DNA
Science: KS3, topic 1.6.24
The Genome
The genome is the entire (all) genetic material of an organism. Within a genome, there are lots of levels of organisation:
DNA
- DNA is double helix polymer, which means it is a polymer (a large molecule made up of many subunits) made up of two strands forming a twisted, ladder shape.
Genes
- A gene is a small section of DNA. Genes code for a sequence of amino acids, which combine to give a specific protein.
Chromosomes
- Long strands of DNA are coiled up to form chromosomes.
- Chromosomes contain many genes.
- Human body cells contain 23 pairs of chromosomes, one of each pair coming from each parent.
Is a Gene Bigger than DNA?
A gene is a segment of DNA. But there can be fragments of DNA that are smaller than a gene. This question is like asking whether a city or a community is bigger. They are kind of the same depending on how you define them.
Test yourself on DNA
Select the correct statement in each pair.
Why is DNA classed as a polymer?
How many chromosomes does a human body cell contain?
In a pair of chromosomes, where does each one come from?
Which structure is larger: a chromosome or a single gene it contains?