GCSE · Biology · AQA · Spec 8461
DNA and the genome
Genome, chromosome, DNA, gene: four words people swap around as if they meant the same thing. They don't. They fit inside each other, like boxes inside boxes.
Zoom in
Explore
start big, then zoom in →
Four words, four levels. The genome is all of it. Zoom in and you meet one chromosome, then its DNA, then one small section: a gene. Tap each part, starting with the nucleus.
Tap any part of the picture, or use the buttons below it.
Your turn
DNA, chromosome or gene?
Pick a description, then pick where it belongs.
Still to sort
DNA (0)
The chemical itself
Where the line is: A gene is DNA too, but only a small section of it. If the description is about the whole chemical or its shape, it's DNA.
Chromosome (0)
The structure that holds the DNA
Where the line is: A chromosome is the structure; DNA is the chemical contained in it.
Gene (0)
One small section, one job
Where the line is: A small section of DNA, or anything about coding for a protein, points to a gene rather than the DNA as a whole.
Each description belongs to exactly one of these. Sort them, then read why.
Why one small section matters
Reason it through
How can a change in one small section of DNA end up affecting your health?
First link · your turn
Start with a gene. It's only a small section of DNA, so what does that section actually do?
WHAT YOU'VE LEARNED
A quick recap of today's lesson.
The genome is all of the genetic material. A gene is one small section of DNA, and a change in that section can alter a protein.
What you need to know
- DNA is the chemical that the genetic material in a cell's nucleus is made of. It is a polymer of two strands that form a double helix.
- DNA is contained in chromosomes. A gene is a small section of DNA on a chromosome.
- Each gene codes for a particular sequence of amino acids, which makes a specific protein.
- The genome is an organism's entire genetic material. Understanding the human genome matters for finding genes linked to disease, for inherited disorders, and for tracing past human migration.
The big picture
The genetic material in the nucleus of a cell is made of DNA, a polymer of two strands forming a double helix. DNA is contained in chromosomes, and a gene is a small section of DNA on a chromosome that codes for a particular sequence of amino acids, making a specific protein. An organism's genome is its entire genetic material. The whole human genome has now been studied: understanding it helps the search for genes linked to disease, the understanding and treatment of inherited disorders, and tracing past human migration.
Key points
Worked example
Problem
A student wrote: 'Your genome is one of your genes. Genes are made of chromosomes, and each chromosome is a double helix.' Find the three mistakes and write a corrected version.
⚠ Watch out
Writing that a change in DNA always causes disease. The accurate version keeps two 'cans': a change in the DNA sequence can alter a protein, and an altered protein can lead to disease.
Memory hook
Picture a recipe book. The whole book is the genome; each chapter is a chromosome; the writing is DNA. One recipe, a small section of that writing, is a gene, and it makes one dish: a specific protein. (The analogy ends at the double helix.)
Check yourself
Without looking back, sketch the zoom from memory: nucleus, chromosome, DNA, gene. Write one fact next to each level, then circle the word that means 'all of the genetic material'.
Flashcards
(12)What chemical is the genetic material in a cell's nucleus made of?
Describe the structure of DNA.
What are chromosomes?
What is a gene?
What does each gene code for?
Define 'genome'.
Gene or genome: which one means 'all of it'?
How can a change in the DNA sequence lead to disease?
What has now happened to the whole human genome, and why does it matter?
How does understanding the human genome help with disease?
How does understanding the human genome help with inherited disorders?
Apart from medicine, what can understanding the human genome help to trace?
Tap any card to flip it, or use Study as deck to go through them one at a time. In the full lesson these run as a spaced-repetition deck — you rate each card Hard, Good or Easy and the tricky ones keep coming back until they stick.
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