulates genes, and comparing genomes between species or individuals reveals evolutionary relationships and variation. A useful check is to ask whether the description covers every piece of DNA in the organism, not merely the genes.
What earns the marks
- Define the genome as the entire genetic material of an organism, including all its DNA.
- Distinguish the genome from a single gene or from the protein-coding genes alone.
- Recognise that the genome includes DNA in chromosomes and, where present, in mitochondria and chloroplasts.
- Explain that the genome can be studied by determining the full base sequence of the DNA.
- Use the concept to compare organisms, for example noting that genome size and content differ between species.
Common mistakes and how to put them right
Equating the genome with all the genes only.
Put it right by stating that the genome is all the genetic material, including non-coding DNA.
Thinking the genome is found only in the nucleus.
Put it right by including mitochondrial DNA and, in plant cells, chloroplast DNA.
Confusing genome with genotype.
Put it right by defining genotype as the alleles an organism has for particular genes, while the genome is all its genetic material.
Exam tips
- Underline the word 'entire' in the question to remind yourself to include all DNA, not just genes.
- When comparing organisms, refer to the genome as the full genetic material rather than to individual genes.
- Use precise wording: 'the entire genetic material of that organism' is safer than 'all the chromosomes'.
Try the lesson
The start of the DNA and the genome: The genome of an organism is the entire genetic material of that organism. lesson, made from checked teaching notes for this specification point.
Have a go first
What is the genome of an organism?
Listen
The genome is the complete set of genetic material in an organism, not just the genes. It includes all the DNA in the chromosomes, plus the DNA in mitochondria and, in plant cells, in chloroplasts. In humans the genome is the whole of the nuclear DNA together with mitochondrial DNA. The word 'entire' matters: a single gene, or even all the protein-coding genes, is only part of the genome. Studying a genome means reading the full base sequence. This matters because non-coding DNA regulates genes, and comparing genomes between species or individuals reveals evolutionary relationships and variation. A useful check is to ask whether the description covers every piece of DNA in the organism, not merely the genes. A strong answer earns marks for these points. Define the genome as the entire genetic material of an organism, including all its DNA. Distinguish the genome from a single gene or from the protein-coding genes alone. Recognise that the genome includes DNA in chromosomes and, where present, in mitochondria and chloroplasts. Explain that the genome can be studied by determining the full base sequence of the DNA. A common slip: Equating the genome with all the genes only. Instead, stating that the genome is all the genetic material, including non-coding DNA. Exam tip: Underline the word 'entire' in the question to remind yourself to include all DNA, not just genes.
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Key words
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The genome as the complete genetic material
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DNA outside the nucleus
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Genome sequencing as a way to read genetic information
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Genetic variation and comparison between organisms
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See every definition
- The genome as the complete genetic material
- The entire genetic material of an organism, including all its DNA, not just the genes.
- DNA outside the nucleus
- The genome includes DNA in mitochondria and, in plant cells, in chloroplasts, as well as the DNA in the chromosomes.
- Genome sequencing as a way to read genetic information
- Studying a genome means reading the full base sequence of the DNA.
- Genetic variation and comparison between organisms
- Comparing genomes between species or individuals reveals evolutionary relationships and variation.
Label the diagram
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1Box 1
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