AQA · GCSE · Combined Science
Course version: 8464 · Version from Sept 2018
The genetic material in the nucleus of a cell is composed of a chemical…
Full specification wording
DNA and the genome: The genetic material in the nucleus of a cell is composed of a chemical called DNA. DNA is a polymer made up of two strands forming a double helix. The DNA is contained in structures called chromosomes.
DNA is the chemical that carries genetic material in the nucleus of a cell.
Checked against the AQA 8464 specification (opens in a new tab) on .
- Point 2 of 8
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
DNA is the chemical that carries genetic material in the nucleus of a cell. It is a polymer, meaning a large molecule built from many repeating smaller units joined together. In DNA, two strands wind around each other to form a double helix, a shape like a twisted ladder. The DNA is packaged into structures called chromosomes, so a chromosome is a coiled molecule of DNA. A useful scale picture is a human body cell: its nucleus contains 46 chromosomes, and each chromosome contains one very long DNA molecule. When a cell divides, the chromosomes must be copied and shared accurately so that each new cell receives the full set of genetic material.
What earns the marks
- DNA is the chemical of which the genetic material in the nucleus is composed.
- DNA is a polymer, built from many repeating units joined into a long molecule.
- DNA consists of two strands that wind around each other to form a double helix.
- DNA is contained in chromosomes, which are the structures visible in the nucleus.
- A chromosome is a coiled or packaged molecule of DNA, so chromosomes carry the DNA.
- The nucleus of a cell contains the DNA, and in human body cells there are 46 chromosomes.
Common mistakes and how to put them right
Saying DNA is made of chromosomes.
Put it right by stating that chromosomes are structures that contain DNA, not the other way round.
Describing DNA as a single strand.
Put it right by stating that DNA has two strands forming a double helix.
Confusing the double helix with a double circle or a flat ladder.
Put it right by describing two strands twisted around each other.
Exam tips
- Use the key terms polymer, two strands, double helix and chromosomes in your answer, because these are the ideas being checked.
- If asked to describe the structure of DNA, work from the general to the specific: chemical, polymer, two strands, double helix, then chromosomes.
- When a question shows a diagram of a nucleus, label the chromosomes and state that they contain DNA rather than writing only 'DNA'.
Try the lesson
The start of the DNA and the genome: The genetic material in the nucleus of a cell is composed of a chemical called DNA. DNA is a polymer made up of two strands forming a double helix. The DNA is contained in structures called chromosomes. lesson, made from checked teaching notes for this specification point.
Have a go first
What is the name of the chemical that makes up the genetic material in the nucleus of a cell?
Listen
DNA is the chemical that carries genetic material in the nucleus of a cell. It is a polymer, meaning a large molecule built from many repeating smaller units joined together. In DNA, two strands wind around each other to form a double helix, a shape like a twisted ladder. The DNA is packaged into structures called chromosomes, so a chromosome is a coiled molecule of DNA. A useful scale picture is a human body cell: its nucleus contains 46 chromosomes, and each chromosome contains one very long DNA molecule. When a cell divides, the chromosomes must be copied and shared accurately so that each new cell receives the full set of genetic material. A strong answer earns marks for these points. DNA is the chemical of which the genetic material in the nucleus is composed. DNA is a polymer, built from many repeating units joined into a long molecule. DNA consists of two strands that wind around each other to form a double helix. DNA is contained in chromosomes, which are the structures visible in the nucleus. A common slip: Saying DNA is made of chromosomes. Instead, stating that chromosomes are structures that contain DNA, not the other way round. Exam tip: Use the key terms polymer, two strands, double helix and chromosomes in your answer, because these are the ideas being checked.
See it
Key words
Say what each word means before you turn the card.
DNA
Try answering aloud or in your head before turning the card.
Polymer
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Double helix
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Chromosomes
Try answering aloud or in your head before turning the card.
See every definition
- DNA
- The chemical of which the genetic material in the nucleus of a cell is composed.
- Polymer
- A large molecule built from many repeating smaller units joined together.
- Double helix
- The shape formed by two strands winding around each other, like a twisted ladder.
- Chromosomes
- Structures in the nucleus that contain the DNA, each being a coiled molecule of DNA.
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
3Box 3
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